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LS2 Max Hp per Ci?

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Old 09-04-2008, 05:43 AM
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Default LS2 Max Hp per Ci?

How many Hp/Ci can you squeeze from a N/A LS2? No holds barred...
Old 09-04-2008, 07:16 AM
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well the cubic inches usually isn't the restriction,it is how much air will your heads/induction system flow. with a great set of heads,huge solid roller cam and a sheet metal intake well over 2hp/ci shouldn't be a problem. most your average street setups is around 1.5 hp/ci give or take. there are alot of variables so it really depends on how radical you want to go.i think cfm wise each cfm you can flow you can make alittle over 2 hp so if you had a set of heads and and an intake that both could flow 400 cfm you could make over 800 hp with the right setup.

*edit = forgot to mention with the radical setups you will have to spin it to the moon also to reach peak hp *

Last edited by slow trap; 09-04-2008 at 07:21 AM.
Old 09-04-2008, 07:22 AM
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Cool
So it would be possible to get +850fwhp from a N/A 427ci engine? Who needs the spray...
Old 09-04-2008, 09:28 AM
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That wouldn't be as tough to achieve as you may think. It will, however, be expensive. https://ls1tech.com/forums/showthrea...t=dyno+guesses
My setup is a 441, but I'm only running pump gas. Bump the compression and run it on race gas and you're there. But, I also built mine to accept a large shot of N2O down the road. You could get away with running lighter pistons and rods than I did. That'll free up a little power too. Oh, and swap my hyd. roller for a solid roller because you're talking about a max effort engine anyway.
Old 09-04-2008, 11:27 AM
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LS engines have more potential to make 2hp/cid mainly because the heads are phenomenal. It is basically a race engine from the factory with 15degree valve angles. With the right cam, heads, intake and compression, a 427 can make 850hp.
Old 09-04-2008, 11:30 AM
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Originally Posted by MarkusG
Cool
So it would be possible to get +850fwhp from a N/A 427ci engine? Who needs the spray...
keep in mind, if you are making that kind of power from a small block, you will need some compression and a big roller cam, which means you need to stay on top of your valve lash and check your valve springs every 20-30 passes.
or you can just make it a 500inch small block and make 850 hp on pump gas with a hydraulic roller cam
Old 09-04-2008, 11:48 AM
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Originally Posted by MarkusG
Cool
So it would be possible to get +850fwhp from a N/A 427ci engine? Who needs the spray...
Definitely. I have seen 427" N/A LSX based motors (C5R block and LS6 block with Darton sleeves make 875 to 930 fwhp.)
Old 09-04-2008, 12:19 PM
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My only issue with hydraulic rollers are the fact that they become unreliable at high rpm. Perfect for the street though...
Will the LS2 hold up as is or is a resleeving mandatory? $2000 for the extra 25ci may feel a little steep if it isn't necessary from a structural point of view.
402ci can make decent power too it seams.
Old 09-04-2008, 08:09 PM
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dammit alex, don't depress me. I will let you know mow much flow loss there is when I get the heads flowed with a 4.125plate and a 4.000 plate.
Old 09-09-2008, 12:00 AM
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Originally Posted by MarkusG
My only issue with hydraulic rollers are the fact that they become unreliable at high rpm.
Clean at 8500... so whats high rpm?
Old 09-09-2008, 01:57 AM
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I've never met anyone who claimed their hydraulic lifters to be reliable above 6500rpm.
There are many who spin them faster but at their own risk.
Old 09-09-2008, 07:21 AM
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I spin to 8k with Comp R's all the time.
Old 09-09-2008, 08:10 AM
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Originally Posted by MarkusG
I've never met anyone who claimed their hydraulic lifters to be reliable above 6500rpm.
There are many who spin them faster but at their own risk.
Change who you talk to! Theres always alot of people willing to give out info, just remember its usually worth exactly what you paid for it. Nada

Ive seen 7200 hundreds of times and have been 7500 a decent bit on 50,000 mile factory lifters. Bad parts combinations and setup is what kills parts. 7500 rpm is nothing for a decent hyd roller valvetrain
Old 09-09-2008, 08:38 AM
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Cool, maybe I'll just have to revise my opinion on that one.
Hydraulic lifters are definately more userfriendly...
I guess the next logical question would be
- What's the limit on hydraulic lifters?
- Which are the best ones?
Old 09-09-2008, 09:12 AM
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Originally Posted by MarkusG
Cool, maybe I'll just have to revise my opinion on that one.
Hydraulic lifters are definately more userfriendly...
I guess the next logical question would be
- What's the limit on hydraulic lifters?
- Which are the best ones?


Depends on the lifter and the setup above the lifter. A lighter valve/spring/retainer combo will allow a higher safe limit when used in conjunction with the proper lobe profiles on the cam.

You are getting into a little more specialized area than most people on here usually do. I would contact a valvetrain specialist and talk to them about your goals and budget. A good designer may be able to get you more power at a lower rpm than you might think..
Old 09-09-2008, 09:47 AM
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Originally Posted by Stang's Bane
Depends on the lifter and the setup above the lifter. A lighter valve/spring/retainer combo will allow a higher safe limit when used in conjunction with the proper lobe profiles on the cam.

You are getting into a little more specialized area than most people on here usually do. I would contact a valvetrain specialist and talk to them about your goals and budget. A good designer may be able to get you more power at a lower rpm than you might think..
Yes, there is no hard "limit". Its a balancing act of valvetrain control, the more weight your slinging around the harder it is to control. This kinda stuff on paper doesnt always pan out in reality. Experience is worth more than the calculations may be more often than not, different springs act differently so on and so forth.

We use different stuff on stock castings, on heavy steel valve ET castings etc etc to suit what each might need, hell I think mechanically we have the stuff to turn near 9K with a hyd but I think there are other issues with these motors that will trip it up before the hyd setup itself is the issue
Old 09-09-2008, 11:05 AM
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The general understanding that I have is if your making 3 hp per CID your going to start eating parts.

In essence a 402cid motor may make a pull @ 1600 hp and survive the pull, the question is for how long, and you can put the best fuel in there and there isnt a guarentee. It can be either a internal part or even the block that can fail.

But like said there are tricks to keep the blocks/engine survive.

and to make power in a small block you gotta rev the **** out of them and thats a whole nother consideration.
Old 09-09-2008, 11:32 AM
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I am running a 402 nitrous motor, and with the n/a timing in it I made 480 to the tires with a 5400 rpm n/a converter and TH400.

It does carry the power to 7200 rpm no problem before it starts to fall off.

That's not 850+ fwhp, but consider this:

fast intake, untouched
stock maf
1 3/4 headers
hydraulic cam only in the 240's 620ish lift area
stock waterpump
no vacum pump, dry sump or any of that
stock ls1 lifters
stock ls1 rockers

It's not a world record holder or any of that, but even with 150 passes on it it's a strong piece, and has nothing more then valvesprings changed, and oil/filter changed after every track trip.

It's a solid 10.5 car n/a, and with a 150 shot has run 9.6 @ over 140 on 2200+ da weather, and there's still some left before I upgrade to a fogger setup (running a little Nos behind the Tb plate)
Old 09-09-2008, 10:35 PM
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No replacement for displacement ?



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