intake/exhaust manifold upgrades instead of increasing boost?

[afwfjustin]

I'm new to a '95 240sx with rb25 (stock boost and side mount intercooler for now) and I'm looking at ways to make the setup more efficient first before adding boost. Can you guys post any real world numbers regarding intake manifold/throttle body/exhaust manifold upgrades and how much power you netted?

My last car was an 00 Honda S2000 which made 400 rwhp on only 11 psi (with lowered compression too) and I'm interested in going with another efficient setup.

[240z4u]

You won't find many people, if any on here, have actually done back to back testing.

What are your power goals?

Evan

[Darius]

The biggest improvement that you'll see is in a bigger front mount IC. The stocker is soo small.

And I understand that you don't want to raise boost, but the stock turbo can be pushed to 10 psi without getting outside its efficiency range. So, getting a boost controller would keep it on the stock injectors and ECU without a problem. You should theoretically tune it, but the stock ECU will be fine at that level of boost.

Keeping the stock throttle body will give better response down low than a larger Q45 TB would. Honestly, the stock manifold design is good, but it is soo bulky and hard to work around/with that nobody "wants" to keep it.

The exhaust manifold is good for 500hp or more before it starts to limit things, so that should satisfy your goals for now.

[afwfjustin]

thanks for the replies - I have a front mount for it it's just not installed yet. I have no problem with raising boost - it's just funny to me seeing people on other car forums (I'm from the s2k world) having to take 18 -20 psi to hit 400 hp and whatnot. I figured I'd try and maximize efficiency of the setup and make the most hp per psi.

Eventually I want around 400 rwhp for this car too and will be going with a GT30 dual bb turbo. I'm setting the car up for road course/grip driving. As for now, I'm interested in possibly going with stuff that'll make it more efficient.

So even an equal length tubular wouldn't gain much? A better flowing intake manifold? More aggressive cams?
Modified by afwfjustin at 7:32 PM 6/26/2008

[Darius]

Efficiency and part matching is very important in a NA application, but with a FI turbo application, the turbo does all the work and fuel/timing tuning make all the difference. Yes, some parts may make the turbo spool faster, but we're talking small rpm increments.

If you want 400hp and a fast spooling turbo, you should run an internally gated 3071R with ~500-550cc injectors at about 20 lbs of boost with a standalone to dial it in. A tubular manifold will help spool it faster, but like I said, only a few hundred rpms faster than the stock log manifold. Stock unit is solid from the factory. Try that setup on for size and if it doesn't meet your expectations, upgrade the intake manifold and valve train.