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Driving across i-80 Nebraska today doin 72 no wind flatland and this pig is sitting between 25 to 30 psi. In my experience at Crete my cascadia would be at 7-10psi and a '14 387 with 500hp paccar would be at 12-15psi at 80mph 90k lbs of grain on this route.

So basically what can be costing me so much power. 200k on overhaul, head as far I know is original 1.1mil has all new parts besides valves/springs. Cams 200k, turbo 150k, everything new in the fuel system besides the gear pump and regulators, cams wedged at 4.5, mm2ed, stock programming previously, virgin 13sp, 3.36s turning into 3.70s Friday, uses 1gal in 15k, overhead good, EGR blocked

Issues

two davco fuel filters for oil change - asphaltine

Tapping noise under load like a ball peen on a solid piece of metal cant identify for the life of me. Jake brake rockers seem to be good.

2 exhaust valve seals leaking oil

So could it be valves?
.5 degree to much timing?
Gears really costing me that much?
Idk any ideas?

Forgot to add I'm at 79 thousand pounds hauling a load of shingles so not very high maybe four feet off the bed in a big square

What engine do you have? And did you have it tuned

Sorry cm871 and it's mm tune. 65mph gets me down to 22-23lbs

It’s the turbo map. What’s your egt. It’s probably really cool. Turbo is pre spooled that’s how mine is hard on fuel. Only running like 400 on egt I’ll bet.

What made you go half a degree mechanical timing advanced? Is the ECM tuned accordingly? Your pinging noise that you described sounds like fuel knock.

The engine was rebuilt by the previous owners so I don't know why they went with the 4.5 wedge.

and that's why I was wondering about the timing I don't know is there some way that I can just take a half a degree out of everything without having to change all the fuel maps to see if that helps?

a 4.5 degree wedge does not equate to 1/2 a degree of timing. The timing tables should be edited to reflect this.

Ideally for the turbo tables you lower them until the egts start to creep then add a few percent and leave it there. It will lower your boost overall and increase your fuel mileage.

Uni

I'm pretty sure the timing was tuned off the notion I had a normal 4.0 set of the 4.5