Generation IV Internal Engine 2005-2014 LS2 | LS3 | LS7 | L92 | LS9

higher duration or higher lift??

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Old 10-08-2011, 11:22 PM
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Default higher duration or higher lift??

currently building a 6.0 ls2 so far have 17/8 longtubs, 102 fast lsx IM, cold air. cam n heads
im planning on NA'in the motor but want to hook up No2.. just for late night/strip racing(farely new to lsx motors)... was lookin at a few cams. some with high lift, low duration, or low lift, high durration... found a couple around 609in 612ex dur@.5 238in 245ex.... seein if anyone has some "trial n errors" or "should haves"????
Old 10-09-2011, 09:27 AM
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I am no cam guru, but I believe anytime you can get some extra lift, that's free hp. Duration and LSA are going to have more of an effect on the powerband and how narrow/wide it is. I know with juice I would run 112 or higher on the lsa. Whats it going in, auto or manual.
Old 10-09-2011, 10:24 AM
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They go hand in hand. To get more duration you have to have more lift. The LS3's seem to be able to handle durations in the 240's- 250's with low lifts say in the .620's.

On a stock build a little extra lift is like a few degrees of duration and say 10-20 HP. Thats why many people added 1.6 rockers to there builds on old school small blocks. You can add 1.8 rockers to an Ls1 but its not worth the price of the parts.IMOP.

The cam specs you gave are about right for an LS2. What heads are you running?

Last edited by 1lejohn; 10-09-2011 at 10:31 AM.
Old 10-09-2011, 01:18 PM
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If you want a great cam have pat g spec you a cam and he can explain much better why you want X lift and X duration
Old 10-09-2011, 11:03 PM
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Originally Posted by Rhino79
I am no cam guru, but I believe anytime you can get some extra lift, that's free hp. Duration and LSA are going to have more of an effect on the powerband and how narrow/wide it is. I know with juice I would run 112 or higher on the lsa. Whats it going in, auto or manual.

its going in a manual 06 gto.. dont know exactly what heads im going to do, pretty much going to base it off the cam i choose... so based of the cam i posted would 1.8 rockers be worth the effort?? i wanna try to put close to 500whp as possible "all NA"...
im used to carbed SBC n all this new lsx EFI computer stuff is confusing but i get the consepy...haha too many options
Old 10-09-2011, 11:05 PM
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Originally Posted by Tainted
If you want a great cam have pat g spec you a cam and he can explain much better why you want X lift and X duration
buddy was tellin me some people can do that. how can i go about gettin "pat g" to grind me up a cam??
Old 10-09-2011, 11:23 PM
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Go to EPS (sponsor on the right) and fill out the pat g spec sheet or Google his name and you will find the same thing.

He will ask you the car, weight, gears, transmission, head flow the works and spec you out a cam based on your needs with what you have. Best $20 spent ever on an engine build!
Old 10-10-2011, 01:01 PM
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Originally Posted by CRZYGTO
its going in a manual 06 gto.. dont know exactly what heads im going to do, pretty much going to base it off the cam i choose... so based of the cam i posted would 1.8 rockers be worth the effort?? i wanna try to put close to 500whp as possible "all NA"...
im used to carbed SBC n all this new lsx EFI computer stuff is confusing but i get the consepy...haha too many options
It should be the other way around base the cam off of the heads and expected use , rpm , intake etc. These engines respond quite differently to the type of heads and intake used. I would call Ed Curtis at FTI for you needs.
Old 10-10-2011, 04:24 PM
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Originally Posted by 1lejohn
It should be the other way around base the cam off of the heads and expected use , rpm , intake etc. These engines respond quite differently to the type of heads and intake used. I would call Ed Curtis at FTI for you needs.
What this guy said!! Cam should be your last major purchase before assembling the engine.
Old 10-11-2011, 04:50 AM
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Originally Posted by 1lejohn
They go hand in hand. To get more duration you have to have more lift. The LS3's seem to be able to handle durations in the 240's- 250's with low lifts say in the .620's.

On a stock build a little extra lift is like a few degrees of duration and say 10-20 HP. Thats why many people added 1.6 rockers to there builds on old school small blocks. You can add 1.8 rockers to an Ls1 but its not worth the price of the parts.IMOP.

The cam specs you gave are about right for an LS2. What heads are you running?
That isnt quite true.

You can have long duration with low lift.

But if you opt for high lift, then duration needs to increase to smoothen the cam profile, otherwise it would hammer the life out of the valvetrain.

But a low lift, long duration profile could be very smooth, and very easy on the valvetrain. Although it may ( or could have ) have a lot of dwell around the max lift area
Old 10-11-2011, 05:30 AM
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I would not change the 1.7 rocker ratios. It's not worth it for 450.00
Old 10-11-2011, 08:47 AM
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Good info in this thread
Old 10-11-2011, 05:05 PM
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If you go with ls3 heads you dont need MASSIVE duration my 418 build only has about
24x duration on it, unfortunetly you are going to be limited on lift with a stock ls2 engine with ls3 heads so some extra duration may make up for smaller lift. from what I have read though ls3 heads tend to like lower duration and higher lift my cam has over 640 on the intake side but about 61x on the exaust it is a LG motorsports g6x5 cam I dont know the specs but it put down 505/505 respectivly in a auto GTO with a very restrictive stock intake system. on my car it should make over 550 to the wheeles and still have good street maners.

I would seriously talk to pat G or a actual engine builder for your head and cam setup for your build. cause it will make or break a engine
Old 10-12-2011, 02:44 PM
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Originally Posted by stevieturbo
That isnt quite true.

You can have long duration with low lift.

But if you opt for high lift, then duration needs to increase to smoothen the cam profile, otherwise it would hammer the life out of the valvetrain.

But a low lift, long duration profile could be very smooth, and very easy on the valvetrain. Although it may ( or could have ) have a lot of dwell around the max lift area
You are correct something like a Stock class car would run. They are limited to stock lift grinds. They don't perform well on street driven engines. The lobes are almost square .LOL.
Old 10-12-2011, 03:03 PM
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Very interesting info, interested myself.
Old 10-14-2011, 09:57 AM
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Carbed ls engines use a little more of a traditional lift/dur cam. Has alot to do with the long intake runners on the fi stuff. My carbed unit runs a 234/238 .602/.604 on a 111 lc. Wouldn't work real well on a fi engine. Way easy on valve train. About 600 fwhp@5700 rpm on a 427.
Old 10-15-2011, 09:40 AM
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Originally Posted by allblowdup
Carbed ls engines use a little more of a traditional lift/dur cam. Has alot to do with the long intake runners on the fi stuff. My carbed unit runs a 234/238 .602/.604 on a 111 lc. Wouldn't work real well on a fi engine. Way easy on valve train. About 600 fwhp@5700 rpm on a 427.
Not much different then some of the EFI cams. The EFI ones seem to like wider lc's 113-117.
Old 10-15-2011, 10:44 AM
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Originally Posted by Rhino79
I am no cam guru, but I believe anytime you can get some extra lift, that's free hp. Duration and LSA are going to have more of an effect on the powerband and how narrow/wide it is.
Originally Posted by stevieturbo
That isnt quite true.

You can have long duration with low lift.

But if you opt for high lift, then duration needs to increase to smoothen the cam profile, otherwise it would hammer the life out of the valvetrain.

But a low lift, long duration profile could be very smooth, and very easy on the valvetrain. Although it may ( or could have ) have a lot of dwell around the max lift area

Yep.



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