LS7 head question
Originally Posted by ftlfirefighter
Heads reqiure a 4.125 (4 1/8) bore, there's not enough meat in the sleaves of an LS2 for that much of an over bore. You'll have to the block resleaved.
what about a 408? will LS7 heads fit on it?
Teching In
Joined: Apr 2006
Posts: 30
Likes: 0
From: Fort Lauderdale, FL
If you mean 408 as in 4.030 x 4.000 then no. A 4.125 x 3.625 (stock stroke) = 387 cu/in. Thats the minimum bore size needed to clear the LS7's valves. Being that "overs-square" you could spin it well into the 7000s. Remember, HP = Tq x RPM / 5252. The more rpm the higher the hp.
I used to build and test gas turbine helo engines in the Marine Corps, a GE-T700 turbo shaft makes 430 ft/lb at 20,000 rpm which when you do the math equals: 1,637 Hp!
I used to build and test gas turbine helo engines in the Marine Corps, a GE-T700 turbo shaft makes 430 ft/lb at 20,000 rpm which when you do the math equals: 1,637 Hp!
Last edited by ftlfirefighter; May 1, 2006 at 09:28 AM.
TECH Fanatic
Joined: Feb 2005
Posts: 1,123
Likes: 0
From: Maypearl, TX
Originally Posted by ftlfirefighter
If you mean 408 as in 4.030 x 4.000 then no. A 4.125 x 3.625 (stock stroke) = 387 cu/in. Thats the minimum bore size needed to clear the LS7's valves. Being that "overs-square" you could spin it well into the 7000s. Remember, HP = Tq x RPM / 5252. The more rpm the higher the hp.
I used to build and test gas turbine helo engines in the Marine Corps, a GE-T700 turbo shaft makes 430 ft/lb at 20,000 rpm which when you do the math equals: 1,637 Hp!
I used to build and test gas turbine helo engines in the Marine Corps, a GE-T700 turbo shaft makes 430 ft/lb at 20,000 rpm which when you do the math equals: 1,637 Hp!
Oohrah Devildawg!!!
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Originally Posted by ftlfirefighter
That depends C5, is it an iron or aluminum block? What's the bore dimension now?
right now im on the stock 346, but i would like to build an engine first, then pull out my old motor, drop the new one in and sell my old motor. im think of maybe a forged 408, 422 or 427 shortblock, with ETP LS7 heads or stock LS7 head and hardware up top. A nice sized cam (yet to be determined) and my goal is 550-600rwhp NA with a 7500rpm redline.
Teching In
Joined: Apr 2006
Posts: 30
Likes: 0
From: Fort Lauderdale, FL
AHH ok, now we're on the same page!! LOL Do what I'm doing, buy an LS7 crate motor for around $13,000, have the reluctor and cam sensors changed to work with your factory ecu and your set!! You're looking at $20-25k to duplicate what GM sells in a box read to go!
Originally Posted by ftlfirefighter
AHH ok, now we're on the same page!! LOL Do what I'm doing, buy an LS7 crate motor for around $13,000, have the reluctor and cam sensors changed to work with your factory ecu and your set!! You're looking at $20-25k to duplicate what GM sells in a box read to go!
that $13000k is really deterring me. i can get a procharger for 4k or turbo for 6k and a built 346ci motor for 4k and make much more power than NA. im still trying to conduct a cost-benefit analysis.
