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LS2-LS3 Differences, what are they?

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Old Jun 25, 2008 | 06:31 PM
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Default LS2-LS3 Differences, what are they?

What is the diff. between the LS 2-3? Is it just the heads, cam, or is there more that makes these engines 30+ hp diff? Is the bore, stroke and blocks the same also or are they totally different designs?
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Old Jun 25, 2008 | 06:35 PM
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No difference, they only changed the engine designation/one number.
Just kidding.




Originally Posted by iw172
What is the diff. between the LS 2-3? Is it just the heads, cam, or is there more that makes these engines 30+ hp diff? Is the bore, stroke and blocks the same also or are they totally different designs?
In a nutshell, yes. The heads, intake manifold and cam (though the cam is quite similar to the LS2 version) are all different plus the basic block has slightly more bore making it a 6.2L versus the LS2's 6.0L but I wouldn't call it totally different otherwise.
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Old Jun 25, 2008 | 07:25 PM
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There are a lot of differences than just bolt on parts. Good read here:

http://www.corvetteactioncenter.com/...008gmpls3.html

And:

http://www.corvetteactioncenter.com/...ls3_page1.html
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Old Jun 25, 2008 | 07:51 PM
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Ahhh yes..
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Old Jun 25, 2008 | 07:52 PM
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Originally Posted by nwc6
There are a lot of differences than just bolt on parts. Good read here:

http://www.corvetteactioncenter.com/...008gmpls3.html

And:

http://www.corvetteactioncenter.com/...ls3_page1.html
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Old Jun 26, 2008 | 12:06 AM
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This is from the Corvette Museum website.

Engine – A new, 6.2L LS3 small-block V-8 is the standard engine in Coupe and Convertible models. It is rated at 430 horsepower (321kW)* and 424 lb.-ft. of torque (586 Nm)* with the standard exhaust system; with the new, optional two-mode exhaust system, power ratings increase to 436 horses / 325 kW and 428 lb.-ft. / 592 Nm. As a result, the standard Corvette is true supercar, capable of 190 mph. The LS3 with the six-speed paddle-shift automatic is the fastest automatic-equipped Corvette ever, with 0-60 mph capability of 4.3 seconds.

This new iteration of the storied small-block family features a revised, larger-bore cylinder block – 4.06-inch / 103.25 mm vs. the previous 6.0L's 4.00-inch / 101.62 mm bores – high-flow, LS7/L92-style cylinder heads; larger-diameter pistons; revised camshaft and camshaft timing; revised valvetrain with offset intake rocker arms; high-flow intake manifold; high-flow fuel injectors from the Z06's LS7 engine; and a new engine beauty cover.

The LS3 features an aluminum cylinder block with cast iron cylinder liners. In addition to its larger bores, which help create a 376-cubic-inch displacement, the block casting also features revisions and machining in the bulkheads that enhance its strength and improved bay to bay breathing. But while the bore of the 6.2L engine is increased when compared with the previous 6.0L engine, the engine's stroke remains at 3.62 inches (92 mm). The pistons for the larger 6.2L engine also are new and are designed for its high-rpm performance capability.

Breathing for the new 6.2L engine is accomplished via new, high-flow cylinder heads. They're based on the large port/large valve design found on the LS7 engine and other GM L92 engines, with larger-capacity, straighter intake ports. The design optimizes intake flow to the combustion chamber and the exhaust ports are also designed for better flow.

Complementing the larger-port design of the heads are commensurately sized valves. The intake valve size alone increases from 2.00 inches (50.8 mm) to 2.16 inches (55 mm) – an increase of nearly 9 percent. The intake valves feature lightweight hollow stems, which enable the engine's 6,600-rpm capability. The exhaust valves also are large, measuring 1.60 inches (40.4 mm) in diameter.

To accommodate the engine's large valves and enable more direct intake port flow, the intake-side rocker arms are offset 6 mm between the valve tip and the push rod. Actuating the valves is a new camshaft, with intake-side lobes providing more than a 5-percent percent in increase in lift, from 0.521-inch to 0.551-inch (13.25 mm to 14 mm). Exhaust-valve lift remains unchanged from the LS2. The camshaft timing was revised to optimize performance with the higher-lift intake cam profile.

Ensuring the cylinder heads receive all the air they can handles falls to a new, acoustically tuned intake manifold. The composite design is manufactured with a “lost core” process that improves runner to runner variation and reduces airflow losses. An acoustic foam material is used to reduce radiated engine noise; it is sandwiched between the outer top of the manifold and an additional “skull cap” acoustic shell. Also new beauty covers atop the engine shield the rocker covers and also feature a noise-reducing, acoustically tuned insert to provide a more refined engine sound.
Source
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Old Jun 26, 2008 | 12:15 AM
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Max effort head cam jobs done to both amount to 10hp differences.

Since there are forged LS1's, LS6's, and LS2's running around with 1000hp FI, any argument for block strength differences are obviously silly to make a point of. Bigger is better so a 6.2 liter is better than a 6 liter.

A cam only LS3 is basically the same a a L92/LS3 headed LS2 with a cam. I have seen the exact same cam with the same heads do within 10hp many times. The heads are so cheap that the conversion is easy to make. In the end, the best of the best will still be with pricey after market castings since the biggest cams wont fit with the LS3 heads milled. To hit the 550rwhp range, which will occur with the LS3, you will need cams and compression out of the range of this head. Trick flow 235's for the LS3 platform and a good intake manifold will break through that barrier.
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Old Jun 26, 2008 | 12:19 PM
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Originally Posted by SpinMonster
A cam only LS3 is basically the same a a L92/LS3 headed LS2 with a cam......
Hallelujah
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