Got Juice?

Actually the point was mean piston speed. from both engines turning 1000 RPMs. The I-6 Piston speed is way higher as are the masses in the CTD's pistons which therefore require stronger rods than a V-8. Bigger is better for an I-6. In fact it is mandatory with the high BMEP an I-6 produces, which is also why the Cummins has a higher peak torque than a V-8 and a FASTER torque rise. If the V-8's had the same effective BMEP as the I-6 the torque would be the same for a given power level, but we do not due to the fact that our effective duration on the power stroke in relation to the cylinder head is less time than the I-6

SoCal-305

Again, IMHO, the internal masses in the Cummins engine aren't a compromising feature at any rpm in its rpm range, especially at 1000rpm. The kinetics of a diesel combustion is an extremely violent explosion vs. a flamefront propagation in a gas engine from a sparkplug ignition source. The beefy construction of the Cummins engine counters the constant impact hammer combustion events much better than its GM/Ford counterparts. When you add mods to your diesel engine, you essentially are make the size of that hammer that much larger. That's why the GM 5.7 deisel engine failed miserably as they didn't take that into account , and many of them cracked their main journals and trashed their rods.

I6 engines don't produce any different brake mean effective pressures (BMEP) than a V8 with the same bore/stroke/compression-ratio/rod length etc. That's a general cylinder/piston design characteristic.

Isn't argumentive engineering fun?!

RamWheelsBy4

Feel like I am back in school again and still don't quite get it .

Got Juice?

Ahh yes, but Rod ratio and BMEP are what produces torque. You either have it. Or you do not. Piston design in and of itself will not yield more torque. Neither eill cylinder head design on a TURBOCHARGED diesel as we are effectively creating our own atmosphere and do not rely on the cylinder filling of strictly atmospheric pressures to provide the needed oxygen.

And we aren't looking at the GM 5.7 Diesel here (IE Don't puss out and draw upon old mistakes 53 block? KDP? LPM?).... We are Speaking Cummins and DMX here!

At 1000 RPMS I grant you there is not much stresses on the reciprocating assy, But at 3200 there is . In scans of 'dry run' engines you will find more distortion of the piston crown of a long stroke engine VS a shorter stroke one, by nature of it's longer stroke.... but it sure ain't no free ride for the bent 8 crowd either! we have higher thrust loading placed on the bores of the cylinders than an I-6.

It's really a tradeoff the engineers strive for. I'd really like to see white papers on both engines and their MTBF/0 over operational hours run.

And then see exactly what failed. Incidentally, CAT's findings on the higher power engine failures? Fuel pump/Injector failure was the most common root cause from contaminated fuel eroding injector seats and torching the pistons. More fuel run= more contaminants passing into the pump and injectors.

It would certainly be a good thing to get clean fuel like European countries do. We can always add conditioner for the needed lubricity... and if one feels nostalgic, a teaspoon of sand sludge and algae and 2 shots of water to the tank!

king d

things do hapen but i have seen a stock bottom end on a dmax turn well over 700 hp for several hundred drag strippasses .any thing can happen but these motors are holding insane power in there stock form,something the others cant say.

sdun

I am playing the stock converter/tranny blues also. Juice/attitude in the 4 setting and you will see the tach stay on 3k until it locks up. DTT on the way!

There is older guy in town with a dmax that went an 8.18 in the 1/8 mile
He is running stacked boxes, intake/exaust, and tranny. I hate to say it but that is very impressive

I don't want to hijack your thread but someone said something about sending the Juice in and upgrading it. Tell me more.

cquestad

Not all 3rd gens have the same CP3 now...

cquestad

Very good post though...keep it up.

Got Juice?

Not all DMX's Either

AAmeeting

I was recently at the Diesel Truck Nationals hear in Indianapolis and let me tell you there were some Duramaxs that were taking care of business. The third truck in the 38000 pound sled class was a 4x4 Reg cab Dmax and it pulled so far it was in the lead for about 25 trucks, then of course the cummins layed the law down and won every competition that was at stake at this event. BUT the point is, and this is key, TIME WILL TELL. The Duramax is a good motor no question, It is very expensive to fix, But I think it is still too new to judge. Some guys in 04 dodges are already pushing 200,000 miles with minimal problems, I have never seen a Duramax with some real mileage yet. Just give it some time fellas. Once we can get some stats and cost of ownership etc. Then you can make an educated decision. But until that time taliking about longevity now we would be shooting in the dark, we might as well be politicians, and every body hates that.

Big Joe

Lets face it, cummins in my opinion is the easiest, and cheapest, most reliable one out there.
Has anyone priced parts for a d-max, or a pooperstroke, injectors alone will break you.
I will admit, ford pooperstrokes are a good engine, but working on them is a shoe horn event let me tell you, and as for the 6.0, well lets just say "jump off a cliff" if you gotta work on one, I think you can see almost 6" of the valve cover on the right side.
As for the d-max, they seem to run ok, but of the 10 friend I know that own them, they dont get much of a chance to enjoy them cause the are adourning the dealers lot, and in my honest opinion, GM has had the wrong idea streching back to the firs 5.7 litre gasser they converted to a diesel.
The things got awesome mileage, but you had to drive a stake in the ground to see if they were moving if you hit a hill, now GM just borrowed an isuzu motor from a tractor.
In my opinion, my dodge is the easiest to work on, gets the best mileage, and will still be running even after the body falls off of it.
I can't say that for any of my d-max buddies, right about the time the warranty is up, they are making trax for the dealer.
As for the ford, I love the truck, and in my opinion if they ditched the Navistar engine, and installed a cummins, they would have a very good truck.
As for GM, Put the Isuzu back in the tractor, and get something else, your long time quest for a diesel power plant is still faltering.

Mntngoat

For whats it's worthmy empolyer only got 35K out of teh original injectors, on his D- max. We had a 2nd generation CTD with 290K on at trade in time.

Michael

Got Juice?

Apples and oranges there. Mechanical injectors VS HPCR injectors.

Mine are almost 100000 Miles and no trouble, 4 3rd gen CTD's i know of on the NWBOMBERS have had injector problems. All are HPCR injected

Got Juice?

No Different than the New Cummins. Although you do have 2 less to deal with.

5.7 is Ancient History.... but whatever.



You really really need to get your facts straight...The Duramax has never been in a tractor. It was a clean sheet design. There is no faltering here other than your lack of research or understanding of the Duramax.
I can produce AND PROVE documentation on how much both Dodges i have had have cost me, and so far the Duramax has been more Economical to run. Not in the fuel mileage department, but in the service department.

I'm not even going to try to change your mind. I have the FACTS to back my decision up. And to be truthful, DCX's service leaves a lot to be desired. I take my truck to the dealership quite happily. Truck gets delivered to my door, Washed, Vacuumed, and looking good. Never had a hassle with GM service about Warranty. With DCX i was lucky to get my truck back in a day!

All that aside, If i could have a CTD in front of my Allison, and keep my GM it would be well nigh a perfect truck.

yosemitesamiam

I agree with those who have stated that the Cummins is no racer...and dude...don't forget you weigh in around 1,000 lbs heavier too! Cummins engines are HEAVY!