Quote:
Originally Posted by b1jetmech
Hey thanks for the response!
After a few months of driving with the converted diesel I'm averaging 20 MPG. That's up from 11 which isn't bad I must say.
If that helps but the mileage doesn't improve much then the injector pump will be looked at.
Then engine runs great. There is NO blow by which is unheard of with these but being a non turbo motor...it didn't have to suffer the abuse of turbo because GM kept these engine's compression ratio very high. Just like Ryan said, Too much compression plus boost = BOOM!
I do have a turbo set up but won't be installing it anytime soon. I'm having the urge to convert back to gas. Want to try a 305 tune port from the late 80's early 90's because they got good mileage and having tune port gave it a real good low end torque but we'll see!
Another item on the to-do list is turn the fuel up. I have a hard time accelerating up to highway speeds because the motor runs out of steam about 55 mph.  The fuel curve is way below because this engine doesn't belch smoke. I have never seen black smoke under any load. so an 8th of turn on the IP should wake it up a little.
over all I do like it but have the tune port ideal in the back of my mind we will see on that one.
Ryan, If I pull the heads for anything I just might install some 6.2 pre cups. I have heard of 6.2 Burbs getting in the mid to upper 20's in MPG.
Chase |
Generally 6.5s never quite match what the lowly early C code 6.2s would achieve, its not tuned for economy as much as it is for safety/reliability.
The precups you would want for improved economy would be similar to a C code 82ish motor.
Naturally aspirated diesels are NOT earth moving rigs, they rumble slowly up to their speed. The best way of improving performance is to have more gears and get the motor in a better RPM band while accelerating.
That said our 93 GAS suburban 2wd would get 20mpg on the highway when running correctly (same as your 6.5) Of coarse only 93 year 2wd 350s got that, a couple years later and they had trouble with 18mpg
So in other words you 6.5 should be able to do better than a 350 gasser, you would just need it geared right with a good selection of gears and tuned right, generally you want it a little on the advanced side and a little rough to get the best FE, otherwise you are just blowing it out the tailpipe.
Also injectors and pump have a massive FE effect if they aren't working as they should, before turning the thing up fix the injectors and if need be pump before you do it, turning up a bad pump can make it badder faster
(and not in the good way)