Mph
 

Running super street. Will I gain any mph going from a 4.86 rear gear to 4.30? 950 hp car trapping about 140-142ish

Re: Mph
 

Difficult to say. I would doubt it, as the car will have a more difficult time getting up to speed when it comes off the stop.

Re: Mph
 

I agree with Lenny5160. Converter lockup will change dramatically, It will slip more. Maybe try the 4.56 gear.
Dan

Re: Mph
 

My thoughts too. Was getting suggestions from others that I would pick up alot but I'm not sold on it

Re: Mph
 

Rpm=mph
That’s the short version

Re: Mph
 

Hear lots of good things about the APD Max Speed....seems like better way to go if you don't mind changing to a different setup. There's another thread on throttle stops which got me doing some research.

Re: Mph
 

That is a 12% change in gear ratio . not taking into account the probable loss of converter efficiency that will occur , that's a nearly 1000 rpm drop in trap rpm.
Not to mention the loss of reaction time and loss of acceleration coming off the stop.
I'd be talking to your converter guy , maybe looking at a lower stall higher efficiency converter using the existing gear.
You didn't mention what your trap RPM is . ....Is that a concern that it's too high ?

Re: Mph
 

Mine did.

Re: Mph
 

I'm a little confused here. What does your car weigh? 950 HP and only 142 mph? Something doesn't calculate. I had a Super Street car that went 148-150 with 875 HP.
Car weighed 3000 lbs. (67 Cuda). I used 4.56 gears and hit the finish at about 7600 rpm. Engine made peak power at 7300.

Re: Mph
 

I have a 505 bbc in a 70 chevelle that made 860 on stinnets dyno a few tears ago and it only runs 137,139 best. 4.88 gear 14.5 32 tires. 3150 with me