Getting ready for twins

L

loganp

hot rod farmboy
Joined
Sep 21, 2008
Messages
506
Had a couple questions as I start getting stuff together to hang an S400 under my HE351.

1) Experienced welders, what do I need to know about welding the steel wastegate flap to the cast exhaust housing?

2) I was looking at parts from Source Automotive, they have S300/S400 hot pipes but not HE351/S400 hot pipes. Is the exhaust flange on an S300 the same as an exhaust flange on the HE351 or will I just have to buy the HE351 flange and build a custom hot pipe?

3) Primary turbo mounting brackets, how did you build yours? I see lots of options from buying one to some that look flimsy but apparently work to some that look like they weigh more than the engine, and some that support by the exhaust flange or by the oil drain fitting.

Thanks in advance.
 
I would go with ED's wastegate spacer. Works like a dream
 
Yeah that's what I have. I figure I'm probably going to have to clock the housings on the turbo so I need a new way to keep the stock wastegate shut, welding seems easiest.
 
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Welding mild steel to cast will get ugly. Might be best to put a piece of all-thread in place of the actuator with a really tight spring to keep it closed. You never know the future of that turbo and welding it will make it less appealing to a prospective buyer in the future.

I believe the 351's have the same flange as an s300 but you can call source to verify.

Don't worry about the bottom turbo mount. If any stress is stopped by a bottom turbo mount, the manifold is already cracked.
 
The He351cw exhaust outlet is different than the common Hx40 outlet machined into most S300's. They do, however, sell S300 turbos with 3rd gen outlets machined into them so that the stock downpipe can be used.


With that said, I'll bet Source or any other twin turbo kit builder sells premade hotpipes with a 3rd gen flange that will perfectly bolt up to the He351 outlet. I don't, however, think you find pre-made hotpipes that will work correctly with a 2nd gen manifold and place the bottom turbo in the correct location to clear the AC, tranny heat exchanger if you have an auto, frame rail, etc.
 
When I talked to Source when I was building my twins, they told me they did not build a HE351 hotpipe because they did not like how the 351 flows. That being said, I do believe they sell an HE351 outlet flange, If not you can buy them on ebay. That is a nasty pipe to make, so if you can find one to buy you'd probably like your life a lot more.
 
Thanks for the info guys! So what if I took this hotpipe and cut the existing flange from the secondary off, then bought this flange and welded in its place? Seems to me that oughtta work.
 
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I had to get it running so I could at least get to work and back, so the wastegate is not hooked up yet and the air filter is a little small, but it'll work for now. Initial testing shows 50psi at the manifold (need to install gauge between turbos too) and 1000* EGT max at 1/2 to 2/3 throttle.
 
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