Ported Chevy 083 heads, the tpi project

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Re: Ported Chevy 083 heads, the tpi project

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CastIron wrote: Thu Apr 29, 2021 9:16 pm If one could get around 380hp out of a TPI 350 with mildly ported 113 heads in an endurance racing situation it would be great. Not gonna happen methinks.

From what I saw on a Holdener vid where he tested a L98 with TPI and then with a carb it does seem the long block may be a good starting point however.
Some have gotten good HP out of the TPI but always it's a limiter and a better intake will jump up in power(Holdener did an article many yrs ago with all the efi intakes vs tpi). Not to mention the high cost of upgrades for that handy cap. 128 and then 113 heads are early editions of the ZZ crate heads I think, of course modern ZZ heads are many revisions better. Also if you look at those early vette heads, then LT1 heads and vortecs, you can see the design progression. The 128/113 heads were designed for injection and I've herd the runner is different from older carb heads, idk how that compares to raised runner vortecs never had them side by side but if they used them in the ZZ crates it must of not been a big deal.

TPI is a good intake for a not so good engine and most try to make it do what it's not good at rather than enhance it. Lots of good TPI info on thirdgen.org if that's what your interested in. I have a TPI on my C4 with 128 heads and it works good for what it is, once I addressed the other SBC & C4 shortcomings.
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Re: Ported Chevy 083 heads, the tpi project

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RevTheory wrote: Mon Mar 11, 2019 12:18 pm I could be wrong but it seems to me like it's just stacking more length to drag along. I wonder how the length from the valve seat to the end of the base jives with Pipemax now that the runners have been siamesed and probably no-longer count, unless I'm wrong in assuming that the big change in csa will behave like a plenum.
That’s exactly what happens. Every dyno I see with Siamese’s runners still peaks in the low to mid 5XXXX range. It just doesn’t seem to raise the RPM much. Guys used to think the flow was going sonic and choking off the flow but… The First Fuel Injection TPI system flows over 300cfm and is MUCH larger but every dyno I see peaks at 4900-5200 with that system. The frequency doesn’t seem to change when you siamese the runners.

What’s crazy is Jim Hall just ran a L98 with OOTB AFR 190 Vortec heads, SDPC plenum that was mildly worked with ASM runners and TPIS lil Chubs cam that peaked at 5900rpm!! What’s up with that? It made 396.7 hp @ 5900 and 452 tq @ 3900. THAT would be a fun combo for someone still using a good L98 bottom end.
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Re: Ported Chevy 083 heads, the tpi project

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Orr89rocz wrote: Fri Mar 15, 2019 6:14 pm
When your duration starts to move up beyond that you're not GAINING anything and you're losing torque down low.

Beyond that there's the typical recommendations for wide LSAs, but I think that's more because most TPI people are using the stock GM ECUs that came on TPI motors and they can't deal with the low vaccuum.
More duration will force air flow in up high. The power curve will tend to hang on after peak. The long runner tunes for lower rpm peak for hp but cam duration will help some in keeping power from falling off to much

Torque loss down low isnt really hurt that much imo. Long runner still tunes for trq at 2800-3400 rpm where most guys will have converter stall near that so off idle to 2400 rpm isnt needed. And more cylinder pressure there could make it sensitive to fuel and timing if you try to put any compression in it

Cams can be tighter lsa on stock tpi comp just fine if you know how to tune. Maf or speed density. Question is does the long runner intake change lsa required? Most sbc seem to run good in the 107-110 lsa range. Vizards formulas have shown some dyno correlation there. But those are shorter runner carb dual and single planes. How does 17-22” of runner change things?
Well, I agree the runner length changes things. It makes it a lot harder to draw through which is obvious. The question is, do you think a narrower LSA would help pull the intake charge in on a long runner?
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Re: Ported Chevy 083 heads, the tpi project

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Awesome thread Charlie!
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Re: Ported Chevy 083 heads, the tpi project

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RobZ28 wrote: Sat Mar 16, 2024 9:57 pm The question is, do you think a narrower LSA would help pull the intake charge in on a long runner?
Earlier intake opening, (If that isn't already optimised) more open area at TDC from the LSA tightening ?

Get the column of air going stronger earlier.

But you'd still need the closing point to get the fill so more intake duration at the start as opposed to moving the existing lobe.
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Re: Ported Chevy 083 heads, the tpi project

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Tom68 wrote: Sat Mar 16, 2024 10:24 pm
RobZ28 wrote: Sat Mar 16, 2024 9:57 pm The question is, do you think a narrower LSA would help pull the intake charge in on a long runner?
Earlier intake opening, (If that isn't already optimised) more open area at TDC from the LSA tightening ?

Get the column of air going stronger earlier.

But you'd still need the closing point to get the fill so more intake duration at the start as opposed to moving the existing lobe.
Do you think the shorter LSA helps higher RPM performance with long runner intakes? The TPIS engine above had a 110 LSA and peaked at 5900, Richard Holdeners TPI mega test on YouTube also had a tighter LSA that peaked at 460hp at 5800-5900rpm.

The theory of a tighter LSA making more RPM on TPI flies in the face of what’s considered the TPI gospel of using at least a 112.
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Re: Ported Chevy 083 heads, the tpi project

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I'd be focusing on intake opening and closing points, not the resultant LSA that's still dependant on your chosen exhaust events.
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Re: Ported Chevy 083 heads, the tpi project

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Tom68 wrote: Sat Mar 16, 2024 10:46 pm I'd be focusing on intake opening and closing points, not the resultant LSA that's still dependant on your chosen exhaust events.
That’s how it’s done but I’m still curious as to what makes some of these TPI cars peak at 4900. Others peak at 5900. That to me is telling me there’s something that’s not well understood. The camshaft LSA is the only thing I can see that’s different.
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Re: Ported Chevy 083 heads, the tpi project

Post by Orr89rocz »

RobZ28 wrote: Sat Mar 16, 2024 10:50 pm
Tom68 wrote: Sat Mar 16, 2024 10:46 pm I'd be focusing on intake opening and closing points, not the resultant LSA that's still dependant on your chosen exhaust events.
That’s how it’s done but I’m still curious as to what makes some of these TPI cars peak at 4900. Others peak at 5900. That to me is telling me there’s something that’s not well understood. The camshaft LSA is the only thing I can see that’s different.
I think some of that late secondary peak is another harmonic effect. The power almost peaks between the typical 4500-4800 or so range and holds on, with another peak spike later on in the rpm range. Possibly i guess. Just a theory. Pipemax can show runner lengths for various rpm peaks, and playing around you might see some similar lengths at various orders of harmonic waves.
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Re: Ported Chevy 083 heads, the tpi project

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Orr89rocz wrote: Sat Mar 23, 2024 9:47 pm
RobZ28 wrote: Sat Mar 16, 2024 10:50 pm
Tom68 wrote: Sat Mar 16, 2024 10:46 pm I'd be focusing on intake opening and closing points, not the resultant LSA that's still dependant on your chosen exhaust events.
That’s how it’s done but I’m still curious as to what makes some of these TPI cars peak at 4900. Others peak at 5900. That to me is telling me there’s something that’s not well understood. The camshaft LSA is the only thing I can see that’s different.
I think some of that late secondary peak is another harmonic effect. The power almost peaks between the typical 4500-4800 or so range and holds on, with another peak spike later on in the rpm range. Possibly i guess. Just a theory. Pipemax can show runner lengths for various rpm peaks, and playing around you might see some similar lengths at various orders of harmonic waves.
I agree Orr. Unfortunately, I cannot get pipemax to correlate TPI stuff correctly and Larry is looking into it. It would have been cool if the guy actually used this stuff Charlie did and had some dyno and track times or something. This would have been fun to see in a stock looking third gen out there running 12's. It's all stock man. I swear!
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Re: Ported Chevy 083 heads, the tpi project

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I'd love to see a purpose built pump gas 427-434 sbc with at least an afr 210, or equivalent and a heavily worked over first tpi, Siamese the runners to make peak tq around 4500, and the runner lengths worked out so it carried peak HP from 5500-6000. It would make for a nice truck engine, or c4/fbody with a modern 6 speed auto. Not enough rpm or power to hurt itself, tractor like torque delivery, with just enough HP to put a 3200 pound car in the high 11's, or pull a trailer across country in a half ton truck. Daily driver reliable. Seems doable but nobody has done it. The few 400 based first tpi I've seen with afr 195 are decent. But the examples I've read about are usually 9:1 compression, mismatched combos. The long runner project 89gta did is nothing short of amazing, and passed California emissions compliance testing.
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Re: Ported Chevy 083 heads, the tpi project

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He worked his ass off to get that right. He still has the record for the highest RPM TPI car as far as I know. Those runners were more like plenum extensions lol.

For what its worth, Siamesing the runners doesnt always equal higher RPM. There are many tests out there that shows it doesn't really gain much. You can see by the video I posted the siamesed runners lay over at 5300rpm. This is what Orr and I are talking about. There is no real correlation of data that shows why some TPI intakes, such as the ones in the video above, are able to make power into the 5800-6000rpm range using big tube NON siamesed runners, while others drop drastically at 4800-5300rpm. First intake manifolds actually have MANY dyno tests showing they lay over at 4800-4900rpm.

You can say camshaft but duration alone doesn't do it. Jim Hall is very proud of his recent 355 that pulled all the way to 5900. The only correlation I can find other than both intakes were ported by Jim, is that the camshafts are using a tighter LSA, which if anyone knows TPI cams they know most are in the 112 LSA range. The one Jim used and the one in the video above are tighter at a 110 LSA.

If you skip to 7:18 on the video you can see what siamesed runners will get you. The test before did better IMO. Ive never been a fan of siamesed runners as they dont do what you think they should to the degree you want them to and they dont look as good as the individual tubes.
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Re: Ported Chevy 083 heads, the tpi project

Post by Bill Chase »

Think you just said it. Plenum volume and smooth entry into each runner is a big factor.
Could explain why the 350/355 stuff revs out higher HP peaks than the 383 tpi stuff does.
He got it to peak higher with not much difference in runner lengths, just more cross section, smoothed out flow in the base. Most of the work he did was centered around increasing plenum volume, and getting good flow into the runners. Would like to see that intake on a 383/406
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Re: Ported Chevy 083 heads, the tpi project

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Plenums that pulled to 6k were stock plenums with port matched runner entry’s. Large tube runners at full length and the bases were port matched to the heads and runner exits.

The 6000 rpm long runner TPI engine in the video above is a 383.

It held out to 6000 rpm with a completely stock TPI intake in the first test. Again, the ONLY thing I’m finding that makes them go to 6k vs 5200 is the tighter LSA. Airflow doesn’t seem to matter for the RPM. The lengths are basically the same between ported and stock. The heads are different. The cubes are different.

I wonder, do you think backing off the timing due to having a fast burn chamber requiring less timing has something to do with it?
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Re: Ported Chevy 083 heads, the tpi project

Post by Bill Chase »

Probably a lot of other variables to consider, quench, pumping losses, ring pack drag. Reciprocating assembly weight, just to name a few. Jim & Holdener's article are not saying anything about where they installed the cam. Retarded/advanced could also be a factor. Just speculation on my part. Not an expert, just intrigued by the tpi like you are dude.
Last edited by Bill Chase on Sun Mar 24, 2024 2:22 pm, edited 1 time in total.
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