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Unread 03-29-2010, 07:15 AM   #16
JrJmisn
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Quote:
Originally Posted by Terrible2 View Post
I also concur with Imped, I ran 3.07 on 33's and it seemed when I lugged the engine less and went to a lower gear, I did get better gas mileage. It seems counterproductive, but heck it works.
So the 3.07 gearing with 33s gave you better MPG than 31s with 3.07? Is that because you HAD to be in a lower gear and keep the RPMs higher as you drove - so your habits of driving changed - or because the ratio is actually more efficient at all times?

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Unread 03-29-2010, 07:24 AM   #17
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I had 3.07's with 31"s and i was getting about 6 klm per litre (15mpg) but when i went to 4.11 diff gears (still on 31"s) it went to 21mpg even though it was revving at 2400rpm at 55mph. Now i'm on 32's it's almost back to where it was with 3.07's but i'll get 4.56's when i can afford it down the track.


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Unread 03-29-2010, 07:55 AM   #18
clintsharley
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was wondering the exact same thing yesterday as i did a 10 hour road trip with 32's and 3.07's.. not sure how much gas i actually saved by keeping my rpms above 2000, and in 4th. but it was alot easier to keep with the flow of traffic, than using 5th and having my rpms around the 1800 area..
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Unread 03-29-2010, 12:14 PM   #19
Terrible2
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Quote:
Originally Posted by JrJmisn View Post
So the 3.07 gearing with 33s gave you better MPG than 31s with 3.07? Is that because you HAD to be in a lower gear and keep the RPMs higher as you drove - so your habits of driving changed - or because the ratio is actually more efficient at all times?
Well I wouldnt know if I got better with 31s, but I do know that was I drove on 3.07 with 33"s, the harder I drove it as in higher RPMs, the better gas mileage I got by a long shot. When I tried to get into 6th gear and have like 1500 RPMs, I got far less gas mileage, I got better results in 5th gear and higher RPMs. This was also driving cross country, I also got 22mpg through New Mexico, and Ill say this again there really was something enchanted about that land.
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Unread 03-29-2010, 01:08 PM   #20
jgorm
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I have disagreed with Imped on this before. My experience with tons of tests using the scan gauge is that lower rpms will get better mpg in most cases. This is once you are up to speed of course. My tests would be as simple as watching the mpg readout, and then shifting up or down. Full throttle in 5th at 2200rpms is less than 1/2 or 3/4 throttle in 4th. It was never big, normally on the order of 1.5 mpg. Shifting at 2000 will kill your mpg.
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Unread 03-29-2010, 01:30 PM   #21
ChrisTJCO
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Quote:
Originally Posted by Imped View Post
Your thought process is correct. 4th gear in your setup will give you better mileage since it's not lugging the engine. I manage 17-18mpg avg. on 4.88's, 35's and the NV3550 and am always in the 2-3k range. Don't lug the engine and it will love you. To prove my point, I had a 100 mile trip to make today and wanted to see what my avg. mileage would be. Running 55-60 mph almost the whole time (about 2-2.25k RPM) I managed 19.3mpg (miles driven/gallons used). I couldn't do that if my life depended on it when I had 3.07's and 31's.
I got 21.2mpg, going about 65-70 on a 100 mile trip this weekend with 31s and 3.07s! Not sure what I was doing right...
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Unread 03-29-2010, 01:35 PM   #22
Terrible2
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Originally Posted by jgorm View Post
I have disagreed with Imped on this before. My experience with tons of tests using the scan gauge is that lower rpms will get better mpg in most cases. This is once you are up to speed of course. My tests would be as simple as watching the mpg readout, and then shifting up or down. Full throttle in 5th at 2200rpms is less than 1/2 or 3/4 throttle in 4th. It was never big, normally on the order of 1.5 mpg. Shifting at 2000 will kill your mpg.
I also tested this out and found out going higher RPMs at full throttle gave me far better results.
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Unread 03-29-2010, 01:36 PM   #23
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Originally Posted by Terrible2 View Post
I also tested this out and found out going higher RPMs at full throttle gave me far better results.
I think you missed the point. If you downshift, you need less throttle to maintain speed. Accelerating is totally different.
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Unread 03-29-2010, 01:42 PM   #24
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I think you missed the point. If you downshift, you need less throttle to maintain speed. Accelerating is totally different.
Youre saying that in 5th gear, you do have to step on the gas less to keep the same speed than if you were in 4th gear right?

If thats true, then I understand what youre saying and I still stick by my point that I got better MPG at higher RPMs when driving. I had to downshift to get higher rpms while driving 60 so that I got better gas mileage.
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Unread 03-29-2010, 01:46 PM   #25
jgorm
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Originally Posted by Terrible2 View Post
Youre saying that in 5th gear, you do have to step on the gas less to keep the same speed than if you were in 4th gear right?
No, its the exact opposite.
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Unread 03-29-2010, 01:47 PM   #26
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Originally Posted by jgorm View Post
in most cases.
Exactly. Setups on smaller tires like yours are very different than larger tires. You are perfectly geared for 31's, which are quite a bit smaller than 35's. They weigh less, they are thinner, and the diameter is smaller. You can run 2000 RPM @ 65mph with no problems and good mileage. Step up to 35's and try to run 2000 RPM's at the same speed. It's a no go. Good mileage on 35's doesn't come until the mid 2k RPM range from my testing.
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Unread 03-29-2010, 02:01 PM   #27
Terrible2
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Err dangit I said it wrong.

you step on the gas less to keep the same speed but higher rpms at 4th gear as opposed to 5th gear where you keep the same speed but have lower rpms but step on the gas more.

So what im trying to say is that I got better results in 4th...is that what youre trying to say?
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Unread 03-29-2010, 02:08 PM   #28
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Originally Posted by Terrible2 View Post
Err dangit I said it wrong.

you step on the gas less to keep the same speed but higher rpms at 4th gear as opposed to 5th gear where you keep the same speed but have lower rpms but step on the gas more.

So what im trying to say is that I got better results in 4th...is that what youre trying to say?
You're talking about engine load vs. RPM's. There is no YES or NO. It all depends on your tire, gearing, transmission, and engine. You just don't want to lug the engine when cruising and when accelerating.
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Unread 03-29-2010, 02:15 PM   #29
Terrible2
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im just on a bad roll today.
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Unread 03-29-2010, 06:49 PM   #30
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That web site is dedicated to vehicles with very little in common with Jeeps. They talk about narrow over inflated tires, wheel covers, improving aerodynamics, ... I don't see them adressing shoving a 4000 lb brick on agressive tread tires down the road. They aren't running vehicles with transfer cases, multiple drive shafts and axles,...
...and if you quoted my ENTIRE post, you would see that I said essentially the same thing. What I was pointing him towards was more the methods for CALCULATING mileage rather than improving it (although some of their ideas are still applicable).
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