I consistantly got 28 mpg (Imperial) empty, summertime(above freezing) before and after adding #5 plate, boost elbow and 3K GSK, and 4"exhaust. My EGT was high so Piers suggested 215 injectors. I bought rebuilts from him, now my EGT is OK, but mileage is down to 19 - 22 (imperial).
One other factor, blew head gasket(2nd. ) on trip to ND last fall. Cummins in Minot did the gasket and said my cylinders were scored, not lightly. I did not see this so don't know the depth of scoring, if at all. They suggested a new block !NOT!
Towed the fifth back home, couldn't tell any difference in power.
After that the mileage was down, but the first no load driving with the 215's.
My conclusion and advice to others is to only do one thing at a time and test for a reasonable time before adding bombs.
One other factor, blew head gasket(2nd. ) on trip to ND last fall. Cummins in Minot did the gasket and said my cylinders were scored, not lightly. I did not see this so don't know the depth of scoring, if at all. They suggested a new block !NOT!
Towed the fifth back home, couldn't tell any difference in power.
After that the mileage was down, but the first no load driving with the 215's.
My conclusion and advice to others is to only do one thing at a time and test for a reasonable time before adding bombs.