Smaller Pulley with a tune bad???

[reeber]

Smaller Pulley without a tune bad???

As some of you may have read in the talk forum, I am in the middle of a Mr. Freeze installation along with dropping pulley size from 3.30 to a 3.12 and the Kenne Bell Boost a Spark. I was able to get the Boost A Spark and pulley done, but waiting on the methanol kit and dyno tune on Monday. My question is that does anyone know how much leaner the car runs with about 2 lbs. more of boost? Is it unsafe, because the car has a very noticeable amount of new power with the smaller pulley and the spark booster.

 

[Gearbanger 101]

Exact figures....not sure. But do you really want to take the chance? An additional 2lbs of boost may not seem like a lot on paper, but at 9psi these modular motors are already running on the ragged edge of failure. Adding 2psi to an engine with stock or (even upgraded components like you have) without increasing fuel delivery or pulling timing may cost you your short block? All it takes is the slightest hint of detonation, or a few degree drop in temperature between different days and it’s all over! I say keep your foot light on the pedal until you can have it retuned, or swap it back to the previous pulley!

 

[jstreet0204]

In theory, if your MAF is dialed in good from the last tune, and your fuel system is good enough to keep up, it should be able to keep the a/f under control, but with forced induction, it is always better to be safe than sorry.