Helping air around a curve?

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NewbVetteGuy
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Helping air around a curve?

Post by NewbVetteGuy »

I remember reading ptuomov's 2016 "Ideal bellmouth shape on a curved runner" thread and seeing the CFD flow diagram that he posted of his Porsch "question mark"-shaped runner and thinking "wow: the top 3/4ths of that look just like TPI runners; I wonder what can be done to help air make it through that curve at speed?

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I finally remembered to come back an actually ask that question...

Is there anything that can be done to help make air make such a "C" shaped turn like in a TPI runner and not end up with such huge losses?

Is a smoother runner interior texture at all helpful? (a rougher texture?)
Is there anything that can be done is it hopeless with such a shape?

There was a statement from David Redszus at the end of the 2nd page: "We also found that sand casting surface irregularities had a negative effect in the curved sections but not the straight sections of the induction system."

--Is there some simple, even tiny gain to be potentially found just buying a flex hone one size bigger than the runner ID and smoothing out the inside of the runners given a rough casting in the interior?



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Re: Helping air around a curve?

Post by Bill Chase »

Richard Holdener did some testing years ago where he tested basically every tpi intake on the market, along with a single plane and dual plane. Look at the very first test of a stock tpi intake, then the 2nd, or 3rd test where the entire intake was extensively extrude hone ported. It was a back to back test, very significant gains.

You may also want to search here and thirdgen.org where a guy did new runners, some base welding and porting, as well as extensively redesigning of the plenum. It turned out looking stock, and he is a California native, so it was done with the intent of passing smog, and making as much power as possible, I would call it "max effort" if you search my posts here I responded to that thread about a year ago asking him if he had done anymore work with it, guess he sold it years ago. But there is a very detailed build thread on that intake at thirdgen.org. lots of pictures, dyno results. He was able to extend rpm range over 1000 rpm with no loss of the world famous tpi torque, in fact it was enhanced from idle to it's new rpm limit. I think he said he had thousands of dollars invested, and about a year of his life doing it on the side. But the end result was really good to say the least.

You can push the tpi much further than most people think, but it isn't cheap, nor practical unless you just have to have smog certificate and as much power as you can get.

Out of the Richard Goldener test video, the welded siamesed as&m runners with the extrude honed base and plenum along with 58/58 mm throttle body produced some interesting results, and at a glance with road grime and dust would pass for stock to the average guy. In that video they used a Holley stealth ram and it basically killed it everywhere from 3800 rpm up, but really didn't lose much torque down low compared to the tpi. And it made within 5 peak hp of the Tpis miniram that was also tested during those test sessions. Again, some good info to get aquatinted with. I wouldn't get to caught up in the peak numbers of the testing, but the graphs and curve from intake to intake was very good info for comparison sake.

I know of no other that has done that extensive amount of testing and was willing to share the results with the world for free. Might be worth your time to check it out.if you are familiar with all this I apologize, just hoping to point you to some info pertinent to this thread. I mean tpi is great until it noses over, and all the above references directly relate to extending rpm capabilities, and broader power range of the tpi, and variations of it
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Re: Helping air around a curve?

Post by NewbVetteGuy »

Bill Chase wrote: Fri May 07, 2021 1:27 pm Richard Holdener did some testing years ago where he tested basically every tpi intake on the market, along with a single plane and dual plane. Look at the very first test of a stock tpi intake, then the 2nd, or 3rd test where the entire intake was extensively extrude hone ported. It was a back to back test, very significant gains.

You may also want to search here and thirdgen.org where a guy did new runners, some base welding and porting, as well as extensively redesigning of the plenum. It turned out looking stock, and he is a California native, so it was done with the intent of passing smog, and making as much power as possible, I would call it "max effort" if you search my posts here I responded to that thread about a year ago asking him if he had done anymore work with it, guess he sold it years ago. But there is a very detailed build thread on that intake at thirdgen.org. lots of pictures, dyno results. He was able to extend rpm range over 1000 rpm with no loss of the world famous tpi torque, in fact it was enhanced from idle to it's new rpm limit. I think he said he had thousands of dollars invested, and about a year of his life doing it on the side. But the end result was really good to say the least.

You can push the tpi much further than most people think, but it isn't cheap, nor practical unless you just have to have smog certificate and as much power as you can get.

Out of the Richard Goldener test video, the welded siamesed as&m runners with the extrude honed base and plenum along with 58/58 mm throttle body produced some interesting results, and at a glance with road grime and dust would pass for stock to the average guy. In that video they used a Holley stealth ram and it basically killed it everywhere from 3800 rpm up, but really didn't lose much torque down low compared to the tpi. And it made within 5 peak hp of the Tpis miniram that was also tested during those test sessions. Again, some good info to get aquatinted with. I wouldn't get to caught up in the peak numbers of the testing, but the graphs and curve from intake to intake was very good info for comparison sake.

I know of no other that has done that extensive amount of testing and was willing to share the results with the world for free. Might be worth your time to check it out.if you are familiar with all this I apologize, just hoping to point you to some info pertinent to this thread. I mean tpi is great until it noses over, and all the above references directly relate to extending rpm capabilities, and broader power range of the tpi, and variations of it
Thanks Bill.

I'm a bit of a collector of good power TPI builds.
I've seen all of "1989GTATransAm's" extreme TPI modifications and builds and some of the other guys in the same ThirdGen club in CA, the list of Lingenfelter builds, the HotRod tests, "Inductive Reasoning" series, "TPI Stealth Induction" from SuperChevy, "Something Old Something New" 5 part Super Chevy article series (Vortec-based TPI), Super Chevy's L98 Turbo tests, the Richard Holdener tests, and 2 fully dressed TPI crate motors that are for sale.

I've got my own FIRST Fuel Injection-based TPI engine, I'm just curious if there's anything specific that can be done when you've already got appropriately sized diameter runners for your engine, to help the air make the turn or potentially have less losses through those long runners. -That 180 degree turn is crazy and seems an almost worst-case; can anything make it less bad?

The stock cast texture is pretty rough; extrude honing obviously enlarges the ports but also makes them smoother. -Is the smooth port texture alone worth anything?

Just curious if there's any tricks that can theoretically help air make that turn better.


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Re: Helping air around a curve?

Post by mag2555 »

The key to getting more of a given air mass around a curve / turn be it a round tube or basically a rectangle,especially if it’s high velocity air is to give extra area to expand.

These two crudely drawn examples are what’s needed .

The outside wall needs to be expanded gradually starting from before the curve starts if possible,
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Re: Helping air around a curve?

Post by BOOT »

NewbVetteGuy wrote: Thu May 06, 2021 8:04 pm Is there anything that can be done to help make air make such a "C" shaped turn like in a TPI runner and not end up with such huge losses?
Push/force it, headers are worse but they have pressure working for them.

NewbVetteGuy wrote: Thu May 06, 2021 8:04 pm There was a statement from David Redszus at the end of the 2nd page: "We also found that sand casting surface irregularities had a negative effect in the curved sections but not the straight sections of the induction system."
Perforated tubes are the same, straight ones supposedly flow better than a solid tube because of lower surface friction.


Once I understood it was the 180 turn, I decided to not waste more time on that intake until I get a tig welder.
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Re: Helping air around a curve?

Post by Calypso »

Widen where it's red. It will slow down the high speed areas and even out the pressure in the tube, using the area better. It will also reduce secondary flow which is a result of having unequal pressures across the port.
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Re: Helping air around a curve?

Post by NewbVetteGuy »

Calypso wrote: Mon May 10, 2021 5:05 am Widen where it's red. It will slow down the high speed areas and even out the pressure in the tube, using the area better. It will also reduce secondary flow which is a result of having unequal pressures across the port.
Mag2555 wrote: The outside wall needs to be expanded gradually starting from before the curve starts if possible
Widening the areas of fastest velocity (in red) makes the most sense to me.

I am having a difficult time with the idea of widening the areas of fastest velocity and Mag2555's proposal to expand the outside wall. The fastest velocity seems to be the inside wall of the curve so that's where it should ideally be made larger right?

-Mentally sounds like port opening can be round then slowly transition to a kind of "squished ellipse" (like a hard boiled eggs with it's shell removed and compressed down on the bottom) and then back to round again on the exit. (But still maintaining a gradually and slightly decreased area / taper (small taper increase as the runners are so long)).

Definitely interesting to think about theoretically ideal shapes; could image the time and skill required to actually port in such a shape or what would be required to actually manufacture such a shape in a curved runner like that.


Super cool and interesting to think through the solution to the problem! Thanks all!

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Re: Helping air around a curve?

Post by David Redszus »

Definitely interesting to think about theoretically ideal shapes; could image the time and skill required to actually port in such a shape or what would be required to actually manufacture such a shape in a curved runner like that.
CFD is the perfect tool for the design of optimum shape induction tubes. It should include the entire induction system, from filter to below the valve.

Actual construction will see an increased us of 3D printing techniques. The engineering students involved in the
Formula SAE competition already have a great deal experience using those tools.
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Re: Helping air around a curve?

Post by BOOT »

Widening the SSR & making the runner taller/bigger could help some but it's much better to reduce the turn from a 180 into a 90, like the accel superram did by making the plenum larger, which is also undersized for the TPI since it was designed for a 305
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