LS3 Carbed build

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MaxFlow
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Re: LS3 Carbed build

Post by MaxFlow » Mon Jul 16, 2018 12:18 am

I have hydraulic roller builds running 8000 rpm every weekend in the summer with .670 lift at the valve with stock GM lifters. I wouldn't worry a bit about that. You can go all season and never adjust a valve..........LOL :lol:
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Re: LS3 Carbed build

Post by CGT » Mon Jul 16, 2018 11:22 am

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Re: LS3 Carbed build

Post by RW TECH » Mon Jul 16, 2018 12:11 pm

cgarb wrote:
Fri Jul 06, 2018 9:43 pm
What are all the stock eliminator cars running for camshafts?
I wouldn't go by that, but here's something to consider.

The graph below compares solid roller cams in a LS3-type engine with LS3 heads that have throats opened and port matching.

- One cam is 272°/280° 110° LCA and was prescribed by a popular cam company.

- The other is a 258°/284° 113°LCA with intake in at 111°

Guess which one is which & Pay particular attention to the 5200-5600 RPM area.
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Re: LS3 Carbed build

Post by RW TECH » Mon Jul 16, 2018 12:15 pm

CGT wrote:
Thu Jul 05, 2018 10:49 pm
cgarb wrote:
Thu Jul 05, 2018 10:32 pm
Will you be using adjustable valvetrain? Have you given any thought to a solid roller?
Would love to have done a solid roller, but im going to try and get it done with the factory valvetrain, non adjustable, travel limited stock lifters and conical springs.

I wont know how all that jives out until I get there(valvetrain). A solid roller would add thousands of dollars to this project, no cheap way around that but may ultimately be inevitable.
Add the LS9 exhaust valve to your lineup. It'll gain you about 750 RPM of limiting speed compared to the stock LS3 exhaust valve. LS7 retainer is required to get the installed spring height to work out but overall valve lengths are the same.

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Re: LS3 Carbed build

Post by RW TECH » Mon Jul 16, 2018 12:19 pm

randy331 wrote:
Sat Nov 18, 2017 1:28 pm
What do the LS engine builders think of the GM 88958675 intake for LS ?
Not a good idea.

Look at the end runner trajectories compared to something good like pretty much all of the modern era Cup intakes.

It couldn't get worse if it had to.

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Re: LS3 Carbed build

Post by CGT » Mon Jul 16, 2018 12:26 pm

RW TECH wrote:
Mon Jul 16, 2018 12:15 pm
CGT wrote:
Thu Jul 05, 2018 10:49 pm
cgarb wrote:
Thu Jul 05, 2018 10:32 pm
Will you be using adjustable valvetrain? Have you given any thought to a solid roller?
Would love to have done a solid roller, but im going to try and get it done with the factory valvetrain, non adjustable, travel limited stock lifters and conical springs.

I wont know how all that jives out until I get there(valvetrain). A solid roller would add thousands of dollars to this project, no cheap way around that but may ultimately be inevitable.
Add the LS9 exhaust valve to your lineup. It'll gain you about 750 RPM of limiting speed compared to the stock LS3 exhaust valve. LS7 retainer is required to get the installed spring height to work out but overall valve lengths are the same.
I have a set of manley exhaust valves I was thinking of using. Any idea what the ls9 valve weighs? 12605525? Ill order one in to look at. 89 grams on the manleys. Can you add anymore input in relation to the above graphs.
Thanks

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Re: LS3 Carbed build

Post by RW TECH » Mon Jul 16, 2018 2:05 pm

CGT wrote:
Mon Jul 16, 2018 12:26 pm
RW TECH wrote:
Mon Jul 16, 2018 12:15 pm
CGT wrote:
Thu Jul 05, 2018 10:49 pm


Would love to have done a solid roller, but im going to try and get it done with the factory valvetrain, non adjustable, travel limited stock lifters and conical springs.

I wont know how all that jives out until I get there(valvetrain). A solid roller would add thousands of dollars to this project, no cheap way around that but may ultimately be inevitable.
Add the LS9 exhaust valve to your lineup. It'll gain you about 750 RPM of limiting speed compared to the stock LS3 exhaust valve. LS7 retainer is required to get the installed spring height to work out but overall valve lengths are the same.
I have a set of manley exhaust valves I was thinking of using. Any idea what the ls9 valve weighs? 12605525? Ill order one in to look at. 89 grams on the manleys. Can you add anymore input in relation to the above graphs.
Thanks
The LS9 valve is 71 grams......All the difference in the world.

The earlier intake valve opening on the cam recommended by a popular cam company was a disaster - the engine was throwing up all over itself below 5300 RPM, especially between 4600-5000 RPM. It doesn't need to open earlier than 18°BTDC, and that's kind of pushing it.

Likewise, there's a popular notion that the LS has to have the exhaust valve closed "early" but the power curves in the graph below do not show that to be true.

This one is a hydraulic roller comparison of a 252° / 276° with 112° centers to a 248°/ 288° with 112° intake CL, 109° exhaust CL (110° LCA). Obviously, later exhaust closing is not the problem.......Early intake opening is.
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Re: LS3 Carbed build

Post by CGT » Mon Jul 16, 2018 3:17 pm

RW TECH wrote:
Mon Jul 16, 2018 2:05 pm
CGT wrote:
Mon Jul 16, 2018 12:26 pm
RW TECH wrote:
Mon Jul 16, 2018 12:15 pm


Add the LS9 exhaust valve to your lineup. It'll gain you about 750 RPM of limiting speed compared to the stock LS3 exhaust valve. LS7 retainer is required to get the installed spring height to work out but overall valve lengths are the same.
I have a set of manley exhaust valves I was thinking of using. Any idea what the ls9 valve weighs? 12605525? Ill order one in to look at. 89 grams on the manleys. Can you add anymore input in relation to the above graphs.
Thanks
The LS9 valve is 71 grams......All the difference in the world.

The earlier intake valve opening on the cam recommended by a popular cam company was a disaster - the engine was throwing up all over itself below 5300 RPM, especially between 4600-5000 RPM. It doesn't need to open earlier than 18°BTDC, and that's kind of pushing it.

Likewise, there's a popular notion that the LS has to have the exhaust valve closed "early" but the power curves in the graph below do not show that to be true.

This one is a hydraulic roller comparison of a 252° / 276° with 112° centers to a 248°/ 288° with 112° intake CL, 109° exhaust CL (110° LCA). Obviously, later exhaust closing is not the problem.......Early intake opening is.
Thanks, appreciate the input.

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Re: LS3 Carbed build

Post by ns158sl » Fri Oct 05, 2018 10:03 pm

any updates? I was curious on this build. Its too much work, but I want to see results of the offset dowels vs straight. I am building a ls3 headed carb engine also. my cam is going to be around a 255 260 on a 110 lsa hyd roller.

Eric

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Re: LS3 Carbed build

Post by CGT » Sat Oct 06, 2018 4:22 pm

ns158sl wrote:
Fri Oct 05, 2018 10:03 pm
any updates? I was curious on this build. Its too much work, but I want to see results of the offset dowels vs straight. I am building a ls3 headed carb engine also. my cam is going to be around a 255 260 on a 110 lsa hyd roller.

Eric
Oh its getting closer, all of the more expensive stuff had to be purchased yet.....manifold, springs, carb, vaccuum, ignition, ex valves, balancer, etc....but im almost there. Im hoping to have it wrapped up this year.

Is your project a LS3?

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Re: LS3 Carbed build

Post by ns158sl » Tue Oct 09, 2018 7:03 pm

Yep, It is kind of a side project so nothing too serious.. yet. 6.0 bored to 4.070. Leaning on my stock ls3 heads ported by LandSpeed, reuse the ls3 valves. ls7 lifters, l92 oil pump. 3/8in pushrods. ls3 rocker trunnions. 14 to 1 e85. 3.9 K1 crank.

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Re: LS3 Carbed build

Post by CGT » Tue Oct 09, 2018 7:07 pm

ns158sl wrote:
Tue Oct 09, 2018 7:03 pm
Yep, It is kind of a side project so nothing too serious.. yet. 6.0 bored to 4.070. Leaning on my stock ls3 heads ported by LandSpeed, reuse the ls3 valves. ls7 lifters, l92 oil pump. 3/8in pushrods. ls3 rocker trunnions. 14 to 1 e85. 3.9 K1 crank.
Cool. What manifold etc?

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Re: LS3 Carbed build

Post by ns158sl » Tue Oct 09, 2018 7:20 pm

For now I am running the GM one. I got it dirt cheap brand new so I will try that before going to a victor or something. Thinking about a 950 carb, or again if I can find a cheap dominator just to try. I already have a turbo 383 6.0, and then I started looking at all the parts in the garage, and was like "I wonder how much HP I can build on a budget" haha. Engine is going in a 2700lb car with a 4 speed and 4.56s on a 28 inch tire.

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Re: LS3 Carbed build

Post by CGT » Tue Oct 09, 2018 8:11 pm

ns158sl wrote:
Tue Oct 09, 2018 7:20 pm
For now I am running the GM one. I got it dirt cheap brand new so I will try that before going to a victor or something. Thinking about a 950 carb, or again if I can find a cheap dominator just to try. I already have a turbo 383 6.0, and then I started looking at all the parts in the garage, and was like "I wonder how much HP I can build on a budget" haha. Engine is going in a 2700lb car with a 4 speed and 4.56s on a 28 inch tire.
Planning on dynoing it?

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Re: LS3 Carbed build

Post by ns158sl » Thu Oct 11, 2018 8:34 pm

Yep! Engine Dyno. Like I said I am a lot farther out than you are, haha. Goal is around july/august. Im hoping to get close to around 700hp around 7500rpm. That's just hopes and dreams right now.

Eric

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