my cummins has a huge intercooler. i have no idea what boost it runs but it is getting 370 hp and 500 ft lb out of 5.9 liters. and the o5s are rated at 600 ft lbs so i am guessing they just turned up the boost and fuel. i guess that is not all that much more than the 603 in terms of power per displacement.

the cummins has four valve head and iron head too. and it doesnt make the temp go up even when towing my 35' travel trailer at 73 mph.

it is fun to watch your progress. hope it all works out for you.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.