Boost limit recommendations?
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On The Tree
Joined: Nov 2007
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Boost limit recommendations? Stock 06 LM7. S475. LilJohn stg 2 cam, springs, pushrods. Trunnion upgrade. Top ring opened up to .028. LS9 head gaskets and arp head bolts. Truck intake, 80# low E injectors, Holley Dominator ecm and fuel. A2W intercooled.80% street car with a half dozen trips to the track. Hoping for low 7's on 93. Can I reach that number on a boost limit that will allow this motor to live?
Last edited by mufflerguy; Dec 29, 2014 at 04:15 PM.
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From: Ohio
Stock 06 LM7. LilJohn stg 2 cam, springs, pushrods. Trunnion upgrade. Top ring opened up to .028. LS9 head gaskets and arp head bolts. Truck intake, 80# low E injectors, Holley Dominator ecm and fuel. A2W intercooled.80% street car with a half dozen trips to the track. Hoping for low 7's on 93. Can I reach that number on a boost limit that will allow this motor to live?
Watch the tune, play it safe. Don't try to lean it out or add timing for the extra power. Getting greedy on timing is what usually causes the failures in these. You can run very very fast times on 93+meth with 12-14 degrees of timing.
Let it eat.
Staging Lane
Joined: Jul 2012
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From: Detroit, MI
Interested in some others opinions as well, but from what I've gathered anything under 800 should be pretty safe. My setup is very similar but with an s475 and I plan to hold it around 700, although mines an 02 LM7. And the boost required to get there is pretty dependent on the turbo
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Depends on the cam, intake, RPM, heads, etc.
700 to the wheels will take 18 PSI on average with a large turbo, more PSI with a smaller one.
That's also a safe power on the gen 4 rods. Sure you can make a lot more, but there need to be extra precautions. The guys making 1000+ on stock bottom ends use either methanol or E85, with very safe tunes and tons of knowledge and experience. Keeping the pistons cool will keep the ring lands in place, which is why water/meth injection is recommended with gas, even race gas.
700 to the wheels will take 18 PSI on average with a large turbo, more PSI with a smaller one.
That's also a safe power on the gen 4 rods. Sure you can make a lot more, but there need to be extra precautions. The guys making 1000+ on stock bottom ends use either methanol or E85, with very safe tunes and tons of knowledge and experience. Keeping the pistons cool will keep the ring lands in place, which is why water/meth injection is recommended with gas, even race gas.
