'86 6.9 with non wastegated Banks setup in a crew cab 4x4 with 3.55:1 gears and C6, PO says never rolled over and 80k miles. Starts easy and runs smooth. Pure highway I was getting about 13.5 at 65. Regular driving about 60/40 city/highway I just recorded 8.25 MPG. Granted a lot of traffic lately with the holiday rush but that seems pretty low, no better than my '86 Supercab with 460 (400 HP/500 ft/lbs, built for torque and towing), ZF5, 3.55:1 gears, lifted on 35s, and the highway was a couple MPG less than I expected. My gasser gets 12.5 MPG unloaded on the highway and 10 MPG towing about 5500 lbs., granted 2k RPM at 70. This is my first IDI so I'm not sure what to expect. Maybe not a fair comparison since the 6.9 has no overdrive and losing more through the converter too.
All I've done to the engine is set timing using pulse method. Was at about 6.5* at 2k RPM I set it to 9* at 2k RPM since I've read here anywhere from 8.5* to 9.5*. I did only set the timing about 50 miles ago before filling out of 350 miles driven, so this MPG is mostly at 6.5* timing. Should I expect better MPG with the timing set at 9*? The truck feels like it has a lot more power down low since I set the timing, I don't have to get into the pedal nearly as much to get it moving. Still a far cry from my 460 truck which I barely touch teh gas and I'm hauling a... Also cleared up the white/gray smoke it had at moderate acceleration. Now I get a little darker smoke if I get on it briefly but it clears up once the turbo spools.
I'd like to know what sort of MPG I should be getting for city/highway and if there's anything I should be checking. I have not checked compression yet but plan to when I have some time and decent weather. The truck will be getting a ZF5 but I gotta find one first. Also will be getting a 4" lift and 35" tires. I plan to do a fair amount of trips towing this summer and want to get this thing running efficiently.
All I've done to the engine is set timing using pulse method. Was at about 6.5* at 2k RPM I set it to 9* at 2k RPM since I've read here anywhere from 8.5* to 9.5*. I did only set the timing about 50 miles ago before filling out of 350 miles driven, so this MPG is mostly at 6.5* timing. Should I expect better MPG with the timing set at 9*? The truck feels like it has a lot more power down low since I set the timing, I don't have to get into the pedal nearly as much to get it moving. Still a far cry from my 460 truck which I barely touch teh gas and I'm hauling a... Also cleared up the white/gray smoke it had at moderate acceleration. Now I get a little darker smoke if I get on it briefly but it clears up once the turbo spools.
I'd like to know what sort of MPG I should be getting for city/highway and if there's anything I should be checking. I have not checked compression yet but plan to when I have some time and decent weather. The truck will be getting a ZF5 but I gotta find one first. Also will be getting a 4" lift and 35" tires. I plan to do a fair amount of trips towing this summer and want to get this thing running efficiently.