snow

Quick question for the brain trust...

So if you were to swap the pulley for example from a 3.25 to 3.0 would you need to have the car re-tuned?

What is the typical increase in PSI with a .25 reduction in a roots SC system like an Eforce.

Just wondering the ramifications.

chefcg1

I would think that a tune would be a must with any increase of boost.

C7&7

You will see 1-2 PSI change from that pulley swap. I would atleast put it on the dyno to check the A/F. It kind of depends on how it was tuned originally. If it is a little fat then it would be fine, but if the original tune is really dialed in then it will need more fuel.

onebad1lE

No tune =. Boom

BlueDevilZ51

Stage 1 E force is a 3 1/2" pulley 7 lbs of boost. Stage 2 E force is a 3 1/4" pulley and 9 lbs of boost. The Edelbrock tune is rich but I'd definitely think a tune would be required.

badass1g

I'd take the guess work out of it and get an AFR guage and let us know how it goes. I am also curious about this subject.

snow

thanks guys for the information.

vrybad

AFR gauge wouldn't be enough, your eyes and mind can't react fast enough to keep the engine out of trouble if it goes lean, besides who wants to look at a gauge when making a pull to check AFR's.

Dyno tune and logging is the only way to really know how safe the tune is.