OK, let's say you could have any Diesel engine choice (CTD, PSD, DMax) in any truck you wanted, what would be your choice for pulling a 7% grade at lets say 75 MPH? What did you choose and why? opcorn:
Dmax opcorn: Why= Hmmm, cuz I own one waytogo The way this engine throws my rig forward I don't see it being an issue, uless I was severly overloaded waytogo
Hah, 3208's are big and heavy. THe newer C7, 3126, or older mechanical 3116 would be a better choice.
If it was also to be a daily driver, exactly what I own now, 2500HD DMax/Alli CC SWB 4x4. Wouldn't change a thing. If it was to "Hot Shot" or primarily just for long haul towing, exactly what I have now, but I would probably go with the Cummins for fuel mileage and longevity, but in the same GM chassis with the Alli, or maybe an old (ha, that sounds weird) NV5600 and HD after market clutch.
Give me a 2nd gen 12v CTD and a deep wallet and I will blow the doors clean off ANY other diesel out there......Keep your 610's.....keep your Durascraps with fueling boxes stacked to the moon and keep your 6.0's (I won't even get into those! )...........I'll take a Piers Stoopid P7100 add some sick twins and o-ring a ported head and blow the rollers off the dyno AND smoke a Mustang on the drive home.....and for towing?....Well, does anyone here think there is another motor as capable of generating as flat a torque curve?.....I am not a brand loyal person.....Ford makes a great truck and if they put a CTD in it, I would even consider buying one - but they don't, so I'll have to stay with a Dodge as long as the CTD is in it. As it has been simply put many times on other forums, "comparing a 12v CTD to any other diesel is comparing apples to oranges"......couldn't have said it better myself. There. That's better.....had to get that off my chest. Hmm.....sounds a little aggressive?! :stir: but this IS the brand wars forum, right? rotfl :stir:
From what I've seen, "flat torque curve" and "Cummins" don't belong in the same sentence unless the topic of that sentence happens to be "lack of". In fact, one of the leading arguements for V8s, other than smoother running, is the flatter torque curves. I'll give you the "deep pockets" resulting in highest ultimate power in the CTD, but that flat "torque curve" won't fly unless you know something I don't...
Granted, these are not stock curves, but I would definitely want the Cummins torque curve over the Dmax. They are both relatively flat, except at the high end for the Cummins (where the engine won't be operated at much), and the Dmax as it lugs down. I don't know about you, but I want an engine with a flat torque curve and good torque below 2000 rpm. The Dmax may be relatively flat, but the torque falls off rapidly below 2000 rpm and obviously that is not well suited for towing.
It flys for me, so I'll tell you what I know.... What I refer to as "flat" means the torque peak is reached very early in the rpm and that level is maintained all the way up to, or close to the hp peak.....to suggest that a Duramax or a 6.0 is capable of matching this curve is silly......this is why the V8's are very strong when unloaded but slow down noticably more than a CTD when loaded down very heavy - the V8's torque curve is on a steady rise in relation to rpm....the torque and hp curves are noticably similar and it is no coincidence that peak hp and peak torque occur not too far apart on the V8's.......Look at the CTD hp/torque relation....the curves are very different and peaks occur quite a distance apart.... Remeber: torque is what moves you - it's a measure of force being applied. Hp is merely a calculation of torque and rpm and does not represent a force measured. Hp is simply the # that tells you fast (rpm) the torque can be applied......Bottom line: if you can make more torque sooner, the flatter your curve will be (because the slope is minmized right from the very beginning) and the more power you have sooner to pull harder.
CatDieselPower: Wow, that CTD graph is way different (and much better) from what I've seen in the past (at least what I recall). It has been a couple of years since I was comparing, so maybe that's just the 600, or maybe it's evolving technology. Either way, I'm impressed with what Edge did with the 600! Frankly, I didn't know they had achieved nearly that much on the CTD with only a "chip". waytogo I guess I will have to revise my view of the DMax as the cheapest way to get "entry level" bombing performance. Anyone got stock graphs on the earlier stock CTD? IIRC, when I was shopping back in '02, the DMax stock graph rose quickly to around 1800 and then was amazingly flat all the way to red line. Almost the same as "stock" shown on the graph above, but I thought I remembered the peak closer to 1800. I wonder if that is a change for the LLY vs. my LB7 or if my memory playing tricks on me. And acording to my memory, the Dodge was comparatively "spikey" rising relatively early then dropping more sharply than the CTD "stock" line in the graph above. In fact, I seem to recall it falling fairly rapidly after around 2600 or so. <confused> CTD Nut: I don't think it's silly at all to claim the DMax curve is flatter than the CTD. The word "flat" is not ambiguous or typically regarded as open to interpretation. If you look at the graph above, IMO, to claim the CTD stock curve is somehow "flatter" than the DMax curve is "silly". Quite simply, based on the graph above, the stock DMax holds a far flatter torque curve over a broader rpm range than the 600 CTD. Granted, the 600 graph above looks better than my memory (which could be faulty) of the earlier versions, but it is still far from "flat", particularly compared to the DMax. Also, what is the red line on a CTD? I seem to recall it much lower than the span of that graph. <shrug> And I'm well aware of the difference between HP and Torque. As far as the lower rpm torque peak of the CTD, yes, I'll grant you it does have it's advantages. I never claimed otherwise. But when I'm running heavily loaded at 75-85 up a 6% grade or better in OD at around 2200 rpm, I'm rather happy with my DMax torque curve thank you. If it does start to bog down a bit, the Alli will shift down and bring the rpms back into the mid to upper 2k range. Same thing for a manual, you shift down instead of lugging it so. Of course that does account for some of the CTD's better fuel mileage. As for getting things moving, it's just a matter of putting the engine in it's preferred rpm range and keeping it close to the peak without falling off the sides. With the more rounded CTD curve you have a more narrow band of "ideal" where as the DMax can roam over a wider range while holding closer to "peak". The only time the lower peak really makes much difference is with a manual and the 0-20mph "getting things moving", so the DMax may take an extra second or two till it can build to the 1800-2k range. But I really couldn't care less about that considering how small the impact is to over all driving experience. Bottom line is that the V8s provide a better over-all driving experience, with the CTD having a small performance advantage for strict towing. The CTD also has a disadvantage when equipped with the 4 speed auto due to it's less flat/broad torque curve and the 4 speeds reduced ability (compared to 5 speed auto or 6 speed manual) to manage engine rpm. Don't get me wrong, I admire the CTD a great deal. Even more so now that I see that graph of the 600 posted from Edge! And as I said before, if my truck was a "hot shot" rig or Snow Bird hauling an RV around 9 months out of the year, I would prefer the CTD to the DMax. But I get really tired of all the "CTD is best!" chest thumping. Each is superior in different categories and each buyer simply needs to figure what is best for them. And, as you said, this IS the "Brand War" forum.
CatDieselPower: Oh, and one more thing, the stock curve is shown on those graphs. And if you notice, they both drop off rapidly below 2200 on the stock line. In fact, the numbers are rather similar except the DMax has if flat beyond 2200 where the CTD starts dropping off at an ever increasing rate (though not exactly falling off as I recalled). But I'm still BLOWN AWAY with what they've done with low rpm power with the Juice for the 600! Wow, I wish they could bring up the DMax bottom end like that! As I said before, it wouldn't make that much difference for me towing (IMO), but it would be a big help for gas mileage and keeping it from dropping out of OD when heavily loaded. Sadly, the "chipped numbers" for the DMax are not nearly as impressive in "curve" as those for the 600 (assuming the diffs and tranny gears can keep the rpms from climbing much past 2600 or so).
Yea, I just noticed that, it's definitely hard to see. It looks like the Cummins still rules at 2000 and below, where IMO it is really important for towing since it would obviously be easier to get the rig moving, and downshifting wouldn't be needed as frequently. From 2000 up, they are very similar, and from 2000 down the Cummins rules, I still think the Cummins has the better curve. By the way, this is Tyler (BlueBlazer62) from CK5, so you can call me by name if you like waytogo
I won't go as far as others and say the Cummins is all superior of the other two diesels but I will say that I think it's inline 6 configuration is superior over a V8 diesel design. The V8 may have better top end and give off slightly less vibration at idle but my ISB hardly ever sees RPM's above 2300RPM's or so anyway, unless I completely floorboard it and is allowed to reach nearly 3K. As far as the vibrations....what vibration really? I will definantly say it's not as smooth as a mild gas engine but the small amount of vibration doesn't bother me or any of my passengers, infact, one would have to actually be thinking about it to even notice. Like I said, I'm not going to say any engine is superior because each have their advantages as well as drawbacks but I'll take an inline 6 ANYDAY over a V8.
Tyler: I wouldn't go nearly so far as to say "it rules" below 2000, but it is clearly higher. Looks like maybe 300 vs. 325 at 1800, but hard to say at that scale. Given how readily I can get heavy loads moving (usually rapidly pulling away from traffic at a light even when I'm loaded) and how little mine downshifts on the open road, even with steep grades, I just don't see the low rpm as being a clear factor. However, it is frustrating that on a steep grade, if I drop below 70(ish) it shifts down and it's pretty much impossible to get it to shift back up till I'm over the top. It's not a problem till some nimrod pulls into the "fast lane" because he can maybe manage 50 and is "trapped" behind someone who can only manage 45. Once it shifts down I can hold most any speed I want (subject to the limiter) on any grade and the EGTs go way down but so does the fuel mileage. <shrug> I don't see it as a big deal, particularly since I spend well over 90% of the time unloaded, but that's just me and my preferences. Like I said, the CTD has advantages, but for a general use, multi-purpose rig that sees most of it's time unloaded, I just don't see that it has any clear overall advantage over the V8s. And in fact, it has a few distinct disadvantages for some people. Bobby: As you say, it's a matter of preference. You're used to it and I'm sure I could get used to it easily enough too. But I do find it distinctly noticeable when I get in a CTD being used to my DMax. One other thing the CTD wins hands down on is it's simplicity. The V8s are much more complex and often more difficult to work on. Either way, "to each their own", and I'm glad we have the choices we have in modern diesels.
It looks more like 300 vs. 350 at 1800, but like you said, it is hard to tell. If you were to extrapolate from that graph below 1800 rpm, the Cummins would in fact "rule" I believe. The Dmax is obviously dropping in torque at a much faster rate. I guess since you drive an auto, its not as noticable because your Allison will just downshift before it lugs, but with a manual trans, the torque below 2000 rpm is VERY important IMO.
At the risk of "beating this to death", if you look at the slope of the CTD graph near 1800 vs the slope of the DMax, unless my eyes deceive me, I do believe the CTD is dropping faster, even though at that point it is still higher than the DMax by some margin. If you extrapolate from say 1800 to 1900 to estimate the curve below 1800, I think you'll find that the CTD will actually drop below the DMax by around 1600-1700 or so. I really wish we had better (real) figures to go on, but I lack the interest to search them out.
