Duramax compare with the 8.1 litre ??

[All-tuned-up]

Had someone pull my 42' Race car trailer the other day with his '02 8.1 gas, pulled it up a hill that my duramax would top out at 50, he did it at 75 mph! With room to move.

Anybody did any other comparison's? My max is stock- no chip. What gives?

[ZFMax]

What gives is that 340hp is more than 300hp.

[Tough Guy]

Duramax- 300HP/520TQ

8.1- 340HP/450TQ

I can't imagine a scenario where a stock 8.1 could out pull a Dmax....He may go faster downhill, but not up.



Cheers

[ZFMax]

What, you think the performance is some kind of combination of the torque and horsepower of the engine?

It ain't. The horsepower is the performance.

[mdrag]

All tuned up,

Your post in the Motor Noise topic indicates that you just picked up your new truck:

http://forum.thedieselpage.com/ubb/u...c&f=3&t=005010

How many miles on your new truck? Most have reported improved performance with the Dmax after putting on 10K+ or more miles. Give it some time...

BTW, is your friends 8.1L completely stock?

[Idle_Chatter]

Okay, alltuned, you two try this: Same loads over the same roads, each only carrying 10 gallons of fuel! Your buddy in the 8.1 will be sidelined in no time!

[ 01-21-2003: Message edited by: Idle_Chatter ]</p>

[2K2AD]

ZFMax,

Is it time for our semi-annual HP vs TQ lesson? I am looking forward to it.

Kevin

[sdaver]

I got both and something does not smell right. dmax hands down with about 40% better economy. dave

[svpdiesel]

Must agree with ZF- horsepower is what does the work, and more HP will win every time. So, if the 8.1 pulls the same load up the same hill faster than the Dmax, it's because it has MORE horsepower. Period.

[All-tuned-up]

ToughGuy,

Imagine it, we have been testing and comparing, the 8.1 will put the max to rest going up a hill with a heavy load. I have always thought the truck with the torque would have the major advantage when pulling a heavy load up a hill. According to ZFmax, the horsepower is the key feature and the torque does not play into the situation. I guess that's why the old Dodge Cummins that always led the pack that had little horsepower and tons of gut pulling torque did so well? Hmmm....

PS. I just traded my '02, which was the truck I compared the 8.1 with, not my '03, I realize there is some time for break in there.

As far as the same loads/same roads goes, to some people the extra couple miles to the gallon aren't a big deal. I personally like and think the diesel is the ticket, but an 8.1 getting 8 mpg compared to a diesel that gets 10 isn't really a big deal-especially if he gets up the hill like he is. I have two friends who have the 8.1 and pretty much claim they are unstoppable. We are talking stock to stock now also. Afterall, a guy shouldn't have to cut his airbox up, set his stainless exhaust in the rafters and reprogram the computer to make this diesel dance. I just paid $42k for my truck and hate the fact that a guy needs to make all these improvements, although I will because I'm into all the power available.

[Dmaxin]

Question. Isnt torque the rate at which a motor makes horsepower?

[Black Dog]

Peak numbers do not tell full the story of an engine's performance. To fairly compare two engines, you need to compare the area under the torque curves. To fairly compare how the engine will pull a load in a given truck, you need to compare the performance of the engine and transmission as a system. Horsepower and torque are two different parameters that both characterize how much work an engine can do. Torque is a measure of force, horsepower is a measure of work. You can do more work with a given amount of torque at a higher rpm.

[ 01-21-2003: Message edited by: Black Dog ]

[ 01-21-2003: Message edited by: Black Dog ]</p>

[All-tuned-up]

Black Dog,

Would that be why the 8.1 does better at pulling?
With the 8.1 your spinning a much higher RPM, thus creating the peak HP the motor puts out, and utilizing the torque. Whereas, the diesel, when it down shifts, puts the RMP up high and out of the torque range??

Is this what your saying?

[Black Dog]

Yes, in theory that could be true. That is why the 8100 can make more HP with less torque. I still am not convinced that the 8100 will always win this race though. If the Allison could really keep the 8100 rpms up where the HP is made all the time, yes it would win the race every time. If you look at the Dmax torque curve though, it is very wide and flat - about 500 lb-ft all the way from 1500 to about 3200 rpm. This means that if both trannies upshift at the same time, the Dmax will have an advatage until the rpms climb back up where the gasser is making good torque. I have seen varying opinions on which motor will win the uphill pulling battle, and it may even depend on the exact load and the exact grade of the hill.

[SS396]

All tuned up, what RPM was the 8.1L running at?

I can only compare my previous stock 1999 6.0L 2500 to my current stock 2003 DMax/Allison. I can haul a 3,100# camper with my DMax up a 6% grade mountain pass at 65mph, 2,200RPM, 4th gear with plenty more. My '99 could also haul that same camper up the same pass at 65mph, but 4,500 - 5000RPM, second gear with none left.

I know the 8.1 is much stronger than the 6.0 (I believe the 6.0 had 300hp, not sure what torque), but that is my only comparison.

Were there possible performance problems with the 02?

[All-tuned-up]

Black Dog.

It was done with same trailer, same weight on same hill.

SS396.

The 6.0 I think is 280 hp? Not sure, have heard it's an awesome motor. The 8.1 was in tow haul mode, did kick down into third and was revving in 4-5000 range, and the diesel also fell on it's face mid way up the hill into third and was revving up near the red. Your 3100 pound trailer is really not much for comparison. You would be better off pulling that with a half ton, getting a nicer ride and saving a ton of $$ on the purchase. We are talking about pulling a trailer that weighs somewhere around 10-12,000 pounds, this is where you find out really how much power you have. Maybe not enough.

[TraceF]

When I joined the DP initially it was to post my concerns (and get feedback) about the lack of performance my new DMax displayed compared to my identically equipped 2000 truck (CC, SB. 4x4) with a 454 and a 4L80E.

In my first post I wrote the 454 would out pull the DMax with the same load, my 10,000+# boat from a dead stop up to any speed. ANY speed. I really thought I would hook up to the trailer and buzz right up to 70 mph and get 15 mpg. Didn't happen, not even close. The DMax could barely take the boat to 60 and I had to hold the pedal to the floor to keep it there.

I still believe the 454 will outrun the DMax with the same load,

But-

The DMax is definitely getting looser as the miles go on. I turned over 4000 today and the fuel mileage is increasing.

I have come to the conclusion that comparing the two trucks is like comparing a quarter horse to a Clydesdale. Also, the DMax "learns" as many of you pointed out. So I run the pi$$ out of it to keep the management systems "alive".

If I run around town for a week and take it easy like I normally drive- the transmission acts differently after a few days. Sometimes I can mash the gas and it won't even downshift. I know the boost is there, my new Banks gauge is telling me 22-23 but no kick down. I'm also confident my truck runs like other DMax's because I bought a GTech and the 0-60 and 1/4 mile times seemed OK for a stock truck.

Also, the diesel will take longer to break in as many have also pointed out. It's just the nature of the design, it's HD !!!

Now, torque vs. HP- torque makes motion (momentum). HP sustains it (speed).

Case in point- work motors generally make more torque than HP as is the case with the DMax. They also usually live longer. Race motors make more HP than torque. They also usually wear out or break sooner. Look at the specs on any overhead single or twin cam engine (import or domestic) or even an outboard motor which is a great example of horsepower technology, needle bearings, etc. and the point is made.

It used to be that the GM big block was rated to pull more than a similarly equipped diesel truck. Why? A combination of both torque and HP I think. Anyone know if this is still true? Diesel vs. 8.1 in the same chassis?

I think break in and time makes these trucks run and perform better but they are still going to be Clydesdales, not quarter horses. They are designed to work and last, not to race. In this design economy of operation is taken into consideration. Shirts and ties writing spec on work trucks care more about fuel economy than gear heads do.

Bottom line- everything is a compromise in some way.

$ .02 more.

[ 01-21-2003: Message edited by: TraceF ]

[ 01-21-2003: Message edited by: TraceF ]</p>

[All-tuned-up]

Tracef,

That's exactly what a guy here in town has said, his old '97 454 vortec would kill his Duramax in a towing contest.

I think the 8.1 is a monster but everyone else is right about the motor longevity etc. The Duramax that I used against this test was an '02 3500 CC with around 25,000 miles on it. My old '93 did pretty close to what the '02 did.

Thanks for the talk fellas!

I love the max but think the 8.1 has some serious advantages!!

[billnourse]

My Dmax will definately out pull the 1991 454 that I had, and do it easier. I don't know about an 8.1 as I don't have one to compare. There was an article in Trailer Life Magazine about 2 years ago that had the two about dead even in pulling capacity in a test that they conducted.

All-tuned-up,
What was the weight of the trailer you were pulling? On a trip this summer I topped Soldier's Summit between Price and Salt Lake City at 19,440 lbs.total weight at 65 MPH, and had some left.
This pass is mostly 6%+ grade for about 10 miles. On that trip I passed a lot of gas rigs (Unknown engine) that sure seemed to be struggling.

Regards,

Bill

[TraceF]

billnourse-

The 1991 454 was a throttle body, the 1997 and 2000's are Vortec motors. Big difference.

I would like to read the mag article, do you have any more details?