Tater_Salad
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Re: Diesel vs gas......................
BertP wrote: Again, giving the CTD a tranny with a single 1:1 gear was just to show that the output numbers of an engine are not the only factors in determining the outcome of a challenge. If you want the dual to be fair, then you must allow both vehicles to optomize their configuration. If you don't the one that is optimum will win - all other things being equal. Bert Sorry, I misunderstood what you were trying to show with the example - I got it now. But I still can't grasp that Dodge would hamstring the Hemi intentionally or ingore it completely - there are some smart sumb!tches up there doing these designs (or are there? ;) ). Is there maybe something that keeps them from designing a tranny that would "level the playing field" for the Hemi?304Views0likes0CommentsRe: Diesel vs gas......................
hemi-kz wrote: Tater, You may be on to something. Any industrial equipment I've used (air compressors, welders, etc)has a "Duty Cycle" rating. Maybe the CTD can put out not more max power, but max power for a longer time. Good point. That would make sense in that Dodge would want to "derate" the Hemi because extended towing of 20K lbs would adversely affect the engine. Whereas it wouldn't for the CTD. But that still points to the CTD as being a "better" engine for a TV, doesn't it?304Views0likes0CommentsRe: Diesel vs gas......................
BertP wrote: Sort of. What is important is that you allow the engine to develop its max power at whatever rpm that is. If we did a pull-off between two trucks - one with a CTD and the other with a Hemi - pulling a 20,000 lb trailer, which would win? I personally believe the CTD would win. You? BertP wrote: What if we gave the CTD truck a tranny that had only one gear with a 1:1 ratio? There's a lot more to determining a truck's towing capability than the output of the engine. Bert Why just hamstring the CTD? What if we gave both a tranny with a 1:1 ratio? And both had either 4.10 or 3.73 REs? Personally, I still think the CTD would win. You?304Views0likes0CommentsRe: Diesel vs gas......................
hemi-kz wrote: Anyway, my thought is the diesel is probably better at getting a load moving because its power is at an RPM that is closer to the zero RPM of the axle. Does that make sense? Sure, but that means that you are saying a truck with a lower HP/higher torque is a better TV than a comparably configured truck with a higher HP/lower torque. And that is counter to the "It's the HP, stupid" theory......304Views0likes0CommentsRe: Diesel vs gas......................
BertP wrote: They are not the same. Engine rpm to axle rpm: Hemi: 3:1 * 4.1:1 = 12.3:1 overall ratio CTD: 2.45:1 * 3.73:1 = 9.14:1 overall ratio At max power rpm: (I believe that the Hemi develops its max power at 5000 rpm) Hemi: 5000/12.3 = 406 axle rpm CTD: 2900/9.14 = 317 axle rpm That means that in first gear, the Hemi will be travelling 28% faster than the CTD if they are both at their max power point. Or, if we slow the Hemi down to the same speed as the CTD, it will be turning at just under 4000 rpm. How much power does the Hemi develop at 4000 rpm? Also, do both transmissions have the same effeciency rating at those rpm? Do the computers for either engine limit engine output in 1st gear? You are looking for a simple answer to a complex question. The answer may be as simple as "marketing", I really don't know. Bert The only problem with that theory is that it means if you put a 3.73 RE into the Hemi truck, the overall 1st gear ratio would be closer to the CTD's (3:1 * 3.73:1 = 11.19:1 instead of the 12.3:1). Sounds good, but Dodge rates the Hemi with 3.73:1 RE even *lower* on GCWR (down to 15000 from 17000 for the 4.10:1 RE). I can think of a MUCH simpler answer........We've eliminated all the other variables - truck platform, transmission, rear end.....the only difference is the engine. Could it simply be that the CTD is a stronger towing engine than the Hemi? That doesn't mean that the Hemi is a "bad" engine for towing, just that the CTD is better at max weights........ And this isn't just a Dodge thing - GM and Ford do the same thing.....gotta be something behind it other than some conspiracy theory that the auto mfgrs are out to make the diesels look better.......305Views0likes0CommentsRe: Diesel vs gas......................
hemi-kz wrote: Tater: This has been said before: It's not only about the engine. DC designates the strength of their transmissions in the name: In 5-45RFE the (2nd) 5 is its rating, the trans with the CTD (48RE) is an 8. Also (at least in 2003) the Hemi got a 10.5 inch rear and the CTD got 11.5" I don't think it's the tranny rating either. The GVWR and GCWR are the same for the CTD with either the 6-speed manual or the 48RE and the Hemi ratings are the same with either the 6-speed manual or the 545RFE. If it were that the 545RFE was weaker, the 6-speed would give it a higher rating. On my 2004, I believe that the 11.50 RE was an option.304Views0likes0CommentsRe: Diesel vs gas......................
5-45RFE: (Hemi) 1st - 3.00:1 4th - 0.75:1 5th - 0.67:1 48RE (CTD) 1st - 2.45:1 4th - 0.69:1 So the Hemi has lower 1st and 4th gear ratios, to put the engine at a higher rev, plus the higher overdrive ratio for highway cruising. Coupled with the Hemi's lower 4.10 RE (as opposed to the CTD's 3.73 RE), the Hemi should be well within it's power range, right? So, again, why is the CTD rated 200 lbs higher for GVWR and 3K lbs higher for GCWR? :?307Views0likes0CommentsRe: Diesel vs gas......................
I'm still not getting this. Are you saying that Dodge optimizes their trannys for the CTD, not for the Hemi? I could *maybe* buy that for the 6-speed manny and the 4-speed auto, but what about the 5-speed auto that isn't even offered in the CTD? A similarly equipped 2500 Hemi should be able to pull more with it than a 2500 CTD with the 4 speed auto, shouldn't it?308Views0likes0CommentsRe: Diesel vs gas......................
OK, so even if you look at the "best" setup for each, you still wind up with the CTD having a 200 lbs higher GVWR and a 3000 lbs higher GCWR. Since Dodge only has 1 manual transmission available, I went to the autos. There is a seperate auto for the CTD and Hemi, so I'd guess that each is optimized for it's target engine. Right? Hemi with 4.10 RE and 5 speed auto = 8800 GVWR and 17000 GCWR. CTD with 3.73 RE and 4 speed auti = 9000 GVWR and 20000 GCWR.308Views0likes0CommentsRe: Diesel vs gas......................
OK, I kinda scanned the 44 pages of this thread, but didn't read every post in-depth and I can't find an answer to this question. Why does Dodge rate the '06 2500 CTD (with the exact same setup as the Hemi -same frame/6 speed trans/3.73 rear end) with a 200 lb higher GVWR and a 5000 lb higher GCWR? The Hemi puts out 20 more max HP, so wouldn't it be rated higher if HP were the determining factor? What am I missing?309Views0likes0Comments
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