1995+ JDM short 5th gear results
 

When my original transmission went bad, I bought my friends trans with the .806 5th since it was just rebuilt. He barely drove his car with it before his engine blew, and he is now going LS1.

The shorter 5th required me totally retune the cruise area of my PFC map because the slightly higher revs and lower engine vacume level made the engine run in a lower P row. At 3500 rpm it does 80mph which will give 160mph at 7000 rpm. My engine is stock port GT35R A-Spec single conversion.

I drove from Houston to Houma last weekend with the A/C on (349 miles) and made it on one tank of gas. I was cruising 65+ mph where posible on I10 and US90 and made two rest stops for each way. Occasionally I let the turbo breath at it's more optimum level. I averaged 21 mpg and 63.5 mph for the trip.

The 5th gear is like a natural extension of 4th. If your revs are above 3000 rpm,
it almost feels like you are in 4th. Above 3500 rpm, it feels like 4th.


Here is some 5th gear info.

1992-1994 RX-7 USA 5th gear .719
1984 RX-7 GSL-SE .758
1989 RX-7 GTU .758
1986-1988 RX-7 S4 T2 .762
1977-1978 Cosmo .791
1995-1999 RX-7 JDM .806

So what was your mileage with your original tranny?

The last trip mileage with the stock 5th was over a year ago and I think it was also in the 21-22 mpg range for the same trip and speeds.

I am still tuning my new 5th.