Post by
The_Scooch »
https://forums.nicoclub.com/the-scooch-u41386.html
Tue Aug 08, 2006 6:56 am
I found the answer in another forum, complete with dyno results and now it all makes sense.
First, the MREV and spacer do work and here’s how:
The revup engine (6MT) differs from the 5AT in a few ways but one significant difference is the shape and port length of the lower plenum. More torque is needed for an automatic transmission and so to give the 5AT engine a different power profile, Nissan engineers created a lower plenum with long ports. This takes up extra space in the chamber, thus lowering the volume of air while increasing port velocity. For the 6MT, the opposite was done. The ports were made shorter and the plenum slightly dished to allow more air volume and less restricted flow.
The result is in the numbers; the 5AT has more torque and the 6MT has more HP.
Installing the spacer alone on a 5AT corrects the volume problem, thus increasing HP. Nothing more needs to be done to the 5AT. Installing a spacer on a 6MT will accomplish next to nothing and could hurt top end power. The solution is to install the MREV kit. The kit consists of a 5AT lower plenum that Motordyne says they have modified for improved flow, and a 5/16 spacer. The ½ spacer allows a little more volume and the pressure drop hurts the midrange power. The result is NOT more top end power, but instead, more torque and more HP in the mid to upper mid range. The dyno shows approximately a 15 HP increase and 18 ftlb torque increase across the powerband. HP peaks slightly higher than stock at around 6200 RPM, levels off and then drops to about 2 HP less than stock at redline. This test was done on a forum member’s 350Z.
I don’t drive around at the redline so I am happy to sacrifice the 2 HP. The usable HP and torque increases are right where they will be the most fun.
So I figure with an exhaust and a Z-tube, I should get over the 300 HP mark ( a claim I want) while still improving the power curve and driveability.