Does anyone have before and after numbers regarding a rear end swap. I have the L98 tpi setup, and I was wanting to change the 272 to the 370 ratio. I am wondering if the tranny will still shift at the same rpm's it used to, and if I will be in fourth gear at the end of the traps. Will the TPI run out of breath before I get there. My ET now is 15.44. I was wondering what I should hope for after the swap. I know the ET is low, It has 193 swirl port heads on it. I assume this is why.

 

Shifts will be at the same RPM but the speeds obviously will change.


What kind of engine combo are you running? Need to know where your powerband is at, but with the TPI its going to top out fairly low...

 

I bought the car 89 iroc cheap. It was not running when I got it. It had some sensors unplugged, and the front end accecories were loose. I am sure someone has changed the heads. I ran the casting numbers and they come back to be swirl port tbi heads. The car comes up short about 40 hp. I have no check engine lights, and all of the blm's, and 02's come out right. I am running the stock TPI setup. Well Stock with an adjustable Fuel Pressure reg. The 9 bol trear end is slipping, so I am taking it in to have the clutches replaced, I was wondering if it is worth changeing the gear while the cover is off. It will add $400 to the cost, according to the shop. $400 would get me well on my way to a set of :98 aluminum vette heads. I am all about the cheap fast car.

 

Well both are definately going to help drop that ET a reasonable ammount.

But i guess in this case your better off getting the gears put in while they have it apart to save on labor.

At least when the time comes that you get some decent heads its just going to be that much better of a result.

 

- 3.70 gears will be fine. No, you won't be in 4th, which is good, cause you shouldn't be using OD racing. - With a stock intake, cam, and less heads, you'll be pretty well out of breath in the 1/4, but it'll be good to go as soon as you start modding it much.