Rebuild and lower compression

kdogg85 · Jan 7, 2013

A guy I work with has an 03 and the egr finally gave up and hydolocked the engine. Got the heads off and 3 cylinders had bad sideways play. Took the rotating assembly out and those 3 have broken rings. Well he has decided to rebuild it and beef up the driveline and outfit a compound setup all in one shot. He has saved up for a few years wanting to do this, so what better time. It's borderline a full restoration.

Anywho, I have read about lowering compression to around 15:1. Is the idea the same as doing it on a gasser with forced induction, or is it along the lines of using huge nitrous amounts and saving something that way. I brought the idea up since he is going in so far and the block has been taken 20 over but haven't seen much info on the subject so far. Thanks in advance for any help.

jdgleason · Jan 7, 2013

Depending on what he is doing with the truck, I wouldn't see a reason to drop compression much. Without big boost/rpms I don't see the gain worth the possible harder cold starts/smoky idle.

NathannialD · Jan 7, 2013

I would agree, i would go no lower than 16.5/1 if its a daily driver.

kdogg85 · Jan 7, 2013

He has everything in his garage already minus the assembled short block ready to go in. Had to get 1 new head due to cracks and had them ported, the intake has been gutted, polished, and gasket matched. Injectors are 265/125's with a reg return and fuel lab pump. Turbos are 366 with .91 t4 housing, lp is still in the air kinda between a 490ish size and something in the gtx 55 series, he's had a couple chats with garret and they say the 55 series is for pure competition use only, even with a small side helping and huge fuel, it would still be a turd due to the small displacement of the 6.0. I know money isn't too much of a concern, but that's one expensive charger just for street use. If that isn't huge fuel/boost combo, I don't know what is. Oh, running adrenaline pump to push injectors. And a 6sp tranny. RCLB as well, ought to be real nasty when out on the street.

That's the skinny on the intended setup.