Ideal All-Purpose RPM for Re-Gearing

By the time you're moving that fast, there are a number of other things that make a lot more noise than the engine.
My wife is louder than my MT tires with the top off. She insists on talking, even when I don't talk back. I once timed her on a 45 minute drive and I said exactly 10 words to her 3,643. It never slowed her down. :unsure:
 
I'm putting 33x10.5's on my 98 TJ with an AX-15 and 4.0L. The motor is going to be stroked and should have peak torque somewhere around 3000RPM hopefully. It will be an all purpose rig, 85% highway cruising during the week, probably 80 miles per day commuting almost all highway.

80 miles per day? You should have bought a Honda Civic.
Yes I know it's a Jeep not a Honda, so please don't tell me I should have bought a Honda Civic.

Don't tell me what to do.


j/k, get the 4.88s. And a commuter car.
 
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I’ve been running 4.56 gears and 35,s for about a year and it’s a great mix between fuel economy for Highway and still does fine off-roading
 
My wife is louder than my MT tires with the top off. She insists on talking, even when I don't talk back. I once timed her on a 45 minute drive and I said exactly 10 words to her 3,643. It never slowed her down. :unsure:

Interesting. I've yet to try that comparison by driving my wife around with her top off. I don't think she'd go for that...
 
Not that it is a deal breaker, but how buzzy/loud/annoying is the engine cruising in the 2750ish RPM range if at all? Does the 4.0l care?

FYI...the stroker is going to be a DIY combo of the "modified poor man's stroker" and either a gasket-matched head done by myself or if I want to cough up some coin get the ported TUPY head from Newcomer. Probably a Comp Cam's 231 or 232 cam. Shooting for 9.5:1 compression or so and 87-89 octane. Prioritizing low and mid range torque.
My stroker is not buzzy at any rpm really. The inherent smoothness of the straight six remains. The block I have is 1992 (IIRC) and pre-dates some changes Chrysler to later 90s block (which were stamped NVH). I presume because of that and heavier valve springs, there is a little more mechanical noise from the motor vs the stock 4.0 (which I don't notice anymore). Chad Golen said "Cam specs are Duration @ .050” 210/219 Lift .500”/.500” LSA 114".

Back to RPM/gearing: at 75 MPH I'm at 2500 which is fine. I have a full 2.5" exhaust w/ a smaller cat and Magnaflow muffler which sound good to me but are loud enough as you approach 3K that I wouldn't like it for cruising. One more thing, as you start doing things which can lead to driveline vibes (lifts/tucks...), higher RPM can make that worse. So, in my view, one advantage the increased power from a stroker is slightly less need for deeper gears especially for street driving.

bottom line: 4.56 is the lowest I recommend.
 
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Chad Golen said "Cam specs are Duration @ .050” 210/219 Lift .500”/.500” LSA 114"
Damn that's a little beefy! The popular "232" cam from Comp Cams is Duration @ .050" 206/212 Lift, .460/.476" LSA = 113.

I've been thinking of buying a copy of Dyno-Sim 6 and putting together a good model of the engine. It wouldn't be 100% accurate but might show torque/hp gains by switching cam profiles, compression, etc.
 
But seriously, with that much commuting I'd get 31s. It's amazing what a jeep on 31s can do and they drive and handle really well. It's really a sweet spot for looks/capability/drivability/cost. That's what I'd do if I was going to put a lot of miles on.

That was my plan before I went goo goo and bought mine on 35s 🤪
 
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Damn that's a little beefy! The popular "232" cam from Comp Cams is Duration @ .050" 206/212 Lift, .460/.476" LSA = 113.

I've been thinking of buying a copy of Dyno-Sim 6 and putting together a good model of the engine. It wouldn't be 100% accurate but might show torque/hp gains by switching cam profiles, compression, etc.
Sounds like you have more knowledge about cams than I. Golen recommends oil with zinc additive because of the heavier valve springs and no roller lifters. Compression is 9.5:1 and 89+ octane is also recommended. I also have stock 4.0 and 4.6 stroker Mustang chassis dyno results in my build thread for comparison (spoiler: the stroker is not as strong as I thought it would be the Golen superflo engine dyno results lead me to believe it would be-but it is still good in the real world).
 
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Interesting. I've yet to try that comparison by driving my wife around with her top off. I don't think she'd go for that...
Fully nude is the way to go. :cool:
Camo Jeep.jpg
 
I’ve been running 4.56 gears and 35,s for about a year and it’s a great mix between fuel economy for Highway and still does fine off-roading
Interesting, I’m looking at re-gearing and I have the NSG370 6 speed with 33” KO2s. Stock gears are 3.73 and here in CO I sort of need a wide variety of capabilities from crawling rocky trails to going 85 on the highway for hours on end. Most people seem to recommend 4.88 with 33-35” tires but I think that’s too low I’m thinking 4.56
 
Interesting, I’m looking at re-gearing and I have the NSG370 6 speed with 33” KO2s. Stock gears are 3.73 and here in CO I sort of need a wide variety of capabilities from crawling rocky trails to going 85 on the highway for hours on end. Most people seem to recommend 4.88 with 33-35” tires but I think that’s too low I’m thinking 4.56

4.88 for 35s, 4.56 for 33s. I didn't like 4.88 with my nsg370 until I got 35s. It was fine with an Ax15, but the lower OD pushes it over the line for me.
 
But seriously, with that much commuting I'd get 31s a commuter car. It's amazing what a jeep on 31s can do and they drive and handle really well. It's really a sweet spot for looks/capability/drivability/cost. That's what I'd do if I was going to put a lot of miles on.
agreed


:geek: