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I'll be following this with interest. Maybe even have something of value to contribute.
I was going to ask in another thread where that Speier chart came from. What software is it?
Most 23-degree SBC heads run between 5.25" to 5.45" long - some will be a little shorter and some a little longer. The AFR 210s are 5.33" long (measured recently).
I’ve intended to join in, but tonight is the first night I’ve had some free time.
I went down a similar path back in 2000, but have no air-speed measurements to share. I ported a stock TPI base, plenum, and SLP runners. As you already stated, the middle section of the stock and aftermarket TPI base is smaller than the first and last third of the base. I spent a lot time porting the middle part of the base, getting the cross-sectional area to about 2.1”. I also concentrated on the top of the exit going into the heads, raising the roof as much as possible without compromising the injector seats. Both the base to heads and the runners to base have terrible transition points as you already stated – anything you can do to help those areas should pay big dividends.
Part of my porting process included removing .5” at a time from the SLP dividers - getting ETs using a 3 run average from the Vericom 200 accelerometer. It took a lot of time and effort, but I ended up stopping a little short of the halfway point, when there was no decrease in ET and only about a 0.2 MPH gain. I’m sure if I would have taken out another .5”, the car would have either slowed down and/or part throttle response would have suffered.
Engine was a 9.8:1, 355 with an old set of box-stock TFS, 180cc, G1 Twisted Wedge heads (flowed around 230cfm at cam lift). I ran a 268/276 (.006), 218/228 (.050), 130/140 (.200), 110 spread, custom (ground for single plane intake) comp hydraulic flat-tappet: 0.494/0.506 lift with stamped steel 1.6 rocker arms. Installed intake centerline on the cam was 108. I added a good bit of timing at idle and it pulled 18” vacuum (what Performance Trends estimated) at 750 rpm. I preferred the way it sounded at 750 rpm, just a slight bump to it - at 800 rpm, it was pretty smooth and didn’t sound a lot different than stock. I already had that cam lying around – if not I would have gone with a single pattern or one with less split on the duration (to get more duration on the intake side, keeping overlap about the same, without hurting vacuum).
Exhaust was Hedman 1,625 shorty headers, 2.25” Y-pipe, no cat, and single 3” exhaust to a Dynomax Ultraflow dual 2.5 exit muffler. The car ran 12.90s shifting out of first gear at 5500 rpm – it labored a bit to get past 5700.
Now, the thing wasn’t that fast, but it was extremely responsive with near violent throttle response. I had to add a spring to the throttle body linkage to keep from spinning the 245/45/17 street tires when getting the car to move from a stop. I let a bunch of people drive it and everyone commented on how responsive it was – some said overly. I truly enjoyed driving it – it felt a LOT faster than it really was – lol.
I would expect yours will be a lot faster with better flowing heads, aftermarket base, and AZ Speed and Marine runners. It should also be even more responsive, which should totally blow your mind!!
Huh. I'd think that your cut outs would be your "termination box" (when open), and the rest of the exhaust would become meaningless.
According to Larry, that's not the case. Yes, the open cutout will generate the strongest pulse and tuned to arrive at the exhaust valve at the appropriate time. However, because the rest of exhaust is still attached, another pulse, although weaker, is generated at the tailpipe. If this weaker reflected wave doesn't arrive at the valve at the same time as the cutout's, then some of that pulse will be cancelled out.
He said to calculate both lengths and be sure that they are complimentary.
Easier said than done though.
Not to sidetrack Rob's thread however it follows in a similar vein to intake tuning.
According to Larry, that's not the case. Yes, the open cutout will generate the strongest pulse and tuned to arrive at the exhaust valve at the appropriate time. However, because the rest of exhaust is still attached, another pulse, although weaker, is generated at the tailpipe. If this weaker reflected wave doesn't arrive at the valve at the same time as the cutout's, then some of that pulse will be cancelled out.
He said to calculate both lengths and be sure that they are complimentary.
How is the cut out different than a termination box (or chambered muffler)...that also has an exhaust system connected to it? I think Larry is wrong, or the effects he is talking about are essentially meaningless and un-influential to the tuned part -the part from the collector the the cut out. I don't think you'll find any tuning at the tail pipie, after ~10' of piping and (especially) the mufflers. To ME, that would be, as I like to say.... "Worryin' about chit that ain't worth worryin' about".
How is the cut out different than a termination box (or chambered muffler)...that also has an exhaust system connected to it? I think Larry is wrong, or the effects he is talking about are essentially meaningless and un-influential to the tuned part -the part from the collector the the cut out. I don't think you'll find any tuning at the tail pipie, after ~10' of piping and (especially) the mufflers. To ME, that would be, as I like to say.... "Worryin' about chit that ain't worth worryin' about".
With the terminator box, the tail pipe reflection is isolated I would think. When it reaches the box from the backside, it's pulse isn't likely to carry across the open chamber.
I doubt Larry is wrong. It's more case of the cutout with a connected tailpipe behaves in a different manner than the boxed version with an isolated tailpipe.
Enough said I think though.
Ain't that the truth.
By the way, I got into that ST thread. Very cool.
And I also explored Speier's website and dug into his formula database. Also very cool.
Raises a lot of questions about airspeed and such. Something I'll have to explore further.
Thanks for the links.
I will add to this, wave tuning starts at the atmospheres inlet to the air box and stops at the exhaust opening to the atmosphere. If you looks at the air inlets to the air filter assembly on many vehicles, even the inlet duct ahead of the air filter has a radiused trumpet on it. Holdener once played with a long intake tube with a radiused inlet he jokingly called snupolopogous on a Hemi engine. It added considerable torque using the LX car intake manifold. Similarly they played around with a full length exhaust on Engine Masters. They ran like 18' of exhaust pipe on each bank in the testing. The crew cab long bed length of exhaust system they put on the 454 had noticeable changes in torque curve compared to a shorter exhaust system.
Termination boxes I've studied to death. Problem is on my car (or a lowered 3rd gen in general), they're all but impossible to be placed in the correct spot. This is why race days will see open collectors. Whatever I drive on the street won't be WOT so that performance gain via the open headers won't matter and the full exhaust will do.
I did see a neat setup on a C4 Corvette that used almost the entirety of the transmission tunnel for a single box (It was a Vizard deal). The C4 though doesn't have the torque arm to deal with. Or the torque tube of later models.
Termination boxes I've studied to death. Problem is on my car (or a lowered 3rd gen in general), they're all but impossible to be placed in the correct spot. This is why race days will see open collectors. Whatever I drive on the street won't be WOT so that performance gain via the open headers won't matter and the full exhaust will do.
I did see a neat setup on a C4 Corvette that used almost the entirety of the transmission tunnel for a single box (It was a Vizard deal). The C4 though doesn't have the torque arm to deal with. Or the torque tube of later models.
I have had very good results with Vibrant Merge-Ys when forced to run a single exhaust. It is hard to get a good dual exhaust on a 4x4 truck or Tahoe for example.
I don't have an answer but I have to ask anyway.
I'll take a step back from the timing question and re-visit the basic architecture. If I'm covering ground already covered, point me in the right direction.
My ignorance of how the TPI intake tract was designed notwithstanding, although I see it clearly now, the question I have is there any data to support exactly where that TPI runner length will tune to? From an analysis standpoint, it's one factor at a time for me. When we're discussing this intake, comments like "doesn't carry power like..." could bring many elements into the picture.
"Ok, heres what I want to ask... Why in some instances are some TPI engines able to carry the peak higher in the RPM range than others if the CID, Cam and intake bases are all different? They are ALL long tube runner cars and harmonics would carry all TPI cars like Jim Halls TPI engine and Richard Holdeners."
Right there we have TPI and different CID, cam and intake bases in the mix. The runner length is another. I was told my too tiny heads would have an extended rev range , towards the top end, with a different cam spec. Does that logic cross over?
On the single plane intake side of things, one example I can offer is that a 1-1/2" change in length (going from 11.5" to 13") moves the tuned induction peak HP and TQ RPM from 6435 and 5019 respectively to 5692 to 4440. That's a 750 RPM swing for HP.
But maybe I'm missing your point.
I do have a question: When you say TPI are you talking strictly stock? Stock modified ? Aftermarket?
I was emailing Alan a good bit when he was planning the 369 AFR build with the FIRST base and modified SLPs adapted to the FIRST base. I tried to get him to NOT cut all the divider out of the gutted SLP runners – to me, it was losing more midrange power than he was picking up on the top-end, but he was chasing RPM.
His first pull with it didn’t come close to what the sims I was running for him showed – power fell off like a rock before 6000 rpm. I had been using EA sims since 1992 and the only way it could be that far off, was if a data input was way off. I asked him to check his cats and mufflers, because we were sure of all the mechanical inputs were right. He was planning to add terminator boxes to his exhaust and I told him he better buy some cats and have on-hand and be ready to replace them. Bottom line, both cats were badly clogged.
The following includes the pull after replacing the cats (really close to the sims), then the pull after adding the terminator boxes (one for each bank). Those are overlaid with the best pull he made after swapping out the FIRST/SLP combo for his custom made 21” long (total tract length), 2” diameter TPI. The 2” TPI runner pull did not have the T-boxes installed. I can’t recall why he had to remove the t-boxes, but I think it had to do with the cats having to be in the stock location for visual inspection in California.
I was in a time crunch when I posted that and intended to come back and say that these longer runner intakes are even more sensitive to header diameter, primary length, and the collector length. And as you said, the dyno pulls holding out the power for so long are typically on an engine dyno with dyno headers and usually some unknown collector length with no mufflers or dumping into a huge dyno muffler.
Alan was running Dyno Don 1.75” kinda shorty headers for sure. I’m pretty sure he was running two three inch 200 cell metallic cats then running a 4” exhaust out back. I’m not sure of the Y pipe, but do remember linking him the 3 to 4” flowmaster. I can’t remember the muffler he was using but I’m partial to the Borla XR-1. They have a pretty long one that will fit a 3rd gen in the stock location while keeping sound to a minimum for a 4” exhaust.
Really good heads that has increasing flow past the cam lift and an intake that won’t choke it down helps to carry power past peak also.
I was in a time crunch when I posted that and intended to come back and say that these longer runner intakes are even more sensitive to header diameter, primary length, and the collector length. And as you said, the dyno pulls holding out the power for so long are typically on an engine dyno with dyno headers and usually some unknown collector length with no mufflers or dumping into a huge dyno muffler.
Alan was running Dyno Don 1.75” kinda shorty headers for sure. I’m pretty sure he was running two three inch 200 cell metallic cats then running a 4” exhaust out back. I’m not sure of the Y pipe, but do remember linking him the 3 to 4” flowmaster. I can’t remember the muffler he was using but I’m partial to the Borla XR-1. They have a pretty long one that will fit a 3rd gen in the stock location while keeping sound to a minimum for a 4” exhaust.
Really good heads that has increasing flow past the cam lift and an intake that won’t choke it down helps to carry power past peak also.
That statement regarding the dyno headers is key and is often overlooked with that kind of testing.
Seems to me I recall Alan's terminator box experiment as there was some back and forth that I was trying to contribute. Might not be the same vehicle though.
Regardless, when it was all said and done, IIRC correctly he wasn't terribly impressed by the work vs reward value. But I may not have all of the info there.
Then it occurred to me much later was that I hadn't considered his cam spec. In particular the overlap as, the way I understand it, this is where the terminator box and it's resultant pressure wave tuning works on the intake valve during that overlap period. Very little overlap means less powerful results. Same deal with the open dyno headers. If the open collector length is in the right place, then the output will be enhanced and develop a peak on it's own. That is if the engine spec is designed for it. Then that engine goes in the car with a choked exhaust and output goes out the window.
Those are my observations anyway. I've done some track testing with something as simple as a single cutout at the turn before our traversely mounted mufflers and gained both MPH and ET on a 1/8 mile drag strip pass. Back to back tests too.
EDIT: I went back an re-read Alan's T box thread. https://www.thirdgen.org/forums/exha...ion-boxes.html
Seems there was a significant benefit from the experiment and that's despite only 54° of overlap.
I see too that PipeMax was used in the development.
Good bit of info there! 12.90's aint bad at all with a head thats around 230cfm.
When I swapped over to a box-stock FIRST it ran 12.60s in similar track conditions. During the initial test drive, I thought the shift-point was going to be 6,000 or 6,100 RPM (the SLP/TPI combo struggled to get to 5700 rpm) At the track it ran the same times shifting at 6000/6000 as it did at 5800/5600, so 5800/5600 was where I shifted it. The throttle response was still off the chart, but not quite as insane as the SLP/TPI combo. It was a good bit easier to launch also.
SLP/TPI Intake - track data – 26x11.5 M/T ET Streets
88*F / 29.92 barometric pressure / 86 percent humidity (358' elevation)
8* initial timing, VERY heavy burnout, foot brake off idle, and staggered throttle launch (pumping the gas well past the 60ft mark), 5,500/5,500 shifts.
Practically impossible to launch at 10-degrees base timing – dropped to 8* to help hooking, 6-degrees helped 60ft, but killed MPH
60ft------ 1/8 ET -----MPH ------ 1/4 ET ----- MPH
1.873 --- 8.268 ----- 83.94 ---- 12.953 --- 104.40
FIRST Intake - track data – 26x11.5 M/T ET Street
83*F / 29.92 barometric pressure / 84 percent humidity (358' elevation)
10* timing, 42 psi fuel, 20 psi tires, heavy burnout, foot-brake 1800 rpm, near full throttle launch, moderate traction problems, 5800/5600 shifts
60ft------ 1/8 ET -----MPH ------ 1/4 ET ----- MPH
1.707 --- 7.992 ----- 85.53 ---- 12.599 --- 106.70
That's the question I've had since the outset. Also, with all of those intakes tested, what are their lengths?
Quick question. To model this (somewhat) in Vizard's Torque Master program, what would you choose for maximum port CFM? Where would you think peak HP RPM would land? Do you have a cam in mind? The LPE 219 was tossed around.
His program will also predict the peak HP/TQ RPMs for a given intake runner length.
That's the question I've had since the outset. Also, with all of those intakes tested, what are their lengths?
Quick question. To model this (somewhat) in Vizard's Torque Master program, what would you choose for maximum port CFM? Where would you think peak HP RPM would land? Do you have a cam in mind? The LPE 219 was tossed around.
His program will also predict the peak HP/TQ RPMs for a given intake runner length.
I've seen quotes for stock TPI runner length ranging from 19" to 25". Some may include the head? I have a TPI in the "museum", I could measure tonight?
Other intakes' runner lengths are covered in my "Hot 80's Intakes" THREAD
I've seen quotes for stock TPI runner length ranging from 19" to 25". Some may include the head? I have a TPI in the "museum", I could measure tonight?
Other intakes' runner lengths are covered in my "Hot 80's Intakes" THREAD
The runner length from where it meets the plenum to the cylinder head interface (so including the base). Then we assume port lengths in the conventional average of 5.25" - 5.50" (at least I think that's the accepted range). Then that total can be used in TM to see where the peaks might fall.
I'll look back into that 80's article. I must have missed it. Thanks.
Sorry it went this way guys but after years of starting and reading threads where there’s always a fight, etc. watching members leave, or get banned because things got hot, I’m really tired of it. Most of the people with these cars don’t even get on here anymore or Facebook and I understand why.
I’m looking at an info page with chat that’s invite only. If you have any ideas let me know. I need a place to put all this info so different parties can log in and look if they need data.
There was a problem? I thought it was moving along quite well. I can't say there was any argument from my side.
You know, the typical trash name calling you get on TGO. I’m too old and I just don’t have time for that. One guy gets going, then the other guy, then others get going… only this time I was called a couple names… so… fine. If that kind of **** flys… I don’t need TGO lol.
I just made a thread right before this which guys got into it over gear ratios, pretty much wasting time and name calling etc. it’s stuff like that I am staunchly against. We’re here for information and there’s a way to handle public forums to keep it constructive with criticism.
Charlie’s texting me… don’t even think he knows what I’m about to say.
You know, the typical trash name calling you get on TGO. I’m too old and I just don’t have time for that. One guy gets going, then the other guy, then others get going… only this time I was called a couple names… so… fine. If that kind of **** flys… I don’t need TGO lol.
I just made a thread right before this which guys got into it over gear ratios, pretty much wasting time and name calling etc. it’s stuff like that I am staunchly against. We’re here for information and there’s a way to handle public forums to keep it constructive with criticism.
Charlie’s texting me… don’t even think he knows what I’m about to say.
I know what you mean. Speed-Talk is often worse. I've been called out and made fun of. What I did in reciprocation was to bite their collective heads off. Then I learned who the antagonists were, who the jokers were that would just make idle unconstructive comments and tried to relate with professionals or like minded enthusiasts who are there for the value that ST has to offer. I do admit though that it can be a struggle.
I was quite enjoying this build thread. The trash talk kind of just floats by me and if it's just unconstructive criticism it tends to fade into the woodwork. That you have Charlie on board and have Vizard in the loop (now there's a guy who take s a shitkicking) had my attention from the get go.
Am I a TPI fan? Can't say that I am but I do enjoy the sciencing out to gain performance. Unity Motorsports has a good string of videos going about building a "sleeper" engine. Am I a sleeper fan? No. Not really. But there again is some great tech and some hands on that any car guy should appreciate.
I know what you mean. Speed-Talk is often worse. I've been called out and made fun of. What I did in reciprocation was to bite their collective heads off. Then I learned who the antagonists were, who the jokers were that would just make idle unconstructive comments and tried to relate with professionals or like minded enthusiasts who are there for the value that ST has to offer. I do admit though that it can be a struggle.
I was quite enjoying this build thread. The trash talk kind of just floats by me and if it's just unconstructive criticism it tends to fade into the woodwork. That you have Charlie on board and have Vizard in the loop (now there's a guy who take s a shitkicking) had my attention from the get go.
Am I a TPI fan? Can't say that I am but I do enjoy the sciencing out to gain performance. Unity Motorsports has a good string of videos going about building a "sleeper" engine. Am I a sleeper fan? No. Not really. But there again is some great tech and some hands on that any car guy should appreciate.
Anyway, that's what I have to say about that.
I’ll probably put a thread on ST. It’ll be brutal but at least there will be some benefit. Charlie is ready for the kind words ST will have towards this project. I’m too busy with work for drama. I’m signing off TGO. Later
I’ll probably put a thread on ST. It’ll be brutal but at least there will be some benefit. Charlie is ready for the kind words ST will have towards this project. I’m too busy with work for drama. I’m signing off TGO. Later
Don't let the negative comments even matter. I wasn't adding to the thread, but I was reading it with every post. Enjoying the efforts and work going into modding the engines and TPI learning. I appreciate all you guys and hard work you put in. I think alot of others do too. Always eager to learn from the info posted on this forum.
Again I’m sorry but I get tired of the negativity on TGO. Like I said I see a lot of arguing pointlessly on here and I just would rather not waste anymore time.
I have a new thread on Speedtalk you can see which will be with a crowd who can maybe contribute. Allen already did most of the hard part by making his intake basically from scratch but this is for guys who just want to see what modified aftermarket parts can do when it’s done with what we know at this point in time. I don’t expect TPI to be popular there but I have to have something that keeps track of it that multiple parties can see at any given time.
You know @MrIROBZ , I don't find TGO to be that bad. Maybe my subject matter is more the mainstream. But to be innovative is all part of the hobby. The racing, or go faster industry really, is all about that and we'd be nowhere without it. And it goes beyond developing the new technology further. Flatheads come to mind. Why modify and race, very competitively I should add, something developed nearly 100 hundred years ago? Because we can. And others do. And we race them. Or whatever.
Anyway, you're in some good company with your project at ST. Positive folks by most accounts. I'm looking forward to it and I'll see you there. Maybe you'll reconsider and share some of that here. TGO has a reputation for being a solid tech based resource. It would be nice to keep it that way. Where else would you go for TPI insight?
TPI is at the heart of 3rd gens. I dare say they overshadow the 'Vette due to sheer numbers. As Skinny said, where else is there such a solid base for TPI engines than here.
04-09-2024, 07:25 PM
