First off I'm a newbie. 2nd I have a 95 z28 lt1 convert. and after reading the different threads I've learned I have a GU5 which is a 3.23.
Now I wanna go to a 2.73 and before everyone jumps through the matrix to get me let me explain. I'm just flat out a highway driver. I take the highway to work and will at a moments notice take me and the shirt on my back on a road trip.
Now my logic is that 2.73 would save gas and lower my rpms. Right now my rpms at 80 are around 2600 or so.i drive 80-110 mph everyday. The freeways are hectic around here.
What is needed to go from a 3.23 -2.73.

 

Not worth the trouble.

 

IMHO the car will have to work harder with the 2.73 gears negating any mpg differance. Go with 3.73s, get beter acceleration, and the motor wont have to work as hard, and youll get the same or beter milage if you keep your foot out of it and let the gear work for you. Hope this helps, prorac1

 

Yup your nuttier than chinese chicken salad
I honestly dont think you would see any gains cause the engine will be working harder to accelarate the vehicle from a stop which will effect the mileage.

 

Just dont drive 80 if you do 70 it will be like you have a 2.73

 

Or you could just swap to a 6 speed.

 

I have 6 speed and 4.10 ! On highway 90-100 mph it is 1500-2000 rpm!

 

I have 4.10's and at 2000 RPM my speed is 72MPH. The factory 3.42's at 2000RPM will get you 80MPH.

Red,
I hope your joking about you speed at 2000RPM, if not you need your PCM calibrated for gears in a big way.

 

Yea ok chinese chicken salad...lol. yea i know crazy.
So now how difficult is it to go from an auto to an m6. New brains, new chips?
What all is involved and am I gonna come out of 3 grand trying to do this. Thanks for the replies you guys are awesome with the knowledge.

 

Try these:
http://www.afrashteh.com/tranny_pics/T56.htm

http://www.ls1tech.com/forums/showthread.php?t=200480

 

Thanks.

 

You won't gain any gas mileage. I got 25mpg with 2.73s and 25mpg with 3.73s - it all depends how you drive.

 

OK, here's the low-down from my perspective :

With 2.73's, the best mileage I've ever seen was 310 miles on a tank of fuel. With 4.10's, I've seen 265 miles to a tank. I'm talking about all highway driving in both cases. I may have done the math wrong, but I think that works out to 21 mpg and 18 mpg respectively? (~50L tank ... ~14.5 gallons?). Does that seem about right to everybody else?

...anyways, point being, ~3 mpg hardly seems worth the expense or hassle of swapping gears. I already tried that last summer (thought I was going to be doing a bunch of highway driving and the 2.73's were going to help out), but it didn't make that much difference, so I'm going back to my 4.10's this spring .

Considering 3.23's in pretty much half-way between 2.73 / 4.10, I'd stick with them and get the best of both worlds (mileage and acceleration ).

BTW, my average mileage is usually somewhere around ~220 miles per tank, or ~15 mpg I guess? That's based on a normal mix of city/hwy driving, and it never changed much regardless of 2.73's, 3.73's, or 4.10's .

 

I'll tell tyou where the confusion is.

I just had a 92 convertible 305 rs 700r4 and I would fly down to VA beach from Detroit and still get close to 400 miles to a tank. Now its been awhile since i had a 350 but it shouldnt be gettin nothing less than 20 mpg. I'm getting nowhere near that now.
.......or maybe is it the trans difference?