thor48

Other than the HP difference and the stick or manual shifter, is there any difference in the reliability of one engine over the other? Is the LS3 better than the L99? Should a person buy one over the other? Thanks.

supernova1972

L99s biggest differance is the AFM that will shut off 4 cylinders during cruising. Im sure longevity will be the same between the two. Personally, Id just get whatever you prefer, because both stock or modified will be great performers.

BTW I have you sig tattooed on my arm.

JasonD

Here's something that might stir some dialog...define "better".

Highlander

I would buy the ls3 over the l99.

If you plan on modding, the ls3 is a better platform and option. Still being a manual is a plus. But the "simpler" the engine, the easier it is to mod and since it's the same engine as the vette, everything will come already for the ls3. You might come up with quite a few different things if you want to retain the AFM on a cammed car.

Rob94hawk

Just catching up on this stuff and from what I've been reading the LS3 have favorable rectangular cylinder head intake ports. Just read this in April 2009 GM High-Tech Performance mag.

MileMan402

They'll both perform nearly identical because no one can shift as fast as the auto and the VVT is great in the l99. To just do a cam in an l99 is tough but to do FI its no harder than a LS3. It really comes down to whether you want manual or auto

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Bucksrgone

There are some differences you may want to think about. There is a cam phaser (for VVT) mounted on the end of the camshaft for the L99 which is operated by oil pressure. The hydraulic roller lifters are very different and are also deactivated mechanically. There have been issues with these lifters in the past but they are warranted by GM for 100,000 miles so at least they think this issue is solved. The L99 has a lower compression ratio (10.4 vs 10.7) due to the flycuts made in piston tops for valve clearance due to the variable valve timing. The L99 is limited to 6200 RPM max while the LS3 is limited to 6600 RPM due to complexity of the AFM control system. The transmission torque converter tuning is coupled with the AFM to make transitions as smooth as possible. All of the this additional mechanical hardware coupled with a more complex electronic control system does add to the chance of failure but this has not shown up in the year or two these two options have been on the road. Hope this helps.

JasonD

Some good info right there!

Vette Pro

You obviously have not driven both cars...the auto does not shift that quickly sir... it is pretty EZ to shift quicker than the auto trans does.

Silverado27

This is a great thread because I had the same question...Because if I was racing (which I never have before) I know I would only win with an auto because I can shift gears well, but I have never shifted to race before. I also know there is some kind of technique and way of shifting that I would have to learn. Definitely have more interest in the manual, though.