Aluminum intake manifolds

Ok so I have seen a bunch of welded aluminum manifolds and I was wondering how you prevent cranks in the aluminum since if you weld something 6061-T6, the welding will take the aluminum down to T0. I mean you might gain back some of that from age hardening but you still have different strengths in something that is getting heated and cooled. Is it just not enough stress or cycles to for the cracks to develop or ????

Basic welding principle: Your filler rod is HARDER then the base material. This gives you the same basic mechanical properties, since your weld is taking most of the stress. Also to avoid the cracks from thermal stress, you heat the parts to be welded. This lessens the thermal shock from welding that leads to the cracks.

But back to your original question, you typically aren't starting with a heat treated material for a manifold. Unless you are playing around with scraps or the only shape you need is already heat treated.

You've seen a bunch of welded manifolds. Did you see any cracks? I think you're worrying a whole lot about nothing.

Just watch out for those hundred shots of NOS...

Here is a great resource

http://webpages.charter.net/beckracing/page04.htm

I was just talking to the other mechanical here who used to work for NASA and they will not let an welded aluminum structures fly because of cracking when welding it. When we welded aluminum at the shop at school, I never saw cracks but I was trying to figure out what was going on.

93EXCivic wrote: I was just talking to the other mechanical here who used to work for NASA and they will not let an welded aluminum structures fly because of cracking when welding it. When we welded aluminum at the shop at school, I never saw cracks but I was trying to figure out what was going on.

News flash: Things made to be nearly 100% reliable in space flight have different requirements than things made to be nearly 100% reliable in automotive racing.

Bryce

Intake manifolds are not highly stressed load bearing items. As long as they are well designed and braced if necessary there is nothing that will make them crack. (barring a fast and furious floor falling out moment)

Long tubes hanging out without support can and will crack aluminum or not, that is just poor design though.

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The first gen Bahn Brenner supercharger kits held the throttle body out over 12 inches from the lysholm on a thin aluminum pipe and I have repaired them dozens of times. They went shorter after a while but it still happens.

This is a shorter one. The air filter was strapped to the firewall and even with a flexible coupler it still put stress on the first weld joint at the supercharger every time the throttle was opened and the engine rocked.

Nashco wrote:

93EXCivic wrote: I was just talking to the other mechanical here who used to work for NASA and they will not let an welded aluminum structures fly because of cracking when welding it. When we welded aluminum at the shop at school, I never saw cracks but I was trying to figure out what was going on.

News flash: Things made to be nearly 100% reliable in space flight have different requirements than things made to be nearly 100% reliable in automotive racing. Bryce

Really?!? I had no idea....

I was just wondering how bad a problem it really was. Obviously cracks in a intake manifold will lead to vacuum leaks and I was wondering if this was a concern or not.

Not a concern. Rest easy.

It's not hard to heat treat 6061 (or whatver) to whatever temper you need (dead soft to fully hard).. Look for heat treat schedules published by Alcoa, etc. I scored a Paragon Kiln for $100, and an eBay thermocouple for the temp for $50. It's a PIA to keep manually monitoring and adjusting the temp, but it works OK. You can get a fully programmable temp controller for another $100 or so, if you need to do it often. Use a compatible welding rod to keep it real, info you need is all available.

Carter