kjl2020
Well-Known Member
- First Name
- Chris
- Joined
- Jul 20, 2020
- Threads
- 11
- Messages
- 101
- Reaction score
- 66
- Location
- DeKalb, Illinois
- Vehicle(s)
- 2020 Wrangler 2-Door
- Thread starter
- #16
How do you figure out which ECM you have?Change gearing. The 3.45 stock gearing is not great. It's basically a 5 speed, best fuel mileage at 60 is 4th gear, 5th gear is good 65 to upper 70's. 6th gear isn't even usable until nearly 80 if there's even a small hill (I live at 3000 ft).
I think that if you can loaf it along at 17-1800 rpm on the flat lands with low load at 65-68 mpg in 5th, you could achieve a little better economy, but we live where it's up and down hill in any direction. Loading it at 1800 in a higher gear on and off, hurts the economy. It does better a little over 2000 rpm. I have over 4000 miles of experimentation playing with this, and these are my observations on a 2 door, 6 speed Willys with 3.45 gears and 33" Falken AT3W's.
In my opinion, 3.73 would be an okay gear for stock tires, but 4.10 with 33" tires puts it in a very good sweet spot.
I've experimented and found the 3.6 likes 2000-2100 for lower speed cruise, and 2200-2300 for freeway speeds and some hills. I'm getting better fuel mileage in 5th at 76-78 mph (commute 30 miles each way to work) than 6th. 6th is only turning 2000 rpm at 80, which won't pull hills. I'm averaging 21 ish (20.5-21.5 on the freeway using 5th, where I lose 1 to 1.5 mpg using 6th (19.5-20).
At 60 on the back roads, 4th at around 2100 rpm does better than 5th at just over 1700. 22-24 mpg at those speeds (hill dependent). 70-72 is the sweet spot for 5th on the 2 lane back road (65-70 zone).
Going to 4.10 puts the rpm in the sweet spot for 4th around 50, 5th is 60-68, 6th is 69+. It's only turning 2400 at 80.
Also, that's a decent reduction in ratio in the lower gears, which will feel a lot peppier. As a bonus, 3rd gear becomes usable in the 25-35 range for offroad gravel road running (mountain gravel roads) which is a good place to be for mountain running. 4th gear becomes the fast gravel gear. Right now, 2nd is too short and 3rd is too tall for the winding mountain gravel roads we like.
I agree with the people that say 4.56 with the 6 speed manual and 35" tires. That puts it at very similar RPM vs. speed.
We'll be swapping out the 3.45's for 4.10 this weekend. Would like to get to where we have a usable 6 spd transmission, instead of a 5 speed, which is what we have now.
As for power, Livernois, depending on which ECM you have. Looks like the 6 speed guys are getting the GPEC2A that can be jail broken. Nothing for the '22 yet, but the older ones have a tune. Even the 87 octane tune is about 11 HP at the peak, but gets rid of the mid-range drop and ends up being 30 HP in the mid-range. The 91 octane tune delivers a lot more at the peak, and more power everywhere from 2000 up.
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