regear -or- tuner??
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Joined: Jun 2011
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From: Hendersonville, Tennessee
Originally Posted by MrDillClinton
The OP's question was "which will put more strain on the engine." I answered " A tuner."
As to the gear thing, more RPM's is nearly ALWAYS more strain on the engine. A 2012 Auto Transmission with 3.21 gears and 33's is NOT going to have a problem getting going from a solid stop. He won't have the performance that higher gears have, but the engine strain will still be less. It all boils down to how much fuel is burning. More RPM's will burn more fuel, and result in more power. Lower RPM's will result in less fuel, and less power. Running higher RPM's will reduce the life of the engine.
I found a chart I will link - it shows an average RPM to Engine life comparison using several different engines.
With the AUTO JK's 2007-2011, I think I would have to agree that the 3.21's would be pretty awful for the 33's, but that is because of the .69 OD ratio on the Automatic for those years. At that ratio, even the new Pentastar engine would most likely have trouble turning tires at +65 mph.
I can compare to a Chevy V8, which I owned before my JK. Even with as much power as it kicked out, the motor had problems with larger tires, but it was because of the very high OD ratio, not just HP & Torque. That said, get up and go suffered some, but the reason to regear the axles was not for 0-60 power, it was for +65 driveability.
http://www.metricmechanic.com/catalog/engine-life.php
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Joined: Jun 2011
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From: Hendersonville, Tennessee
Originally Posted by AJMBLAZER
Regearing to a lower (higher numerically) ratio puts LESS strain on the drivetrain and engine assuming you regear to the optimal gear ratio. If you went 5.38's and 33's then yes you'd be wringing the life out of the engine just to get up to around town speeds. Fast off the line though...
The easier it is for the engine to spin up and the less the transmission has to hunt for gears the better it is. Regearing would return your system to optimal condition and result in it driving better.
Example - once had a '96 Ford Ranger 4x4 4.0L V6 and 5 speed stick. Came from the factory with 3.27 gears and 29" tires. When I bought it 31's were on it and I was lucky to see 12mpg. Very slow off the line and OD was hard to use except at freeway speeds (60+).
I regeared to 4.56's and put narrow 33" Swamper radials and despite the heavier, taller tire I immediately was getting a solid 14-15mpg. Owned it 3 more years and got that consistently the whole time.
The engine had to work less to move the vehicle and was in a better rpm range the whole time so I saw better performance and mpg as a result.
YMMV.
To me, unless you're just slightly bumping up the tire size, doing performance mods to counteract the bigger tires is a bandaid. 20 more hp won't make up for the fact that you're vehicle is now high geared and wheezing off the line and dropping out of OD at 55mph.
The easier it is for the engine to spin up and the less the transmission has to hunt for gears the better it is. Regearing would return your system to optimal condition and result in it driving better.
Example - once had a '96 Ford Ranger 4x4 4.0L V6 and 5 speed stick. Came from the factory with 3.27 gears and 29" tires. When I bought it 31's were on it and I was lucky to see 12mpg. Very slow off the line and OD was hard to use except at freeway speeds (60+).
I regeared to 4.56's and put narrow 33" Swamper radials and despite the heavier, taller tire I immediately was getting a solid 14-15mpg. Owned it 3 more years and got that consistently the whole time.
The engine had to work less to move the vehicle and was in a better rpm range the whole time so I saw better performance and mpg as a result.
YMMV.
To me, unless you're just slightly bumping up the tire size, doing performance mods to counteract the bigger tires is a bandaid. 20 more hp won't make up for the fact that you're vehicle is now high geared and wheezing off the line and dropping out of OD at 55mph.
JK Enthusiast
Joined: Jan 2012
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From: Paducah, KY
Tuners have their place. The good ones can squeeze a little more power/torque/efficiency out of the OEM setup and also some can help with power adding modifications, correcting for tire/gear changes, etc.
A tuner can't replace the leverage lost on your drivetrain when you put larger, heavier tires in place of the stockers.
A tuner can't replace the leverage lost on your drivetrain when you put larger, heavier tires in place of the stockers.
JK Freak
Joined: Jun 2011
Posts: 598
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From: Little Rock
Anyways, that is neither here nor there. I know full well that if an Auto transmission is having to sputter to get going from a dead stop, then new gears are a must. The truth is, the 2012 with an auto transmission would be able to turn 35's from a dead stop, and would still have an overall lower gear ratio than I would starting off in 2nd gear with 3.73's and my stock SRA's. I start off in 2nd gear ALL THE TIME.
As for the 1/2 hour of highway driving a week that he does, if the 3.21's could not keep up the pace at 70 (and I'm sure there will be some gear hunting) then the OP can turn OD off.
This entire argument is a bit worthless because in the case of this specific thread, the extra RPM's from gearing down to 4.11's would not be enough to effect the engine life significantly. The 3.21 gears are not high enough with 33's (on a 2012 especially) to negatively effect engine life either. And I think everyone agrees that using a performance tuner on a vehicle can have some negative long term effects, but definitely nothing major.
The fact of the matter is, putting in a superchip AND/OR regearing should not put an unbearable amount of strain on your engine. Neither will leaving the 3.21's. A JK with 3.21's and 33's drives within 50-75 RPM's difference of a JK with 3.73's and 35's, which is one of the most used sets on the forum.
My point is, every time the engine strokes, the life of that engine is lowered by that stroke, all things the same. Undergearing & overgearing can BOTH cause oil problems, but I don't believe 3.21's are enough to do this with 33" tires, the 4.11's definitely won't.
No! Not at all. We just have different views on the OP's question about gearing. None of this is detrimental to the engine.
Super Moderator
Joined: Jun 2011
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From: Hendersonville, Tennessee
Originally Posted by MrDillClinton
I can't speak to a Ford Ranger, because I don't know anything about the transmission. Of course, if the 31" tires were causing the engine to sputter when starting in 1st gear from a dead stop, then it needed to be regeared. Obviously, the axle gear and transmission gears were not quite up to the 33's he put on there in terms of MPG. However, the OP did not ask anything about MPG. In fact, if regearing saved you 2 mpg, it would literally take tens of thousands of miles before you broke even on the cost savings. Since the OP only drives 1/2 hour on the highway a week, I doubt he will EVER see a cost saving in MPG.
Anyways, that is neither here nor there. I know full well that if an Auto transmission is having to sputter to get going from a dead stop, then new gears are a must. The truth is, the 2012 with an auto transmission would be able to turn 35's from a dead stop, and would still have an overall lower gear ratio than I would starting off in 2nd gear with 3.73's and my stock SRA's. I start off in 2nd gear ALL THE TIME.
As for the 1/2 hour of highway driving a week that he does, if the 3.21's could not keep up the pace at 70 (and I'm sure there will be some gear hunting) then the OP can turn OD off.
This entire argument is a bit worthless because in the case of this specific thread, the extra RPM's from gearing down to 4.11's would not be enough to effect the engine life significantly. The 3.21 gears are not high enough with 33's (on a 2012 especially) to negatively effect engine life either. And I think everyone agrees that using a performance tuner on a vehicle can have some negative long term effects, but definitely nothing major.
The fact of the matter is, putting in a superchip AND/OR regearing should not put an unbearable amount of strain on your engine. Neither will leaving the 3.21's. A JK with 3.21's and 33's drives within 50-75 RPM's difference of a JK with 3.73's and 35's, which is one of the most used sets on the forum.
My point is, every time the engine strokes, the life of that engine is lowered by that stroke, all things the same. Undergearing & overgearing can BOTH cause oil problems, but I don't believe 3.21's are enough to do this with 33" tires, the 4.11's definitely won't.
No! Not at all. We just have different views on the OP's question about gearing. None of this is detrimental to the engine.
Super Moderator
Joined: Jun 2011
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From: Hendersonville, Tennessee
Originally Posted by AJMBLAZER
Tuners have their place. The good ones can squeeze a little more power/torque/efficiency out of the OEM setup and also some can help with power adding modifications, correcting for tire/gear changes, etc.
A tuner can't replace the leverage lost on your drivetrain when you put larger, heavier tires in place of the stockers.
A tuner can't replace the leverage lost on your drivetrain when you put larger, heavier tires in place of the stockers.
JK Freak
Joined: Jun 2011
Posts: 598
Likes: 1
From: Little Rock
Ok, you asked which would have MORE strain on the engine - and the answer to that would be a tuner. Now, just so you'll know, the higher (lower #) gears wil put LESS strain on the engine that lower (higher #) gears. This is why a JK with 3.21 gears gets better MPG than one with 4.11's.
And this one:
My last post (where I changed the conversation) is regarding these things above.
So, again, my point is that running 3.21's & 33" tires on a 2012 Auto is not putting any significant amount of strain on the engine than running 4.11's and 33's on a 2012 Auto and vice versa.
I don't see how that doesn't stay on topic with the thread.....
Super Moderator
Joined: Jun 2011
Posts: 11,054
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From: Hendersonville, Tennessee
Again....you stated that higher (lower #) gears put less strain on the motor than lower (Higher #) gears, which is absolutely wrong. That's all I'm talking about. Its basic physics man. Ill explain it this way to make it easy.....
Take a 10 speed bicycle for example. Pedal up a hill in the highest gear. Its very difficult and puts a huge load on the legs.
Now take that same bike in the lowest gear up that same hill. It is now very easy and puts little load on the legs. That is torque at work. The same principles apply to any vehicle.
I never said a '12 wont turn 35" tires with 3.21 gears, but a '12 with 4.10 gears will turn them easier due to more torque. More torque = less load on the engine. This can be backed by science
Take a 10 speed bicycle for example. Pedal up a hill in the highest gear. Its very difficult and puts a huge load on the legs.
Now take that same bike in the lowest gear up that same hill. It is now very easy and puts little load on the legs. That is torque at work. The same principles apply to any vehicle.
I never said a '12 wont turn 35" tires with 3.21 gears, but a '12 with 4.10 gears will turn them easier due to more torque. More torque = less load on the engine. This can be backed by science