hi,
i was just wondering what everyones gas mileage is with there 6 speed car,and higher horsepower levels,thanks

With my old 700r4, I got a best of 21 mpg on the highway. Right now, my car is running pretty bad, still haven't found whats wrong, but even like that, I got 30 mpg last week. That was on an 80% highway and 20% city trip. Between the 2.73 gears (which are definitely not staying there much longer) and the .5 6th gear ratio, mileage is pretty good on the highway.

I pulled 31mpg averaging 65-70mph on very flat highway, engine specs are in the link below.

92Blue

By my calculations, with roughly a 26 inch diameter tire, you are turning only 1100 rpm at 60 mph in 6th. How does it behave on the highway in top gear?

I run 3.70s in a nine inch with the same .5 6th. It works out to about 1500 rpm at 60 and is fine. The factory cars with 6 speeds use the 3.42 I believe. I have driven that and it seems fine.

Best I have done was 32 mpg averaging 65 mph stock 88 L98 with speed desity and aftermarket fuel/spark control. The air fuel was leaned to about 16.0-16.5 to 1 for the vacuum I was running steady cruising. Pretty strange feeling to get into the 30+ mpg with a relatively heavy car and a relatively large V8. Good aero helps I am sure.

In 6th gear, you can cruise at just above idle with the 2.73 gears. Don't expect to accelerate at all though. I have to downshift if I want to move. If you are at 1700 or 2000 rpm, its not as terrible, but acceleration is next to nothing. You can actually accelerate, just don't expect to feel it. If you didn't look at the speedo you wouldn't be able to tell.

I'm definitely doing a gear swap though. The car is a dog off the line, and I don't have a need to run the speed limit here in Miami at idle almost. This gearing is disgustingly tall.

how much did you guys pay all in all for your swaps?

all included right down to the trans oil I'm out $$2115 for my aftermarket box

I got everything for about $1500, including the SGI-5 conversion box, and my spohn crossmember. After the install, my clutch master cylinder started to leak like crazy, so I had to get a new one. So grant total is about $1650.

what are your tranny's rated to? hp/tq

450 ft-lbs tq.

Ratios are identical to the 93 stock 4th gen T-56 so I didn't have to change rear gears either (I have 3.73's). Take that into consideration too if your trying to figure out which one would be cheaper.