LS7 head On a 6.2 block.
LS7 head On a 6.2 block. What would keep you from running a ls7 head on a 4.07 bore 6.2 L Block?
Mocked it all up today and they seem to fit fine. Yes the chamber hangs over alittle,but nothing a little valve notching (.01-.020 max) wouldn't take care of.
I got a little over .040 clearence from the exhaust valve the the bore @4.062.
Intake has a mile atleast .200.
Anyone ever try this?
Thanks
Dave
Mocked it all up today and they seem to fit fine. Yes the chamber hangs over alittle,but nothing a little valve notching (.01-.020 max) wouldn't take care of.
I got a little over .040 clearence from the exhaust valve the the bore @4.062.
Intake has a mile atleast .200.
Anyone ever try this?
Thanks
Dave
I think they say valve shrouding. doesn’t matter what size valve but it wouldn’t be worth the benefit because of the shrouding. Kinda like running 4 inch exhaust on a 4 cylinder. It hurts more then it helps
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From: Upstate NY
I think the idea has merit. It isn't a cheap thing to try, but the cost/hp might be not that unreasonable.
Jon
The whole reason i was thinking about it was, because i got a couple 6.2 block, a set of cnc ported ls7 heads,new 4.07 bore pistons(may need notching).
Thinkin about putting a stock crank, recon rods w/arps, hang pistons,throw a cam at it, and for less then $2000 Bang.
I guess my question is do you think they would out proform a set of ported l92.
Thinkin about putting a stock crank, recon rods w/arps, hang pistons,throw a cam at it, and for less then $2000 Bang.
I guess my question is do you think they would out proform a set of ported l92.
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Joined: Jun 2002
Posts: 1,979
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From: Upstate NY
The whole reason i was thinking about it was, because i got a couple 6.2 block, a set of cnc ported ls7 heads,new 4.07 bore pistons(may need notching).
Thinkin about putting a stock crank, recon rods w/arps, hang pistons,throw a cam at it, and for less then $2000 Bang.
I guess my question is do you think they would out proform a set of ported l92.
Thinkin about putting a stock crank, recon rods w/arps, hang pistons,throw a cam at it, and for less then $2000 Bang.
I guess my question is do you think they would out proform a set of ported l92.
My guess is that stock OEM CNC LS7 heads with the correct valvetrain parts, the LS7 intake and the correct cam will outdo most of the ported L92 heads I've seen. The shorter LS7 intake runners will allow a higher power peak rpm if you are willing to spin it a little for power. The correct cam will also be driveable, if that's what you are after.
Keep thinkin' OTB.
Jon
did some measuring
Stock l92 heads and stock gm ported ls7
Clearence to the bore @~ .625 lift
LS7 (2.200 in 1.610 ex)
intake .120-.130
exhaust .040-.050
L92(2.160 in 1.60 ex)
intake .07-08
exhaust .070-.080
Dont it seem odd that the ls7 intake valve has more clearence.
Stock l92 heads and stock gm ported ls7
Clearence to the bore @~ .625 lift
LS7 (2.200 in 1.610 ex)
intake .120-.130
exhaust .040-.050
L92(2.160 in 1.60 ex)
intake .07-08
exhaust .070-.080
Dont it seem odd that the ls7 intake valve has more clearence.
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And the shrouding is arguably only relevant at low lift numbers as once the valve is open the head is out of the way. Plus the exhaust is less sensitive to the intake on shrouding.
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Correct me if I'm wrong but I think the LS7 heads have 12-degree valve angles whereas the L92 heads have 15-degree valve angles. Hence, maybe a little more room from a little flatter valve face.
did some measuring
Stock l92 heads and stock gm ported ls7
Clearence to the bore @~ .625 lift
LS7 (2.200 in 1.610 ex)
intake .120-.130
exhaust .040-.050
L92(2.160 in 1.60 ex)
intake .07-08
exhaust .070-.080
Dont it seem odd that the ls7 intake valve has more clearence.
Stock l92 heads and stock gm ported ls7
Clearence to the bore @~ .625 lift
LS7 (2.200 in 1.610 ex)
intake .120-.130
exhaust .040-.050
L92(2.160 in 1.60 ex)
intake .07-08
exhaust .070-.080
Dont it seem odd that the ls7 intake valve has more clearence.
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Texas Speed had a set of PRC After market casting Ls7 style Heads for this very same set up....
I talked to them 4wks ago about it, They said stock bottom end Ls3 block w a Cam and There PRC 265cc, Small Bore Ls7 head made 600 CRANK HP,
But...The Trq Curve Sucked
He said w a Ls3 Storker 418/417 is what there where Really designed for
I talked to them 4wks ago about it, They said stock bottom end Ls3 block w a Cam and There PRC 265cc, Small Bore Ls7 head made 600 CRANK HP,
But...The Trq Curve Sucked
He said w a Ls3 Storker 418/417 is what there where Really designed for
did some measuring
Stock l92 heads and stock gm ported ls7
Clearence to the bore @~ .625 lift
LS7 (2.200 in 1.610 ex)
intake .120-.130
exhaust .040-.050
L92(2.160 in 1.60 ex)
intake .07-08
exhaust .070-.080
Dont it seem odd that the ls7 intake valve has more clearence.
Stock l92 heads and stock gm ported ls7
Clearence to the bore @~ .625 lift
LS7 (2.200 in 1.610 ex)
intake .120-.130
exhaust .040-.050
L92(2.160 in 1.60 ex)
intake .07-08
exhaust .070-.080
Dont it seem odd that the ls7 intake valve has more clearence.
It stands to reason that if the measurments are accurate on a 4.062 bore then whos to say a .060 over 4" bore is out of the question. Is there any data on combustion chamber overhang onto the deck surface ?? And would this even be a issue to worry about ?? The difference is only .064/ = .032 around of deck surface (LS7 to 6.0).
So....with 2.20/1.61 valves and a 1.9685 spacing = 3.8735 total valve area (linear). Which gives a .0635 space between the valves.
Is anyone putting the LS7 on small bores, other than the 4.125 ???
Thanks.....
So....with 2.20/1.61 valves and a 1.9685 spacing = 3.8735 total valve area (linear). Which gives a .0635 space between the valves.
Is anyone putting the LS7 on small bores, other than the 4.125 ???
Thanks.....
