i have a terrible rear that spins one wheel and has 2.73 gears amd 225 tires.
I run a 14.1 right now with that . what kind of gains could I expect if i got a 3.73 posi rear with 255 tires?
thanks

 

I would say with a 2800 stall converter and 373's matched with 255 50 16 drag's ( you have subframe connectors ) you will pick up 3(maybe 4-5) and if you could pull off 1.8 or a high 1.7 60ft times you should see mid to low 13's

 

hi ,i own a 83 z-28 ,350,lt1 intake,headers and 2 21/2 exsaust

and 373's and im pulling 13.6 with an open dif ,hope this helps

good luck

 

Bad idea

I'm running a very similar setup to yours and have found out the hardway that 3.42's are much better suited to TPI cars than 3.73's. If you were running an HSR, TPS Miniram, or even an LT1 intake, than 3.73's are the way to go. The TPI setup doesn't breathe well enough beyond 5500 or so rpms to make full use of the gears. You will be outside your power band more often than not.

Just my expierence

 

I've got 3.73's also, and they take my car way out of it's power band. I put 3.73's in my car back when it was stock from 2.73's, and I ran like a tenth better. To say the least I was very disappointed. 3.42's are definitely the way to go when sticking with TPI.

 

yea i was thinking the same thing about the RPM range. But, I am getting the holley stealth ram and around 200cc heads. So would the 3.73's go good with that?
thanks

 

Well if you are going to upgrade to the HSR, then the 3.73's would be a better choice. Not sure about those heads, as 200cc's is a lot to fill, and I'm not sure if the HSR could support that. 190's are probably a better match to that intake. Do a lot of research before deciding on a cam for that setup. Then of course, the convertor should match the cam and gears.

Good luck