Diesel vs gas......................

[blt2ski]

OK folks, there have been a few to many diesel vs gas threads that have shall we say gone to "Hell and a hand basket"! So if all of you would put in you BEST, no flaming reasons for going gas vs diesel, pro and con, I will either leave your thread, or copy and paste pertinant info to the 4 posts of pro and con of diesel or gas. This can include the GM 8.1 vs Dmax or Ford V-8/10 vs PSD etc too.

Be real and honest in you answers, not hear say, flaming etc PLEASE!

If posts are good ones, I will leave, if inflamatory or trolling in nature, they will be deleted! I will get this stick'd to the top for future parusing for those that need this type of info.

Added 6-23-04

We are getting closer to answers I am looking for etc.

Stuff like Ken's - T-Bone posts are good. There are a few others of you that have not posted, some with a 9 point question and answer type to figure out how you went with one or the other. If you are one of those, PLEASE repost in this thread. I may have to look up whom has done this and PM you, but if you think this is you, you now know what to do.

Also, for those of you with $ per gallon for either fuel right now, I would prefer to see a post with ...."in my area, diesel is typically .10 less than unleaded" then explain your numbers. As currently in the Seattle area, diesel and unleaded are any where from 2.05 -2.30 per gallon, with mid test .10 more and premium about .20 more, with equal high low splits. Two weeks ago those prices were upwards of .30 -.40 per gallon more. people were posting $ per gallon that were for me. "I wish" If someone is reading your post a year from now, they may want to know where your paying 1.65, when the price of fuel is over $3 per gallon. Let's keep prices out of it if possible.

Bert and tin tipi, got into a good discusion on the pros and cons of RPM's, drive train etc. I would prefer to NOT see the quote of the other in responding threads, maybe just write a quick wording of re tranny gearing, instead of the whole 40 words or so in that paragragh, so the repsonse is shorter if possible quicker and easier to read etc.

I have deleted some 15+/- posts, that were off topic etc. Please note, I am trying to keep this at the top, as the ONLY gas/diesel thread in this area. So if one is trying to decide, we do not have to go thru this BS any more. As such, I will be deleting ANY future posts close to resembling this type of topic. I may have to change "this" title to a better one, if one has a better sounding title, to be more positive, better claification, let me know here, or in a PM/e-mail, what ever you feel most comfortible with.

Again thank you for all of you that are keeping responses positive, etc.

Also we could use a few more positive reasons to go gas, as many can see I have both gas and diesel, both have a place! Both have positive reasons to buy that fuel, lets keep the threads etc to that purpose only!

Marty

[BertP]

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

[hemi-kz]

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"

[chasd60]

My 235hp diesel gets 16 mpg towing my camper. My 235hp gas truck got 10 mpg. The diesel truck is much heavier too.

[Tater_Salad]

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? :?

[BertP]

What is the 1st gear ratio in the trannies offerd with the CTD? The Hemi? What is the rpm at which the CTD develops its max power? The Hemi? Based upon that information, which engine has a tranny available that more closely matches its operating specs?

Bert

[Tater_Salad]

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?

[BertP]

Absolutely true and basically what I was referring to in my comments to tater. If the tranny is optomized for a gasser, diesel performance will suck - especially at the top end. On the other hand, if the tranny is optomized for a diesel, gasser perfomance will suck - especially at the bottom end. The two engines are different and need to be treated differently to optomize their performance.

Bert

[firebird]

What the engine can pull in a 1:1 ratio is limited by tq but low engine tq can be made up for with gearing.

[BertP]

Tater - Not necessarily. It wasn't until the advent of the current diesels that the auto manufacturers started to get serious about tranny design. For years, we had simple three speed trannies. Now look at them: 5 and 6 speed are the norm. But, you also have to bear in mind one simple fact: in order to increase the power available at the drive axle for a given speed, you must increase the HP output of the engine even if that involves a decrease in the torque output of the engine.

firebird - While it is true that HP will control the speed at which you can pull a load, torque does not indicate how much of a load you can pull. Gearing does. Just look at the mules at the airport. They have small (usually gas, but that is changing) engines but the regularly pull aircraft weighing in the 100's of thousands of pounds. They don't go very fast, but they do go.

Bert

[firebird]

All right I'll bite.
HP is not the determing factor the cummins diesel will drag the Hemi around like a rag doll. You need to go back and reread the 44 pages.
Torque determins how much and engine can pull HP determins how fast you can pull it.

[Tater_Salad]

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.

[BertP]

Do they have exactly the same RE, frame, suspension, etc? If so, then the transmission can only be optomized for one of the engines. There's more to a truck than an engine.

Bert

[Tater_Salad]

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?

[BertP]

mowsley wrote:
Bert,

Definitely not flaming here just wanting to make a correction. You stated the engine in the M-1 only has 300ft lb of torque. This is WAY off. Honeywell's website lists torque for the AGT-1500 turbine as 2,750ft lb at 3,000rpm with 1,500hp. No way is 300ft lbs going to move 70tons to 20mph in 6 seconds no matter how it is geared.

Mark

Think about it, Mark: Have you ever seen a turbine engine that ran at 3,000 rpm? The engine in the Abrhams tank runs at 26,600 rpm. If it generated 2,750 lb ft of torque at that rpm, it would put out a total of almost 14,000 HP. The 2750 lb ft of torque you found is the output of the gear reduction unit, not the engine itself. But, just as I could not realistically claim that my DMax generates over 5800 lb ft of torque (520 lb ft from the engine * 3 (first gear) * 3.73 (RE ratio)) claiming that the AGT-1500 generates 2,750 lb ft of torque isn't accurate either. T = HP * 5252 / RPM = 1500 * 5252 / 26,600 = 296.2 lb ft of torque from the engine. You can change that number to anything you want (up or down) via gearing, but the engine output will not exceed 296.2 lb ft of torque.

Bert

[mowsley]

BertP wrote:

TexasBorn wrote:
Well in my mind that is a no brainer. The diesel has less power and less torque BUT it makes what is important when trying to move something weather its a trailer or the car its self, TORQUE!

I don't understand your point here. The 302 generates more torque than the diesel, so by your logic, the 302 should be the better TV engine.

You should reread my post about the tank. The engine in the Abrhams, which weighs around 70 tons, produces less than 300 lb ft of torque - less than half the torque produced by my DMax. By your theory, my DMax would be a better engine for that tank than the one that is in it. But, the engine in the tank produces 1500 HP - almost 5 times the power output of my DMax. I doubt that my DMax could move that tank at anything over a crawl.

TexasBorn wrote:
And BTW as you know HP IS juat a mathmatical calutation of torque and work.

You mean torque and rpm (HP = Torque * RPM / 5252). Then, torque is just a mathematical calculation based upon HP and RPM (Torque = HP * 5252 / RPM). Then, RPM is just a mathematical calculation based upon torque and HP (RPM = HP * 5252 / Torque).

TexasBorn wrote:
Also I am puling 400ftlb at 1500rpm, as to 3000rpm at 400ftlb with the Mustang.

And the difference is? The bottom line is that, with the correct gearing, that Mustang engine will drag two of those diesels all over the back 40 without breaking a sweat. It develops more than twice the power of the diesel. As long as you have the proper gearing, the torque output of the engine is meaningless as far as determining the capabilities of an engine is concerned.

Bert

Bert,

Definitely not flaming here just wanting to make a correction. You stated the engine in the M-1 only has 300ft lb of torque. This is WAY off. Honeywell's website lists torque for the AGT-1500 turbine as 2,750ft lb at 3,000rpm with 1,500hp. No way is 300ft lbs going to move 70tons to 20mph in 6 seconds no matter how it is geared.

Mark