BFG KM3's are heavy compared to Goodyear Duratracs. Getting 8.7 MPGs (1 Viewer)

[Randy88FJ62]

Years ago ran Goodyear MTRs w/ kevlar, then ran Goodyear Duratracs for 4 years, now BFG KM3 MTRs. These suckers are heavy and my slow old 3FE is not happy with them. Pulling hills is a battle and my A440F is pissed mostly hanging in 3rd gear not being able to get to 4th and lock up.

The difference between the all terrain style Duratrac and the KM3's is night and day difference. I really hope they kill it in the rocks this summer.

My 62 stats:
Tire size 35"
Spring over lifted high.
Heavy as all get out, bumpers etc.
4.88 regeared differentials
Tired 3FE with bad compression
A440F w/ cooler is hanging in there.

Average highway driving with hills is now at 8.7 mpg. I used to get almost 10 with the Duratracs.

And no, I don't want to do a V8 swap this year.

 

[doug720]

I had the old BFG Mud Terrains a couple years ago on my diesel 60. They were 33"'s and replaced old style 33" AT BFG's.

Right off, my mileage went down by about 15-20%, acceleration was slower, and after a few thousand miles the noise was terrible and they started to wear unevenly. They also always felt "Wallowey" at highway speeds, they sucked in snow, and I'm glad I never used them on ice!

I decided to replace them with the new style BFG AT's, and sold the Mudders.

Immediately, mileage went back to normal, as did acceleration, and they are soooo quiet.

I'm not hardcore, and AT's work much better for me. But the KM's looked good!

 

[cruisermatt]

Tired 3FE with bad compression
A440F w/ cooler is hanging in there.

found your problem

 

[tmxmotorsports]

Start collecting parts for the swap now

 

[Paul DiNapoli]

Average highway driving with hills is now at 8.7 mpg. I used to get almost 10 with the Duratracs.

are you adjusting for the speedo being off by a country mile in your fuel burn calcs?

i put BFG AT KO2 33s on my 88 FJ62 - it was a dog - even with a good strong engine and good trans...50mph on the highway was hard to maintain...a440 trying to kick into OD around 50, and then TC lockup at like 53 ish - revs would drop and i'd have to bury my foot to get the revs back up.

now with the H55 - total night & day. i can climb and accelerate. granted we're not talking 10% grade....but around portland we have hills - and i can maintain decent highway speeds and can actually run up an incline and gain speed in 4th or 5th.

you should probably fix the dead hole(s), and do a 5 speed swap.

 

[ZCissner]

i get 12.4mpg on 315 75r16 duratracs with a desmogged 2F.

 

[Randy88FJ62]

Mileage was not taken from speedometer.

 

[Cruzerman]

Even the old 10mpg hurts. But under 9? Too painful for me to take. I'd be thinking gears or smaller tires.

 

[Randy88FJ62]

4.88's apparently aren't enough. Wish I had a cheap blown 2F block with the accessories to bolt my 3FE head onto....

 

[BGarcia88FJ62]

"Wish I had a cheap blown 2F block with the accessories to bolt my 3FE head onto...."

These are readily available.

 

[FJ60Seth]

4.88's apparently aren't enough. Wish I had a cheap blown 2F block with the accessories to bolt my 3FE head onto....

I know where there’s one.

 

[SilverKast]

My 1990 62 with the 3FE and auto was the same thing. Ran 33" duratracs and my mileage was horrendous, to the point I thought I was leaking fuel or something.

Got a 1988 FJ62 with the 5.3L vortec and H55F and I get such better fuel economy it's not even funny. Add in the fun factor of feeling like I can actually pass people and the swap is pretty much the best thing since sliced bread.

 

[MANUCHAO]

Tired 3FE with bad compression
A440F w/ cooler is hanging in there.
And no, I don't want to do a V8 swap this year.

What about that might 3-FE you offered me the other day ?
Seriously dude.... A swap be it diesel or gas... would benefit you 10x fold.........
Then you would move on to the next upgrade (yah coils).........

Just saying..........

 

[Randy88FJ62]

Frank,
Give me your blown V8 setup and the CARB sticker

 

[Tennessee80]

I am getting a little over 12 miles per gallon with my 88, and I have a four speed conversion, I bet it would be a little bit better if I had a five speed.

I do have FJ60 gears though, so I am in a pretty good range on the highway, but getting there, now that is another story! LOL