Pulley down without a tune

[The Beast 2014]

Ok, dumb question but maybe you can help. My tuner is swamped so I don't want to harass him as we are all getting ready for an event next weekend. Currently I am running a 3.25 inch pulley on about 6.5lb of boost. Can I pulley down to a 3 inch without a new tune? I know I will get more benefit from the new tune but if I can't get into my tuner for a bit I was curious if there are any benefits?

My fuel system is ID1000's with a BAP so I think I have the room. Plus with these cars I thought the computer will make adjustments from timing if you are running short on fuel.

Thoughts?

 

[jn2]

Normally I like to subtract a few degrees of spark timing when increasing boost. You may run into some KR, this really depends on how aggressive your tune is now.

If you have some cushion you will prob be okay. It sounds like your fueling can handle it so if you do decide to pulley down the car will handle fuel adjustments by going into positive fuel trims Daily driving you will be fine, the smaller pulley won't affect normal driving.

 

[The Beast 2014]

I was thinking of putting on the smaller pulley and running MS109 for events until I can get a new tune. Currently it's 14 degrees of timing on 91 octane so with MS109 I am thinking it would be ok.

 

[jn2]

I was thinking of putting on the smaller pulley and running MS109 for events until I can get a new tune. Currently it's 14 degrees of timing on 91 octane so with MS109 I am thinking it would be ok.

If your current tune is set up for 91 and you are okay, adding the 109 will keep it fine. That is more than enough octane to keep knock at bay. Just be sure to at least datalog to make sure KR stays at or below zero.

 

[The Beast 2014]

Thank you

 

[Vert]

A tune is not needed if its a 13 or 14, as long as youre going down just one pulley size or up one pulley size.

 

[The Beast 2014]

Great, thank you. Yes, 3.25 to 3 inch.

 

[Vert]

Great, thank you. Yes, 3.25 to 3 inch.

As jn2 mentioned, still do a catalog but since you have all the supporting mods, the pcm should adjust for the extra air and add fuel.