Maximum boost on stock springs?

MaxPF

MaxPF

Expert (please obsess)
Joined
Mar 23, 2011
Messages
61
Like the title says, what is the maximum boost that stock valve springs will tolerate?
 
Higher pressure springs run a higher risk of losing a cam lobe. If I don't need them, there's no reason to put the extra load on the parts.
 
MaxPF said:
Higher pressure springs run a higher risk of losing a cam lobe. If I don't need them, there's no reason to put the extra load on the parts.
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This may be a valid point with some springs, but not so much with the 60lb springs. The benefits of better valve control outweigh the risk of premature cam wear.
 
I was floating mine at 30psi. But i could make 48psi still. Went away with 110's

Cheap insurance. Get them.
 
The headgasket will be fine at 35psi. 40psi is the redline for a head fastened with stock head bolts. However, Similar to EGTs, it can support more than 40psi so long as it's not sustained for long periods. Auto trans trucks are more susceptible to this condition if sustaining above 40psi for long periods as they are continually spooling the turbo(s). Manuals are less susceptible as the turbo is having to spool in each gear and high boost levels are sustained for short periods on the top-end.

Back on-topic, although I don't know the range of boost pressure that will float the valves, I can add 60lbs springs don't offer a seat pressure that is much higher than stock springs. That bit of info being taken directly from Hamilton Cam's website. Just food for thought.
 
Boost is not the only variable that dictates whether you need aftermarket springs or not. Engine RPM combined with boost is what you need to look at. If you make 40psi at 2000 rpm on stock springs, you might be just fine. However, the same amount of boost at 4500rpm may yield different results
 
teddybear said:
Boost is not the only variable that dictates whether you need aftermarket springs or not. Engine RPM combined with boost is what you need to look at. If you make 40psi at 2000 rpm on stock springs, you might be just fine. However, the same amount of boost at 4500rpm may yield different results
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I second that. The bit of information I left out. As for the Cummins, 3500-3600 is about where the valves start floating. I'm assuming even under no-boost. Adding boost to that would only compound the issue.
 
I have run 60psi on stock springs under 3k rpm with no known issues. How do you know if your floating valves?
 
Mine had a bad miss at light load in boost. And on a dyno video i had you could hear it sounded like a power stroke a bit out the exhaust
 
I've run about 50 psi at 2800 rpm on stock springs. I doubt the valve control is accurate.

How are stock push rods holding up to CompCams springs and 3000 rpm?
 
jimbo486 said:
I can add 60lbs springs don't offer a seat pressure that is much higher than stock springs. That bit of info being taken directly from Hamilton Cam's website.
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You sure about that?

Hamilton Cams said:
lift Stock 60lb HD175
1.940 88 150 150
1.900 98 156 165
1.800 125 170 200
1.700 150 187 240
1.600 182 210 285
1.500 210 225 327
1.400 245 245 365
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It's sad to see this website being plagued with CF level posting.
 
bracker8040 said:
...It's sad to see this website being plagued with CF level posting.
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This X 10000

I have run over 70psi on a stock headgasket, with stock bolts, stock springs, stock cam, 4k gsk, without failure. Yes it probably would have made more power at that point to have a stiffer valve spring in, but it never had an issue. Made over 650hp on the dyno too...
 
bracker8040 said:
It's sad to see this website being plagued with CF level posting.
Click to expand...

CF level posting huh? Seems as though you didn't read where I typed that I got that bit of info from Hamilton Cams' website. That's no CF level posting, pal. Merely quoting what somebody else said.
 
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