HO trucks with their higher static compression ratio seem to loose head gaskets easier than the SO trucks. This is nearly always when someone runs a high boost situation. Higher than needed.

Don~

 

Stands to reason, and that's what Alpine said. Numbers would be nice, though. Lots of HO gaskets fail? Just a few? At 20 psi? 30 or 40? Every once in a while, or does the high boost need to be consistent?

A baseline, in other words, so the average tower with a few mods and the the aspiring racer can both make intelligent decisions.

 

I know that the Edge boxes are fueling boxes, but they do timing too.(see my sig) As Don said, with the higher static compression, combined with high boost, early timing and a big injector they are a bit more risky than the SOs. As far as I know going up to 50 psi with an SO (stock head gasket) is about the borderline-and about 5-7 psi less with the HO. (This is from reading and talking to some techs that work with the HO Cummins in european trucks)
I'm running an Edge pulse and Don's mach3s in my SO- and need around 35-38 psi of boost to keep EGTs in check and have no smoke at WOT, so I assume that it can be done with the HO too. But if you raise boost too much (eg blocking the wastegate) the odds seem worse with the HO than with the SO.
Some people reported that they had better results with the VanAaken(I think) with the HO and injectors.
Maybe the failures over here are also a result of the higher cetane numbers that will also lead to a steeper raise in pressure for the same timing.

Just my 2c

AlpineRAM

 

OK, that's great information, and I appreciate it!

 

I think a lot of the headgasket failures can be attributed to running high boost numbers with the engine not FULLY warmed up. A Cummins tech told me that he feels it's safe to go for max boost after the engine has been at operating temp for at least 5 minutes. The headgasket failures were usually there when using a bigger turbo without wastegate. He said that they constantly blew out more than 10% of all trucks around 45 psi when equipped with an Edge Comp box. (And big injectors)- but you'd have good chances to blow them out with everything over 20 psi on a cold engine. He also said that you wouldn't necessarily notice it very quickly, but might be able to complete one or more run cycles without noticing and then wonder why the headgasket had failed just running 20 psi on a warm engine.
The 275 inj isn't that critical, since it's a really mild one compared to a Mach 2 or up. (Still keeping boost low until fully warm isn't a bad idea even for a stock engine if you want to keep it)

AlpineRAM