Naive intake manifold porting question by a novice

[Walter R. Malik]

Just a random thought - if there is so much improvement to be had, why did all the OEM engineers leave it on the table when it wouldn't have cost them anything to optimize the cross-sections prior to production?

The short answer is that most manufacturers simply are there to make the available money and not to produce things the "best that they can be" but, merely to be ADEQUATE.

[panic]

Just my 2¢?
I think the definitive guide to porting for a turbo intake path has yet to be written. Air at high density, temperature and pressure doesn't behave the way the bench tells you it does. The Reynolds, Poiseville etc. numbers are very different.
An example of a perfectly good (but nothing special) NA engine, where porting does just what you would expect: mild power gain at peak, perhaps some minor loss below the torque curve: Toyota/Lexus 2JZ-GE (3 liter, 220 hp).
An almost identical engine in which porting is not cost effective below 1,000 hp: the turbo 2JZ-GTE.

How many people have broken their backs and bank accounts trying to squeeze that last CFM out of a very special project, and discover that adding 5 psi does more for 25% of the money?

[Newold1]

If I understand correctly what you are trying to accomplish here, I would do as much porting or reshaping the intake tract as much as safely and reasonably practical. I would then start adding my turbocharging to see if I could achieve my hoped for power levels before I got into the more extensive over grinding and epoxy rebuilding that you are describing.

Use the KISS theory!

TRY NOT TO DESIGN OR BUILD SOMETHING MORE COMPLEX OR DIFFICULT THAN IT NEEDS TO BE TO ACHIEVE THE DESIRED RESULTS! JMHO

[Frankshaft]

I get it, boost is king. But, that doesn't mean porting, intake mods, etc do nothing. I have heard this argument so many times, that I want to puke, the funniest part, its usually the guy we just put 12 car lengths on at the top end. I just shake my head and laugh. Whatever, that's cool, don't port your heads, and you wonder why we drive away from you so hard, with less boost and the same turbo. I had a "discussion" with someone about boost and heads. He went on and on. I just said, ok, so, your saying John Force could bolt some stock, 1969 hemi heads on his funny car and go just as fast, assuming they didn't break in half? He looked at me and said, oh, yah, well, maybe not. Most certainly not. I bet it would be down 1000hp. But bolt John Forces' heads on that same 1969 hemi, and it would probably lose power. Think about it. So to say good heads/porting doesn't help boosted applications is ridiculous. John Forces combo is the ultimate extreme, but you get the point.

[PackardV8]

So there's no issue with welding these components, other than everything warps a little bit and that means that a lot of machining operations on these parts have to be repeated.

When making a custom manifold, if the components are bolted together and bolted to the engine on which they'll be run, they form a welding jig. In your case, we might assume a complex intake in which sections needing weld reinforcement might be inaccessible while assembled. However, if as much of the welding as possible is done in situ, then a jig constructed for the rest, it might be preferable to trying to remachine complex parts.

Done that when making intake manifolds for obsolete engines from available aftermarket intakes.

[ptuomov]

So there's no issue with welding these components, other than everything warps a little bit and that means that a lot of machining operations on these parts have to be repeated.

When making a custom manifold, if the components are bolted together and bolted to the engine on which they'll be run, they form a welding jig. In your case, we might assume a complex intake in which sections needing weld reinforcement might be inaccessible while assembled. However, if as much of the welding as possible is done in situ, then a jig constructed for the rest, it might be preferable to trying to remachine complex parts.

I was thinking about it along those same lines, however, here we are. The particular component under work now (aluminum throttle body element with a T-junction) can't be bolted on to the rest of the manifold for welding. To reduce warpage, a strong steel girdle was fabricated to simulate the rest of the manifold and the work piece was bolted on to that during the welding and cooling. A professional did the welding. Yet it warped enough that basically all the machining operations have to be repeated.

See the photos in the early posts of this thread:
viewtopic.php?f=15&t=51165#p692331
viewtopic.php?f=15&t=51165#p692332
viewtopic.php?f=15&t=51165#p692334

If only minor reshaping is needed, I'd much rather go with epoxy to strengthen the outside of the casting than start redoing the whole piece as if it were a new casting fresh out of the foundry.

[ptuomov]

Just my 2¢? I think the definitive guide to porting for a turbo intake path has yet to be written. Air at high density, temperature and pressure doesn't behave the way the bench tells you it does. The Reynolds, Poiseville etc. numbers are very different. An example of a perfectly good (but nothing special) NA engine, where porting does just what you would expect: mild power gain at peak, perhaps some minor loss below the torque curve: Toyota/Lexus 2JZ-GE (3 liter, 220 hp). An almost identical engine in which porting is not cost effective below 1,000 hp: the turbo 2JZ-GTE. How many people have broken their backs and bank accounts trying to squeeze that last CFM out of a very special project, and discover that adding 5 psi does more for 25% of the money?

If I understand correctly what you are trying to accomplish here, I would do as much porting or reshaping the intake tract as much as safely and reasonably practical. I would then start adding my turbocharging to see if I could achieve my hoped for power levels before I got into the more extensive over grinding and epoxy rebuilding that you are describing. Use the KISS theory! TRY NOT TO DESIGN OR BUILD SOMETHING MORE COMPLEX OR DIFFICULT THAN IT NEEDS TO BE TO ACHIEVE THE DESIRED RESULTS! JMHO

I get it, boost is king. But, that doesn't mean porting, intake mods, etc do nothing. I have heard this argument so many times, that I want to puke, the funniest part, its usually the guy we just put 12 car lengths on at the top end. I just shake my head and laugh. Whatever, that's cool, don't port your heads, and you wonder why we drive away from you so hard, with less boost and the same turbo. I had a "discussion" with someone about boost and heads. He went on and on. I just said, ok, so, your saying John Force could bolt some stock, 1969 hemi heads on his funny car and go just as fast, assuming they didn't break in half? He looked at me and said, oh, yah, well, maybe not. Most certainly not. I bet it would be down 1000hp. But bolt John Forces' heads on that same 1969 hemi, and it would probably lose power. Think about it. So to say good heads/porting doesn't help boosted applications is ridiculous. John Forces combo is the ultimate extreme, but you get the point.

A little background for the project. This is a turbo conversion V8 that has two turbochargers and will run pump gas. There's very little room for anything. The exhaust manifolds are from pulse tuning perspective very well flowing and smoothly merging log manifolds. Despite the nice shapes, the runner length is such that the exhaust pressure pulses try to screw up the overlap. This leads to us hitting the knock limit as hot residual gas remains in the combustion chambers at certain cylinders at certain rpms. On race gas, we could just shut the wastegate and not worry so much, with pump gas we needed to stop and think.

To help push out the knock limit, I need to run the lowest possible exhaust manifold back pressure relative to the intake manifold pressure while still maintaining nice driveability. In my opinion, there are two very good ways to do that: Eliminate turbo-back exhaust back pressure to maximum extent possible, and to eliminate as much of the pressure drop as possible between the compressor outlet and the intake port (while still adequately intercooling the charge). The pipes are now as large as they can be, and we're chasing the last psi of pressure drop in various spots in the intake track. This is part of that effort. It may very well be that we're already deep, deep into the region of greatly diminished returns...

Beyond that, there are some more general objectives. First, to learn more in general. Second, to provide some relief to human beings living under oppressive regimes (think North Korea and equivalent) and owning normally aspirated cars of the same make and model, while having to pass some sort of cruel and unusual visual inspection. Coming up with a recipe how to improve stock components deep under the hood might provide some relief to those unfortunate souls.

[MadBill]

FWIW, the Meta-Lax process is often used during as well as after welding fabrication to dissipate stress as it is developing...

[panic]

So to say good heads/porting doesn't help boosted applications is ridiculous
Exactly who said that?
You may find that insulting people trying to answer a question causes them to lose interest in your future remarks.

[cgarb]

Guy I work with owns a pulling tractor with twin Allison aircraft engines. Alky, supercharged. Took his heads to Larry Ladd and had them ported. He called Larry after the first pull and asked what he did to his heads because they lost 12lbs of boost. Larry said good to hear that...that means I did my job. More boost don't always mean more horsepower if you lose boost because you uncorked a restriction.

[Carnut1]

That is true, less pumping losses and higher efficiency of the ported head. Notice the customer didn't complain about the extra power just the loss of boost.

[ptuomov]

Guy I work with owns a pulling tractor with twin Allison aircraft engines. Alky, supercharged. Took his heads to Larry Ladd and had them ported. He called Larry after the first pull and asked what he did to his heads because they lost 12lbs of boost. Larry said good to hear that...that means I did my job. More boost don't always mean more horsepower if you lose boost because you uncorked a restriction.

How much did the exhaust manifold pressure go down? That would in my opinion as telling or perhaps even more telling.

[cgarb]

Supercharged....shouldn't be much exhaust pressure there. Has a zoomie style header on the tractor. After the head porting boost went down, but the length of pulls went farther. That's all they were concerned with.

[ptuomov]

Supercharged....shouldn't be much exhaust pressure there. Has a zoomie style header on the tractor. After the head porting boost went down, but the length of pulls went farther. That's all they were concerned with.

My bad, always thinking turbo nowadays.

[cgarb]

Get your mind out of the turbo gutter...lol