is it necessary to have it made from aluminum or can i use steel?>

 

you can use anything you like. Steel is just heavier.


BC

 

Any material that can handle the heat, pressure and vibration can be used. Common ones are fiberglass, carbon fibre, aluminum, steel and plastic.

But if you have to ask what kind of material to use when making a manifold, perhaps you should consider a different project?

 

You'll See Some Pics Of My Project Soon Cake

 

Well, here's a few of mine:
https://www.rx7club.com/forum/showthread.php?t=498432

 

Aaron, that comment on fiberglass gets me thinking of a possibility for my possible project.

 

cake can i use fiberglass and resign instead of welds, im good with fiberglass and good with welder but i dont have 1..

 

"instead of welding"

 

i doubt anything aside from a solid metal will be able to withstand the temps that it will see, keep in mind it is going to sit about an inch away from the VERY hot exhaust manifold.

 

Even if you are good with fiberglass, building moulds for an intake manifold that would have the proper tolerances on the flanges, runner length/consistent diameter would be (IMHO) far more difficult then using steel or aluminum. Not to mention the heat factor.....

Give it a try with steel, IIRC, Aaron's steel intake mani. actually weighs LESS (or maybe it was just close?) then the stock aluminum one because of so much excess casting.

 

4lbs at that.

 

I had a good look at the intake manifold that was built for the white supercahrged Mazdaspeed RX-8 that was in the magazines a couple of years ago. It is no longer on the car so I picked it up and took pictures of it from every angle. They used part of the stock aluminum lower intake manifold but the upper was built from stainless steel. A little heavy compared to aluminum but the heat rejection properties of it vs aluminum were worth it. Beautiful piece of work.

 

Fiberglass would work well for the upper intake (commonly done) but the lower is too close to the exhaust as others have mentioned. Probably won't handle the heat. Depending on what you are doing, custom making a lower intake could be very pointless since the stock lower intake is just a set of runners anyway.

Getting a consistent runner length and diameter shouldn't be too hard if you make a mold first. Mold the runners in two halves and then glass them together on the outside. Flanges are another story of course... My guess would be that you would have to make a metal flange and then surround it with glass to secure the runners, then take it to a machine shop and have the mating surfaces ground smooth. Really you would also need this done with a pure metal intake since welding will distort the flange (though mine doesn't leak).

About 4 pounds less. And I only measured the stocker with the intake and throttle body, not all the injector hardware, bolts, nuts, etc.