Quote Originally Posted by Frank87 View Post
Regarding the air intake project I have fit an M62 4.4 throttle valve to the M60 throttle valve housing. I have calibrated this throttle valve properly and when closed, it is closed without sticking to the house. When opened, it is 100% opened.

I have polished the house and the valve in the direction of the airflow.

I will compare this to the original 4.0 valve and the 3.0 valve+housing.

1 - M60B40 housing + M62B44 valve compared to the M60B40 housing + 4.0 original valve:
- definately makes the car slower on pickup. This throttle valve contains a buffer plate which means it restricts some flow right after you press the accelerator. This is probably done to ensure the 4.0 doesn't launch itself. On a 3.0 this plate is not nessecary;
- definately faster / quicker / more powerful above +/- 3200 RPM all the way to redline;
The gain is high RPM horsepower and a noticeable sacrifice of low end torque.

2 -
M60B40 housing + M62B44 valve compared to the M60B30 housing + 3.0 original valve:
- I think the car is a bit slower on pickup. It is almost not noticeable but I do have the feeling it is a bit slower;- definately faster / quicker / more powerful above +/- 3200 RPM all the way to redline. Even compared to situation 1, it feels even faster. The throttle valve is now non-restrictive and totalle flat open;
The gain is high RPM horsepower sacrificing a little bit of low end torque.

On my rebuilt engine I will also fit the 4.0 intake WITHOUT the 3.0 buffer plate. I will basically turn the entire car into a 4.0 intake.
I think the only solution is to play with the cam timing to bring it alive at lower RPM's. The only reason I think they have so much overlap is to eliminate detonation sub 3200. I used to chose cam profiles so I could run 10+:1 but it didn't kill much torque since the engines I tuned were 450+ CI.