Going from a 3.7 to a 3.4. What do I need to change on the tune? Cut back on timing a couple deg, what else?

 

More air in will need more fuel.

 

x2 on more fuel.

 

new tires.... lol

 

....

 

No doubt. A new trans also...

 

Also check the setting (forgot what it is called) which switches over to PE mode. When I put the 3.25" pulley on the old 4.8 there was a range where I was getting boost while still in 14.7 AFR closed loop mode. Not the best situation. There are 2 settings: MAP and % throttle. I believe I had to lower the % throttle value.

 

how much boost was the 3.7" pulley putting in ?

 

5.5psi at the shift. Hope to see about 8psi or so with the 3.4

 

Good call. I'll verify this. Thanks