I am in the process of making a feed pipe for a new turbo setup.
I will be using 2.25" for both banks. One bank will be very short and close to the turbo (say a foot), while the other bank will cross over under the engine and merge into a 2.5" pipe which then will go into the Turbo's flange.

My question is, would there be any issues having such setup (difference in EGT, AFR, Pressure, among both legs)
The manifold pressure would be about what I have now, 15psi.

My theory is that once pressure builds up in the exhaust preturbo, the distance does not matter. But would be great to here from other more experiences folks out there. My projected power would be 500-600, unknown what I am currently at with my rear mount setup.

notes: this is a FWD built VQ35, hence why i cannot exactly make it equal length (not easily at least).

 

depending what the difference length is, could potentially be causing additional unneeded back pressure from the pulses being improperly spaced. like you said backpressure is going to happen regardless but it might be just a little sooner from pulses hitting each other and slowing down. who knows the exact effect though without dyno testing a equal length and unequal length though.

 

Thanks for the response.
I guess it may be difficult to actually analyse unless there were back to back dyno's or pressure, egt and afr data was collected from both exhaust sides.

From the looks of it (by pictures), the Powerlab kit seems to have such crossover pipe like I described, I am going to look up what kind of power has been achieved with their setup.

 

pretty much all the singles for the z/g use a cross over. only one which is close to equal length is the boosted performance mid mount kit.

 

Cool, yeah I found the midmount equal length interesting. Now, what diameter for the crossover would be acceptable for ~600whp? My research tells me 2.25 is plenty; Merging into a 2.5" then turbo.

 

considering that all the after market headers outside of custom built are 2.25 i dont see any reason why what your suggesting wouldnt work. cant remember what size sasha uses and rather not crawl under my car atm but the i wanna say its 2.75 and will easily support over 800 so you should be good with 2.5 for 600. alot will also depend on having a free flowing exhaust though.

 

Thank you for your feedback, much appreciated. As for Turbine outlet I will be using a 3.5" dump, no muffler, resonator, or cat.

 

that will easily flow more then enough, originally i had 3 inch that split into dual 3 inch before i switched to 4 inch single and straight through muffler.

 

All single turbo engine bay area setups have an unequal length exhaust setup leading to them, as you mentioned the pressure builds very equally, there isn't a lot of area in that piping to pressurize once it starts to build up and like any other manifold design that's under pressure, the pressure will level itself out everywhere. You'll be fine.

 

I just read the name on this... That beast of a maxima is still out running around? Glad to hear it. Not enough fast nissans around here anymore that aren't GT-Rs.

 

Haha yes sir, still running strong. Time for more power though. Now as for headers, what you guys recommend for the individual runner diameter to be?

 

are you building your own? all the ones ive seen use the same design with the same runner diameter so ive never given it much thought dont want to build my own unless i decide to go twin EFR turbos and buy a tig.

a bunch of calculators online though i think wallace race engines website has one helps a **** ton doing the math. they all seem to also have similar collectors too exception obviously being the long tubes, SFR's which seem to be like a mid length header but hard to tell from the web pics and i havnt looked too hard, and the momentum/z1 which have burns collectors

 

Doesn't matter too much on your setup since it's turbo and feeding an unequal manifold. I'd go a tad big all over if you are trying to make big power, more flow won't hurt.

Same as above, are you building them yourself?

What are you using for manifolds now?

 

Not sure what to do yet, as far as buildin, buying already made ones, or porting mine out.

Currently have VQ30 stock headers (no precat), which I dont know exactly how much power I can squeeze out of them. I think MardiGras came across issues above 500whp with stock headers.

My next task is to figure out what to do about turbine. Currently have a Bullseye T3 .70AR, I understand that it might be too small for our motor so I am going to have a T4 turbine housing fitted to my HX40 Holset, I just have to figure out what AR turbine to use.

 

You should get with t6378tp, I know he used 350z headers on one of his builds.

 

Thanks, yeah I talk to Thomas almost every day, we pick each others brain and he has helped me with ideas for my new setup.