When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Charlie did some flow testing to check the numbers again. They went 241 stock and 251/171 with just a bowl blend! Now we know why Chad uses these for Super Stockers. As far as iron heads go, I really like these Darts. 251 for just blending the bowls is pretty awesome and there is plenty more to do. Right now they are CC'ing at 172cc out of the box. You gotta understand, this whole time I have been stressing about not using the small port Vortec Bowties, as that was the only other head I wanted to run... Turns out I am way better off with these Dart Iron Eagles. Right ports, right bolt pattern, good chamber, good flow, nice manufacturing and the exhaust port wont give me any fits with headers.
About the only gripe so far is the 67cc combustion chamber size, which will probably get a little bigger as they get some work but we'll see.
Your opinion and Charlie's results give me hope my own heads will do the job. Very similar in design to the Darts. Small port (advertised as 170cc), 2.02/1.60, 64 cc (now at 65.4) and like yours, a little valve job blending and they flow very much like your Darts. And the valve job is truly pedestrian (sort of bummed on that).
Your heads really pique my interest. Even more than before.
Should you decide to ditch the TPI and go for a dual plane and carb, you could see 460+ at the crank (as seen on an engine dyno) by 6000.
But I know the TPI is here to stay. I wish I could offer more insight into that area that was in discussion but you certainly have the right guy trying to sort it out.
Somewhat on topic, Hall's 355 and the dyno headers used was mentioned. Off the top, do you recall the specs?
Your opinion and Charlie's results give me hope my own heads will do the job. Very similar in design to the Darts. Small port (advertised as 170cc), 2.02/1.60, 64 cc (now at 65.4) and like yours, a little valve job blending and they flow very much like your Darts. And the valve job is truly pedestrian (sort of bummed on that).
Your heads really pique my interest. Even more than before.
Should you decide to ditch the TPI and go for a dual plane and carb, you could see 460+ at the crank (as seen on an engine dyno) by 6000.
But I know the TPI is here to stay. I wish I could offer more insight into that area that was in discussion but you certainly have the right guy trying to sort it out.
Somewhat on topic, Hall's 355 and the dyno headers used was mentioned. Off the top, do you recall the specs?
The TPI is definitely here to stay. Its funny, because if this was 2010 or earlier, I may have a different point of view on that. Back then these cars with a modified 350 could run with a lot of the newer stuff and even beat it. Today, I just dont see the point in trying unless you are building the car to drive a certain way. Like a 6500-7000rpm screamer with a TKO or something for tearing up the back roads, or maybe a 434 SBC with a killer auto for street/strip action.... As for me... Its simple. I really want the car to drive near stock with power on tap. I like the wifes twin turbo SUV to be honest. Its tame and unassuming for cruising but its got so much power you can get around in it ...however you like. Thats pretty much what Im going for here. Just a really nice car that cruises well and has tons of power. No rattles, nice stereo, updated AC... Like a nice and tight Touring deal that you enjoy driving. Dialed in. I think the TPI is more than capable of delivering that. Im even looking at the gear ratio planetary change too. I think thatll help.
I have no idea what size headers TPIS uses. I would assume the 1 3/4 for that engine. I don't know if hes got the primary lengths tuned for TPI or not.
He's on the FB Tuned Performance page if you want to ask him. He usually answers any questions. I like Jim to be honest. We have a messenger chat going on right now where Im trying to out do his vortec motor... lol I think he's at least amused. LOL
Update for Arizona Speed and Marine... The runner flanges are done and they are being sent to get the finish done. Shouldnt be too much longer. Jim is a good guy over there and you can tell he really cares about what he makes. He is definitely one of the last men standing for these cars. Everyone else just about has sold out or dropped us completely. I understand they are pricey but they are the best runners ever made for these cars. They outflow all others. No question. Im totally curious to see these babies on a bench. I cant even believe this will be the first real test these have ever had on TGO. How is that possible???
Update for Arizona Speed and Marine... The runner flanges are done and they are being sent to get the finish done. Shouldnt be too much longer. Jim is a good guy over there and you can tell he really cares about what he makes. He is definitely one of the last men standing for these cars. Everyone else just about has sold out or dropped us completely. I understand they are pricey but they are the best runners ever made for these cars. They outflow all others. No question. Im totally curious to see these babies on a bench. I cant even believe this will be the first real test these have ever had on TGO. How is that possible???
Those runners and the edelbrock base were flowed on the ST thread all assembled with a similar head you are using the poster claimed it flows of 185cfm, over on the vette forums the TPI intake was also heavily tested https://www.corvetteforum.com/forums...low-bench.html
Most people weren't tested/flowing these back in the day because they where on a budget, the cars they were installing them were also budget, it wasn't ordinary to even being modding them to this extent let alone paying someone like Charlie to do all this extensive extra work
With all due respect to all TGO members, I think the majority are owners and not necessarily builders / testers. There are many notable exceptions (and I don't need to name them) but it's an enthusiasts forum rather than a racers forum. Speed-Talk has hefty quantity of the latter. Specialists at that.
Further to that, and regarding my own direction here at TGO, I've built about a half dozen engines (all various iterations of the same sized SBC), more than few transmissions, gone through a couple or three converters, rear gear ratios, tires, et al. But testing has come about by way of results from the dragstrip and highway. Hard data, like a dyno sheet, with the exception of one chassis run, aren't part of my thread repertoire in as much as I'd like them to be. I had my latest cylinder heads on the flow bench but that was more to correlate the simulation data with the real world.
This is why I'm appreciative when a thread like this comes along. It does tend to bring out the people that are more "racer" to the core than say the owner looking for this part or that. Some are a combination of the two, some are bent more one way than the other. I am however grateful to all that contribute and / or ask questions. It's what keeps our hobby and these cars alive.
All the more power to you Rob. It's been fun to tag along here. Interesting too to note that there's some crossover between TGO and ST. It's neat to see the same characters going back and forth.
Im a day late. Long day yesterday and I crashed out. I didnt even get to see it until this morning. Bowl blended with a rough bur to expand the boundary layer and shrink the port some. Just to get an idea of what is doing what where. 251cfm@.600 lets me know they are carrying. Heads that fall off rapidly IMO have a chance of laying over when running engine depression gets higher. To say I am happy with these is an understatement. I think for an iron head these are the best thing going right now. RHS used to have a KILLER iron head back when they were made by the Kiwis... but just like all good things, they went to China and now pretty much suck. I hear Dart has been recently bought out by Racing Brands so I dont know what the future holds for Dart either. You can look at Racing Brands and form your own opinions but I hope RB just shuts up and lets Dart do what has made them successful. This iron head certainly doesnt hurt their reputation.
Those runners and the edelbrock base were flowed on the ST thread all assembled with a similar head you are using the poster claimed it flows of 185cfm, over on the vette forums the TPI intake was also heavily tested https://www.corvetteforum.com/forums...low-bench.html
Most people weren't tested/flowing these back in the day because they where on a budget, the cars they were installing them were also budget, it wasn't ordinary to even being modding them to this extent let alone paying someone like Charlie to do all this extensive extra work
BHR, the runners on the ST thread were the SLP's, not the ASM's...and then he tested some stock ones and then modified them to see what he could improve on. But you bring up a good point. Back then nobody in the third gen world was looking at pitot tube stuff, just the gasket size, runner size and cfm. I dont think TPI has ever been looked at in this much detail but for me thats part of the fun. If I could afford to make a clear TPI system and run it on a dyno just for information I would. The knowledge gained is why I like to do stuff like this. Its also why I like Charlies channel. He doesnt care to hide the info, he likes to put it out there.
Talking to him yesterday he still likes the idea of a taper. 2.08csa tapered some down to the head. How much taper? Not much. Its a good plan to start with and see where we end up. We can always take more metal out but you cant put it back in.
I prepaid for the ASM runners yesterday btw.
With all due respect to all TGO members, I think the majority are owners and not necessarily builders / testers. There are many notable exceptions (and I don't need to name them) but it's an enthusiasts forum rather than a racers forum. Speed-Talk has hefty quantity of the latter. Specialists at that.
Further to that, and regarding my own direction here at TGO, I've built about a half dozen engines (all various iterations of the same sized SBC), more than few transmissions, gone through a couple or three converters, rear gear ratios, tires, et al. But testing has come about by way of results from the dragstrip and highway. Hard data, like a dyno sheet, with the exception of one chassis run, aren't part of my thread repertoire in as much as I'd like them to be. I had my latest cylinder heads on the flow bench but that was more to correlate the simulation data with the real world.
This is why I'm appreciative when a thread like this comes along. It does tend to bring out the people that are more "racer" to the core than say the owner looking for this part or that. Some are a combination of the two, some are bent more one way than the other. I am however grateful to all that contribute and / or ask questions. It's what keeps our hobby and these cars alive.
All the more power to you Rob. It's been fun to tag along here. Interesting too to note that there's some crossover between TGO and ST. It's neat to see the same characters going back and forth.
Lord knows Ive asked a **** ton of questions. Some off track.. Some essential. Were all learning everyday.
Man, I know this sounds like a total stoner moment, but if someone created a clear TPI intake and drilled holes into the ports at different lengths and ran different colored smoke into those tubes to see what the air is doing at different cycles/speeds and lifts... that would be most interesting to watch. The closest thing I have to that is this...
Seeing as the ASM runners are on the way and earlier in the thread there was a TPIS base, is that the plan along with the Dart heads?
As for the cam...
Originally Posted by MrIROBZ
Camshaft wise is to be determined and is something I would like to talk about.
I will probably have Mike Jones cut a custom cam for this so I am leaving as little on table as possible.
That would be an interesting result to see. His cam recommendation form asks for port flow (.300", .400", .500" and max flow at "X") but doesn't differentiate on the induction style when choosing the "street performance" form. It does however ask for the intake manifold information if the "drag race" form is selected. Then again, that's what the phone is for. Once he had generated my spec (two actually) I called him up and we talked at length. Very insightful conversation I can tell you that.
The difference in the specs was primarily in the LSA as well as the lobe intensity.
He doesn't include seat to seat timing unless you ask specifically. If you examine his lobe profiles, you'll find that the finished product will be a tweaked version of one of those lobes.
His EHR72360 lobe is listed as: 280°, 234°
The EHR73360 lobe is: 284°, 238°.
So there's a couple of degrees at .050" shaved off of each.
BHR, the runners on the ST thread were the SLP's, not the ASM's...and then he tested some stock ones and then modified them to see what he could improve on. But you bring up a good point. Back then nobody in the third gen world was looking at pitot tube stuff, just the gasket size, runner size and cfm. I dont think TPI has ever been looked at in this much detail but for me thats part of the fun. If I could afford to make a clear TPI system and run it on a dyno just for information I would. The knowledge gained is why I like to do stuff like this. Its also why I like Charlies channel. He doesnt care to hide the info, he likes to put it out there.
Talking to him yesterday he still likes the idea of a taper. 2.08csa tapered some down to the head. How much taper? Not much. Its a good plan to start with and see where we end up. We can always take more metal out but you cant put it back in.
I prepaid for the ASM runners yesterday btw.
the ASM where flowed in the ST and the vette forum i linked
the ST thread flow was poted by Kenny M, he post a pic showing the ASM runners on the bench, ASM and TPS are the same runner
"Yep I'm playing with the same junk. A 89 305 stroked to 334 LB9. Only I'm using the Trickflow 175 heads. With a Edelbrock lower, TPS Runners I'm at a Big 187CFM."
From the vette thread linked lots of good info and TPI testing
A clear/cut out tpi was also tested in that vette thread linked
Seeing as the ASM runners are on the way and earlier in the thread there was a TPIS base, is that the plan along with the Dart heads?
As for the cam...
That would be an interesting result to see. His cam recommendation form asks for port flow (.300", .400", .500" and max flow at "X") but doesn't differentiate on the induction style when choosing the "street performance" form. It does however ask for the intake manifold information if the "drag race" form is selected. Then again, that's what the phone is for. Once he had generated my spec (two actually) I called him up and we talked at length. Very insightful conversation I can tell you that.
The difference in the specs was primarily in the LSA as well as the lobe intensity.
He doesn't include seat to seat timing unless you ask specifically. If you examine his lobe profiles, you'll find that the finished product will be a tweaked version of one of those lobes.
His EHR72360 lobe is listed as: 280°, 234°
The EHR73360 lobe is: 284°, 238°.
So there's a couple of degrees at .050" shaved off of each.
The plan:
Port the plenum runner entrances to the ASM ID runner size
Radius around the runner entrances of plenum (Have an extra plenum to play with to see if change of radius degree effects CFM)
Do some interior flow corrections to the throttle body entrance and maybe the bolt bosses inside the plenum.
Port match the TPIS base to ASM runner exits
Reverse radius or blend the entrances of the base to help the air transition to new shape more efficiently
Do light finishing and correct sizing of runner ports inside TPIS base for desired taper and CSA while improving flow and velocity.
Port match Dart heads to match TPIS base runner taper
Open pushrod pinch to corresponding size and and shape to help the air on the roof for intake to cylinder head alignment angle
Work the bowls
Work the short side radius
Do some slight chamber work
Hopefully we can do more than 219cfm the ported stock parts got. I would like to see 240cfm all bolted together personally.
I called Mike about my cam yesterday, he didnt answer.
I have a bigger problem right now Im trying to work out. The static compression ratio. The heads are 67cc and after Charlie is done theyll be a little bigger. I could mill them and the intake and then get different pushrods but then the flow changes some. It moves the valve closer to the wall when you do that. So....
I called VortecPro today and we had a chat about what I need to do to correct my compression and I got a price on that. I can do what everyone wants me to do... which is go 383... Not like anyone could tell its not the stock stroke anyway.... which is more money... of course.
Or, just hone the block because its low mileage and install new bearings, pistons, rods and bolts.
Do I want to add more money to a project thats already getting expensive? (FYI the pricing isnt bad, as everything is getting ported but its definitely more expensive than just a set of AFR's). The thing I like about a 383... I know itll make 440hp or more. Its a no brainer right? Well... Not when you refuse to buy Chinese stuff. Not Chinese stuff is more expensive. A lot more expensive.
Disclaimer: I will not buy cheap chinese stoker parts for a cheap bump in power. I am not supporting that country. Period!
My feelings... Just hone the block, put in a good Mahle piston with a thinner ring pack for another 8-10hp, use good ARP rod bolts and maybe a set of GM powdered metal rods with new bearings since im there and let it roll.
Unless someone can tell me where to get a NOT CHINESIUM SBC stoker kit for a good price.
the ASM where flowed in the ST and the vette forum i linked
the ST thread flow was poted by Kenny M, he post a pic showing the ASM runners on the bench, ASM and TPS are the same runner
"Yep I'm playing with the same junk. A 89 305 stroked to 334 LB9. Only I'm using the Trickflow 175 heads. With a Edelbrock lower, TPS Runners I'm at a Big 187CFM."
From the vette thread linked lots of good info and TPI testing
A clear/cut out tpi was also tested in that vette thread linked
Ok. I thought you were talking about the stuff Charlie had. The Vette stuff is interesting, what a nice homemade bench that is! A buddy of mine would love to read that.
What Im having problems with is the all stock system, all assembled flows 185cfm. So all those aftermarket parts only flowed 2cfm more? Somethings not right.
FWIW, my latest shortblock started as a 355 with a Mahle 5/64ths ring pack hypereutectic piston (5cc) at .014" down, 65.4 cc heads, .026" gasket for 10.2:1
For the latest rebuild I went another .010" over and found reasonably priced USA built Wiseco forged pistons with a 1/16th ring pack and 5cc valve relief. The compression height on the Wiseco piston was about .005-.006" taller than the Mahle which pushed the CR up. But the main deal was the piston to head clearance. It was getting awfully tight at .034" or thereabouts with my .026" go to gasket of choice. The resulting 10.4:1 CR I think I could have handled but the quench was something I wasn't comfortable with. I settled on a .032" Mahle head gasket and called it a day a 10.25:1 and .040" quench.
I too am a made in the USA purchaser. The pistons were a score. I have to admit though when the Elgin rods in the 355 were deemed to be junk I was forced into some Eagle SIR forgings. Yeah. I know . Chinese sourced on some level. I went out of my way sourcing a US cam and lifters. That's where Jones came in. Also competitively priced. Rockers are also Crower US made.
When I was shopping for a 383 stroker kit, I was prepared to bite the bullet for US built parts. But budget is relative. At what percent difference in cost do you draw the line? I never came to determination as I decided on budget 355 refresh. But that quickly spiralled and I was soon at a point of no return. Hence, a 357 was born.
FWIW, my latest shortblock started as a 355 with a Mahle 5/64ths ring pack hypereutectic piston (5cc) at .014" down, 65.4 cc heads, .026" gasket for 10.2:1
For the latest rebuild I went another .010" over and found reasonably priced USA built Wiseco forged pistons with a 1/16th ring pack and 5cc valve relief. The compression height on the Wiseco piston was about .005-.006" taller than the Mahle which pushed the CR up. But the main deal was the piston to head clearance. It was getting awfully tight at .034" or thereabouts with my .026" go to gasket of choice. The resulting 10.4:1 CR I think I could have handled but the quench was something I wasn't comfortable with. I settled on a .032" Mahle head gasket and called it a day a 10.25:1 and .040" quench.
I too am a made in the USA purchaser. The pistons were a score. I have to admit though when the Elgin rods in the 355 were deemed to be junk I was forced into some Eagle SIR forgings. Yeah. I know . Chinese sourced on some level. I went out of my way sourcing a US cam and lifters. That's where Jones came in. Also competitively priced. Rockers are also Crower US made.
When I was shopping for a 383 stroker kit, I was prepared to bite the bullet for US built parts. But budget is relative. At what percent difference in cost do you draw the line? I never came to determination as I decided on budget 355 refresh. But that quickly spiralled and I was soon at a point of no return. Hence, a 357 was born.
Glad to know other guys are putting their foot down on Chinese stuff. People reading this may think i'm virtue signaling of some sort but i'm not. The problem I am seeing is we are in big trouble not having the manufacturing capabilities to protect ourselves if need be. Any other war America gets into with a big economy will be a war of attrition. Attrition of supplies and attrition of men. During WW2 we had to convert automotive companies to make war equipment, foundries that casted engine blocks made tank engines, plane engines and heavy artillery 240mm shells and other big guns. The list on what manufacturing does for our freedoms can go on and on. I will even partially admit I bought an iron head made here because we need to, and itll do the job. I have some pretty bad *** WW2 war bonds in my garage. One of them says "How Johnny Gets His Zeros" and its got 2 American fighters swooping down on a Jap going down in flames! Its one of the coolest Shell ads i've ever seen. My Grandfather was a paratrooper captain in the 82nd and was air dropped in Africa, Sicily, France and Germany. The greatest man i've ever known, period. I also served during the Iraq war as an 11B with the 25th ID after being trained at Ft. Benning with the 2/19th. So I have a big military thing going on in my family. Gotta buy the American stuff. No exceptions. If you are forced, I understand but at least try to find another way. If you have to make sacrifices or changes, then do it and know you did it for the right reasons. Otherwise... Anyway...
Talking to Mark (VortecPro), he wants the pistons .003" above deck and use a 038" gasket for .035" quench on a 6000rpm deal. Being this isnt a racecar, and primarily susceptible to pump gas issues like bad gas, Im going to stick at 9.5:1. I know I could go more with these chambers and probably be fine but it's the crappy gas you dont see coming that gets you. Ive had to drop several tanks in my day and clean out bad gas at a gas stations expense. When it happens usually 3 or 4 cars will show up with the same symptoms. Point is, it does happen and I don't want to chance ruining an engine over 10 or so hp average.
I see you used Mahle pistons which is exactly what I would use. I think theyre made in Tennessee if I am not mistaken. I honestly don't know until I get there but theres quite a few options. Im thinking gas ported, 5cc with a 1.550" ch., and thin ring pack on some GM rods would do the trick. The stock crank should survive.
Yes, I have a real 1992 Firehawk. Car #005. Purchased the car in Germany 5 years ago. It was in rough shape (relative to most other 92 Hawks). Runs but not well yet. Want to learn from your experience here with the tuner. I'm not going to put an aftermarket control computer in the car.
Freshened up
I love that header design. Makes the most average torque of anything you can put on these milder engines. Had a pair years ago on a crossfire car, huge torque gains everywhere. They would probably choke a big cube, high rpm setup but for a 305, 350 or 383 with some form of LTR, FIRST, T-Ram or Super Ram manifold they kick butt. The tri-y design promotes scavenging in the low-midrange and still work admirably well on a sub ~6,500 rpm small block.
I love that header design. Makes the most average torque of anything you can put on these milder engines. Had a pair years ago on a crossfire car, huge torque gains everywhere. They would probably choke a big cube, high rpm setup but for a 305, 350 or 383 with some form of LTR, FIRST, T-Ram or Super Ram manifold they kick butt. The tri-y design promotes scavenging in the low-midrange and still work admirably well on a sub ~6,500 rpm small block.
No doubt! Wish they were still being made.
Man, I dont get it... Third gens and aftermarket parts were cheap when I left and so were the cars. Now its the complete opposite. What gets me is, if the cars arent cheap anymore and with restoration parts being made, youd think the aftermarket would come back to life knowing money is being spent on them... Makes no sense.
I love that header design. Makes the most average torque of anything you can put on these milder engines.
I would agree if that was qualified with most average torque of any "short" header. I suppose too that "mild" needs some definition.
But I understand packaging is sometimes king. Or convenience.
____________________________________________________
This on the other hand, would be excellent. But fitment on a 3rd gen would be a tall ask I think.
Big update today. Charlie actually got into changing the texture in the port and basically did a full clean up (sans floor) and checked the airspeeds. Question. How much total CFM do you think a performance rebuild like this needs? How much of that head flow is really going to be utlized?
LIFT --- INTAKE--EXHAUST ----SWIRL -----AIRSPEED INTAKE PORT ---EXHAUST PORT
.100 ----84 ------ -52 ---------------164----- -----Pushrod Pinch 320fps--------- 245.4fps (which I dont think my math is correct)
.200 ----156 -----98---------- --------987 ---------Roof 176.5fps
.300 ----205----- 39.6 -------------2050 ---------Short side radius 374.6fps
.400 ----239 ----168.6 -------------2194
.500 ----251.5---183.6 -------------2669
.600---- 250 ----181.2 -------------2809
You had mentioned DV before so I'm pretty sure I won't get flamed (like I might get elsewhere...)
I've messed around with his TM program looking for cam suggestions. One of the features, which can either be an input (white data box) or a result (yellow box), is the minimum required intake port CFM for a given target. Far right column. You can also see some data for port volume.
Below are two 10:1 355's I was working with. In one I used 210 CFM minimum. The other I used 220.
Maybe there's something to take away from this.
I have others as well where CFM creeps on my maximum (as flowed) 255 CFM. That is with slightly more CR although that tends to reflect more on the cam spec (as it is a cam spec program and not an engine simulation program as per Stan Weiss). That said, there's definitely a trend that can be seen and again maybe there's something in that for your project.
FTR: I labelled them as "Vortec" as that's the intake valve size. 1.94".
I understand the DV works with the coefficient of discharge for some of his other predictors (the 128 rule comes to mind here) but it's CFM that's the topic of discussion so I picked something representative. That said, I have many others saved for reference.
Don't pay attention (in this case) to the induction length. It's a separate calculation unto itself (also per Stan Weiss) and has no bearing on the other results.
Those examples sound about right. 210-220cfm total intake port flow can yield about 410-440hp with RPM. With TPI you basically have to cut the HP curve off at 5200rpm and thats about what it'll make which is why I am shooting for average power and hopefully carry the power to 6000rpm. I think as TPI guys thats the best you can hope for. Your induction length is set way shorter than what I have. You are set up for the third harmonic and TPI works off the 2nd.
260cfm is probably all I need for something like this. I dont think the intake manifold is going to support much more and total airflow will probably be a lot less than that... so why give up low end flow for something that I wont ever see anyway?
What were interested in is the seat angles... a 50 degree is good for high lift flow and less reversion... DV loves 40's... I just don't know what the airspeeds will like with low RPM. Its an interesting concept to think about.
Those examples sound about right. 210-220cfm total intake port flow can yield about 410-440hp with RPM. With TPI you basically have to cut the HP curve off at 5200rpm and thats about what it'll make which is why I am shooting for average power and hopefully carry the power to 6000rpm. I think as TPI guys thats the best you can hope for. Your induction length is set way shorter than what I have. You are set up for the third harmonic and TPI works off the 2nd.
260cfm is probably all I need for something like this. I dont think the intake manifold is going to support much more and total airflow will probably be a lot less than that... so why give up low end flow for something that I wont ever see anyway?
What were interested in is the seat angles... a 50 degree is good for high lift flow and less reversion... DV loves 40's... I just don't know what the airspeeds will like with low RPM. Its an interesting concept to think about.
So. based on that, it raises a couple of questions.
Despite having the port CFM needed for 400+ HP, is it your understanding that the stock TPI intake won't let you get there? For the most part, 400 HP would take 6000 RPM to achieve with 355 CID if I understand correctly.
On a similar note, and a question I've asked elsewhere with no definitive answer is, with a given port CFM, are we still limited in total output after any given intake is installed? That is: if a set of heads can move 260 CFM, but the intake (TPI aside) kills that to a best of say, 210, are we then limited to HP production based on that? The answer may be obvious as this how restrictor plates or two barrel carb classes operate if I'm not mistaken.
I apologize if this takes the thread off track although, seeing as you're very much involved and have some good source information, I think it's a relevant question.
Seat angles on the other hand, are another story unto themselves. Check out what Weingartner has tested. Or the likes of the crowd at ST. Isn't that a 50° seat helps high lift whereas the shallower angle aids low lift? Much the same as a back cut intake valve. As for DV, from what I've read of his exploits, he's a big proponent of low lift flow.
So. based on that, it raises a couple of questions.
Despite having the port CFM needed for 400+ HP, is it your understanding that the stock TPI intake won't let you get there? For the most part, 400 HP would take 6000 RPM to achieve with 355 CID if I understand correctly.
On a similar note, and a question I've asked elsewhere with no definitive answer is, with a given port CFM, are we still limited in total output after any given intake is installed? That is: if a set of heads can move 260 CFM, but the intake (TPI aside) kills that to a best of say, 210, are we then limited to HP production based on that? The answer may be obvious as this how restrictor plates or two barrel carb classes operate if I'm not mistaken.
I apologize if this takes the thread off track although, seeing as you're very much involved and have some good source information, I think it's a relevant question.
Seat angles on the other hand, are another story unto themselves. Check out what Weingartner has tested. Or the likes of the crowd at ST. Isn't that a 50° seat helps high lift whereas the shallower angle aids low lift? Much the same as a back cut intake valve. As for DV, from what I've read of his exploits, he's a big proponent of low lift flow.
No its the perfect question. I see some TPI guys wanting 300cfm heads and then use the long runner intake on top of it like they are going to be able to use all 300cfm. It doesnt work that way. An engine doesnt know it has a 300cfm head on it. It just knows a total. I myself have screwed up on this by using nice ported heads and then a box stock intake. One that comes to mind that I wish I did better on was my old 85 Mustang GT. I had Bennett Racing ported GT40 irons on on it, O ringed for boost and then I had a Weiand Stealth intake on it box stock.... I know these days I gave up A LOT of power because I didnt port the intake and the ports were WAY smaller than the head. No wonder it layed over at 5500rpm. It could have gone 6500+. An engine sees the total CFM number, from throttle body to intake valve.
By using a big 300cfm head (or whatever) and small port intake... You are speeding the air in the intake faster than you are the head and thats backwards from ideal. This makes a nice street engine but lays over very quickly up top. You want the faster air to be in the cylinder head's intake port and slower air in the intake manifold which is speeding up as it approaches the head...which is why racers use a tapered, short intake manifold thats port matched to build velocity and smother the intake port in flow... Disclaimer: (some guys like a small step on the bottom of the intake manifold port where its smaller to help with reversion, but the idea is still there to use an intake thatll flow what the head needs).
This is why I am staunchly against having an AFR head on a long tube runner TPI intake... Its not like youre going to use all of it...and like the beginning of the thread states, now your airspeed and CSA is backwards.
This is why Charlie is paying close attention to leaving the head ports as small as possible and not going after every bit of cfm. We want the port to shrink as it gets to the head. It wont shrink much and it may very well end up the same CSA throughout as far as the engine is concerned ---- but the airspeeds will be even and thus, it should make a better TPI system than just bolting parts on. This is what were testing.
Look at it this way. Take youre average CSA. That CSA is worth a certain airspeed in a straight pipe. Most intakes arent straight by the way, thell flow less than the CSA says. Take your head. That head has a CSA, a minimum CSA and an airspeed associated with it. Say your head flows 285cfm. Now say your intake flows 300cfm. When you bolt this together, you still arent guaranteed to get 285cfm out of the valve. Intake pieces are like electrical resistors. Each piece has a resistance to flow which is comparable to.... say ...boost pressure. When you take these resistors and put them in series, your whole intake track is now the sum of those resistors (parts) and that will determine what your total intake cfm is, and what its resistance to flow also is. So you gotta 300cfm intake and 285cfm head? Prob like 265-ish as a guess as to what the whole system flows together. Take a TPI system, that probably flows 240-250 ported... Put it on a 280cfm head.... youre looking at like 220cfm or so. (these are guesstimates) and that 220 is the only number that matters.
What Charlie is doing by talking about all these airspeeds, is he is managing the resistance to flow. He wants to equalize the intake airspeeds and try to get rid of the high localized velocities that will go "sonic" and choke the port, by making the average velocity through the whole system more constant. By doing this, you are getting rid of anything that will shut the party down earlier than the next part and also maximizing flow for the given cross sectional area. This is making the head work with the intake instead of being choked by it.
Its going to take a really thoughtful small port head, an intelligently ported intake base, properly ported runner entrances and exits and even some tricks in the plenum to do all this. He has his work cut out for him. IF he tries to port the head like a carbureted deal, it may be maximized for a much higher RPM that what TPI is wanting to work with and could leave power on the table. If its too small and restrictive, it wont even flow enough to make any power. Air too fast. Chokes at 4500rpm or so... Typical TPI nosedive after 5000-5200rpm. He gets it right... It should make a nice average power number, then peak at the typical TPI resonance and hold that number for a while. Maybe even build on it.
Sorry for the long post. Anyone can call BS. This thread is awfully quiet. Its just a street car TPI experiment guys.. Lotta work for who knows what. But if it does produce something good... Well, then we all learned something and Robs IROC gets to be one of the fastest slow cars on TGO.
Sorry for the long post. Anyone can call BS. This thread is awfully quiet. Its just a street car TPI experiment guys.. Lotta work for who knows what. But if it does produce something good... Well, then we all learned something and Robs IROC gets to be one of the fastest slow cars on TGO.
No apologies required.
At one time, TGO had a solid reputation for tech. So much so that it's my understanding that the powers that be didn't want a chat forum that would turn it into a social club. The likes of the crew in California taking the TPI to smog legal limits was truly a zenith for the 3rd gen at the time. Lots of testing. Even a header manufacturer.
What's happened though, and there a couple of exceptions, is that the tech, such as your TPI, have lost relevance. At least to the general population. It's a niche thing like flathead engines. They're not everybody's "cup of tea" but there's still some fantastic tech that's attached to them.
Bring that back around to this thread and the same applies. Your work, I think is vital to the marque. And it's unique in a way. There are still plenty of TPI's putting around I'm sure but I'll bet the majority of their owners are content with a good running car and little else. All the more power to them. That said, if they want to realize greater potential, this is one place they'll look.
The same applies for the ubiquitous LS swap. I think if you want to go down that path (and I may have a very distant project along those lines with a spare 82 chassis and an LM7) this is the place to be. There's a stack of firsthand information and just about any level of performance.
Same too with the high end builds. IRS swaps. Twin turbo big blocks. Full on racers. Have I left anybody out?
If Rob's IROC is one of the fastest slow cars around I'll join him with one of the slowest fast cars. We can meet in the middle.
Keep the project going. And thanks for not packing your tent and going home.
Well.. I appreciate that and I agree, the TPI ship has sailed and its kind of a bummer. I waited too long to do one because it's a lot of work for not a lot of return. But these are the cars that got me into cars as a kid so I knew I would do this eventually. Im about to pick a little fight here... bare with me.
Ive been looking at the Corvette thread and I think I understand why they are only getting the CFM they are. Take a look at his post. He writes:
Just like the previous equation for flow through the valve, except the valve curtain area times it's discharge coefficient has been replaced by the minimum port cross sectional area times it's discharged coefficient.
The discharge coefficient can be approximated by dividing the measured intake runner cfm's by the theoretical maximum cfm's ( port area x 146 cfm @ 28 in-hg ).
Here are some discharge coefficient examples.
First off, his formula is right... but the TPIS Big Mouth and runner ID is wrong. The ASM runners are 1.63" ID. The manifold is probably a littel bigger...but you gotta look at the MCSA of it all. The MCSA is the ASM runners and they are smaller. This is coming from the owner and the one who designed these, Jim. They are 1.75" OD tubing with a .060" wall thickness.
1.75 - .120 = 1.63 - yeah I know not a big difference but the math matters. Especially for a project like this.
Second he is saying, at a 2.16" CSA , it should flow 316cfm but its only flowing 225. While I think his flow figures are close if not exactly correct at 225, the fact is for a 2.16" CSA to flow 225 youre only moving the air at a too slow 250fps. You may lose power at 250fps with low RPM stuff. On top of it all....To get the 316cfm he thinks it should flow he's at a borderline too fast 350fps. You may get pumping losses there. I also don't think he's understanding what he should be going for flow wise nor what the problem is. There is too much resistance in the port. The fast areas are too narrow and the slow areas are too fat, to put it in simple terms.
Realistically it should read 1.63" port dia. / 2.08" port area (csa) / 277.33 ideal cfm (320fps) / 225 measured CFM (260fps). So the ideal runner CFM for ASM runners is 277.33cfm. and the C/D as far as i'm concerned is perfect. We can all agree that if you are getting 277.3 cfm out of the valve of a TPI manifold with the runners on, you are doing damn good. The plenum and TB will knock that down significantly. The air has to do a 90 degree turn to make it into the runners. That right there is a BIG problem. The angle (radius) of the plenum to runner entrance is going to have an effect on how much more or less that hurts flow. I wonder what head he was using?
Im not on a high horse btw... Theres real super Speier/Meaux/Morgan/Servedio/ETC science going on here... I''ll prove it.
Charlies stock ported stuff actually looks better than you think. He got 233cfm with just the runners on it mocked up just like the Vette guys stuff but Charlies stock stuff flowed more than his aftermarket stuff. It gets better. The stock runners he used are only 1.525" for a 1.82" CSA ...So lets take a look at airspeeds. 233cfm/1.82" CSA = 307fps. Pretty ideal. So he got more cfm and thus more power from a smaller area all thanks to a good porting design. Case in point. AIRSPEED MATTERS! Complete from TB to valve he was almost 220cfm. Thats enough to make a 350-400hp TPI engine that really looks totally stock. Not bad at all man. I shouldve just saved my money and bought heads and ported the stock stuff but just maybe the aftermarket stuff touched up will have more of an easier to obtain average airspeed because its a little straighter... We'll see.
I know what the next video to drop is and its an eye opener. Lots to talk about very soon. I hope this data here gives you something to think about on your next engine and why guys like Morgan and Meaux are real gifts to us these days. The info is priceless.
One from ST explaining aispeeds and their effect on power further. A very well known post I might add. I think nearly everyone has read this a time or two before but it fits here too.
Originally Posted by maxracesoftware
"here's some Threads from a couple of Posts that might explain
CHOKE to you
here's a very good quote from STEVES
that explains the general idea and reason why Choke
or too fast FPS hurts HP+TQ
just read rest of Posts with that in mind .
As I understand it, ports don't actually go into sonic choke at .55 Mach -
but at this point (approx.) we reach the trade off where the energy
required to move the air through the port becomes higher than the power
increase (cylinder filling) that comes from higher velocity.
---SteveS
Posts=>
From a previous Thread
too fast Velocity FPS can be a total disaster
Note=>all 3 of these Heads were tried on
the same Short Block with all the same pieces
and Dyno Tuned for best possible HP/TQ Curve
with those pieces.
#041x SBC Heads = 165.0 CCs
1.940/1.500 valves
these are the very Hi-Velocity Heads
with too much velocity everywhere inside
the Intake Port, same FlowBench numbers
and the "BEST" Dyno test with them
600 RPM/SEC , i don't have the Sheets
that we started at 3000 RPMs and all the
rest of the Sheets , but only kept the
Copies that stood out, and these are every
200 Hundred RPM increments as its too much Info to type
every 100 RPMs, but it should give you enough Info ?
note=> at 600 RPM/SEC you get a little Needle/Seat
action showing up especially with small gas bowl
chamber in Q-Jet, so look at Fuel Lbs/Hour trend
as well as rate (Same Q-Jet Carb all Dyno Tests)
with #041x Heads back-to-back on same Short Block
same basic Flow CFM Numbers, same valves, same CC's
but with Port Velocity slower and more acceptable
throughout the entire Intake Port
with #462 castings 1.940/1.500 162.0 CC Ports
differences just 3 CCs can make when ground out in the
correct places, again FlowBench CFM between the
#462 and the other 2 #041x Heads were very close
and CFM numbers don't indicate the HP/TQ differences observed
and Ports had different Velocity Profiles.
Same ShortBlock and all pieces the same.
Quote:
Very well put - I have thought for some time that "Choke" is actually a
misleading term here. David Vizard has called it "Power Limiting Port
Area", a more accurate description, but unlikely to catch on.
i just use the word "Choke" because sometimes the Engine will be Choked
by an Area and sometimes by the same cross-sectional, but now has one
of the walls with too much local velocity FPS and/or diverging too quickly
on 1 wall
in the above Dyno Test examples the one extreme hi-velocity #041x SBC
Heads is using more Fuel, but if you try to lean it out, you loose even
more Torque and HP...notice it makes Peak TQ and Peak HP lower and
runs out quickly with rapid rising BSFC numbers as rising RPMs show
Choke problem even more.
the 2nd pair of #041x heads
make more Peak TQ & HP and at higher points,
and don't lay over top end.
the #462 castings with 3 less CC's
make Peak TQ at same point, but past Peak HP point start to layover
more than the #041x
Fuel consumption is about identical
Same FlowBench CFM Numbers
but different Intake Port Pitot Probe profiles/velocities
note thats a 117.9 HP "LOSS" for the extreme hi-velocity Heads at 7600
yet..on a steady-state FlowBench test,
"BOTH" Heads flowed almost as exact CFM as you could possibly
make them be equal on both Intake + Exhaust sides.
even used and swapped the same exact Valves out of both Heads
for those tests
same #041x castings , both same Chamber+Port volumes
what i call the extreme velocity FPS #041x Heads were;
every possible portion of that Intake port that could have
Epoxy added to it, and that Flow CFM was not reduced at all,
was epoxied up.
and the rest of that Port was enlarged just enough
to hold the same Port Volume CC's
the Short Turn Apex speed was to the moon
and so was the pushrod area...and just about every where else in the
Port....the Floor had some "Ski-Jump" shape to it also...as it kept
the CFM Numbers up and the velocity sky-high
i guess you could call it an experiment to see how far
you could "shrink" certain CSA areas of a Port
and not reduce the FlowBench CFM numbers .
pretty evident from Fuel Consumed Numbers -vs- Dyno HP/TQ Numbers
that Intake Port could not handle that much speed FPS
without Choke or Separation
you can also see why just about everyone i know
will Run the #041x heads over the other Legal #462 castings,
those 3 more CC's can be used to "SLOW DOWN" the already
too fast FPS
one other thing that stood out in some of the Tests, was the very
hi-velocity too fast FPS Heads that had a choke problem, often liked
"more" low to mid lift flow. The engine's being fed sooner and more, so
the cylinder depression is lesser until Choke occurs...and you still have
good low-lift to take advantage of high velocity at end of stroke
also the velocity FPS is slower in the smallest CSA areas, in the low to mid
lift portions of the Flow/Cam Lift Curve...pumping losses working thru rod
angle leverage in early and latter parts of stroke are going to be lesser
than at Peak Piston CFM demand point where leverage is great and Choke
makes more losses.
a Closed Intake Valve has "ZERO Port Velocity FPS" at Max-Lift , typically
the Cyl Head has its best FlowBench CFM Number or about in that
vicinity...so Port Velocity FPS is highest at Peak Lift or so. as the valve
starts to move towards max lift, Port FPS is increasing...also the
minimum csa area FPS is starting to really increase or any too fast FPS
area is also increasing in FPS (add to that max Piston CFM demand in
vicinity of 70-80 deg ATDC and volume CCs increasing till BDC, + Flow
Lag Times, pumping losses working thru Rod Angle leverage/velocity, etc.)
FPS = (CFM * 2.4 ) / CSA
if Head Flows 127 CFM at .200" Lift = 156.6 fps @ 1.948 csa
if head flows 260 CFM at .700" Lift = 320.3 fps @ 1.948" CSA
but in reality there will be CSA spots in Heads that will be
smaller than 1.948 sqinches, so the FPS will be higher than 320.3
other CSA will be larger than 1.948
and other localized spots can have too high FPS
even though your Average CSA of 1.948 says its only 320.3 fps
the Port Volume is the same in both cases,
the FPS changes up or down inside the Port
in relation to the Lift/Flow Curve -vs- Piston CFM demand
picking up the Low to Mid lift flow in the too-fast-velocity heads
helped...but it still didn't run as fast down the DragStrip.
the best way i've found so far is to slow the FPS to as close
to reasonable speed as possible, as long as its not too slow,
take the choke CSA out of the picture as much as possible.
As I understand it, ports don't actually go into sonic choke at .55 Mach -
but at this point (approx.) we reach the trade off where the energy
required to move the air through the port becomes higher than the power
increase (cylinder filling) that comes from higher velocity."
what are they after plans, are you going to dyno before and after, maybe some draggy runs. cars to nice to beat up doing drag strip stuff but seems a few pulls would be helpful to see if all this is worth it. it's always been my thoughts that they 3 gear ratio of the 700r4 aren't great for the tpi power band, just spins first, pulls well in 2nd and bogs 3rd where the manual 4 gears keep it on the power band better
what about plenum volume, any benefits to making that larger?
3rd gens and C4 Vettes got the wrong induction system (TPI) and automatic transmission (700 R4). This is the perfect setup for a truck, van, SUV, heavy body on frame car.
3rd gens and C4 Vettes would have been better off with a high performance version of TBI and a 200 4R transmission.
3rd gens and C4 Vettes got the wrong induction system (TPI) and automatic transmission (700 R4). This is the perfect setup for a truck, van, SUV, heavy body on frame car.
3rd gens and C4 Vettes would have been better off with a high performance version of TBI and a 200 4R transmission.
TPI is not good at all on a heavy vehicle, unless you want to gear it where it adds its midrange torque. Dual plane intake has more low-speed grunt even with TBI on it.
TPI is not good at all on a heavy vehicle, unless you want to gear it where it adds its midrange torque. Dual plane intake has more low-speed grunt even with TBI on it.
TPI is not good at all on a heavy vehicle, unless you want to gear it where it adds its midrange torque. Dual plane intake has more low-speed grunt even with TBI on it.
I disagree with you there. TPI would be one of my top choices for an EFI SBC deal in a pick up. 450+ft lbs 383 at very low RPM. You could literally just cruise with a load or trailer and probably still get some good mileage. I think you just like to push those Vans like they were Vettes.
I love the look and I’m a fan… enough of them have been wrecked and twisted up with just 245hp because they’re still fun to drive.
what are they after plans, are you going to dyno before and after, maybe some draggy runs. cars to nice to beat up doing drag strip stuff but seems a few pulls would be helpful to see if all this is worth it. it's always been my thoughts that they 3 gear ratio of the 700r4 aren't great for the tpi power band, just spins first, pulls well in 2nd and bogs 3rd where the manual 4 gears keep it on the power band better
what about plenum volume, any benefits to making that larger?
You nailed it. It’s not a racer. It’s pretty much what the classic car guys do… keep the original drivetrain for sentimental and originality purposes and just add 75-125hp or so.
I honestly don’t think a bigger plenum at this low of an RPM would be worth it. 1989TransAmGTA did that but he was swinging for the fences. This is just a cruiser that’ll do the car some justice.
I have a few ideas going on for testing. I’m not quite sure which one will be done but it will be done and results will be posted.
I disagree with you there. TPI would be one of my top choices for an EFI SBC deal in a pick up. 450+ft lbs 383 at very low RPM. You could literally just cruise with a load or trailer and probably still get some good mileage. I think you just like to push those Vans like they were Vettes.
I love the look and I’m a fan… enough of them have been wrecked and twisted up with just 245hp because they’re still fun to drive.
I disagree with you there. TPI would be one of my top choices for an EFI SBC deal in a pick up. 450+ft lbs 383 at very low RPM. You could literally just cruise with a load or trailer and probably still get some good mileage. I think you just like to push those Vans like they were Vettes.
I love the look and I’m a fan… enough of them have been wrecked and twisted up with just 245hp because they’re still fun to drive.
I had a TPI and I had it on a 383. Dual plane had more off-idle torque than the TPI. Now that I have run dual plane MPFI manifolds, best of both worlds and they will rev out 6,500 rpm no problem.
TPI is not good at all on a heavy vehicle, unless you want to gear it where it adds its midrange torque. Dual plane intake has more low-speed grunt even with TBI on it.
I was thinking more along the lines of ever tightening emissions standards and C.A.F.E. fleet standards for GM. The fact that GM believed the 5.0L V8 was going to be new engine going forward. Use TPI on the 5.0L engine it was designed for to begin with. Put it on top of the L03 swirl port headed long block with a roller cam somewhere between the "peanut cam" and the hotter TPI cam. The stock TPI induction and swirl port heads run out of steam at about the same 4400 to 4600 RPM range. Pair that engine with the 700 R4 transmission with the low 1st gear to make up for the missing 45 cubic inches to get the light duty trucks, vans, SUVs, and body of frame cars moving off the line. Do same thing with a 5.7L L05 engine for heavier duty trucks, vans, SUVs, and trailer towing package cars. Use the HD version of the L05 with the hardened exhaust valve seats and HD exhaust valves on the heavy duty versions of the trucks and vans. The big trucks and vans get the diesel and big blocks.
EDIT: One flaw in my idea is the TPI system is much more expensive than the simple TBI system.
I was thinking more along the lines of ever tightening emissions standards and C.A.F.E. fleet standards for GM. The fact that GM believed the 5.0L V8 was going to be new engine going forward. Use TPI on the 5.0L engine it was designed for to begin with. Put it on top of the L03 swirl port headed long block with a roller cam somewhere between the "peanut cam" and the hotter TPI cam. The stock TPI induction and swirl port heads run out of steam at about the same 4400 to 4600 RPM range. Pair that engine with the 700 R4 transmission with the low 1st gear to make up for the missing 45 cubic inches to get the light duty trucks, vans, SUVs, and body of frame cars moving off the line. Do same thing with a 5.7L L05 engine for heavier duty trucks, vans, SUVs, and trailer towing package cars. Use the HD version of the L05 with the hardened exhaust valve seats and HD exhaust valves on the heavy duty versions of the trucks and vans. The big trucks and vans get the diesel and big blocks.
EDIT: One flaw in my idea is the TPI system is much more expensive than the simple TBI system.
TPI is beyond stupid expensive, the runners and base I bought were more than the heads! I could’ve had a First or a HSR or even a MR. Thats the real downfall of TPI and from what I’m seeing here, if all you want is 350-400hp, stick with ported stock stuff and just add runners.
of course, we’re not even close to done yet… so don’t take that as gospel.
Right now I’ve got a 4 day kidney stone I’m battling so forgive me I’m not writing much. Getting old sucks.
so I've got some old aftermarket tpi runners and plenum. I believe these runners where used with this plenum. I'm guessing because plastic of the time couldn't handle making the runners. but they look very stock, the coating is cracking form being in a box over the years moved around states.
I have no idea who made these back then, but I'm guessing MRP
and the plenum. not really relvent to the thread besides what had been tried in the past. looks like someone made smooth round runners in larger size that looked as stock as they could
Wow I've never seen that MRP composite plastic TPI plenum before. You won't get heat soak with that plenum like a aluminum one. Shame the corner where the throttle body mounts is broken but it looks like it could be repaired.
The smaller left side runner looks to be stock and the larger right side runner looks to be an AS&M runner.
MRP Composite Plastic TPI System on the cover of September 1990 Car Craft magazine.
sadly I think I broke it, I seem to remember had the part taped to it for a while, but it's been lost, 15 years and 4 moves later. I think you could easily epoxy around it and sand it flat so you didn't see it. the insert seems solid still.
I ended up with a super ram and never installed this stuff.
*edit, yeah. the left is a stock one to compare sixe. I have both of each laying around.
if they are as&m, I should have sold them years ago haha. I had no idea haha.
Found a TGO thread about the MRP TPI system. Seems they had throttle body, plenum, runners, and I guess the distributor cover in plastic composite. Guys in the thread said they were JUNK. Flash in the pan products. Here in 89/90 and gone by 92/93. I guess probably a waste of time to try to repair the plenum. More of a conversation starter cool piece to look at now thing.
If you have both of those AS&M runners the OP @MrIROBZ of this thread may be interested in them if the runners he ordered from AS&M don't work out. The AS&M large tube runners are the hold up on him proceeding with his build right now.
MRP Composite Plastic TPI System on the cover of September 1990 Car Craft magazine.
I've never found that Pic before searching. looks like they used slp runners.
I do have 3 throttle body's too. 2 mono blades and one dual blade I'd guess is a 58mm ish.
they were all the older 86 styles, I had a 91. I do remember trying to use one of the tb's. I took it all apart and tack welded the different style ends to the shaft. it worked OK, but I had supercharger back then and it seemed the blade would get stuck from the back pressure when slammed shut. and tuning AE was hard. so I took it off.
Found a TGO thread about the MRP TPI system. Seems they had throttle body, plenum, runners, and I guess the distributor cover in plastic composite. Guys in the thread said they were JUNK. Flash in the pan products. Here in 89/90 and gone by 92/93. I guess probably a waste of time to try to repair the plenum. More of a conversation starter cool piece to look at now thing.
If you have both of those AS&M runners the OP @MrIROBZ of this thread may be interested in them if the runners he ordered from AS&M don't work out. The AS&M large tube runners are the hold up on him proceeding with his build right now.
if he needs them, I'd sell them.
who knows about the MRP stuff, we all new so little about tpi back then, they might have worked fine with the as&m runners and a ported base. we all had such little money back then to waste. if it didn't make enough power in a test no one wanted it lol.
besides this thread I can't remember anyone trying to make any hp these days with tpi. like you say, Just would be a conversation starter at a 3rd Gen meet up haha.
04-24-2024, 10:04 AM
