Whats worse high EGT's or high cylinder pressures

[HANK1948]

Iam running my boost at 19psi peak boost with stock CR ratio but my egt's are only at 800 max (post turbo)towing 8000 lbs Iam just wondering if I should back down the boost alittle, Iam I going to have head gasket problems in the future with higher cylinder pressures?

[rjschoolcraft]

I would say leave it where it is.

[markrinker]

High EGTs and/or uneccessarily high cylinder pressures can't be good. We aren't dealing with a bullet-proof engine here by any measure. Block web cracking, crankshaft failures, piston failures are all typical.

Why press your luck for every last lb/ft of torque?

There are different 'school(craft)s' :D of thought on this one. After I upgraded #2 (mods listed below) I ran similar boost (~18psi) pressures until I noticed a marked increase in oil consumption and lots of new blow-by at the CDR.

At that point, I decided to back off my peak boost to about 12 / nominal of 8 under load. Oil consumption decreased, power and EGTs remained about the same.

Note: I am NOT running an intercooler.

My thought is once you have attained stable EGTs and are not seeing black smoke under heavy loaded acceleration, any further boost is uneeded and counterproductive. Some will argue that the dyno will tell otherwise - I will argue that the dyno is far from real world, i.e. loaded/unloaded towing with wind, widely varying ambient temperatures and road grades.

That is the way I have tuned - real world, dragging a load, and the end result is always close to a ~12/8 (max/nomial) setting for my stock compression, non-intercooled 6.5s, all factors (power, mileage, EGTs, blowby, etc.) considered.

[ 10-31-2005, 08:10 AM: Message edited by: Mark Rinker ]