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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Spun a bearing in the 305 (stock motor in an 86 TRans am.
I have a 350 roller block I want to build to put into the car.
Would Dart Iron Eagle Platinum heads (215 runners and 64cc chambers) bee too much head for this car (running the stock TPI setup).
The alternative is a pair of 882's I also have on the shelf.
I've gotten conflicting info--while I know the Darts are a bit big for a street build, I have been told I will be VERY disappointed if I use them...
Car has a 700R4 and stock 2.77 posi 9 bolt
Any thoughts on a real world build (it will be a daily driver)
A vehicle is a combination of parts, like a sandwich or a musical piece
Put one wrong item in, it falls apart, poor performance
Yes I think its a mistake to use some crazy amazing high flow heads on a setup combo without addressing literally every other component, rear gear, tire height, trans internals, converter, accessory weights front and back, compression, valvetrain, intake, ECU everything... The head is a centerpiece which more or less defines the rest of the combo.
It's not that they are 'too big' for anything. They can be successfully used in a correctly implemented sammich. With the correct supporting meats, breads and fibers.
Appreciate the input. I am trying to be budget minded, as I have those Iron eagles sitting on the shelf. I also have a couple pair if the 882's I mentioned.
The 882's give a compression on stock block of about 8:1, which feels terribly low, as well as being not a great head to begin with. Maybe with the right cam, I can still make pretty respectable power that won't tax the rest of the stock components too heavily.
As this is a daily driver (and would like to run on 87 Octane), we do plan on using almost all other stock components, save for a chip to be tailored to the 350, cam we end up choosing, etc).
If you don't have forced induction I recommend a compression approaching 10:1 perhaps 9.8:1 or so, will work well using pump fuel 87 octane with the right cam
If economy is a consideration always use the highest compression possible with respect to the lowest quality fuel you intent to use
You would also prefer some lightweight drivetrain components, that rotate, such as light weight wheels, light flexplate if auto, lighter driveshaft maybe, use numerically low gear ratio 2.7 to 3.15 or so, taller tires for drop cruise rpm, reduce vehicle weight as much as possible take everything out, the lighter you can get the parts especially rotating parts the superior economy
make sure alignment is spot on and camber is ideal nearly straight up 0* for the rear especially max longevity tires
The most reliability and economical will be using an LS style engine with OEM computer, tuned properly MPFI port injected with dialed injector timing (post exhaust valve closed) and using a stock untouched LS engine like a modern 02+ even high mileage is fine, superior economy and reliability, set the rev limit low like 5800rpm keep OEM parts inside, dont touch with human hands anything inside the engine
The 882s would be an absolute disaster. Worst of the worst in stock heads or very close to it. A downgrade from a stock 350 TPI (L98) in every possible way. Maybe even a few ways that aren't possible, they'd manage to downgrade it anyway.
Therefore while those particular Darts aren't right for the combo, they're the lesser of the 2 evils. I don't think you'll be "disappointed" except to the extent that something else might be better. They'll be better than what would have come on the 86 L98 (which wasn't available in these cars of course). They won't "hurt" anything. But many other head choices would be more nearly optimum.
I'd suggest the Comp "502" grind 008-502-8 and possibly 1.6 steel roller rockers.
Your primary "disappointment" will be the stock converter and those horrible worst-of-the-worst gears.
The 882s would be an absolute disaster. Worst of the worst in stock heads or very close to it. A downgrade from a stock 350 TPI (L98) in every possible way. Maybe even a few ways that aren't possible, they'd manage to downgrade it anyway.
Therefore while those particular Darts aren't right for the combo, they're the lesser of the 2 evils. I don't think you'll be "disappointed" except to the extent that something else might be better. They'll be better than what would have come on the 86 L98 (which wasn't available in these cars of course). They won't "hurt" anything. But many other head choices would be more nearly optimum.
I'd suggest the Comp "502" grind 008-502-8 and possibly 1.6 steel roller rockers.
Your primary "disappointment" will be the stock converter and those horrible worst-of-the-worst gears.
Interesting--the 2 cams that I kept coming back to (with the dart heads) were the "502" grind that you mention, and the "501 grind (008-501-8)...Appreciate the insight. At the end of the day, it if is a significant upgrade over the stock 305, I think we'll be pretty happy. Just got a doubt put in my mind talking to someone that kept saying the heads were just "too big." I understand we are leaving peak performance and high RPM on the table (that the darts are capable of)--that's OK--it is a daily driver after all, and not meant for the track.
We'll also be running headers (the old SLP ones that I picked up a few years ago) on the new motor (that we were not running on the 305.
I just don't want to end up with a build that ends up falling on its face.
215cc runners could have a low port velocity right where TPI needs port velocity. I feel like you will lose 100lbf-ft of torque or more from 2500 to 4500rpm and then the TPI will shut down at 4800 leaving you with nothing. You won't miss what you never had... install them and it will 'work' but 350torque vs 450torque... how will you know without a dyno?
The TPI can make incredible low and mid-range torque but it needs that port velocity to match the runner diameter throughout the intake section and that include the part of the head where the runner will open up and velocity will drop off at low flow rates
If it was any other intake I would be 'okay' with it but TPI just happens to be the one intake on the planet where length of the runner and velocity profile is absolutely critical to achieve it's ideal affect
What I would recommend is search for a dynojet result that uses those heads with TPI intake and just look at the output, compare with the stock torque and mild cam torque.
Its been 25 or 30 years so if there is no dynojet data image available by now... well lets just pray
Run them if you got them. It certainly isnt ideal. They arent the greatest heads and could benefit from some port clean up. Good valve job at the minimum. Put good hyd roller springs in it
Fast355 ran them on a mild 350 just fine. But with a performer rpm intake.
the bigger problem you will have to deal with is those heads i believe are 1206 port and the base is slightly less than 1205 and not a lot of material around it. Im not sure how well they will fit and seal. Porting stock base would help with flow but not gonna get it to match in area. So i would maybe take some measurements and mock it up to see if it will work
Agree with what most have said here that neither head listed is close to ideal. The 882s are just bad all around and the darts (while a good head) are a big mismatch for the rest of your combo. The TPI, gears, and converter are all screaming for low end meaning small heads and moderate cam.
My advice is sell the other heads and get a decent set in the 180ish range and pair it with the cam sofa recommended. After tuning it, it will be a massive improvement over your 305, be matched with the TPI pretty well, and work with the TC and gears you have now, but will work even better if/when you upgrade those later.
BTW you said you are putting in the headers, have you also done the cat back as well? ALL parts of the factory exhaust have to be junked to realize the potential gains of the new engine otherwise it will be choked.
The 215's good with a stealthram, decent 220's @ .050 cam, headers, 3200 9.5" converter , built trans, 3.23 to 3.5's gears, 26.5" tall tires
iirc you might break the 10-bolt at that point with traction though leading to another chain of upgrades in the rear, this whole mess is turning a basic 350 swap into a 13k project with weeks of downtime and too many mistakes if you are not advanced mechanic capable of rebuilding/diagnosing a transmission yourself, this isn't the pathway for saving money
IMO just stick to the TPI get the right heads on it, leave everything else alone save your money, use normal tires don't break anything, keep the economy, use a very low lift cam low lift to preserve the valvetrain and maintain reliability, don't need lift to make decent mid-range TPI torque with the right head, use low pressure springs is the key that will keep the lifters/guides/lobes alive and free up economy and again lighten everything you can lighten up
Maybe I'll just hold onto the Darts for a their original plans (an EVENTUAL 406+ build for either my 1977 vette, or a future nova project--you never know ).
Are 997's any better than the 882's? I have a pair of them on a 400 block waiting for a teardown. I'd imagine they are basically the same low performance, smog crap, though.
I also have a set of 461's on the shelf, but I cannot use them as they have no accessory holes.
What about the existing 305 heads? It would put compression a bit too high with 58cc chambers, no?
Guess I'll start looking for a decent pair of used heads that might match the car better.
Appreciate all the input. Lot of knowledge out there!
Yup, 997 is pretty much the same smogger 70s garbage.
305 heads give higher compression but then you get to deal with the reduced flow from the smaller valves. Butt by the time you clean that up, the higher compression goes away, because you have to open up the chambers.
Yup, 461 isn't really an option. Not a good head for anything in this day and time outside of "numbers matching". Due to chamber design they tend to require gasoline that's no longer available except at FBOs.
If it was me I'd keep looking. Doesn't sound like your situation is urgent, might as well not make a mistake you can't easily undo, in unnecessary haste.
The reason the "502" gets suggested alot is because it was targeted specifically at TPI and matches it well. TPI places unique constraints on the cam profile; it's REAL EEEEEZY to make a car slower than stock by picking the wrong cam. Even a "good" cam for something else is no guarantee of compatibility with TPI. But most especially with a stock converter and those crappy 2.xx gears. Doesn't get much worse than that.
Last edited by sofakingdom; 06-30-2022 at 08:13 PM.
How about bolting on the 305 heads on that 350? Bump the compression and with a cam suited to the heads you could still get most of the power possible with the tuned port.
I love the "lose 100 ft/lbs" comment from mr thinks he knows it all. Worst case it gives up 10-15 ft/lbs in the midrange and gains low-speed torque. Big heads work great with small cams. LS engines start at 205cc on the ports and they are running them on 294 CID. Cam will dictate torque, much more than cylinder head runner cc. My stock runner TPI made peak HP at 5,300 rpm and carried power well to 6,000 rpm. I mean you could hardly call it a HP peak. The HP just leveled off and held perfectly table top flat for 800 rpm.
I love the "lose 100 ft/lbs" comment from mr thinks he knows it all. Worst case it gives up 10-15 ft/lbs in the midrange and gains low-speed torque. Big heads work great with small cams. LS engines start at 205cc on the ports and they are running them on 294 CID. Cam will dictate torque, much more than cylinder head runner cc. My stock runner TPI made peak HP at 5,300 rpm and carried power well to 6,000 rpm. I mean you could hardly call it a HP peak. The HP just leveled off and held perfectly table top flat for 800 rpm.
TPI can make an incredible peak torque of 450ft*lbs iirc. Its been years but its def worth 50 to 80 perhaps 100 torque at the engine. You better look up some dyno curves or give me a chance to review some. I promise you its more than 15 or 40
Im not trying to be a know it all I just know from 20 years ago setting up TPI and dyno vs the stealthram it was around 100 lbf-ft of torque I gave up all else equal on the same engine. Night and day difference. The car really really pulled hard through the midrange with the TPI- @#* top end power. Ill take the 25mpg and midrange torque, it stuck with me. Lets compare some graphs, look up stock TPI and slight mod TPI vs some stealthram stuff. Let me see what you find. I will do some leg work also but not right now idk when
be reasonable and don't call names on the internet we all share the hobby just have fun with it and good nature
I lost 15 lb ft total peak to peak with stealth ram vs stock tpi. Losing a ton of torque something has to be very off for that to happen lol
If you are keeping stock tpi then you arent trying to set the world on fire with performance so imo, as long as the base seals against the heads (gasket port sizes) then might as well keep car running and throw the 215’s on. Its not gonna be a total turd and intake was never gonna be great even on a afr 180-190 head.
My stock runner TPI made peak HP at 5,300 rpm and carried power well to 6,000 rpm. I mean you could hardly call it a HP peak. The HP just leveled off and held perfectly table top flat for 800 rpm.
basically what happens when intake or head ends up being restricted and the cam wants to make power above it. Hp curve will flatline. Extends rpm range abit even tho it’s not making anymore peak
Words are useless in a torque/power comparison, use dynojet numbers ONLY to keep comparisons equivalent.
These tests, manifold and mods were done early as 2003. This information is very old.
This assumes the port shapes match correctly and the velocity is maintained for both examples. Thus, when losing both resonance effect of TPI AND the port velocity associated with 215CC mismatched heads, and presumably the port shape incorrectly mated, there will be an additional 50~ torque loss making for a total of 100~ lbf-ft of torque lost IMO.
Next we will research what people think about the combo in question here in this thread.
The TPI motor is mostly based upon port velocityand this is what generates all the torque your TPI motor is famous for. The larger the runners the slower your port velocity will be. Unless your running more cubic inch and something different than a TPI type intake your going to knock the wind out of any bottom end power your motor might make.
200+ is too big. You'll lose velocity, power and they're too big to work with that cam. Mince cc'd at 198, flowed 280 and make power to 6300.
Save the big runners for 240*@.050"+ cams with single plane intakes.
I agree with these, they match with what my conceptualization is telling me. If you have experience designing fluid flow and fluid mechanics applications you will instinctively know this is the case for the comparison being offered here.
Funny I stumbled on this thread- I won't dig too deeply here but I will say the numbers provided are not dynojet so they could be anything. I never trust anything besides dynojet. The dynojet uses a known mass roller and algorithm which cannot be fooled easily, most people lack the photoshop or hex editing skills to do so. https://www.thirdgen.org/forums/tpi/...ml#post3802309
and with the smaller port volume (170 cc vs 215 cc), the flow speed will be much better so the swirl and turbulence will be much better.
...if using TPI intake system yes those heads will be too much, anything over a 1204 gasket on the intake ports is too much for the TPI based intake.
Sounds like the ports won't even match up. That is a dead give away right there. IF the head port doesn't exactly match the intake port- in a natural aspirated application this is a combo killer no matter what parts are used. I've seen 427cid engines lose around 100hp to the tires just from mis-matched port shapes. Air does not like to separate, the flow through a tube or structure must be kept as "smooth" & laminar as possible, and even in turbulent situation it helps reduce separation if there is no sudden edge or change in diameter or shape of a tube.
hehe thought this was funny... crucify you for suggesting 215cc on a TPI 383... how does he know?? HOW DOES HE KNOW? Somebody has gotten crucified for suggesting this combo it seems. https://www.aussiev8.com.au/showthre...ish)-383-build
p=491071&viewfull=1#post491071
I will get absolutely crucified for suggesting 215cc heads
ron eagles to 215 C. C. heads (pocket ported with a three angle valve job) .... But the combo would be an absolute disaster to stick that engine in a Corvette with the late model TPI intake...
absolute disaster you say... Yes I agree. TPI with 215CC would be an absolute disaster. Taken out of context, the combo he is associated with a low numerical rear gear and so forth.
Here's some flow figures, right off the manufactures sites in many cases. Keep in mind the concept of the chains weakest link. It does ABSOLUTELY no good to match a base or runners on a TPI intake that flows 250cfm if the other part flows 200cfm. You'll still only flow 200cfm.
Id point out that the stock TPI intake and heads are BOTH very restrictive and even after max porting it will never provide near the upgraded power potential that the better aftermarket cam and heads, and TPI intake will provide.
the stock heads barely flow 200cfm even ported they rarely exceed 230cfm and even stock, mildly cleaned up vortec heads exceed that flow rate.
that hardly maters as the stock TUNED PORT INTAKE barely keeps up with stock heads as it was originally designed for a 305 displacement engine.
the stock cams designed to max out power near 4500 rpm
What I'm seeing here is the port flow match making stuff, well read it and see for yourself. They should match flow rates, port size, etc... combo is a like a sammich... put in the good meats and cheeses... blah blah blah It goes back to matching parts and ports and smooth flow. What you need for NATURAL ASPIRATION Is to prioritize these properties because every scrap of energy wasted forcing air to bend, separate, disorganize, etc... is lost power and torque.
You want to match the intake runner size with the size of the engine.My experience of many,many,yrs of building engines is a minimum of 180cc's for a 350/355 and a minimum of 195cc's to 200cc's for a 383 to 406.You can somewhat plot out a power curve with these choices of heads.
Another vote for 180's @ 350cid mild builds. I Mean, you see it everywhere. Its like some people don't learn after 20 years- what the @#(%&$ are they doing? Just disagree with me because its me, thats what it seems like.
After reviewing around 10x dynojet curves of various TPI engines I will add my personal input. I have tuned hundreds of vehicles and always use dynojet because it provides a standar with so I am sure when I see some number that I understand how that number got there. I am confident in my ability to gain information from dynojet curves after tuning so many different types of engines.
What I noticed is that in many curves, the factory TPI tends to provide 40 to 60lbf-ft of torque in the mid-range of typical 350cid dyno graphs to the tires. This would be maybe 75ft*lbs of torque at the flywheel for many engines. Knowing that and working backwards, due to lost port velocity associated with mis-matching runner I can easily predict roughly 100 low end torque loss around 2000-2500rpm due to turbulence, lack of flow organization, separation, etc.... essentially "A disaster" to use 215CC intake runners coupled to TPI intake and a TPI suited camshaft profile. And that is assuming you can actually mate the port diameters properly, without that I can't even predict how bad it will be.
Maybe if they matched its not so bad once the engine can reach 4500rpm~ but that is where the TPI gives up the ghost and so... I can not in good faith recommend this combo even for the sake of just passing. You'd be better off with a 180cc or 190cc head combo with a matching intake port to the TPI intake regardless of the bottom line flow numbers- because the TPI is not centered around peak flow or peak HP, its strength is the low and mid-range torque, high velocity ports are it's defining feature. Reliability demands a low lift cam and a stock converter and numerically low gear ratio demands torque at 2000rpm~.
To put this another way, I cannot find a single dyno of 215cc runner head using TPI intake on a 350cid engine.
Its almost like nobody is stupid enough to try it.
Cylinder head selection will MAKE or BREAK your combination. Selecting and setting up the heads is even more important than selecting the cam. The cam has to match the heads, intake, exhaust, and short block
take this guys advice, Fast does he trust himself anymore?
Don't BREAK your combination, pretty funny contradictory advice, if you argue it is only with yourself.
That's a lot of info to digest for the weekend hot rodder/hobbyist!! LOL, but all very informative, which is what this is about--learning.
My initial thought was (even at a loss of 100 ft'lbs of the 450ft/lb potential), 350ft/lbs is still a remarkable upgrade over the stock 240 that was spec'd on the 1986 305.
After that deep dive (and thank you for posting it all), I will see if I can find a better matched head to the stock bottom end and TPI...and 502 cam. Maybe a set of 180-190's.
That's a lot of info to digest for the weekend hot rodder/hobbyist!! LOL, but all very informative, which is what this is about--learning.
My initial thought was (even at a loss of 100 ft'lbs of the 450ft/lb potential), 350ft/lbs is still a remarkable upgrade over the stock 240 that was spec'd on the 1986 305.
After that deep dive (and thank you for posting it all), I will see if I can find a better matched head to the stock bottom end and TPI...and 502 cam. Maybe a set of 180-190's.
Sorry I didn't mean to confuse you. The torque thing is a percentage based. I was just using 350/450 as an example. I think TPI adds about 15% torque (300/350) by itself and the head mismatch is perhaps worth another 10 to 20% of torque. So if you have only 250 you would lose 15% of that and perhaps another 15% to 20% on top of that, lost resonance from TPI and lost organization from port mismatching is possible. Up to 30 or 40% of torque at low RPM lost is possible. It may only be 20% though. So best case scenario if you made 240 it could drop to (240 * .85 = 200~) as an example. I don't see a V8 engine losing all that much torque honestly 240 is very weakly done, and you gota watch out whether its to the tires or at the engine how you regard the numbers. Suffice to say its better just get the most you can get by using the correct combination of parts and not trying to guess anything because if you don't like the results you have to rip it all apart and thats not fun.
The torque aspect isn't flow capacity- flow is for power, like top end capability during a portion of usable lift or port area at some maximum flow rate velocity where the port is being choked by the airflow as it approaches the speed of sound or inhibited due to water hammer. For torque its not the flow but the velocity and packing air into a cylinder at LOW flow rates that becomes important. So looking at flow numbers isn't really helpful. (For Torque) We have to look at momentum of airflow and pressure waves in air, and the ability of air to change direction rapidly and respond quickly to alternative valve events, an engine is a cyclic frequency like a processor with specific programmed events and how overlap influences those events. The exhaust system can pull much harder on a cylinder during overlap bringing in fresh air charge to produce massive torque and nice cylinder pressure than the piston can, for example. But the port and cam config needs to be mated well to put that energy to good use, that is where port matching and velocity and momentum/kinetic energy are the players. A too-large port with poor velocity, poor energy conservation and poor organization is going to be all over the place during overlap instead of producing a healthy defined column of air stacking into the cylinder.
Have an old idle clip of a 350TPI on commander950 from 20 years ago, flat tappet can 230's duration still made great torque, Edelbrock performer RPM heads and long tubes.
Plenty of cheap 113 Aluminum heads or Summit brand heads out there that will fit your intake and run great. Wont make huge power but your stock TP I system wasn't made for huge power anyhow. It will be fun enough
Looking around to see what's out there...are 370 heads any good? Cant see any numbers on runner size, but combustion chamber is 64, valves are 2.02/1.60, and they appear to be old school "over the counter" performance heads (300hp)?
Also see a pair of edelbrock heads, but the casting number says 6088--can't seemt o find anyhting on that number (I can find 60887 and 60889, but NOTHING on the 4 digit.
I agree with these, they match with what my conceptualization is telling me. If you have experience designing fluid flow and fluid mechanics applications you will instinctively know this is the case for the comparison being offered here.
Funny I stumbled on this thread- I won't dig too deeply here but I will say the numbers provided are not dynojet so they could be anything. I never trust anything besides dynojet. The dynojet uses a known mass roller and algorithm which cannot be fooled easily, most people lack the photoshop or hex editing skills to do so. https://www.thirdgen.org/forums/tpi/...ml#post3802309
Sounds like the ports won't even match up. That is a dead give away right there. IF the head port doesn't exactly match the intake port- in a natural aspirated application this is a combo killer no matter what parts are used. I've seen 427cid engines lose around 100hp to the tires just from mis-matched port shapes. Air does not like to separate, the flow through a tube or structure must be kept as "smooth" & laminar as possible, and even in turbulent situation it helps reduce separation if there is no sudden edge or change in diameter or shape of a tube.
hehe thought this was funny... crucify you for suggesting 215cc on a TPI 383... how does he know?? HOW DOES HE KNOW? Somebody has gotten crucified for suggesting this combo it seems. https://www.aussiev8.com.au/showthre...ish)-383-build
p=491071&viewfull=1#post491071
absolute disaster you say... Yes I agree. TPI with 215CC would be an absolute disaster. Taken out of context, the combo he is associated with a low numerical rear gear and so forth.
What I'm seeing here is the port flow match making stuff, well read it and see for yourself. They should match flow rates, port size, etc... combo is a like a sammich... put in the good meats and cheeses... blah blah blah It goes back to matching parts and ports and smooth flow. What you need for NATURAL ASPIRATION Is to prioritize these properties because every scrap of energy wasted forcing air to bend, separate, disorganize, etc... is lost power and torque.
Another vote for 180's @ 350cid mild builds. I Mean, you see it everywhere. Its like some people don't learn after 20 years- what the @#(%&$ are they doing? Just disagree with me because its me, thats what it seems like.
After reviewing around 10x dynojet curves of various TPI engines I will add my personal input. I have tuned hundreds of vehicles and always use dynojet because it provides a standar with so I am sure when I see some number that I understand how that number got there. I am confident in my ability to gain information from dynojet curves after tuning so many different types of engines.
What I noticed is that in many curves, the factory TPI tends to provide 40 to 60lbf-ft of torque in the mid-range of typical 350cid dyno graphs to the tires. This would be maybe 75ft*lbs of torque at the flywheel for many engines. Knowing that and working backwards, due to lost port velocity associated with mis-matching runner I can easily predict roughly 100 low end torque loss around 2000-2500rpm due to turbulence, lack of flow organization, separation, etc.... essentially "A disaster" to use 215CC intake runners coupled to TPI intake and a TPI suited camshaft profile. And that is assuming you can actually mate the port diameters properly, without that I can't even predict how bad it will be.
Maybe if they matched its not so bad once the engine can reach 4500rpm~ but that is where the TPI gives up the ghost and so... I can not in good faith recommend this combo even for the sake of just passing. You'd be better off with a 180cc or 190cc head combo with a matching intake port to the TPI intake regardless of the bottom line flow numbers- because the TPI is not centered around peak flow or peak HP, its strength is the low and mid-range torque, high velocity ports are it's defining feature. Reliability demands a low lift cam and a stock converter and numerically low gear ratio demands torque at 2000rpm~.
To put this another way, I cannot find a single dyno of 215cc runner head using TPI intake on a 350cid engine.
Its almost like nobody is stupid enough to try it.
take this guys advice, Fast does he trust himself anymore?
Don't BREAK your combination, pretty funny contradictory advice, if you argue it is only with yourself.
I have learned alot over the years. As I said, I doubt you would see 15 ft/lbs between a 180cc runner and a 215cc runner. I have run a 180cc and a 200cc runner under a TPI. The 200s lost zero torque to the 180s anywhere. A 350 will not signifigantly lose torque output until you are up over 220cc. I ran aluminum 200s on a 350 in a towing application and those gained everywhere compared to a vortec head.
There was an old test where all 5 of the Dart Iron Eagles were tested on a 355 using the same shortblock, cam, headers, intake manifold, etc. Under 4,000 rpm the 230cc heads made the highest average torque and between 2,600 and 6,000 the 215s had the highest average torque. Up to 4,000 rpm the 215s gave up 1 ft/lbs average to 180s. The 215s made the same exact 411 ft/lbs at peak but made it at 3,800 rpm compared to 4,000 for the 180s.
Richard Holdener has also done tests with varying in the cylinder heads. Same trend there as well. Biggest and best flowing heads made the most low-speed power. Look at how big the head ports are on a rectangle port LS or a 2nd gen modern Hemi. They make power with broomsticks for a cam. Want power and good manners, use great flowing heads and a small cam.
notice the 220cc heads on this 415 displacement engine!
415CID without TPI- sure thing use the 215-220CC
larger head ports are DESIGNED for high RPM operation with longer duration cams and higher flowing intakes, theres little to be gained with out matching all the parts to the desired rpm and hp range
Thus, when losing both resonance effect of TPI AND the port velocity associated with 215CC mismatched heads, and presumably the port shape incorrectly mated, there will be an additional 50~ torque loss making for a total of 100~ lbf-ft of torque lost IMO.
thAts just speculation. Words are useless use dyno numbers… lol
If he already has the heads, theres no shame in throwing together a parts bin build, as long as it seals up, as i had already mentioned earlier with the manifold/head port sizes. Theres nothing wrong with a slight step in the port. Actually that restriction may act to help increase velocity in that portion of the head. Wont know til you get it on a bench or try it out.
if you can sell them great. Iron heads however are a tough sell imo when you have tons of aluminum options that flow as good or better and save 50 lbs.
could run it for now to enjoy the car until the 400” motor is done or throw in a single plane efi setup. Can still use stock efi electronics, just need elbow and ls throttle, splice in the new tps and iac sensors
Serious street performance, modified oval track and bracket racing. Mid-range to 7,000 RPM.
Dart Iron Eagle Platinum 23° 215cc heads are for big cubic inch, high RPM applications which favor peak power over low end flexibility
OVAL Track and Bracket racing, midrange to 7000RPM for big cubic inch HIGH rpm application which favor PEAK POWER?
On a TPI setup?
Its laughable. I wouldn't even use this head on a dual plane in a street application because I know better than to try and rely on a daily driver that wants to turn 7k.
They are clearly intended for racing purposes. "SERIOUS application that favors PEAK HP" It needs a 3800converter , gears, 380+cid and a shot of nitrous to really take advantage. And I would single plane it. And then realize I wanted EFI and start all over... its not even an option. Not even ALUMINUM!???
Please just read the manufacturers recommendation and leave it at that. Use at own risk
Yet then again I know nothing on running 215cc heads on a 350. I even had log manifolds on it at the time. I ended up pulling it apart for reasons other than a lack in low-end torque. The valve stem clearence was too tight, when I was running it hard and got it hot it seized a valve and broke a pushrod. Even with a 72cc head in place of a 65cc head (I erroniously stated 76cc back in the day for 810 swirl ports because that is what everyone claimed they were and I later cc'd them) it had enough power to break the tires loose with ease and slide a fullsize TBI 350 powered G20 around like it was on ice. Stock cam with 1.6 roller rockers.
I am also currently running a 210cc port on a 383 in a 6,500 lbs vehicle that frequently tows a 6,000 lbs trailer. It has a ported stock GM intake on it too.
I find it funny you suggest a LS swap, those head ports are big, the intake is mismatched as is the LSA of the cam.
See that bothers me. Pulling **** apart. Always working on your car. Thats not a good place. That was me in 1998 to 2001.
The goal is the LS is to avoid working on your car/engine. You can install a stock engine, have 600rwhp or whatever, and just drive it. Who cares about the ports? Heads? I don't touch any of that. I Know better. I don't like to work on my vehicle. I prefer to utilize a proven OEM platform engine, LS/SR/RB/2J those are the hot tickets for reliable daily drivers.
It isn't how much you spend on an engine. Its how little. The weakest, longest life, cheapest engine, with the most power per investment and highest mileage is the win.
Power isn't difficult to make. Reliability is. Combo can be whatever- if you don't want 600 or 800 reliable hp thats your decision. But the offer is there, turbo an LS application and drive the car. Or keep pulling stuff apart and telling people how bad their LS engines are? SBC is far inferior in so many ways I don't even want to start listing them. If you aren't into engineering let me at least point out that the computer modelling is what turned the LS around and made it similar to a 2jz-gte and sr20det engine. Main girdle, pan support, is integral, necessary to produce the reliability of the LS platform. I don't mean to start a debate- just feed the reality. I had the SBC. Now I have the LS. I won't ever go back. My plug wires have 40k miles at 600rwhp! Not a single misfire. Holy sheet. I never removed the spark plugs once since I tuned the engine before dyno day. No need to work on it. Just change the oil.
See that bothers me. Pulling **** apart. Always working on your car. Thats not a good place. That was me in 1998 to 2001.
The goal is the LS is to avoid working on your car/engine. You can install a stock engine, have 600rwhp or whatever, and just drive it. Who cares about the ports? Heads? I don't touch any of that. I Know better. I don't like to work on my vehicle. I prefer to utilize a proven OEM platform engine, LS/SR/RB/2J those are the hot tickets for reliable daily drivers.
It isn't how much you spend on an engine. Its how little. The weakest, longest life, cheapest engine, with the most power per investment and highest mileage is the win.
Power isn't difficult to make. Reliability is. Combo can be whatever- if you don't want 600 or 800 reliable hp thats your decision. But the offer is there, turbo an LS application and drive the car. Or keep pulling stuff apart and telling people how bad their LS engines are? SBC is far inferior in so many ways I don't even want to start listing them. If you aren't into engineering let me at least point out that the computer modelling is what turned the LS around and made it similar to a 2jz-gte and sr20det engine. Main girdle, pan support, is integral, necessary to produce the reliability of the LS platform. I don't mean to start a debate- just feed the reality. I had the SBC. Now I have the LS. I won't ever go back. My plug wires have 40k miles at 600rwhp! Not a single misfire. Holy sheet. I never removed the spark plugs once since I tuned the engine before dyno day. No need to work on it. Just change the oil.
I don't consider forced induction reliable. Too many leak sources and potential for problems and that is on OEM engineered platforms. N/A I do not like a stock or near stock LS. I have owned and driven both and the SBC holds its own for cheap torque even in 2022. The LS has its own string of problems can anybody say cracked heads, trunion failures, broken valve springs, piston slap, cam and lifter failure and almost chronic rear main seal failures. Not having to work on it is why I over built the 383, built it myself double and triple measuring everything and doing everything right. I mean its not like I needed H-beam rods or forged pistons for 500 hp, but it has them. Its not like it needed double valve springs for 0.578 lift at 6,500 rpm but it has them. I do not plan to have to touch it for years now.
I have a buddy that ran GM Fastburns on a 305 with excellent results as well.
When displacement is equal, and engine powerower is being pushed to the maximum of a block, there is nothing more reliable than turbo. Even in a SBC application.
For example
1200hp NA vs 1200hp Turbo
1200hp nitrous vs 1200hp Turbo
2000hp Supercharged vs 2000hp Turbo
Turbo always wins reliability contest when power is at stake and equal
Reasons:
1. Turbo allows you to use low lift camshaft and slow cam ramp lobes which brings valvetrain stress and maintenance down to OEM levels and still make any power
2. Turbo holds rod to crankshaft on exhaust stroke which protects the rod cap and allows much higher redline/rpm and racing conditions reliably
3. Turbo allows instant adjustment of pressure and temperature allowing the use of low quality fuel on the fly or adjust for poor conditions to preserve the engine
4. Turbo allows low compression which keeps starters alive, engine easy to turn, and low stress on battery and cable component
5. Turbo provides kinetic energy in excess which can be effectively used as a vacuum pump to drive crankcase evacuation without having to use external pump or electric pump
6. Turbo acts as a control point in control theory applications
Sure a 200hp corolla toyota is technically more reliable than a turbo engine. I am not saying turbos ADD reliability to anything. Or even economy- they suck fuel no doubt. But in a performance app where you desire max power from a given displacement, the turbo always wins hands down, nothing can beat it to this day and age in terms of reliability, control.
Et Al;
How much power does a 2L engine make with 500hp turbo? How much power does 6L engine make with 500hp turbo? Its the same thing. Turbo makes the power you desire, engine displacement is meaningless. The engine becomes a reliable air pump and the turbo does the pushing to protect the engine from stress.
Maybe this would help. There is a computer program “Desktop Dyno” (Comp has one called DynoSim5, maybe it’s the same thing) that runs on a PC desktop (check to make sure your system will support the program). I see it listed for $59.00. You can enter everything for your engine. Bore, stroke, head flow, exhaust type, cam specs, intake type w/specs, and more. I used years ago to model my engine to get what I wanted in the power band I wanted. The car was ran on a dyno (Mustang I think) and it came out close to what the computer modeled. Now I see a place called Engine Labs used the computer program to model 2 engines they had actually built and ran on a dyno previously (an LS and a Coyote) and the results were ever so close. Differences of 1.5% on torque, and 3% on horsepower. I probably ran 100+ combinations to get what I wanted.
I build a 406 TPI with all emissions equipment in-tact. I wanted all torque, a fun street machine for cruising. I was using a 4500rpm limit since the factory TPI just won’t flow enough air to support a 406 at 6000 rpm. Heads are a World Products S/R Torquer with big valves and a 170 runner for plenty of velocity. When I compared a high buck head like an A/R 195, sure the A/R was great at 600 & 700 lift, but my cam only goes up to 500. The flow numbers under 500 were almost the same at the 200, 300. 400 lift so I was able to save a few bucks. Good engine, good fun. Drove it about 100,000 miles so far and still going strong.
06-29-2022, 01:22 PM
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ower is being pushed to the maximum of a block, there is nothing more reliable than turbo. Even in a SBC application.
