4.8 lsa head swap test
#1
4.8 lsa head swap test
I did a head swap from what most people would consider a really good cyl head, the stock 799's as they had exhaust valve seat pitting, wich is fairly common, to some dirty old 862 heads from 2002 4.8 i had laying around.
dropped them on and picked up almost 40whp up top. funny considering the intake valve is smaller, but the head chamber is also smaller
it raised my compression from 8.8:1 to 9.53:1
it was an interesting experiment to see if it would be a push or worth it.
food for thought a hellcat makes 640whp on my dyno
dropped them on and picked up almost 40whp up top. funny considering the intake valve is smaller, but the head chamber is also smaller
it raised my compression from 8.8:1 to 9.53:1
it was an interesting experiment to see if it would be a push or worth it.
food for thought a hellcat makes 640whp on my dyno
#3
TECH Resident
Not busting your chops. I really appreciate what you have done for the automotive community. But that test isn't very accurate. The"good" heads had leaking valves. And you said it makes another 1-2psi of boost as a result of the changes. But we always appreciate the honest data anyhow!
#4
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That said I too went from 317's to 862's on the same setup and picked up a few MPH on the same boost, but was still 5-6MPH down from the aftermarket heads.
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#8
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I went and watched your youtube video on this... I'm shocked that the 862 heads actually made slightly less down low, but made a lot more up top. Can someone explain how this happened? Maybe the 799's with issues actually are what caused them not to perform as well up top? Not a criticism at all as no one is really doing these type of comparisons, but I'm seriously interested in learning.
#11
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At relatively low power or a setup that's not maxed out I agree 100%, under 1000hp on most setups you can easily turn up the boost and save the money. But when you're already at 35+psi on the largest S400 offered and you are looking for a few more MPH aftermarket heads are a viable option if you don't want to completely rework the turbo kit or build another engine. You can take that 1200 hp or so limit of stock heads chucking gaskets and bump it up to 1400hp or more keeping the heads down. Between a turbo upgrade to S500 or GT55, bigger engine, or better flowing heads in some cases a set of TFS heads is the cheapest option and we did see them perform, easily picked up MPH on less boost.
That said I too went from 317's to 862's on the same setup and picked up a few MPH on the same boost, but was still 5-6MPH down from the aftermarket heads.
That said I too went from 317's to 862's on the same setup and picked up a few MPH on the same boost, but was still 5-6MPH down from the aftermarket heads.
#16
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