I was looking on Dieselplace.com and a guy posted some Dyno numbers on his brand new Stock LBZ. Well here was his numbers were

Dyno Chevy LBZ
316rwhp at 3250rpm using STP, 304 using SAE 310 RWHP
526ftlb at 3000rpm using STP, 506 using SAE 516 RWTQ

the bolded out numbers were averaged between the 2.

Well a few guys on here have posted there Stock Dynos on the 06's and this is what i got when i averaged the 2 numbers from 2 different guys

Average HP 274 HP
Average TQ 540 ft/lbs

It looks to me that the Cummins is more efficent and makes better power am i right? what are your guys thoughts on this

 

HP is great but the torque is what matters......

 

WOW! this is something I was curious about for a long time!
l6 torque is a lot better!! what about the 6.0? what would that one dyno?

what does:
LBZ,
STP,
SAE,
stand for?

 

12VALVE...

LBZ is the newest Chevy Duramax Engine 360 HP and 650 TQ I am not sure what the other abbreviations stand for. I was just shocked to see what the numbers were...The 6.Oh No...i would be curious about that since thats 325 HP and 570 TQ I am sure its not too impressive...But i am happy with my truck!!!

 

In DP I THINK the 6.0 with an auto put out around 448, I THINK so dont quote me.

 

LBZ-Latest GM Duramax engine
STP-Standard Temperature and Pressure correction
SAE-Society of Automotive Engineers

MikeyB

 

That lines up with what is going on while towing with some of the LBZ/s around here. They don't cut it like their numbers say they should. The ally is not putting it to the ground. As soon as we hit a steep grade its bye bye baby.

The STP correction factor is based on the old standard before the June 1990 SAE correction factor was introduced as being the numbers for internal combustion, naturally aspirated engines. The numbers for forced aspirated vehicles whether they use trubos or super chargers should be the actual measured numbers and not corrected ones. My truck made 312 HP and 560 lbft of TQ using the SAE correction factor. The same run using no correction factor yielded 265 HP and 474 TQ. Which one do people quote when they post or talk about their truck.....right. It doesn't make it proper though.

With that being said, wait until GM figures out a 6 speed that will put that power to the gorund and then you'll have a worthy opponent on the hills.

 

I've read several times of duramaxes running off from dodges with the cummins, loaded and often up hills. The duramax is known to generally select the right gear for the situation, putting the engine at an rpm that works well for whatever the driver happens to be trying to do at the time.

Saying that torque matters more than hp is not correct in the comparison between these two trucks, and here's why:

First, the torque converter behind the dodge auto is too loose. If you flatfoot your stock 04.5 or later truck from a standstill with either a heavy load or holding it with the brakes (do this for ONLY a few seconds!) you will notice that the tach goes to about 2200 rpm. Guess where the rated torque peak starts? Yep-1600. Congratulations-the stock converter has just effectively rendered useless the bottom 600 rpm of the torque curve. Making things worse, 1st gear in the 48re is much higher (numerically lower) than 1st in the allison, making the converter slip more than it would if 1st was lower. Each time the allison shifts, the change in gear ratio from one gear to the next is smaller than the change in ratios when the 48re shifts. This means that the narrower powerband of the duramax doesn't really hurt it, because gears spaced closer together drop rpm less during shifts, thus helping the duramax stay right where it needs to be for max power.

Add on top of all this that the duramax simply makes more power and torque to start with, and you have a situation where they often are faster (stock) both empty and under load than a cummins with an auto behind it. I know, everyone has seen or heard of a 6 speed auto duramax getting beaten by a stock cummins, and I'm sure it happens. But generally speaking, due to differences in the transmissions, the balance is going to tip in favor of the duramax. There's a reason why dodge is about to put a 6 speed aisin automatic in the cab and chassis sometime during the '07 model year.

 

I'd say the ally is putting it to the ground quiet efficiently actually. An auto normally soaks up about 20% of the power. 360hpx.2=72 360-72=288hp 650tqx.2=130 650-130=520tq

 

Stock LB7 was rated 300/520 I dynoed 242/446 box stock. (19.4% loss)

 

The 20% is a very rough guess at best. The numbers above weren't quoted as actual numbers either nor did they include the actual correction number used so it is hard to say what the real numbers are for the truck that was measured. Are your numbers corrected or uncorrected? No auto trans can efficiently transfer power to the rear wheels, just ain't gonna happen like it or not. That's why the big numbers on the Dmax don't net any better pulling or dyno results but only a loss in fuel mileage. I wouldn't want to drag race one though with my 6 speed.

I did say however that when GM figures out a 6 speed manual then there will be some serious pulling competition until then I won't even bother with the marketing efforts being tried on the market place with "big" numbers.

 

A fully built auto can put down some very impressive, efficient numbers on a stock truck cause it locks up and holds and transfers fluid a lot more efficiently. More efficient TC equals more power to the ground. Can't argue specifics cause I don't know enough about tranny's but I do know that 450hp in a built trans truck feels and does a lot better than 450hp in a stock trans truck. Believe me, I know. Two of my buddies have the same power I do but both have built trannies and they both walk up and leave me fast. Look at Got Juice?'s numbers. 20% is usually right on par with everything I've ever noticed.

 

There's no question a properly built tranny will be more efficient.

The only way to truly quantify the power loss on a drive train is to yank the motor out and dyno it on an engine dyno and then put it back in the vehicle and dyno it on a chassis dyno. If you dyno on an engine dyno using a retarder or other absorbsion unit you have to use a loaded chassis dyno that uses a similar type of absorbsion as well and not just a chassis dyno. A load dyno measures torque and calculates HP. An inertia dyno measures HP and calulates TQ. The torque quoted however using both methods is always at the output shaft of the motor and not at the rear wheels like most think because the common denominator is always RPM of the motor. On a chassis dyno the HP is at the rear wheels. That's why it's always nice to know what kind of dyno the run was on and what correction factors as well as the actual applied number was used to correct the numbers are. I've done it many times and the results can be quite humbling on both dynos and quite confusing as well. Simple things like pinion angle, tire size and weight, backlash in the ring and pinion, greased hubs vs. oiled hubs, etc. can all effect power as well.