Does anybody know what gearing the 1993 Bonneville with the 3.8 (L27) uses. I'm looking for the differential ratio and the drive/driven gear ratio which are used.

Mine has a 3.06 final, but thats an RPO code, and yours could be different. I have a 93 with an L27 as well.

Which ones have what performance, which ones the fastest, which ones accelerates quickest and which ones the best for fuel?

2.84 for gas milage, 3.06 for performance

Reason I ask is a friend is wanting to put a Buick Le Sabre (same body as the Bonneville i think) transmission into his Lumina Z34 so he can sell it. Right now the trans is shot, but the 3.4 DOHC got a 3.43 FDR and he is afraid of the 3.06 or below being slow as sin and nobody wanting to buy it.

I don't consider my car a slouch, i beat a cutlass supreme with the DOHC like your car pretty easily with my stock 93 with an L27. I have the 3.06 as mentioned above. If you are really worried about it, just go find another one that has the same as the original gearing.

Woa, lil defensive there. I NEVER said you car was a slouch. What I did say was that 3.06 or worse gearing on a 3.4 DOHC would be slow, it takes 3.43 just to get the car moving with that engine. Its called a TOTAL LACK OF LOW END.

He can get that Buick transmission for dirt cheap and is only interested in selling the car ASAP. The other problem is that the 3.43 gearing was only used on the 3.4 DOHC and a few minivans, trouble is finding either in a junk yard with very low milage, if you get 100k on a DOHC transmission and can consider yourself very lucky.

Sorry I didn't ,mean to attack you like that, yeah these engines have a nice torque curve, but i was just giving you a reference point for how it works for me. I considered a cutlass, but they were kinda pricey, and cost more/harder for me - to fix. I like your turbo job, and the gauges you did a custom job on. Who are you trying to sell the car to? Over 99% of the people wouldn't even know the difference, and most would actually appreciate the improved gas mileage. I bet it won't matter too much for a car like that, but you might wanna talk to a tranny shop or something to get their opinion on it.

If there is one thing the 3800 has it is torque, and if there is one thing the 3.4 doesn't have it is torque.

Anyways, its not my car, its a friend and he knows what he'* doing aside from this gear ratio crap. He bought the car to fix it up and re-sell it and the transmission blew up, right now he just wants to get rid of it.

And thanks, all that is left to do is get this beast of a motor running right :?

Nope, the car in my sig is my car (amazingly enough I'm a lucky SOB with a 110k original trans :P) When it does finally go I'm contemplating a 4T65 HD or possibly a 5spd depending on if I have a chunk of time to swap it.

My friend turned off the torque management and raised the rev limiter to 7k and the next day the trans died, I was contemplating doing the same but not anymore.

http://www.brian89gp.com/turbo/index.htm
http://www.brian89gp.com/car.htm

What I wouldnt give for a way to shove a 4t80 in my engine bay... I was talking with Intense and they swear up and down that their transmission will hold 400hp/tq at 7000 during a shift, I just find it hard to justify $4000 for a transmission.

I got lucky and the turbo I picked is a tad on the small side, the wastegate diaphram blew out and I got 10psi at 3300rpm with only 40% throttle . Its definately a different motor now, much more low end nut.