Cam gurus step in need ls3 cam help
12-10-2012, 03:33 PM
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Cam gurus step in need ls3 cam help Changing cams due to the one I have isn't spec for my engine just something I threw in. So I have had 2 different vendors soec me a cam and needed advice on which one you think will work best with my setup. Here we go engine specs.
370 lq9
4.030 bore
4.080 head gasket .051
6.125 rods
Stock ls crank balanced and blue printe with Mallory slugs
Ls3 heads milled to 62cc VERY light touch up port work
Prc .650 springs
11cc some wise co pistons 13.7:1 static
1.75 lgm longtubes off road xpipe dumped
Double roller chain
Slp dampener
Ls3 Edelbrock Vic jr intake
90mm t.b.
110 or e85 fuel
150-225 shot of nitrous
Stalled a4 4l60e
gear ratio 3.42
Weight 3350
Which one
Cam spec A. 248 / 266 .649" / .646" - 112 +4
Cam spec B. 235/246 .638/.615" 114LSA +3
Any opinions input and or tweaks to either or would be appreciated.
370 lq9
4.030 bore
4.080 head gasket .051
6.125 rods
Stock ls crank balanced and blue printe with Mallory slugs
Ls3 heads milled to 62cc VERY light touch up port work
Prc .650 springs
11cc some wise co pistons 13.7:1 static
1.75 lgm longtubes off road xpipe dumped
Double roller chain
Slp dampener
Ls3 Edelbrock Vic jr intake
90mm t.b.
110 or e85 fuel
150-225 shot of nitrous
Stalled a4 4l60e
gear ratio 3.42
Weight 3350
Which one
Cam spec A. 248 / 266 .649" / .646" - 112 +4
Cam spec B. 235/246 .638/.615" 114LSA +3
Any opinions input and or tweaks to either or would be appreciated.
12-10-2012, 05:13 PM
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Well I was running an ls3 stock mani and seen a comparison on gm high perf they gained about 32 bhp with the Vic jr and I traded my stock one for the Vic jr so no loss to me really.I am just trying to pick up peak power a little bit and paying 850 for the 12 whp fast mani is not worth it. Ill be running either a Aaron's 90* high flow elbow or have a adaptor made to fit the 90mm to the 4150 flange no elbow gotta measure clearances
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12-11-2012, 02:53 PM
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Agree with WKMCD.... elbows kill power.
I did an LS2 427 w/single plane intake and 4 barrel TB. The engine made 672HP with an open TB. When I added a 90 degree elbow with 4" OD tube for a maf set up... the peak power dropped to 598 HP. This test was done on an engine dyno with back to back runs. I ditched the elbow idea.... I was suprised how much the power dropped.
I did an LS2 427 w/single plane intake and 4 barrel TB. The engine made 672HP with an open TB. When I added a 90 degree elbow with 4" OD tube for a maf set up... the peak power dropped to 598 HP. This test was done on an engine dyno with back to back runs. I ditched the elbow idea.... I was suprised how much the power dropped.
12-11-2012, 05:27 PM
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That's why I am thinking of doing a ls2 tb bolted directly to manifold instead of elbow I'm dbw and no one makes a 4 barrel tb
Last edited by 370cidZ06; 12-11-2012 at 05:59 PM.
12-11-2012, 08:14 PM
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I guess all I can offer is that under no circumstance would I use a 90 degree elbow set-up on a single plane intake on naturally aspirated engine. Disrupts air flow too much. Would be better of with a LS intake.
12-11-2012, 09:15 PM
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If you did bolt up an LS2 TB bolted directly to the single plane intake it seems like it could work. Might be worth a try. Not sure about driveability off idle and at lower RPM's. The fast 4 barrel TB I'm using opens two barrels very slowly off idle, and then at half throttle the other two barrels start to open. Tip in and drivability are good... not sure on the mono blade... maybe others have tried this.
I guess all I can offer is that under no circumstance would I use a 90 degree elbow set-up on a single plane intake on naturally aspirated engine. Disrupts air flow too much. Would be better of with a LS intake.
I guess all I can offer is that under no circumstance would I use a 90 degree elbow set-up on a single plane intake on naturally aspirated engine. Disrupts air flow too much. Would be better of with a LS intake.
Last edited by 370cidZ06; 12-11-2012 at 09:31 PM.
12-14-2012, 03:05 PM
#13
Clearance is going to be an issue on the C5. I just noticed this the other day. Not my style but either is a carb manifold on the vette.
https://ls1tech.com/forums/corvette-...lable-vfn.html
https://ls1tech.com/forums/corvette-...lable-vfn.html
12-14-2012, 03:23 PM
#14
Neither cam. Not with an LS3 manifold and especially not with a Victor Jr. I've never seen that wide of an LSA with a Victor.
235/239 .617/.622 110+2. Or something along there. You need a much tighter LSA with carb type manifolds and the LS3 heads don't love a ton of overlap or a huge split because of reversion.
The wide-split has pretty much been debunked, especially on Corvette Forum. I'm not sure why it's still the norm here? Most guys run a 230/234 114 or thereabouts and touch 500rwhp with stock heads on a 376. You're not any bigger than those with a much smaller bore (and therefore more shrouding of the valves). But the Victor throws a wrench into that so I suggested a tighter LSA and a little more duration.
235/239 .617/.622 110+2. Or something along there. You need a much tighter LSA with carb type manifolds and the LS3 heads don't love a ton of overlap or a huge split because of reversion.
The wide-split has pretty much been debunked, especially on Corvette Forum. I'm not sure why it's still the norm here? Most guys run a 230/234 114 or thereabouts and touch 500rwhp with stock heads on a 376. You're not any bigger than those with a much smaller bore (and therefore more shrouding of the valves). But the Victor throws a wrench into that so I suggested a tighter LSA and a little more duration.
12-19-2012, 06:36 PM
#16
Neither cam. Not with an LS3 manifold and especially not with a Victor Jr. I've never seen that wide of an LSA with a Victor.
235/239 .617/.622 110+2. Or something along there. You need a much tighter LSA with carb type manifolds and the LS3 heads don't love a ton of overlap or a huge split because of reversion.
The wide-split has pretty much been debunked, especially on Corvette Forum. I'm not sure why it's still the norm here? Most guys run a 230/234 114 or thereabouts and touch 500rwhp with stock heads on a 376. You're not any bigger than those with a much smaller bore (and therefore more shrouding of the valves). But the Victor throws a wrench into that so I suggested a tighter LSA and a little more duration.
235/239 .617/.622 110+2. Or something along there. You need a much tighter LSA with carb type manifolds and the LS3 heads don't love a ton of overlap or a huge split because of reversion.
The wide-split has pretty much been debunked, especially on Corvette Forum. I'm not sure why it's still the norm here? Most guys run a 230/234 114 or thereabouts and touch 500rwhp with stock heads on a 376. You're not any bigger than those with a much smaller bore (and therefore more shrouding of the valves). But the Victor throws a wrench into that so I suggested a tighter LSA and a little more duration.
12-19-2012, 08:29 PM
#17
That's fine. They also recommend 8 degrees on cathedral port heads. A lot of folks go that way. A lot go single pattern or smaller splits and make the same power. The original thought process was the huge intake needed more exhaust duration - but the exhaust actually flows well. Just not as great as the intake.
Most who have dyno tested them show the additional overlap just causes reversion. Hell even TSP only has 4-6 degree splits on their LS3 shelf cams due to their Engine dyno testing.
Most who have dyno tested them show the additional overlap just causes reversion. Hell even TSP only has 4-6 degree splits on their LS3 shelf cams due to their Engine dyno testing.
12-21-2012, 02:04 PM
#19
Agree with WKMCD.... elbows kill power.
I did an LS2 427 w/single plane intake and 4 barrel TB. The engine made 672HP with an open TB. When I added a 90 degree elbow with 4" OD tube for a maf set up... the peak power dropped to 598 HP. This test was done on an engine dyno with back to back runs. I ditched the elbow idea.... I was suprised how much the power dropped.
I did an LS2 427 w/single plane intake and 4 barrel TB. The engine made 672HP with an open TB. When I added a 90 degree elbow with 4" OD tube for a maf set up... the peak power dropped to 598 HP. This test was done on an engine dyno with back to back runs. I ditched the elbow idea.... I was suprised how much the power dropped.
As for the cam I would chose B between the 2 but do a 108 LSA and shorten the exhaust a bit.
12-21-2012, 04:28 PM
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I'm using an off the shelf Comp Cams 231 239 .617 .624 113 in a crate LS3 in our 2001 Monaro, which weighs in at 3880lbs.
Ancillaries are 25% under drive, RAMJET OTR, 90mm throttle body, 1 7/8" into 3" collectors, 3" cats into 2 1/2" twin system, 4,500 convertor and 4.1:1 diff gears.
Any thoughts on this combo?
Ancillaries are 25% under drive, RAMJET OTR, 90mm throttle body, 1 7/8" into 3" collectors, 3" cats into 2 1/2" twin system, 4,500 convertor and 4.1:1 diff gears.
Any thoughts on this combo?