Texas850Turbo, on 21 November 2011 - 04:57 AM, said:
I'd rethink that exhaust setup if I were you. That GT35 is never going to spool the way you have it set up, unless you plan on revving it out to 10k or something. When the wastegate starts to open at 15 psi only a small amount of exhaust is going to the big turbo- only exhaust from 3 cylinders that finds its way around that 90 bend and into and out of the wastegate at that.
The other problem is that having the cylinders going to different turbos means some cylinders will have higher backpressure (the ones going to the 15g or whatever), and the others will be breathing somewhat easier out the GT35. This effects the volumetric efficiency balance between cylinders, which means different ones will need different amounts of fuel and will have different optimal spark timing. When you go to tune the engine, whichever cylinder has the worst efficiency or highest backpressure/reversion will probably get the hottest piston crown temps and start knocking first, so you will have to tune for that one, leaving a bunch of power untapped in the other cylinders.
I know it sounds fun to do a "twin turbo" setup, but I would really advise against it. The problem with the GT3076 is that the turbine is much smaller than the compressor wheel, driving down the turbine efficiency and making it take longer to spool. If you get a properly matched Garrett or other turbo (the new GTX3071R should do the trick, or any EFR turbo), you will be much happier and your engine will appreciate it.
Go look at other people compound setup. You dont understand how it works. All 5 cylinders exhaust will go through the big turbo. Back pressure will not be that diffrent...or enough to matter. Does it matter on a stock manifold? Have you seen a stock manifold? How do you think that work for tuning. We are not talking a tuned manifold. There is no tuned pressure waves we are working with. Just flow.
boosted_brick, on 21 November 2011 - 05:33 AM, said:
i was just about to ask about this

i've heard different sized turbos get you both low and high rpm power so i'm sure benefit you. what made you not want to go with ITB's? maybe i missed your post about that but i know you can get 'em from bikes like hyabusa. just have to cut one off to make it fit!
anywho, this is a neat build. are you going to powdercoat anything while you're building or just leave it how it is?
Price is the main reason. Plus then I would have to seal them and that might be tricky. Not to mention getting 5 bike throttle bodies.
99 V70R M6 Twin Turbo 35r & 16t Megasquirt V3, 95 Eagle Talon TS1 2.4 Long rod High comp motor 272's cams AEM EMS, Turbocharged Hayabusa 347HP Never Selling, 93 Mazda RX7 SOLD and wrecked, Astro Van LS1 swapped SOLD, 81 242 6.0 LS motor AEM Standalone YES IT HAS A TURBO!
http://TurboTims.com