Engine/Transmission (1998.5 - 2002) Max. MPG + Gearing

[kcoffman]

What modifications will significantly improve mpg? I have a stock '01 5-speed with 3. 55 rearend. I currently get 18+ running 80-90mph (Socal Freeways). Is it possible to gear the rearend lower(numerically) than 3. 55? Also, will opening-up the intake and exhaust help significantly? I am not planning on pulling anything over 10,000 lbs. with this truck.



Thanks

 

[LSMITH]

Man, you are getting economy that most can only dream of already. You MIGHT get a tad better with 275RV injectors, and if you are really running 80+ a 3. 2 rear end gear or some 235/85/16 tires might help. Intake and exhuast will not help fuel economy that I know of.



Nothing as far as hardware goes will significantly improve your fuel economy. Slow down 20 MPH, THAT will gain you a couple miles to the gallon minimum. My truck gets 18 MPG at 75-80 MPH, I can get over 23 at 55-60 MPH.

 

[mikel]

I know you're not going to like this answer, but the easiest way to get better mileage is to slow down. 80-90 puts way more wind drag on your truck than maybe 65-70, and even if you gear the engine to turn 1600 rpm at say 85mph, it's still going to be working real hard to pull the truck along.



Just FYI, I get 18 or so at those speeds, and 22-23 at 65-70, of course *everything* on the road will pass you so if being passed bothers you then, well... .



As they say, "speed is only a question of money, how fast do you want to go?"



Good Luck,

Mike

 

[Groover]

mileage and rpms

I have the 4. 10 gears and when truck was new and on stock tires I got 18 mpg at 60 mph (2200+/- RPM). Drove truck 3000 miles at 75-80 MPH and got 17. 5 MPG avg for the entire trip. 80 mph with 4. 10 on 245 tires is about 2750+/- RPM.



I was amazed that all I lost was 1/2 MPG. Of course now that I run 35" tires my RPMs are a lot lower and cruising speed is a lot quieter. I have not run that fast in a while either.



My point is that on 24 valve anyway RPM doesn't seem to matter as much in regards to MPG. I have always heard the 24 valve likes to rev and is more efficient at higher RPM than the 12 valve.



With the larger tires and maybe the truck is broke in I can get 20-21 MPG on a trip at 60-65 if I keep my foot out of it.

 

[Whitmore]

I have found that 65 mph is good mpg 20-21 and any faster than that and the mpg goes down.



cheers, Kevin

 

[Dkevdog]

Originally posted by LSMITH

Man, you are getting economy that most can only dream of already.

MAN you got that right! Best I've seen yet is around 15MPG, with a 3500 6Sp w/ 4:10. :{ Quit complaining!!



Welcome aboad BTW, if you are interested in Local TDR happenings in So Cal, drop me a line.



Kev

 

[StinkyCheeze]

4:10 MPG

I was amazed at the "good mileage" with MY 4:10 lower gearing.

I think the engine LOVES High RPM (I THINK APROX 2500rpm @75 MPH stock 265/75 tires and rims 6 SPEED IN o/d ) aprox 16 MPG at this rate (EMPTY) flat interstate... Engine tone & vibration/ballance seem better at the higher end for me... I was concerned at first about driveability of this PKG as I bought off dealer stock for best deal . I am thinking about larger wheels/tires soon. . then white line feaver! Great Engine! CHEERS!

 

[Camara]

I average 70 MPH. Best I can do is 15. 7mpg. 99 quadcab 5sp 3. 55 Stock Michelins. My truck is always loaded and close to 9000lb. I will say that when I did ad the ME kit from Geno's my mileage went up 1 mpg.

 

[dflack]

mpg

1. Keep the air as unrestricted as possible - K&N or aftermarket setup

2. Keep the fuel flowing - gauge + filter changes

3. Some people swear synthetics help - they sure won't hurt!

4. Air your tires to max. - lower rolling resistance

5. And for Pete's sake, slow down. (Pete's the guy your gonna have an accident with, wreck your beloved truck and then Pete's attorney is gonna find you. )

 

[WadePatton]

I got 19. 7 today over 500 miles of 70-80mph driving. It runs 18. x around town. 3. 54x265's. I might put bigger tires on in the future.