mileage question....

[K5dreamer]

Im down at school, and trying to save up money, but an alumni in my fraturnity (also a huge blazer head, he's got one of every generation) has informed me my front springs are dangerously worn out. He's got a lift kit (4in) and two 12bolt axles with 3.73 gears (two wheels and 33x12.50 tires on each axle) he has offered to sell me, for a very low price. Im debating it, but i also use the truck to drive home and down to school, so gas mileage is something i bought the truck for (over a gas model anyway).

Ive crunched some numbers, and it looks like with the 3.73 gears, and a set of 35in tires, ill only go up around 270rpm, ive got 3.08 gears and 33's now.

question is, on an 86 blazer, do yall think that rise in rpm will hurt my mileage too bad? id like to stay above 20mpg if at all possible, i get around 21-22 right now, and i cruse at around 60 in the slow lane.

 

[muddybuddy]

what tranny are you running?

22mpg? i dont see that happening. your carb right now, and those things dont get good gas milage from the start. i had 35's with 3.73's and a 350tbi (more power and more efficient than carb) and i got about 14-15mpg because you cant really use overdrive so it struggles and will shift into 3rd. personally if you want mpg, get 3.73s and keep the 33's.

 

[K5dreamer]

i dont have a carb...... or spark plugs......

its a 1986 CUCV, M1009, military rig with the 6.2L diesel

The full drivetrain is the N/A 6.2L diesel, TH400 tranny, NP208 T-case, and 10 bolt axles front and rear with 3.08 gears. And i do get 21-22 mpg cruising the highway at 60 so long as the tires are aired up and the truck is running good. Im loosing a little lately, but im also starting to blow some smoke on startup, so im thinking the loss im mileage is due to somethin else. either burnin some oil, or *knocks on wood* coolant

but yeah, the diesels do pretty good on the highway..... for a big a$$ truck anyway

 

[muddybuddy]

alright makes sense now, ive got a diesel truck as well. the peak mpg for the 6.2's is 1800rpms, so the closer to that the better. 3.73s and 35s should be pretty good since u dont have overdrive

 

[BKinzey]

Your front springs. Are they flat or have a slight down turn? That's the way they are supposed to look on a diesel.

Oh, and it's "Fraternity" college boy!

 

[K5dreamer]

lol, yeah, i cant spell to save my life, never could. i'm an engineering major, we don't need language or people skills

as for the springs, they are curved the "wrong" way. viewed from the side, they are a frown instead of a smile.

 

[bp71k5]

That's the way they came from the factory.

 

[colbystephens]

for what it's worth, i have 4.10 gears, 35" tires and 4" lift with a manual tranny (no overdrive) and my 6.2 still puts out 21mpg. it was at 18 mpg till i started using ACES II fuel catalyst (talk to 4by4bygod), that bumped me up 3mpg... pays for itself.

 

[AJMBLAZER]

I say go for it! 35's, the lift, and the 3.73's would be sweet.

I'm half convinced the reason the M1009's got the 3.08's was they were the cheapest option GM gave the government. Certainly not for drivability.

 

[YZEATER]

how are you gonna steer with 2 12 bolt axles in your blazer?