Our 4th generation Maxes have 190hp and 205ft-lb and the 5th have 222hp and 217ft-lb. Everyone raves about the new muffler, which I do like, but that wasn't the main restriction in the first place. I believe the intake manifold becomes extreamely restrictive at higher engine speeds and coincidentally was improved for the 5th. I know that the 5th has a variable resonance manifold which is controlled by the ECU which has discouraged people from the upgrade, but couldn't someone get one and modify it to always remain in the high RPM mode? This may reduce lowend efficiency slightly but the gains in the mid and high ranges should be excellent. Simply put, the 5th didn't gain ALL that damn power from a better damn muffler, damn it. Power being equal, 4th vs. 5th we win, because they are fatter, so to speak . Get the 5th intake manifold, maybe you should check out the junk yard or something, I don't know, just someone try this out damn it.

 

heheheheh.....that looks like a 30 HP gain to me...
just kidding...
I wonder why our 4th gen has a very ugly looking center trim for the auto stick..the 5th gens have much better cover..
...

 

What are you talking about? I'm talking about intake manifolds. Anyone with a real response?

 

my previou post was a wasted post..sigh....i like the trim piece for the auto stick...

here is my reply
from what I know
they, NISSAN did some internal engine modification, not just the intake manifold. what exactly, I do not recall. Some other people might remember. And note that they also play with the ECU. You probably already know all this.

I do not know how much HP we will gain by just changing an INTAKE MANIFOLD, keeping everything else constant....
I think there is more beneath the eyes that nissan did to get the 30+ hp ....
can't just go and put an intake manifold and expect a gain...I don't think anyone will do that out of curiousity, since the task requires some money and skills...not to mention the probabilty of messing things up..

 

You're right about the other changes to the engine other than the intake manifold, but it is known that our manifold is very restrictive and the new one is of much better design. Also, the other changes to the engine are very minor, and I personally don't think they affected output significantly. What I suggesting as a possibility is to get the 5th generation intake manifold and exclude the ecu that controls (unless you want it and have the $$$) it and "jam" the intake manifold into the position where it would be during high RPMs. I don't think it's responsible for the entire gain, but I can confidentally say that it was for a large portion of it. The following is from the Nissan web site:

For 2000, the engine has been refined through use of new intake and exhaust manifolds, Nissan Variable Induction System (NVIS) air intake control with a resin intake collector, new equal length exhaust pipes and the addition of a new variable capacity muffler derived from the one on the high performance Nissan Skyline GT-R. A special muffler flap valve, using high temperature aerospace spring technology and materials, opens at 2,000 – 2,400 rpm and above – reducing exhaust system backpressure. These changes help increase the engine's horsepower from 190 to 222 and torque from 205 ft-lbs to 217 ft-lbs.

I think it's worth a look.

 

The 5th gen's valves also have diff spec than
the 4th's. So back pressure has been reduced
even before reaching the exhaust manifold.

 

I vaguely recall someone mentioning that the fuel delivery is slightly different, too. The Fuel rails in the 4th Gen are feed cylinders 1 thru 6, bringing a a potential issue of feul starvation in the last cylinder if the feul pump is not able to keep the pressure up. In the 5th Gen, the feul rail is split so that feul pressure is equalized between each bank of 3 cylinders. I think they said that it wouldn't be hard to transfer that to a 4th Gen.

DW