Precups?

[3500_6.5]

Has anyone done any testing with dyno results with different precups? From what I have read, most seem to agree that the Diamond precups are the best to run for performance, but I have also seen some saying they have had good luck running different precups and even some custom machined ones. The engine going in my truck has the diamond precups, but the majority of them have cracks in them, so they will need to be replaced. What I am wondering is, should I be sticking with the same precups or go with something different? The engine had roughly 50-60,000 miles on it, but its hard to say how long the precups have been cracked. Didn't know if maybe larger ones would cure the cracking or if it's just part of the idi heat problems.

 

[Burning oil]

FWIW I had NA cups machined out bigger. Will see what it does for performance??

 

[3500_6.5]

That's another question I have, where is everyone getting their precups machined? Don't know of any machinist around here that would know how to machine them for best results. Their guess would be as good as mine on what would work and what wouldn't.

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[ak diesel driver]

pm Slim Shady

 

[3500_6.5]

I talked to him a while back about it. Last I heard he was still trying to get in contact with his guy. Never heard anymore. That was late fall last year if I remember right.

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[WarWagon]

There are service limits to 'acceptable' cracks in precups. The Diamond precups are an off the shelf replacement.

Going smaller starts to limit the fuel you can get through them without smoke - unless you blow the smoke out with extreme boost levels. Even then you are limiting power. Trade off somewhere is MPG. Going bigger than diamonds appears to be interesting.

Peninsular Diesel could answer some questions on keeping the Marine setup cool enough in automotive. Ask them what precups the Marine pump uses.

 

[turbovanman]

At what point do you lose MPG over power? Or what size precup?