I have a 4" suspension lift and 33" tires and my truck is getting like 15mpg with the stock gearing of 4.10. I was just wondering if my mileage will improve if I get 4.88 gears and if so what could I expect to be getting once I do? I'm just kinda frustrated I have a toyota tundra with a v8 and it gets 18mpg I bought this little truck to save money lol. I have never had a lifted truck and wasn't planning on getting one but I just happened to find this one and I liked the way it looked I just didn't know it affected the gas mileage this much.

Thanks,
Brian

First off, are you correcting your mileage for the mismatch of gearing and tire size? If not, do so, you may be doing better than you think.

But yes, your mileage will improve with better gearing. With 33s, I used to get ~20 MPG with 5.29s and when I changed to 4.88s my mileage dropped about 10% - 15% (or conversely MPG would have increased by that amount if I had gone up from 4.88 to 5.29).

Assuming a 4-cyl engine, you'll get better mileage up in 2800-3200 RPM range than you will below that. For a test, you could try running no higher than 4th gear and compare mileage to running in 5th gear (assuming you can use it).

But that said, a 4" lift plus an additional 2.5" of added height from the 33s means your frontal area is now 6.5" taller than stock, and than reduces gas mileage, especially at speed. I know I get at least 10% better MPG at 55 than I do at 65.

Yep, it's called 'drag' with a lift. My stock carbie gets 23 mpg around 60 mph when she's tuned and happy.

If you haven't done a compression check, the magic numbers are 142-171 psi, but I remember you've got a rod knock and are looking at a new long block anyway. <img src="/forums/images/graemlins/kewl.gif" alt="" />

The 33's are about 10.71%(generally) bigger than then the 33's, so your mileage/speedometer is off by 10.71%. Right now your 15mpg is actually 16.6mpg. Is your stated 15mpg highway/city/combined?, and what transmission do you have?, if an auto that might not be far from average.

Drive style also effects mpg in these heavy trucks, if you "Jack Rabbit Start", your mileage will drop a lot, yu should basically take off using light throttle. Also other than the lift how else is the truck set-up? My heavy(1000lb over stock), mod'd 3.0, lifted, large tires, safari rack/lights rig averages 15-17combined, and about 19-21 on the highway.

I would give the truck a tune-up/comp check and see if mpg's improve, as mentioned you should see north of 20mpg w/the 4 cyl.

I checked the compression when I bought it and they were all at 150psi. 15mpg is already corrected it was actually like 13. I drive mostly on a 55mph highway with a few stops in between. I am mostly on the gas though because I don't want to piss people off by driving to slow lol. Well I hope once I put my new engine in and regear I will be getting around 20mpg.

is this true for the turbo motors also?

Probably so, usually you want to be at or a little above the peak torque RPM for the engine. On a 22RE, that is around 2800:
- http://www.4crawler.com/4x4/4R_TechInfo.shtml#Engine

Not sure on the 22RET what RPM that is.

Also makes highway driving nicer, since if you are a little above the peak torque RPM and hit an uphill grade, as your RPM starts to drop a little, the torque is holding even or even rising a little. If you are driving right at 2800 or below, you hit a slight upgrade, engine starts to slow, torque falls off and you need to down shift sooner and more often.

With my scangauge hooked up to my 3.4 auto no matter what im doing the mileage is better with O/D on (it tells you realtime MPG, OBDII only tho)....