HD Motor Comparisons

OUMike · July 17, 2003

Alright guys,

Gotta brain teaser for ya. Can anyone tell me the major differences between the 2003 Silverado HD, 2003 Silverado SS and the 2003 Hummer H2. All 3 of these have the 6.0 OHV V8s. I would emagine that all 3 use the same motor. But what are the differences?

HD:

300hp - 360 lb-ft

SS:

345hp - 380 lb-ft

H2:

316hp - 360 lb-ft

What kind of transitions do these motors go from one truck to the next?? Any theories??

ridnlow · July 17, 2003

I can tell you the SS engine is the same engine as the Escalade and drive train as well.. The SS motor is called LQ9.. i believe it has a bigger cam and a higher compression... It also has the 4l65e i belive.. i am not sure about the others..

dcairns · July 17, 2003

HD: LQ4

300hp - 360 lb-ft

SS: LQ9

345hp - 380 lb-ft

H2: LQ4

316hp - 360 lb-ft

You can have some fun rummaging around this site:

GM Powertrain

In particular, the LQ4 and LQ9 have some fun specs here (scroll down below the LQ4 to see the LQ9):

Engine specs

WEFs99 · July 17, 2003

HD: LQ4
300hp - 360 lb-ft

SS: LQ9

345hp - 380 lb-ft

H2: LQ4

316hp - 360 lb-ft

You can have some fun rummaging around this site:

GM Powertrain

In particular, the LQ4 and LQ9 have some fun specs here (scroll down below the LQ4 to see the LQ9):

Engine specs

Good site! Thanks

ShortCrew · July 18, 2003

Don't forget. These are just ratings. GM is know to rate the same motor differently for marketing reasons. For example. My 2000 Camaro SS make 299rwhp bone stock. a 2000 Corvette makes about 285rwhp bone stock. The Vette is rated at 345hp and my Camaro was rated at 320hp. Go figure.

MCourson · July 18, 2003

Don't forget. These are just ratings. GM is know to rate the same motor differently for marketing reasons. For example. My 2000 Camaro SS make 299rwhp bone stock. a 2000 Corvette makes about 285rwhp bone stock. The Vette is rated at 345hp and my Camaro was rated at 320hp. Go figure.

That and a 454 in a '70 Chevelle was rated at 450hp I dont know why they do it now but I know back then chevy fudged on the numbers for insurance reasons. Now as for what HP a 1970 454 Chevelle really makes:

OUMike · July 18, 2003

My 2000 Camaro SS make 299rwhp bone stock.

You definatly got the strong side of the SS batch. That is rare. Camaro SSs are 320 net hp. And the f-body I believe has about a 18% driveline loss, so thats about 262.4 rwhp. So assuming the 18% figure is acurate (I based that off the C4 Vette which has a 16% driveline loss) your car would produce 364.63 net hp. I'd be interested to see a dyno of your SS. A 1990-1992 Corvette ZR-1 produces 385 net hp, so you'd be fairly close to King of the Hill status.

OUMike · July 18, 2003

That and a 454 in a '70 Chevelle was rated at 450hp I dont know why they do it now but I know back then chevy fudged on the numbers for insurance reasons. Now as for what HP a 1970 454 Chevelle really makes:

Ah yes...the great LS6 debate. Actually the LS6 was rated by Chevrolet at 460 hp. I've heard two sides to the coin. The myth goes that the L88 (alum. 427) was overrated a tad. In order for GM to keep the new LS6 looking stout is was overrated to 460hp. I've heard claims to people that say the LS6 actually dynoed at closer to 377 hp. The other claim to fame the LS6 is actually closer to 500 hp. This is the tale that we'll never know the answer to. I've spoken with people who worked on the Corvette project during the LT1/L88/LS6 days and they won't say anything. IMHO GM did in fact lie their tales off. I believe the LS6 to be about 500 net hp. And the 70' Vette to be one of the best lookin' muscle cars, along with the 67' that is...

OUMike · July 18, 2003

ok..so I went over the Powertrains site. Seems the only major difference is compression ratio. Different Pistons and maybe camshaft??

ToeJam · July 18, 2003

Alright guys,
Gotta brain teaser for ya. Can anyone tell me the major differences between the 2003 Silverado HD, 2003 Silverado SS and the 2003 Hummer H2. All 3 of these have the 6.0 OHV V8s. I would emagine that all 3 use the same motor. But what are the differences?

HD:

300hp - 360 lb-ft

SS:

345hp - 380 lb-ft

H2:

316hp - 360 lb-ft

What kind of transitions do these motors go from one truck to the next?? Any theories??

And don't forget abou the 6.0 V8 in the Sierra Denali. Its rated 325 hp and I believe either 360 or 365 lbs-ft torque...

99-2door · July 18, 2003

Actually the LS6 was rated by Chevrolet at 460 hp. I've heard two sides to the coin. The myth goes that the L88 (alum. 427) was overrated a tad. In order for GM to keep the new LS6 looking stout is was overrated to 460hp.

The L-88 was severely underrated, not overrated. LS6 rated at 425HP, not 460HP, so the arguement that it was overrated to look better than the L-88 is false too.

According to the"Corvette Black Book"

1969 L-88 : 430HP gross

1969 L-71: 435HP gross

1970 LS5 : 390HP gross

1971 LS5 : 365HP gross

1971 LS6 : 425HP gross

1972 LS5 : 270 HP net

The L-88 was offered during the years 67, 68 and 69. It was rated at 430 HP every year it was available. The L-71 was offered those same years and rated 435HP each of those years.

9374 units were equipped with L-71s over the 3 years, while only 216 units were equipped with the L-88. The L-88 was rated at 5 HP less than the L-71 even though it cost $500-$600 more for the option.

In fact the HP output of the L-88 topped 500HP, the lower rating and higher price were put in place to discourage non-racing purchases. Not knowing this 1014 people paid over $800 dollars for the L-89 option (aluminum heads for the L-71), when they could have purchased the L-88 for less money.

The LS6 was available only in 1971 and was rated at 425 HP not 460HP. The LS5 had a lower ocane requirement at 91 and ran on unleaded in 1971, making it less HP than the 1970 version.

1972, the HP rating switches to net horsepower rather than gross horsepower

Of course this applies only to vettes and some of these engines were available in other cars, but in very limited production.

ShortCrew · July 18, 2003

At 299rwhp, my Camaro was far from a factory freak. I had countless freinds with new Camaro's that dyno'd between 290-310rwhp BONE STOCK with manual trans. My points is, in this example, that the 5.7L LS1 engine in the Camaro made exactly the same power as the one in the Corvette. Chevy just stated a lower number for the Camaro for marketing reasons. The Corvette's make a little less at the rear wheels than the Camaro because the independant rear suspensions soaks up a few more pony's than the solid axle in the Camaro. At the flywheel, both motors make the same power, because they are the same motor.