It's not that much fabrication realy. And I would try VNT if they used a divided exhaust housing, I'm trying to cut down on reversion by using the twin scroll(devided) exhaust. The oil line can be fead from the engine and back and have an accusump in the back for added oil after engine shut down. I can use a separate water cooler in the rear using the current turbo water pump or an aftermarket one of need be, for cooling the CHRA of the turbo. And have a small one gallon coolant resivoir just for the turbo in the upper spare tire area after I cut most of it out. Aluminum pipe is easy to work with for the intake pluming. Just have to piece already made items together. The wastegate tie in flanges are easy to weld onto the exaust pipe as well. Also I'm going to use just v band clamps on all exhaust connections. And use 38mm tial wastgates. And it's easier then making a twin scroll crossover. I can use the area where the 3" down pipe was for the intake pipe route. There's only a couple of bends in the exhaust pipe and it will have plenty of ground clearance also. The turbo exhaust will be the shortest off the turbo with only 3 bends of 3" mandrel bent pipe about a foot and a half long to the tip. Just have to buy the pieces and mock it up. I could cut just the lower spare tire area off and use the inside for mounting accusump, coolant resivoir, and the pumps. I would have room for a muffler then. I seen that flow master sells a muffler with the in/out on one end. That would work great to run the turbo exaust strait to it and have it come strait out with one bend to the rear to the exhaust tip. And it would fit right where the lowere spare tire area was. That would be if there was a sound resrtiction at the track.
Here are someBenefits I see:
Heat reduction to the oil pan from crossover
Heat reduction from turbo to intake manifold
No more dealing with the turbo under the manifold!
Heat reduction to the engine bay by not using a front intercooler
Much easier access to the turbo
Better ground clearance using a twin scroll exhaust
No more dealing with the crossover
No more turbo mount with those turbo bolts to deal with
More room in the engine bay
Less heat shields under the hood
Heat is out the back not under the hood
That's just to name a few.

 

Liquid nitrogen cooled flux capacitor could be added to the muffler also.

 

Well I didn't hit my head on the toilet bowl like the good doc did in back to the future so I hadn't thought of that to add yet. It's still an open design and you can add that to your car but I'm trying to stick to reality. Thank you though for your well thought out criticism. However, I'm still going to go with this idea and going to make it happen. I like to think outside the box. I guess I have to build it then dyno it and post my results to get positive feedback. That's too bad few minds can see why I see...

 

I think having that much volume between the turbo and the intake would be a huge disadvantage and increase lag. Must keep the turbo relatively close to the intake to reduce the volume of gas that you have to compress.

 

I realy don't think it's a problem. I'm running strait pipe to the intake and it's being cooled the whole way there. May add a few feet of intake tubing but I'm not running a intercooler so to say so that less drag on the charged air. So the air will have 2-1/4" aluminum pipe to cool in from the turbo to the intake. And I can add aluminum cooling fines to the pipe for added cooling if needed. I'm not the first to use this idea! Just the first to use it our 951 it seems. Look up rear mounted turbos on the Internet. Also using a twin scroll turbo will help with turbo leg like I've mention so so so so many times now!

 

I cant understand why you would go rear mounted turbo when theres enough space in the engine bay for a gt35r which is still to big for a 2.5L

all the effort for really no gain what so ever.

 

Twin scroll is not just about reversion, it reduces the volume of the pipes, and the less volume the better the response. And 1 7/8 is to big btw.

 

is reversion something you think you are experiencing, enough to worry about and redesign the system?
equal length headers are one thing, but the RMT is a whole nuther project.

 

I can reduce the pipe size if it to big that not a problem. Remember is still an idea I haven't built it yet but I will. The reason I don't want the turbo in the engine bay is bacause of the list I described already. It may even help with weight distribution in the rear due to the design of the stock fuel tank having more fuel on the right side of the car. Having the turbo on the left may help. Not that is a problem just may help. And at 20+ psi yea reversion is something to think about. In fact if you have a turbo car reversion is something to think about.
However what size would be recomended to use going from the headers to the turbo on a twin scroll design?

 

If you build it with head shields like factory did, then heat soak wont be a problem with sump. same goes with the intake. besides the air travels quick enough (300km/h+) though the intake for it not to heat up.

 

i guess I'm being a rebel buy biulding a 2.5L DOHC non interference turbo with 928 86 4V head, 944 S Pistons(same 25cc as turbo) , rear mounted turbo, 944 S intake with welded on 928 intake flanges. Bla bla bla...

 

i like the DOCH non interface with the 928 head ect but i don't see any benefit to rear mounted turbo.
I can understand when there's no room in the engine bay (most v8's) but we've got plenty of room.
Going to need an oil pump to pull the oil from the turbo. If you're running a garrett GT series turbo it does need water. the oil isn't enough to cool it.

 

I bet an undivided manifold feeding a twin scroll turbine with a quick spool valve would perform better and weight less than a full twin-scroll setup. I haven't seen an actual back-to-back dyno with the same engine of this, but the spool improvements I've seen with a QSV seem to be as good or better than twin-scroll improvements. Granted, it does take some dyno time to properly set the crossover and you need to be running electronic boost and QSV control. But, you should be doing that anyways if you want the best powerband.

 

I've seen the QSV in action vs one with out. But i think with the whole twin scroll done properly its more for bottom end + top end.

But 2 wastegates is good but can get away with one and just normal boost control.

 

I see... Another benefit of the rear mount turbo for me is I can use the 944 S intake manifold and the 928 intake manifold flanges welded onto it. There is no room for a turbo with that manifold. As I mentioned before you could use any 944 manifold with a rear mount turbo. I just happen to have an S not an S2 which I would like. That's ok because I have two sets of 928 flanges. I can make one in the future.