4.3 mileage and performance....

[dougg01]

Let me start off with - I still need to change the spark plugs. They aren't horrible, but have been in this thing for a couple of years (I bought it in February of this year).

things that matter:
2000 4dr 4wd Jimmy
162,000mi
1.5" crank/shackles
31x10.50 Firestone ATs
K&N drop-in with opened up air box
Dynomax cat-back
accel super coil
!cat

truck runs pretty good. The power doesn't seem to be as good as my 1999 Blazer had (w/o any mods). Mileage on my blazer was 200,000 when it left.

I get between 200-250mi on a tank. I usually run it just under 1/4 tank before I refill. Last tank got 17.0 mpg. I'd like a little more. I was averaging about 18.5 on my blazer.

I admit up front that changing the plugs could help some.

Am I expecting too much from this 4.3 in a 5,300lb envelope...?

My TBI 4.3 in my old 94 S-10 ext-cab 2wd with many bolt ons (turbo city stuff, edelbrock headers/intake manifold, and more) got 22-23 in regular driving and could hit 25-28 on the highway. It also weighed about 1,500lbs less than the Jimmy. IT's still a torquey little fart with around 150,000 on the clock even after sitting for the past 6 years until I got it back from my brother-in-law.

[HenryJ]

What gear ratio and tire size?
Are you using ethanol fuels now?

Am I expecting too much from this 4.3 in a 5,300lb envelope...?

I think so. 17 mpg is pretty normal to good for this platform.

[dougg01]

What gear ratio and tire size?
Are you using ethanol fuels now?

Am I expecting too much from this 4.3 in a 5,300lb envelope...?

I think so. 17 mpg is pretty normal to good for this platform.

31x10.50 (the blazer had 235/75s)
3.42s (one day I want to swap to 3.73s. My firebird actually got better mileage when I swapped from 3.23 to 3.73s.....and never kicks down on hills while cruise is engaged).

Cruise RPM is about 2k in the Jimmy.

[HenryJ]

Sounds all about right to me.

[dougg01]

Sounds all about right to me.

That doesn't help with my dirt cheap 300hp and 30mpg goals....

I just need to strap a 88mm turbo on this thing and see how long the drivetrain holds.....

[HenryJ]

Over 300 hp and 30 mpg is going to mean moving to South America or Australia to get the turbo diesels. That or go to a fullsize with a diesel.