GM 6.2 L99 vs. L86

[Ron172]

The L99 engine used in Gen. 5 camaros with automatic transmissions is rated at 400 hp. and 410 lbs./ft. of torque. The L99's compression ratio is 10.4 to 1. The L86 engine is rated at 420 hp. and 460 lb./ft. of torque. The L86's compression ratio is 11.0 to 1. Both incorporate GM's AFM system. The L99's recommended fuel is premium while the L86 recommended fuel is regular. So, two questions come to mind immediately: 1. Why does the L99 need premium fuel with a lower compression ratio and lower output (you can use regular, but performance suffers)? 2. Why wasn't the L86 used in the camaro rather than the L99? I know that the L86 is marketed as a "truck" engine, but its higher output should provide the camaro with at least equal performance vs. the L99 while using regular fuel.

[JerTM]

I would imagine it has to do with how and where the engine makes the power. In a Camaro you would want an even pull up to redline, on a truck you would want a good amount of grunt down low.

[two_wheel_mayhem]

Because it's a direct injected engine like the 3.6 that has 11:1 compression yet can still be run on 87 octane fuel.

I'd assume the L86 is an iron block too, which GM didn't want to use in the Camaro for weight reasons. (they are already too heavy)

[2010reddevil]

All GM engines nowadays are aluminum. The L86 is newer than the LS3. The Gen 6 uses the higher output variant called the LT1. It's the same engine with a few things different for more power in the Gen 6 Camaro vs the truck. And the DI is why it can run regular fuel.

[Flotek]

High octane is not just for high compression applications ..it can be to ward off detonation due to high output ignition timing curves as well sonething newer engine designs thrive on

[Ron172]

Thank you all for your feedback; the explanations do make it a little more clear. I read a road test of the Cadillac Escalade in Car and Driver with the L86 engine and 8 speed automatic. It reached 60 mph in 5.6 seconds and turned the 1/4 in 14.1 seconds with a curb weight of 5800+ lbs. I would think that the same engine in the nearly 2000 lb. lighter Camaro would run the 1/4 mile at least a second quicker. Interesting conjecture. Thank you again for your responses.

[two_wheel_mayhem]

Originally Posted by Ron172

Thank you all for your feedback; the explanations do make it a little more clear. I read a road test of the Cadillac Escalade in Car and Driver with the L86 engine and 8 speed automatic. It reached 60 mph in 5.6 seconds and turned the 1/4 in 14.1 seconds with a curb weight of 5800+ lbs. I would think that the same engine in the almost 2000 lb. lighter Camaro would run the 1/4 mile at least a second quicker. Interesting conjecture. Thank you again for your responses.

20 horsepower isn't gonna make you a second faster. I'm not researching that article but something is a miss. That Caddy is all wheel drive or something is up.

Or are you just saying a Camaro will run a 13.1 with an L86? Sure it will, but so will a L99.

[Ron172]

That is my original point: The L86 could be used in place of the L99 giving the same performance while using regular (87 octane) fuel. It's not a big deal, just curious. And true, 20 hp. will not make the car run a second faster, but the 2000 lb. decrease in weight vs. the Escalade would surely improve performance noticeably.

[Chevy_cowboy]

Beyond the answers you've already gotten above... the obvious reason they didn't use the L86 in the 5th gen is the engine wasn't released until 2014.

And based on what I can find online, the L86 does recommend premium gas, just like the L99/LS3

[two_wheel_mayhem]

Originally Posted by Ron172

That is my original point: The L86 could be used in place of the L99 giving the same performance while using regular (87 octane) fuel. It's not a big deal, just curious. And true, 20 hp. will not make the car run a second faster, but the 2000 lb. decrease in weight vs. the Escalade would surely improve performance noticeably.

I get ya, the fuel thing. Would have been interesting if GM would have tried that but they probably had a bunch of L99s laying around they needed to get rid of. Changing engine types and injection type on the platform costs money and most boats already have an anchor so what to do with all those L99s? Sometimes it really does work that way.

[Chevy_cowboy]

Also might have to do with fuel economy, remember the L99 just barely squeaked by the gas guzzler tax, (which is why it was detuned and had AFM), the L86 would have had to go through all the epa testing and perhaps detuning to meet those requirements or buyers would have been paying GG tax, just not worth the cost and trouble for the last year or two of a generation.

[two_wheel_mayhem]

Originally Posted by Chevy_cowboy

Also might have to do with fuel economy, remember the L99 just barely squeaked by the gas guzzler tax, (which is why it was detuned and had AFM), the L86 would have had to go through all the epa testing and perhaps detuning to meet those requirements or buyers would have been paying GG tax, just not worth the cost and trouble for the last year or two of a generation.

Mention the LT1 was probably already around in test if anything, so L86 what? I also think the last 3 years of production they stalled development on the car because they knew they were gonna dump the platform anyway. Changing engines was surely the last thing on their mind.

[motorhead]

I don't know, but it pisses me off the you have to buy the highend models to get the 6.2l in the trucks. Another reason to street clear of their 1500s.

The motor was designed with a truck in mind anyhow. Buy a 16 camaro SS and you have a souped up verison with the LT1 anyhow.

[Ron172]

Thank you all again. I appreciate your input.