I recently made 452whp on NS BNR stage 3's running 21psi and I'm looking for more ways to make power as I'm currently maxing out the turbos. One of the things I was thinking about was the layout of the y-pipe on the twins. Even if you're running the efini y-pipe the design isn't exactly optimized for NS twins, with the turbos having to fight each other before the air goes through the outlet. Then you have all the bends in the intercooler piping associated with running the air to a SMIC.

I was thinking about designing two 2" pipes that will feed into a 2.75" collector. The air coming out of the turbos would then have a direct path to the intercooler.

What do you guys think? Has this ever been done before with twins?

 

that sounds like a good idea, so from your design, air will come out from both turbos, and then into a 3" collector before entering the IC? but how would this be more beneficial than compare to a single turbo setup? you can achieve about the same HP with alot less boost??

 

That's correct. I have a extra y-pipe that I'm going to cut the flanges off of and then weld the 2" piping to them. Both pipes will then feed into a 2.75" collector.

I'm very happy with the amount of power the car is making and am not looking for alot more. I'm more looking to see just how much power can be made on these turbos. That and my current piping setup has always bothered me.I guess if there's any benefit to this setup it's cost. I got the BNR's for $1,700 during the group buy and it would cost me alot more then that to make the same amount of power on a single setup.

Here's a pic of my setup

 

I might actually modify this pipe from a 3000gt/Stealth to make it work. It already has two 2" inlets and all I'd have to do would cut the part off where it bends and weld on a 2.75" pipe.

 

very interesting....whats the benefit of pre-turbo AI injection??

 

There's a lot to it and I'd recommend reading some articles in the auxiliary injection forum but to summarize it cools the air as soon as it exits the turbo which effectively extends the efficiency range of the turbo. It also further atomizes the water by sending it through the compressor.

BNR's are only supposed to be efficient to around 18 psi. This system helps me push beyond that to run 21psi.

 

I see your thinking, but... The exhaust backpressure in the cast stock crapƤ#I)P#%/Æ#)¤%/ exhaust manifold at those boostpressures, will reach near-black-hole-pressures and put a good strain on your engine before this becomes a consern i think. How bout designing a new exhaust manifold with the flappers and all instead?

 

I believe AFGMOTO (sp?) has a 100% custom Y pipe design...IIRC.

Here's my super-hacked up "99 spec" Y-Pipe. Added a splitter, welded up the bungs, and chopped it about 1" shorter, and rotated the flanger for the IC pipe:



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Then I chopped it about 1" shorter and rotated the flange:





Ditched the "crossover pipe" for this more direct routed pipe:

 

The splitter in the Y-pipe is popular in Japan, I've seen that many times on Yahoo! Japan auctions and in RX-7 magazines. I've wanted to try it for some time to see if it would help things.

That would be a good first step, easy enough to try and see if it makes a difference, and if so go from there.

I do think that I've seen someone do a 3000gt style Y-pipe like you have pictured on an FD, don't know the results though.

Dale

 

Have you done a boost leak test lately? If you have any little boost leaks it will hurt the ability of those turbos to hold high boost. I should have done a test when I had the stock turbos but never did, I learned alot when I just did a boost leak test and found several small leaks and realized those t bolt clamps have to be super tight or there will be leaks. When I had the stock turbos I didn't have t bolt clamps and probably had boost leaks which might explain some of the boost drop off at high rpms. I also made a block off plate to go in between the uim and lim and tested right after the turbo. Too much pressure leakage goes down into the motor and through the turbo.

the more direct crossover pipe seems like a good idea to reduce turbo lag when shifting gears, but other than that I can't see any ypipe mods making much of a difference to justify the hassle, the divider would help a little though I guess.

 

The compressors are efficient enough, they are not the problem.

You're on the right track here.... however the problem is that the turbine housings are too restrictive (above about 400rwhp). A significant improvement can be made by properly porting the inlets to the turbines. The Exhaust manifold is actually not that bad, and not a major restriction, even with the flappers, etc..

 

Do you have any examples of the porting you're talking about?