What makes the LS3 so much more powerful? - Pontiac G8 Forum: G8 Forums - G8Board.com
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post #1 of 31 (permalink) Old 04-22-2019, 09:24 AM Thread Starter
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What makes the LS3 so much more powerful?

Well I've read and saw a few videos of CAMMED L76 G8s going against LS3 G8s and SSs and barely keeping up or losing. So what makes the LS3 perform so much better than the LS2 and L76?
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post #2 of 31 (permalink) Old 04-22-2019, 09:28 AM
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First thing that comes to my mind would be displacement. I know it's not much, but as the old saying goes, "there's no replacement for displacement". I would also have to assume, crank, rods and possibly other internal parts that might be lighter and stronger. Just my thoughts.
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post #3 of 31 (permalink) Old 04-22-2019, 10:16 AM
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First thing that comes to my mind would be displacement. I know it's not much, but as the old saying goes, "there's no replacement for displacement". I would also have to assume, crank, rods and possibly other internal parts that might be lighter and stronger. Just my thoughts.
This. Those extra .2L make a world of difference. It's funny cause the L76 actually could be seen as a transitional engine between the LS2 and LS3 as far as parts go. The L76 has the LS2's block but has the heads of an L98 which was then in turn used on the LS3.

That said I think the only way you can get an L76 to beat an LS3 is to fit the L76 with some sort of blower and even then I think the stock LS3 would hold its own.

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post #4 of 31 (permalink) Old 04-22-2019, 10:54 AM
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The .2 liters of displacement are nice but its the larger bore that's the real key. It unshrouds the valves and lets it breath.
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post #5 of 31 (permalink) Old 04-22-2019, 10:54 AM
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IMHO, the L76 is really underutilized because they had to use such a mild cam to deal with the DOD stuff.
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post #6 of 31 (permalink) Old 04-22-2019, 10:56 AM
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More displacement
Lighter valve train
Better gearing in the LS3 cars

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post #7 of 31 (permalink) Old 04-22-2019, 11:02 AM Thread Starter
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More displacement
Lighter valve train
Better gearing in the LS3 cars
What is the difference in gearing? Are you talking the transmission or just the rear?

Edit: So it looks like the transmissions were identical (I thought for some reason the SS had the 8 speed) and the G8 had 2.92 vs the SS 3.27. Minimal difference but everything adds up here.
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post #8 of 31 (permalink) Old 04-22-2019, 11:02 AM
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IMHO, the L76 is really underutilized because they had to use such a mild cam to deal with the DOD stuff.
Yup. This is why I'm going to do a cam upgrade when I do my DOD delete.
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post #9 of 31 (permalink) Old 04-22-2019, 11:10 AM Thread Starter
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The .2 liters of displacement are nice but its the larger bore that's the real key. It unshrouds the valves and lets it breath.
I think this might be the key. The larger bore.

Are the heads identical between the two other than the valvetrain? I wonder if head work on the L76 heads shows much improvement. I know in SBF land the big bore cars were the key to making power. Hmmmm.....
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post #10 of 31 (permalink) Old 04-22-2019, 11:51 AM
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LS3 Heads flow better than just about anything else
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post #11 of 31 (permalink) Old 04-22-2019, 12:35 PM
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Our GTs had a really tall 2.92 gear while the GXPs had 3.27 stock. Which of course helps acceleration
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post #12 of 31 (permalink) Old 04-22-2019, 12:38 PM Thread Starter
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LS3 Heads flow better than just about anything else
Please bear with me, I'm fresh off the boat new to GM stuff. The L76 has LS2 bottom end with LS3 top end right? But the valvetrain isn't the same as LS3 right? So other than that are the L76 ports and style identical to the LS3?
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post #13 of 31 (permalink) Old 04-22-2019, 12:39 PM Thread Starter
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Our GTs had a really tall 2.92 gear while the GXPs had 3.27 stock. Which of course helps acceleration
Looks like 3.45 Camaro diff needs to be high on the priority list for me...
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post #14 of 31 (permalink) Old 04-22-2019, 12:45 PM
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Please bear with me, I'm fresh off the boat new to GM stuff. The L76 has LS2 bottom end with LS3 top end right? But the valvetrain isn't the same as LS3 right? So other than that are the L76 ports and style identical to the LS3?
Pretty much.

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post #15 of 31 (permalink) Old 04-22-2019, 12:51 PM
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Looks like 3.45 Camaro diff needs to be high on the priority list for me...
Indeed, the 3.45 or the 3.27 in my opinion need to be a priority. The 2.92 is a very nice hwy setup, but personally I have purchased a 3.27 Camaro setup to help from a dig. This will be going in shortly along with all new suspension components. I also have stock heads fully machined and ported by TSP. Very nice work!!
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post #16 of 31 (permalink) Old 04-22-2019, 01:09 PM Thread Starter
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Indeed, the 3.45 or the 3.27 in my opinion need to be a priority. The 2.92 is a very nice hwy setup, but personally I have purchased a 3.27 Camaro setup to help from a dig. This will be going in shortly along with all new suspension components. I also have stock heads fully machined and ported by TSP. Very nice work!!
Oh I plan to have a dig monster.

The only thing I'm worried about is traction. A Mustang, I can get to hook up fine. A GM...G8...I have NO clue. But I did research these cars are rear tire width limited. I'd like 305/17 in the rear but I know getting 305s to fit isn't easy at all.
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post #17 of 31 (permalink) Old 04-23-2019, 12:07 AM
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It's really the valve train that makes the biggest difference in the performance between these engines. Displacement of 10 cubic inches is not going to make a 60+ horsepower difference! Numerous 6.0 owners have installed LS 3 cams & Valve Springs in otherwise stock engines and have produced similar power levels. One only needs to look at the Lift and Duration of the L76 cam vs LS3 and you will see the glaring difference.

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post #18 of 31 (permalink) Old 04-23-2019, 07:21 AM Thread Starter
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It's really the valve train that makes the biggest difference in the performance between these engines. Displacement of 10 cubic inches is not going to make a 60+ horsepower difference! Numerous 6.0 owners have installed LS 3 cams & Valve Springs in otherwise stock engines and have produced similar power levels. One only needs to look at the Lift and Duration of the L76 cam vs LS3 and you will see the glaring difference.
That doesn't explain why CAMMED L76 cars can barely keep up with LS3 cars.
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post #19 of 31 (permalink) Old 04-23-2019, 08:23 AM
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That doesn't explain why CAMMED L76 cars can barely keep up with LS3 cars.
Exactly, the two engines are very similar, its not the crank or rods or even the heads castings. The LS3 has the same rod length and stroke as our L76. The head casting can also be the exact same casting used on both engines, if you were lucky. I got 5364 castings on my G8 which are not as desirable the 823's that some G8s came with. And yes its true that the LS3 heads have hollow stem intake valves, which are lighter and give better upper rpm head room with a bigger cam. (I added them to my heads when I got mine ported for this reason.)
But its been my understanding that the larger bore is the key to the LS3's advantage, because it unshrounds the valves and lets the heads breath better than the smaller bore L76.
My engine guy told me that if I took my same parts and moved them onto a 6.2 short block I would see about a 40-50 hp increase for this reason.
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post #20 of 31 (permalink) Old 04-23-2019, 08:29 AM Thread Starter
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Is the 6.2 block the same as a 6.0 block, just bored out? At what point does the cylinder walls become compromised due to thinness? I was disappointed to see the LS doesn't appear to be a closed deck block.
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