Thumper33

Don't worry, it's in a Jeep Conversion

Anyway, I'm not sure exactly how the LS1 was meant to run. I know it's going to have more torque then the 4.0L 6 cylinder it replaced. I'm trying to figure out what rear axle gears I should run. I think the 4.56s I have in there now are going to be too short.

Transmission: NV3550 -

First Gear 4.01
Second Gear 2.33
Third Gear 1.39
Fourth Gear 1.00
Fifth Gear 0.78
Reverse 3.57

As I mentioned, I have 4.56 gears in there now, and I'm actually running 34" tires. I'm going to drop back down to 33" tires, so I think I'll likely want 4.11s, but maybe even 3.73s.

Suggestions?

Thanks!

DynoDR

iTrader: (1)

Going from a 34" to a 33" is not enough to even worry about changing your ratio. You would be the same as putting a 4.70 in it now with the 34"s.

In other words a 4.43 ratio with the 33"s is like what you have now with the 34" tires and 4.56.

Thumper33

I understand that there isn't much difference in the tires that I'm going to, but maybe what I neglected to mention is that my RPMs at 70 mph are at about 3k. I had to rev that high for the I6 to be able to push me through the wind at that speed, but I'm guessing that the LS1 will have more torque at lower RPMs.

One thought I had was to compare dyno charts of my 4.0 to the 5.7 and see how low I can take the RPMs based on that. I know the cars that these engines come in cruise at something like 1500 RPM, but my jeep is more like pushing a 4000 lb lego through the wind compared to a corvette.

That's the source of my debates.