2.93 to a 2.76 . Do I Need to re-tune?

[eatonmufs]

Wondering if I replace my 2.93 with the 2.76, would I need to re-tune the car? Seem to be such a small difference between the two. What type of gains do you think I will see? I wanted to go to a 4ib lower but Ill try the 2.76 first.

Thx,
joe

 

[NMRAcer]

It wont hurt. It really comes down to how conservative your old tune is and what the new A/F ratio is gonna be with te new pulley. I personally wouldn't do the swap without a retune. You're forcing more air in. The A/F IS GONNA GO LEANER. Lean enough to cause damage depends on the old tune. Save youself some trouble and put it on a dyno when you do the pulley swap.

 

[RickSvt]

Only one way to find out, go to the dyno.....

Rick

 

[IronTerp]

If you have the interchangeable lower pulley setup, you may want to think about trying the 4 lb lower first. Keeping the 2.93 will help with belt wrap on that upper pulley. The 2.76 w/ the 2 lb lower is spinning that ole' Eaton pretty good at high engine rpm.......same as the 2.93/4 lb, but with more upper belt wrap.

 

[CobraBob]

More than likely you will need a re-tune. Word of advice. NEVER take anyone's word for it. ALWAYS check your A/F after every motor mod and see what's changed. Correct with a re-tune as is necessary. Do this and you'll be happy. Don't do it and you'll always be wondering what you have and whether it is safe or not.

 

[eatonmufs]

More than likely you will need a re-tune. Word of advice. NEVER take anyone's word for it. ALWAYS check your A/F after every motor mod and see what's changed. Correct with a re-tune as is necessary. Do this and you'll be happy. Don't do it and you'll always be wondering what you have and whether it is safe or not.

good advice. thx

 

[CobraBob]

Any time!

You really should consider keeping your 2.93 upper and adding the 4 lb. lower. I think you'll be happier with the results. A bit harder to install, but it's a very popular combo. JMO.

 

[03SoCalCobra]

Going from a 2.93 to a 2.80 (close enough) will lean you out by about .3-.4 a/f. I did this as a test in the middle of my first dyno session. It also shifts the power curve 500 rpm sooner in the band with little change in peak HP and TQ and slightly faster drop off at the very top ( >6200 rpm).

At least that's what it did with MY combo.

 

[dynobobstieg]

Cobra Bob makes a very good point!

 

[combatstang]

While I agree with bob anr robyn, you will need a new tune either way. One is adding 2lbs of boost and the other is adding 4lbs.

 

[BANDIT HPT]

I swaped my 2.93 for a 2.76 and kept my 2.93 tune it. My A/F was okay because my tune for the 2.93 was pretty rich but you still need to get you A/F checked.