Engine/Transmission (1994 - 1998) How much psi stock head gasket will take

[Weatherly]

Folks,



Have friend with 94 2500 5sp with 375,000 miles who wants to put a Banks Big Head wastegate controller on. He said it was rated to 43 psi. I thought the stock Cummins head gasket was only good to about 30 pound? Any thoughts



Bobby

 

[tony597fitter]

He could blow the stock gasket at 45-50 psi. It could also last forever. It is also recommended not to go over 35psi with the stock turbo. Even though it says it has more boost it is just hot air causing EGTs, and anything over 35psi WILL do damage to the turbo.

He could do an adjustable boost elbow instead for $25. It does the same thing for alot less. All the big diesel shops sell them, TST, PDR, even Ebay has them.

 

[16919]

55psi is what I was told they will take but I have heard them blow earlier, drive press also plays a part as well... ... ... ... .

 

[Jetpilot]

What is your timing set to? Any additional mods? Its cylinder pressure that blows HG's not boost pressure. Hence the reason you can just change the timing and blow a HG... ...

 

[MMcCallie]

A diesel performance shop just told me the same, the head gasket is made to last at 50 psi all day. They also said properly torqued factory head bolts should hold to about the same, that they are meant to allow just a slight amount of expansion. But most folks who've i've heard of blowing their head gasket did it at much lower psi.

 

[Jetpilot]

I have seen HG blow with a LOT less than 50 PSI..... When drive pressure goes up so does cylinder pressure. So 50 PSi from and HX35 is a lot more cylinder pressure than 50 PSI rm say a Super Phat Shaft 66. Also try bumping the timing up on a 12v and watch what happens to a HG even running low boost numbers.

 

[Bandit1]

mine went at 32lbs with a 35.

 

[Forrest Nearing]

timing hurts more than boost... drive pressure doesn't really matter, it's a minimal pressure number... FAR less than cylinder pressures at injection/ignition



I ran 42psi with my HX40 for a good while... from about 200k to 235k or so? stocker was run at 35psi before that. found out my timing was low... 12. 5! I bumped it up to 16. 5. head gasket let go at 38psi on the HX40 about 5-10k later

 

[DBraunig]

I got away with 50+ psi for almost 2 years and 20k miles. truck had about 175k on it, but i had a 3pc manifold, sps66 charger and about 18 degrees timing. The 1st time i turned on the water/meth the stock gasket let go. i doubt it would have lasted long with a 35 and stock manifold.



Dave

 

[tony597fitter]

A diesel performance shop just told me the same, the head gasket is made to last at 50 psi all day. They also said properly torqued factory head bolts should hold to about the same, that they are meant to allow just a slight amount of expansion. But most folks who've i've heard of blowing their head gasket did it at much lower psi.

Problem with head bolts is that they stretch. This is why we use studs, the material they are made of is alot better.

 

[Forrest Nearing]

also, tell your buddy not to waste his money on a big-head wastegate actuator... buy him a $10 boost elbow as an early xmas present