mild steel intake manifold

Is it a bad idea to make an inake manifold from mild steel? Could it corrode and the rust could go in my engine?

Older cars had cast iron intakes and heads. if you're concerned, you could powdercoat the inside.

Unless they are big flakes, it shouldn't be a large problem.

Here is an example: http://www.sdsefi.com/air12.html

I've seen homemade sheet metal intakes on Brit cars. It's not difficult to do, the hardest part would be making the flange accurately and IMHO it should be a minimum of 3/8" thick to keep warping under bolt torque to a minimum. That would probably require an extra head so you could keep checking the fit. As noted powdercoating can take care of any possible rust formation.

I recently saw a setup online where a guy made his own steel 'spigots' to allow mounting Mikuni motorcycle carbs on a rotary. Don't remember exactly where, unfortunately.

I don't see a problem if you powdercoat - but why not use aluminum tubing? Its lighter, cooler and easier to work with. I have even seen it in oval shapes that look almost like BMW S52 intake runners and said to myself...

Self: "I bet you could make some wicked cool velocity stacks out of that"

I think the problem is that it is easier for the average person to weld mild steel than it is aluminum

That said I did see a site that sold intake manifold fabrication parts. I'll see if I can find it and post it here.

Edit: Found it! http://www.rossmachineracing.com/intakepartspage.html All aluminum, but you may find someone willing to do the welding for you if you do all the fitment. Do some reading on manifold design, grab a spare head, build the flange, order some pieces and go from there....

You could also ceramic coat the manifold. Check out the Techline DIY ceramic coatings, which Eastwood sells. They have a stainless steel colored ceramic coating that you can polish.

I'd probably make it out of aluminum... hell... Tegler did it for his Spit6 "FIS6":

http://www.teglerizer.com/fi/GT6_manifold/ms_gt6_manifold.html

...and IIRC, he said this was his first aluminum welding project...

One thing I have to give Paul credit for... he doesn't over-think stuff (as I tend to do)... he makes a rough plan and dives in... overcoming problems as they present themselves...

I have a mild steel intake manifold for my turbo opel project. I was planning on having it jet-hot coated, but I doubt it's really a big deal. Just hook a crankcase breather up near the throttle body and it'll get plenty of oil vapor lubrication inside to inhibit rust.

Yeah, once it holes a piston you'll have plenty of blowby.

Hey now, that's not nice. Everyone knows Opel pistons break out the ring lands way before they get holes melted in them.

If the inside of the intake manifold gets a chance to rust, your first concern should be getting the car out of the lake.

I'm not really joking... between the fuel that ends up permeating the steel, and the oil that will find its way in the intake, you pretty much never have to worry about corrosion on the inside.

The main problem as I see it is that steel is difficult to work compared to nice soft aluminum. Making an intake manifold out of steel sucked, and I've done it twice. OTOH I do not have the wherewithal to weld aluminum, yet, so it was either steel, or try to make something with fiberglass. And I don't quite trust plastics enough yet.

Plastics are usually no good in boosted applications unless properly designed... But I'm no expert, so take it for what it's worth... Better yet, in this economic environment, find a good used TIG on Craigslist like I did and learn yourself how to weld aluminum!

I've done pulse MIG aluminum welding and it wasn't to much differrent than MIG welding mild steel. I may get a used MIG welder and try aluminum on it.

Paul T used a MIG to weld up the manifold for FIS6 (that I posted above)... he did use a spool gun MIG, but it seems to have turned out ok.

Dr. Hess's racecar is on the Rossmachineracing website, under gallery.