Turboing when a manifold isn't available?

Any particular draw backs to j pipes? Apart from potentially more lag or positioning issues?

Porsche used them on the 944 Turbo. It mounted the turbo under the intake on a cross-flow 4-cylinder. Seemed to work out for them.

Yes they can induce lag and that much metal expanding and contracting can make mounts more difficult, but it just requires proper turbo sizing and adding a flex joint in the system.

Just be aware that most turbos need a good straight 45 degree shot to the oil pan for oil drain and so you don't want it mounted too low.

Another vote for weld elbows and a laser cut flange. Been teaching myself to tig weld on my current project.

Stefan (Not Bruce) wrote: Porsche used them on the 944 Turbo. It mounted the turbo under the intake on a cross-flow 4-cylinder. Seemed to work out for them. Yes they can induce lag and that much metal expanding and contracting can make mounts more difficult, but it just requires proper turbo sizing and adding a flex joint in the system.

Subaru turbo engines, too.

The turbo should really always be hung off of a bracket. Buick GN turbos are, need to support all of that weight. It's not just the weight of the turbo that gets supported but also the front part of the exhaust, and that is also going to be torquing on everything when the drivetrain moves around.

Pretty much the only OE turbos that aren't supported are when they used cast manifolds. (BGNs have stainless tubular manifolds) And some cast, too - Audi was fond of support brackets for the turbo five manifolds even though they were castings.

My first attempt at a slant six turbo build had a cut and welded stock manifold. The guy who did this didn't do the best job and the welds cracked. Welding cast iron is pretty tough.

I am now working on a J-pipe.

airwerks wrote: Another vote for weld elbows and a laser cut flange. Been teaching myself to tig weld on my current project.

Now this is a good example of a home-welded turbo manifold.

There are no pictures extant of our bad example of a cut and welded cast manifold I know I saw some 13 years ago, but I can only find exterior shots of the truck now.

In the Saturn world, the hacked & welded cast manifolds are some of the most reliable in existence. One company even produced them as part of their turbo kit. Most of the aftermarket tubular manifolds crack under the weight & heat of the turbo.

Mr_Clutch42 wrote:

airwerks wrote: Another vote for weld elbows and a laser cut flange. Been teaching myself to tig weld on my current project.

Now this is a good example of a home-welded turbo manifold.

Unless it's stainless, and didn't have Solar Flux or was backpurged during welding and has stalagmites on the inside ready to break off and eat your turbine wheel. Ask me how I know that can happen.

Keep the manifold stock and rear mount the turbo?

Yes always brace the turbo. Hell even the cast manifolds and baby turbos I screw with all still have a brace. And if you cantilever the turbo way off the block with a j pipe all the more reason to brace it. That's usually the problem with why cheap tubular manifolds crack, they don't have a proper brace

Interestingly, we used to put a brace on our turbo downpipes for the Mazdaspeed Miatas. It was a copy of the one put there by Mazda. And we kept cracking downpipes. We took the brace off and the cracking went away. The brace was keeping the downpipe from expanding the way it wanted to expand.

Not mine, but just remember it doesnt have to be pretty to work..

Infamous sloppy mechanics work...

"i foot braked a 10.72@136 in a full weight street fairmont on a radial tire 3500lbs 99 4.8, paper head gaskets, isky cam, stock ecu, 2800rpm foot brake 18psi pumpgas on3 7665 turbo"

Thanks for all the input so far, there's definitely some food for thought here.

Because I've got no real idea how much punishment a stock Mazda g6 can handle I'll be evolving the thing by stages which means I'll probably start with a j pipe and progress from there.

I've got a lot of other things to do to get this thing up and running so the simpler and cheaper I can get the turbo mounted and working the better.

No doubt I'll start a thread soon looking for pointers and assistance in setting up an ems stinger ecu because its kind of new ground to me.

ProDarwin wrote: In the Saturn world, the hacked & welded cast manifolds are some of the most reliable in existence. One company even produced them as part of their turbo kit. Most of the aftermarket tubular manifolds crack under the weight & heat of the turbo.

Because most people who install tubular manifolds don't realize that they need to install braces. Thin tubes at 1500+F won't last long if they are expected to hold up 20-40lb of turbo and exhaust.

Paul_VR6 wrote:

Mr_Clutch42 wrote:

airwerks wrote: Another vote for weld elbows and a laser cut flange. Been teaching myself to tig weld on my current project.

Now this is a good example of a home-welded turbo manifold.

Unless it's stainless, and didn't have Solar Flux or was backpurged during welding and has stalagmites on the inside ready to break off and eat your turbine wheel. Ask me how I know that can happen.

It is stainless (304), I did not use solar flux, nor did I back purge. I kept the gaps tight to minimize burn through and flapper wheeled the ID's of what I could get to while it was going together. Hope I avoid anything breaking loose and going through the turbo, but if it does it's not the end of the world. It's a cheapie DSM take off I can cheaply replace. Hope for the best at this point, I guess.