Steve Chryssos
10-01-2008, 03:56 PM
Here's a cool gear calculator I found with graphical results.
http://www.gtsparkplugs.com/GearCalc.html
meenaggie
10-01-2008, 05:19 PM
Nice! So do you think 4.11s running 2635 rpms or 3.73s running 2391 rpms @ 70 mph will be better in my 1968 camaro with LS2 / 4L60e? Do you really expect much gas mileage difference in those two points? It will be a weekend cruiser. Thanks Steve.
Steve Chryssos
10-02-2008, 08:18 AM
Empirically, not much difference in gas mileage, but every drop seems to count these days. And 2300 rpm is more "comfortable". More RPM means more noise. That noise tends to beat you up on long trips. With an e-trans, we can tune for either combination for around town driving. With the 4.11, the trans will be calibrated to drop into overdrive sooner than with the 3.73.
The bigger issue is on the other end: 1st gear. 12.58 with the 4.11 vs 11.4 with the 3.73's. I don't think you'll care much for the 4.11's off the line at very light throttle. The 1-2 shift will come almost immediately in auto mode. Also it's hard enough to plant the typical pro-touring tire off the line at WOT. So for the most part, I tend to lean towards the 3.73's for true multi-purpose cars.
Next year, I intend to try a set of 4.11's on the road course to make better use of 2nd and 3rd gears. I don't hardly use 1st or 4th on road courses. But 3.73's seem to be the perfect all around gear for 26" tire pro-touring cars with overdrive automatics.