texas94z

I've been doing a lot of research on fabricated intake manifolds for a LSX and i thinks its time to weld one up. I am an experienced welder and fabricator so it im looking forward to this challenge. I have a few question though. What type of material should i use, aluminum, stainless, or mild steel? I want the manifold to handle hardcore abuse. Ive seen tons made with aluminum so thats what im leaning towards. Also, how thick of material should i use? Like i said i want to make it bomb proof. What do yall think?

1989TransAm

Since there have been no replys yet I will jump in. If I was building an intake manifold I would go with aluminum. Far easier to work with. Plus you will need to get the proper cross sectional area, taper and length of the runners for the motor you are building.

FASTFATBOY

There is alot more to "welding up" a sheetmetal intake. Length and taper of runner and plenum volume per application are important.

If the engine is built and tuned correctly the intake should not have to withstand "hardcore abuse". A nitrous backfire should be all the "abuse" it should ever see.

You may want to do some reading before you waste alot of time.


David

OldSStroker

Excellent thoughts, David.


texas, don't get lost in the fabrication at the expense of the design. IMO, mediocre fabrication of an excellent design will make more power than world class fabrication of a mediocre design. This is definitely a case where you can "polish a turd" to look like jewelry, but in the end it's still a turd.

I, too, question "hadcore abuse" of an intake. Any manifold which might get a nitrous backfire or similar ovepressure will have built in burst panels, so I don't understand your point.

Steel or stainless would be a waste of time and probably outweigh even a clunky aluminum manifold. If you want an alternative to aluminum, carbon fibre would be a good choice.

As to thickness(es), they will vary all over the manifold, of course. Thin (2 mm for example) runners may have an advantage for cooling the charge..or perhaps not depending on how much hot engine air is around the manifold.

The design is the thing..not the fabrication. I've seen a well-designed sheet metal manifold manufacturered by a non-fabricator which works well. I've also seen some polished turds.

IMO, you fabricate a manifold when what the engine needs is not available to you.

n2ceptor

Have you contacted manifold builders ??? IE: www.hogansracingmanifolds.com/

They might give you some insite....

SStrokerAce

Anyone who builds them isin't going to tell you how to get them to do what you want. That's the real trick, it also sounds a LOT easier than it actually is to build trust me on that one. Sometimes it's the only way to go but it's NOT the easiest!

texas94z

Thanks for the imput guys.

I know how hard it is to make one. Trust me. Ive been doing tons of research on design and its going to be a tough fabricate. I have been doing the math and everything for my application. I started a autocad drawing and so far it looks pretty good. My main goal is, of course, design and efficiency but i was concerned if i should over built it.

OldSStroker

Be more concerned about "overdesigning" it.

Any competent fab shop could build one. There are tons of them out there. The problem is getting someone to design the manifold that the engine wants. Those guys who can do an effective design without building a dozen different manifolds to test are not as prolific as the fab shops.

If you must have one, get with a good engine designer and hire him to design the entire engine and spec out the important shapes and sizes for the manifold and then have at it! It won't be much more work to fabricate, and it might actually make more power.

The pitfall to fabing up you own "design" is that you may make something that is easier to build vs. a shape the engine likes. I call it a CFCD Compromised For Convenience Design. It happens is most arenas, but especially in things mechanical. Look closely at virtually any new home, especially one built to a budget if you want to see CFCD.



Listen to SStrokerAce. He's BTDT.

FASTFATBOY

Imagine how many are in a scrap bin in a Pro Stock engine development program...ALOT! It aint easy.


David

OldSStroker

I'll bet they are all cut up into little pieces if they are thrown out. P/S intakes seem to be the place where a lot of development is going on. You can't get a look at them for all the skirts or shields around them. My guess is that they play with runner taper a lot.

If they build them in-house, the fab guy probably gets faster and better with practice.

SStrokerAce

FWIW you can't design the intake without a lot of measurements from the intake port of the cylinder heads.... Hell once you make the head a exentsion of the intake manifold things really start to work.

I can help you with the design but it's not going to be free and having your heads here would be the only way to give you the details.

I usually start with a wax "flow box" to get the internal shape I want and flow test the manifold, once you have that the rest is just building the thing, which it sounds like you can do.

Bret

1989TransAm

"Hell once you make the head a exentsion of the intake manifold things really start to work."

I'm probably reading it wrong. But I think it should read, "Hell once you make the intake manifold an extension and the head things really start to work."

Bret any clues on taper from your experience. I'm at 2 1/2% on my highly modified TPI intake manifold.

SStrokerAce

No I wrote it that way for a reason!

Taper changes with a lot of things, a higher taper angle will change the runner length needed.

RedLT4Mike

Start on one knowing that you may or more likely may not
get it right the first time. I've got faith in ya man!