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View Full Version : Change final drive ratio, fuel mileage increase?



beaver
05-23-2014, 07:46 AM
How hard would it be to slow down my revs? Its nice to be able to climb hills in 5th but I have no problem downshifting. At 100kph (60mph) I'm turning about 3200 rpm. I'm using my car as a daily commuter and figure I could increase my fuel milage if I could slow the engine rpms a bit. At $1.40/l, 8.4l/100 isn't cutting it.

Lonestag
05-23-2014, 01:35 PM
What year is your car? If it is an 85 or older, you could probably change the rear end much more easily...

beaver
05-24-2014, 02:06 AM
'91 GTS

pitcelica
05-24-2014, 11:29 PM
You can use a 5th gear/driven gear setup from a S51 Camry Transmission. This gear ratio is 0.731:1 instead of the S53 0.82:1 ratio. I did this gear swap in my '91 GT-S and the RPM at 60mph was down to about 2600-2700 RPM. This yield to a non-negligible fuel consumption reduction. Also, the noise from my 3'' exhaust was quieter. I recommend it!

beaver
08-26-2014, 02:07 AM
You can use a 5th gear/driven gear setup from a S51 Camry Transmission. This gear ratio is 0.731:1 instead of the S53 0.82:1 ratio. I did this gear swap in my '91 GT-S and the RPM at 60mph was down to about 2600-2700 RPM. This yield to a non-negligible fuel consumption reduction. Also, the noise from my 3'' exhaust was quieter. I recommend it!

Non negotiable meaning something noticeable I assume. 1 mpg? More?

METDeath
08-26-2014, 12:12 PM
Or if you want to be really awesome, stick that fifth gear in a S54 from a 94-99 Celica, then you get sporty low gears, with the highway gear from the Camry.

Depending on what the highway mileage is in pitcelica's car.

pitcelica
08-26-2014, 12:38 PM
I gained around 1-2 MPG (from 27-28 to 29-30). But for me, the huge advantage was the low noise. My 3'' exhaust was a lot more noisy at 3000-3100 RPM than at 2600-2700.

Sam

VavAlephVav
08-26-2014, 06:12 PM
Here's the thread from 6gc for the Camry 5th gear swap. I'm not sure if you have the same transmission or not, but I doubt it's much different
http://www.6gc.net/forums/index.php?showtopic=92975

They say it lowers it a good 500 rpm

Luni
09-01-2014, 12:31 AM
Keep in mind, incresing your tire size will change your final drive as well.

It will knock your speedo off, but you can simply put on larger diameter tires as well if you dont wanna go through changing the differential.