In our family car burb (91 1500 4x4) I have been thinking about building a small cube v8 to try to help mpg. The thing is rarely driven on the highway and gets about 11 usually. With 3.73s and stock tires it feels like it could get around with alot less motor.
anybody have any experience with something like this?
My first thought was build a tbi 292 six banger, but always hear that they were lousy for mpg. I dont know if a 4.3 or a 250 would be enough motor, but somewhere in the 283-307 range seems like it would be ok.
the plan would be to keep it tbi.
Stick with the 350 TBI setup, they got the best mileage out of this generation of blazers and burbs. The 3:73's seem to work great with stock 31" all season street tires.
When I bought mine I was averaging 11 to 12 mpg commuting to work, it ran really good, but not as good as I thought it should/could. After a year of tinkering and rebuilding/replacing things, I could average 15 to 17 mpg's consistently while driving it conservatively for fuel mileage.
Things that helped:
1. Cleaning/rebuilding the throttle body
2. Fixing the intake manifold gasket leak(vacuum leak I couldn't find) and replacing the TBI base gasket
3. Setting idle and timing back to factory specs
4. New O2 sensor, IAC sensor, and TPS sensor
5. New EGR valve (mine seemed fine, but was sticking occasionally)
6. New plugs, wires, cap, rotor, etc.
7. Replacing the 180* thermostat with the proper 195* one!!!
8. K&N filter in stock air cleaner housing with some mods
9. I've done some other mods that helped with seat of the pants power, but made no difference in mileage
My best mpg so far was almost 18 mpg, but I drove my blazer from Pennsylvania to New Orleans 1,323 miles one way and averaged 17.3 mpg for the trip doing 70 to 75 mph with the AC on with 3 guys and all our gear in the back for a month.
The Bad:
I recently put a set of 32" Goodyear mud terrains on and lost almost 2 mpg immediately. The winter blend fuels we run here also typically decrease my fuel mileage by 1 to 2 mpg.
I hope some of that helps somebody, my fuel cost savings have more than paid for all the parts! I no longer DD the blazer due to rising fuel expense, but it's better than buying a new $50k truck to replace it! I personally believe that the TBI setup is capable of masking performance issues that the average person wouldn't notice, fooling people into thinking their trucks run fine. I was amazed how well mine ran with all the issues it had.