m7 rocket

Does anyone know what the compression should be on a 2004 GMC 6.0L 2500 HD 4wd? I am at 2200 ft elevation and need to check it. For some reason my dads truck has way more torque (seem's that way when you drive them one behind the other) and they are identical trucks, other than his is a long box and mine is a shorty. He also has 30,000 km and I have 106,000 km, he still has stock 245 tires and I have 265's. I added e-fans, AFE intake, Superchip programmer, and high flow muffler, but it is still less of a truck. Currently I have removed the air intake because it shifts like crap on hills, but is still not even close to his without air intake installed. Any help is appreciated, but I need really to check compression to make sure all is okay before I add a Radix supercharger. Does not burn oil but uses gas almost twice as much as the other truck.

1SlowHoe

iTrader: (28)

Compression should check in at about 180+psi, your elevation shouldnt play a role in that as far as I know. Are you sure both trucks have the same gearing? Maybe you have 3.42 and he has 3.73 or something like that? As far as using twice as much gas, that is either the programmer has fattened your tune way up AND/OR your heavy right foot is pushing the skinny pedal on the right too far too often

P.s. Your compression might be lower but as long as they are within 10% of each other you are ok. So if you get 155, 160, 158, 164 blah blah...you should be fine

m7 rocket

I bought the truck second hand at 90,000 km and ever since then it has gotten worse milage than his. The gearing is 4:10 in both trucks (they are identical other than what was stated) We both drove one behind the other for a 5 hour drive. I did not make it on fuel and he did. His tank is 140 L and mine is 100 L. I used just under 100 L and he use 74 L. Both trucks were empty of cargo and he had 3 people in cab and I had 2. I added the parts to improve milage and they did not help in that but seemed to give it a little more go. Untill today when I removed the intake and prgrammer and realized it does very little other than shifts beter. I have done a full tune up at 90,000 km. WTF???