weld an external wastegate to a standard cast manifold? Success!

[dylan5084]

im planning on putting an external wastegate on a standard cast iron manifold,(if i cant find one to buy?) the pipe im welding on is made of 304l stainless, whats the best way to weld it on? cast iron welding rods? dissimilar rods??

Thanks, Dylan.

[shinny]

When I had this done, I was told you couldn't weld it on, but you could "braize" (sic) it on. I'm no welder so cant' say anything more than that I'm afraid.

[dylan5084]

Cheers man, I can remember seeing pictures of one's welded in so if it can be done I'll give it a go, got nothing to lose really just could be doing with some pointers

[CalMac]

I may be wrong, but most of the external wastegates that I've seen are aluminium alloy and therefore can't be welded to the cast iron manifold. You'll have fun trying to weld anything to cast items really - they're not so simple as they require pre-heating etc. and have a tendency to crack if not done correctly.

You're probably best to use and adapter block with an outlet to bolt on the wastegate like this

http://i.ebayimg.com/00/s/NTMyWDgwMA==/ ... 880000500F

Obviously this will affect position of the turbo and DP etc. though

[dylan5084]

The pipe that attaches to the EWG has a stainless steel flange (vband) I was thinking I could weld in some mild steel to the cast and then the s/s flange to the m/s pipe... Advice from someone that's done it is what I'm after

[C35Rob]

you're asking for trouble trying to weld stainless to cast iron. can you get the flange in normal carbon steel?

the key when welding cast iron is to properly preheat and post heat the job, if you're a welder by trade then take it into work, leave it in a rod oven overnight, do the weld then stick it back into the rod oven immediately to post heat, that'll minimise chances of cracking

as for rods, I would use a cast iron rod, knock all the flux off it and use that as a tig filler rod





granted that's cast to cast, but shows that it can be done, quite neatly too

[rgb]

I don't think anything is cast iron any more . the manifold is cast but its still made of steel . it would be better if the bit you were welding to it was not stainless

[dylan5084]

I don't think anything is cast iron any more . the manifold is cast but its still made of steel . it would be better if the bit you were welding to it was not stainless

yea i was thinking the nickle in the stainless would cause problems and make it brittle... ive spotted another thread where shinny was going to use an anti-lag wrc manifold and use the anti-lag holes for the EWG, looks and interesting idea.....

http://www.mr2oc.co.uk/forums/41/159956.html?start=42

[shinny]

I don't think anything is cast iron any more . the manifold is cast but its still made of steel . it would be better if the bit you were welding to it was not stainless

yea i was thinking the nickle in the stainless would cause problems and make it brittle... ive spotted another thread where shinny was going to use an anti-lag wrc manifold and use the anti-lag holes for the EWG, looks and interesting idea.....

http://www.mr2oc.co.uk/forums/41/159956.html?start=42

Yeah - I never actually did that though. I doubt the components I was planning to use would actually have stood up to the heat, TBH. However I did find someone else who welded / braised pipes onto the manifold and collected them to use as a wastegate. I tried to contact them but never got a reply.

[dylan5084]

cool... my plan was to screw them in then slap some weld about them, or maybe braze them

[dylan5084]

just been reading through some welding forums, i think ill give it a go on this old cast manifold i have here, there saying stainless to cast is done all the time when welding v-band flanges to standard cast turbo's etc. ive got nothing to lose basically...

[rgb]

the cast manifolds can warp so if you weld it make sure its still flat

[dylan5084]

well ive managed to get the hole drilled in the outer 2 pipes, and popped small drill through the inner 2 and opened it up with a burr....

[dylan5084]

Progress....

I preheated it and tigged the cast to mild steel pipe using stainless filler wire (high nickel content wire) post heated and dumped into a box with sand, was still hot 2 hours later and no pinking noises coming from the cast which is always a good sign... Pics









Just need to chop to length and weld vband flange in place and fit!

[shinny]

Looks great! I don't think you're going to have any trouble controlling boost with that

[dylan5084]

Job done!

[toecutter]

Nice work, have you tried it on the road yet?

[shinny]

Great work!

Just a thought: can you add any support bracket? Might help defend against cracking, given the length of the screamer and the vibrations of the engine.

[dylan5084]

not had a chance to road test it yet, wont have until a couple of weeks time, i was thinking add a bracer between the downpipe and the screamer pipe

[dylan5084]

Ok so finally got it up and running, there's definitely something wrong... I donno if the spring in the EWG isn't strong enough or what but when it's running it's just bypassing the turbo and dumping all the exhaust gas on tick over, it sounds terrible!


When looking at the face of the piston inside the tial wg there's a 1mm gap all the way round, is that right?