I just went to the Diesel World Magazine Crude Drags II in Bakersfield CA. It was my first race event of any kind. There were so many D-max's that were flat out fast! They would almost always stomp whoever they were head to head with. I have also noticed some of the better sled pulls were by Chevy or GMC's. And these are all stock looking trucks except for the requisite missing head light! side piped and all! are they heavier? does the IFS make for better launches? Do they build power in a different way than CTD?

 

all i can say is rpm

 

the rpms do help. From what i've seen the IFS dosent do them any good and with stock parts wont last long doing 4wd boost launches. The stock tie rods on them are like tooth picks. I saw a kid try to boost launch his duramax and he ended up breaking both of his tie rods due to the geometry change of the suspension from the launch

 

They are a lot lighter when compared to a 3rd gen Dodge.
One of the main reasons I sled pull is to go against the Duramax, Some of the Durmax owners have such a attitude because they know their truck is fast on the street that they just assume they are going to kick it pulling the sled. All I can say is I have never been close to being outpulled by a duramax yet.

 

like said before RPM and weight

 

thats an easy 100 dollar fix though, w/ some tie rod sleeves

 

stock front suspension is pathetic. You could probably break it with a big boosted 4wd launch and a stock tune.

350$ will get you a "bulletproof" setup though. Tie rod sleeves alone are not enough. You need pitman/idler arm braces too.

On average a dmax weighs probably 200lbs less than a compareable dodge. Mine is 7680 with me in it when I race, crew cab short bed 4x4, but I have a toolbox and stuff. The engines different power curve vs a ctd probably helps too, because you are WOT and above 2500rpm the whole time.

In 'stock' form the engine, for whatever reason, responds to tuning very well. Stock injectors will flow up to 750rwhp, and the stock turbo will pretty easilly do 500rwhp. EFILive and the ability to fine tune things without stacking is probably the other main reason.

and, in general, they are a lot cheaper to mod than a CTD, so you see a lot more guys running fairly fast because they dont have to put in as much money, you dont have to spend money on an aftermarket turbo and dont have to spend money on aftermarket trans hard parts.

Doesnt in any way mean its better, at 1200ft lbs you blow rods out the side of the block, and to build a dmax that will hold what a stock ctd will hold will probably set you back at least 8 or 9 grand, and the general pain of building the engine etc...

ben

 

The v8 also picks up rpm' quicker and alot more and I also think the 6 speed auto makes a little better

 

This pretty much hits the nail on the head. RPM makes a big difference, weight, tunability, etc. I will say this though, if you get real serious (i.e. 700+) a DMax gets real expensive real fast, as in engine internals. In the end, dependin on how radical you get, a Cummins and DMax build is pretty close to costing the same...but under, say, 600hp (MAYBE up to 650-700) the DMax is more than likely cheaper to build.

 

I am really starting to see the "irony" in some of this stuff. I remember about 2 years ago being on the diesel place forum (still had my 03 Dmax) and reading a similar headline. "Why are all the Cummins so fast!!!???"

 

Duramaxs have definitely picked up a reputation in the past few years. Seems like the Cummins finally has a competitor at the track. The Duramax may be fast but the Cummins is still a better built engine. The sound says it all. I see lots of Duramaxs here. I guess people figure they're not going to keep the truck longer than 10 years so who cares if the engine doesn't make it to 300k miles, just as long as it's quick.

Again it goes back to the fact that the Dmax was designed for a pickup and was geared towards performance, being daily driver friendly, pulling campers, etc. The Cummins was designed for heavy industrial applications including running at WOT 24/7. I believe the internal parts are heavier and take more energy to get moving.

 

Cummins is a dedicated engine manufacturer. All of it's platforms are designed for application across the board: Auto, Marine and Industrial. When General Motors actually manufactured diesels big time it did exactly the same thing. However, that division was sold decades ago.

The Dmax is made for the current market. The diesel market is no longer 'hardcore'. There has been tremendous entry by people who only a few years ago poo-pooed the sluggish nature and rattle of a diesel.

By making their diesel perform much like a gas engine GM stands to draw in even more people who could care less about the type of engine. Rather, it's performance/economy. Diesel is the short term solution to the present cost of fuel. We are about to see significant offerings very soon. We have no choice but to follow the European model.

Diesels are becoming cleaner than gas engines and have multifuel capability without significant modification (Various grades of Biodiesel, used cooking oil etc.). CAFE standards are going up. It will be easier to meet the new standard with a handful of diesels in the lineup.

GM is currently positioned better than Ford or Dodge. There are three Dmaxes. Everyone knows about the V blocks. However, I never hear anyone mention the 7.8 liter I6 which is listed as commercial grade. I take that to mean it is inframeable. Between Izusu and GM they claim to have 300,000 of these engines running worldwide.

Even if Toyota introduces the Tundra with an 8.0 liter commercial grade Hino diesel, GM is already positioned to counter the threat. As for the current Dmax not being a medium duty engine: Someone forgot to tell GM. Because it is being installed in 4500 and 5500 Series trucks. Medium duty begins at the 450/4500 class of vehicle.

 

Both the cummins and dmax are purpose built engines. You would never want to spin a cummins at 5,500 rpm like the dmax can. However the dmax will never have the low end towing grunt that we all love around here.

The dmax is just like any gasser engine where yes you can make it fast but no it won't come that way from the factory and you'll have to put allot of $$ in it to even stand close to the strengh of the cummins stock.

I've heard rumors that there will be some nice aftermarket de-stroked super strong rods comming out for the cummins where we will be able to spin to 5,500 or beyond.

Remember when sled pulling the first 1/3 of the course is like a drag race where you want to get going as fast as possible where rpm's are your best friend. But the last 1/3 of the course your under full load and max torque and
preferred rpm is desired. If the cummins could get down the sled track at around 4,000-4,500 rpm range in the beginning it would drag the rpm down to about 3,100-3,300 which is perfect for the final grunt work with large chargers.

And sadly even though I love my smarty I would so much rather had a fully custom setup like EFI Live where you could truly tune your truck by a professional to get every ounce of power. Once the cummins can spin faster and get full control of engine function and transmission I don't see how a dmax could stand a chance

 

Hello,

trefling your comment "I've heard rumors that there will be some nice aftermarket de-stroked super strong rods comming out for the cummins where we will be able to spin to 5,500 or beyond." is confusing to me. A de-stroked crank would be required. This set up requires a longer rod. Is this what you meant?

Damon

 

I don't agree it costing less to build a duramax. Yeah maybe to get to the 500-600hp mark but after that it starts taking big money.