Difference in 6.0L motors?

[samckitt]

The LQ4 that is in the 1500HD & 2500HD Silverado is rated at 300hp at 4400rpm. In the Hummer it is rated at 315hp @ 5000rpm, Suburban & Yukon XL 320hp @ 5000rpm, & 320hp @ 5000rpm in the Denali. What are the differences in these motors? I would think if they are all LQ4s that they would all be the same, maybe some computer programming differences or intake / exhaust differences. I know it is not an apple to apples comparison because the rpm is different. And then there is the LQ9 6.0L HO, which is in the Silverado SS. It is rated at 345hp @ 5200rpm. It is listed as having 10:1 compression while the LQ4 only has 9.4:1 compression. Are the heads different or just a thinner head gasket? Is there more changes like pistons, cam & so on? I assume the computer, intake & exhaust are all "enhanced" on the SS as well.

 

I want those extra 45 ponies in my 1500HD! How can I corral them?

 

Thanks,

Scot

[gave20]

Drive it at 5200rpm and should get close to those extra horseys. I could care less what the max hp is, I find it wonderful they can make a motor produce 800 hp at 15000 rpm's, what would reallly tickle me is to make 300 hp at 1800 rpms then they might have something to write home about.

[Butch 02 Denali]

The LQ4 that is in the 1500HD & 2500HD Silverado is rated at 300hp at 4400rpm. In the Hummer it is rated at 315hp @ 5000rpm, Suburban & Yukon XL 320hp @ 5000rpm, & 320hp @ 5000rpm in the Denali. What are the differences in these motors? I would think if they are all LQ4s that they would all be the same, maybe some computer programming differences or intake / exhaust differences. I know it is not an apple to apples comparison because the rpm is different. And then there is the LQ9 6.0L HO, which is in the Silverado SS. It is rated at 345hp @ 5200rpm. It is listed as having 10:1 compression while the LQ4 only has 9.4:1 compression. Are the heads different or just a thinner head gasket? Is there more changes like pistons, cam & so on? I assume the computer, intake & exhaust are all "enhanced" on the SS as well.

 

I want those extra 45 ponies in my 1500HD! How can I corral them?

 

Thanks,

Scot

You forgot the GMC C3 and Sierra Denali at 325HP.

 

The 300, 315, 320 and 325 HP 6.0's are EXACTLY the same engine. They all are tuned for 87 octane fuel. The differences are more free flowing exhaust systems and GM computer tweaking.

 

The 345 HP used in the SS and all the Caddys has .6 more compression achieved by piston shape, and has GM computer tuning to run on 93 octane.

 

That's it, those are the differences. It's not difficult to get your 6.0 up to or way above these levels with some GOOD computer tuning.

 

Butch 02 Sierra Denali

[robsawatsky]

... what would reallly tickle me is to make 300 hp at 1800 rpms then they might have something to write home about.

Since HP is a function of torque and RPM, a close solution to your request is a Caterpillar C7 7.2L diesel I-6 (LRS option in the GMC medium duty trucks) with the following spec's:

 

300 HP 2400 RPM

860 ft-lbs 1440 RPM

 

Now, about a tranny to go with the torque? And a front-end to hold up the weight of the engine and tranny?

 

The only practical way to get high HP at low RPM is with whole lotta torque either through big cubic inches and mucho forced induction.