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]

Yes, this is basic stuff. But, your formula HP = T * rpm / 5252 assumes that you have rpm. In our gas and diesel engines, yes you have rpm. My point is that HP also exists in situations where there is no rpm: jet engines, rocket engines, steam engines, horses, us, etc, etc.

Secondly, your assertion that if you chage one of HP or torque then the other must change is not correct. Without reference to rpm, no such claim can be made. If you claimed that, at a given rpm, if you change HP or torque then the other will change then you would be correct. Without that reference to rpm, though, it is impossible to determine what, if any, change is caused in one of those values by a change in the other.

Dynos also do not always measure torque. Chassis dynos, for example, measure HP and calculate torque. Other types of dynos measure other valuse and calculate both HP and torque.

Bert

[blt2ski]

dubdub07,

If torque is sooo important to a motor, why are the current tanks the army is using have something like 2000HP and some 400 lb ft of torque?

BOTH torque and HP are important in the end. BUT, one also needs to spec how the HP and torque is transferred to the drive unit. Torque will multiply, HP will not. So if you have a high HP/low torque motor, but the correct gearing to multiply the torque so it is equal to a high HP/torque motor, they will have the same potential.

There is more to it than just HP and torque figures.

Marty

[dubdub07]

The link, for everyone's viewing pleasure!

Torque vs Horsepower

[dubdub07]

BertP wrote:

dubdub07 wrote:
Can't have one without the other!

Sure you can. Horses don't produce any torque.....

dubdub07 wrote:
You point is misleading. If you have 1000hp, you can tow a cruise ship. Torque is how the engine uses that 1000hp. If you only have 350HP, high torque is VERY important in towing.

Why? Hp is HP regardless of what rpm it is developed at.

dubdub07 wrote:
Anything less than 400hp will need a very high torque rating, or how efficiently the engine is using the hp and at what RPM does the power come on.

I'm afraid I don't follow that at all. Can you please explain what you mean?

dubdub07 wrote:
If you have unlimited use of hp, the torque will always follow the hp. if one goes up, so does the other. They are the same, but different.

Torque does not always follow HP. If I remember the torque curve of the PSD for example, the torque rises up to a point around 2000 rpm and then begins to drop all the way up to its redline. HP, OTOH, continues to rise all the way from min rpm to redline.

Bert

Bert, you are taking too many cheap Canadian meds.........I am quoting, so this IS NOT ME TALKING!

So one horsepower is a force (a torque to be exact) of 5252 lb-ft @ 1 rpm. Now it is easy to come up with a formula for horsepower given engine rpm and torque. Say we have X lb-ft of torque @ Y rpm and we want to convert that amount of power to horsepower. The last equation tells us we can convert from (lb-ft * rpm) units to horsepower units by multiplying torque and rpm and then dividing by 5252:

power = X lb-ft * Y rpm
power = X lb-ft * Y rpm * (1 hp / (5252 lb-ft * 1 rpm))
power = (X lb-ft * Y rpm / 5252) hp

So,

horsepower = torque * rpm / 5252

Now you know exactly how horsepower and torque are related. There are no exceptions to this rule; they will always be related by this formula. In fact, it might be better to see them as just flip sides of the same coin. One result of this formula is that below 5252 rpm, torque will always be less than horsepower, at 5252 rpm they will be equal, and above 5252 rpm torque will be less. Note that a dyno never measures horsepower; it can only measure torque and then use the above formula to get horsepower.

Acceleration
So we now know that horsepower and torque are basically two different views of the same thing - change one and the other most also change. What we are really interested in is how they work together to affect a car's overall acceleration.


Bert, this is basic stuff. So why are you arguing?

[BertP]

dubdub07 wrote:
Can't have one without the other!

Sure you can. Horses don't produce any torque.....

dubdub07 wrote:
You point is misleading. If you have 1000hp, you can tow a cruise ship. Torque is how the engine uses that 1000hp. If you only have 350HP, high torque is VERY important in towing.

Why? Hp is HP regardless of what rpm it is developed at.

dubdub07 wrote:
Anything less than 400hp will need a very high torque rating, or how efficiently the engine is using the hp and at what RPM does the power come on.

I'm afraid I don't follow that at all. Can you please explain what you mean?

dubdub07 wrote:
If you have unlimited use of hp, the torque will always follow the hp. if one goes up, so does the other. They are the same, but different.

Torque does not always follow HP. If I remember the torque curve of the PSD for example, the torque rises up to a point around 2000 rpm and then begins to drop all the way up to its redline. HP, OTOH, continues to rise all the way from min rpm to redline.

Bert

[dubdub07]

BertP wrote:
You should read more of the posts in this thread. Cole's Notes version: you don't need torque to tow a big load, you need HP.

Bert

Can't have one without the other!

You point is misleading. If you have 1000hp, you can tow a cruise ship. Torque is how the engine uses that 1000hp. If you only have 350HP, high torque is VERY important in towing. Anything less than 400hp will need a very high torque rating, or how efficiently the engine is using the hp and at what RPM does the power come on. If you have unlimited use of hp, the torque will always follow the hp. if one goes up, so does the other. They are the same, but different.

[BertP]

You should read more of the posts in this thread. Cole's Notes version: you don't need torque to tow a big load, you need HP.

Bert

[Madhatter1]

Unless you look at the RPM where the HP is produced (318X5252/2100=795 lbs torque). This is why a 475 Hp OTR truck is acually very powerful and also why I choose the CTD. Forget the latest high HP numbers, much earlier versions (especially the 12V engines) produce plenty of torque for towing. I love my 08 6.7 but miss my 97 5.9.

[BertP]

Very true. My point was simply that the engine in my truck produces almost as much power as the 8V71 did (does?) but it is not called upon to pull anywhere near the weight that the 8V71 was. 318 HP ain't very much power when you are pulling that kind of a load.

Bert

[Madhatter1]

The Dmax 318 and the Detroit 318 are two different things. Our pickup engines (my 6.7 CTD included) are not in the same leage as these OTR truck engines, even the older ones. I am learning a lot by these posts about the history and performance of some big diesels. Thanks for all the info. I own a pair of 8-71N's in an old 45 Hatt we are working on and enjoy all the info. I will add that in the marine side the 71 series is known to last much longer that the 92 series (excluding the J&T 6-71). Keep the stories coming.

[BertP]

I didn't say that 8V71's were not used in OTR rigs just that they weren't used that often. As your story proves, the 8V71 simply didn't produce enough power to be used on highways. They worked perfectly in local haulers but for highway work, the 8V92 was preferred. The 8V92 had a nominal HP rating of 475 but a quick Google search turned up engines pushing up to 750 HP. Those engines won't slow down a lot on the hills :). Remember that the problem with the 8V71's is not that they are V8's or 2 stroke or anything else. The problem was that they only proguced 318 HP. As a comparison, my Dmax puts out 310 HP and I don't haul 80,000 lb......

Bert

[Jarlaxle]

The 8V71 (or 72) was not used that often in OTR vehicles because it didn't produce enough power.

Really? Don't tell my uncle that, because he'll laugh in your face. I rode with him through the Adirondacks a while back. For once he didn't have his beloved Kenworth COE (turned-up 855ci Cummins big-cam)...another driver was in the hospital & he was filling on this guy's run, with this guy's tractor. It was what he called "Captain America", a beautiful 1976 GMC General with the entire thing painted like a rippling American flag. (It was a beautiful--and probably $15,000--paint job.)

It was powered by an 8V71N, with an 18-speed Road Ranger. They'd bought it from an owner-op (well, who else would have the Captain America paint job?), and the engine was turned up. As we rolled along, he had been going back-and-forth on the CB with another driver (both football nuts) for a while. Just as we hit the foothills, the other driver (in a Kenworth T2000, one of the first either of us had seen) said, "Well, nice talking to you...we'll be losing the signal soon." My uncle, honestly curious, asked why...and the guy in the Kenworth replied, "I have a 550HP Cummins...we're getting into the hills and that old Jimmy won't keep up." (I'd expect that to be an N14.) As he said this, my uncle dropped two gears, wound the engine to about 2400 (governed about 2800), and really put the spurs to that Detroit. My uncle's reply: "We'll be losing the signal, but not for the reason you think. Check your mirrors."

About 3 seconds later, we went tearing past the Kenworth, both stacks pouring out huge soot clouds. As we passed him, my uncle shifted, resulting in flames shooting about 4' out of both stacks. As long as you keep the RPM's up, they climb hills just fine. 😄 😄

Seriously, they aren't bad on hills...but they CANNOT be driven like most other diesels. Especially an 855 Cummins...it WANTS to lug, happiest under 1600RPM. A Detroit, OTOH, is lugging BELOW about 16-1700. Heck, the 6V53 I drove (ironically, in a Ford C6000) wasn't happy unless it was on its (2900RPM) governor. (And adding even more confusion, a 6V53 Detroit is actually 318ci!) They really need lots of gears...that General's 18-speed wasn't just there for the original owner's ego.

I drove a GMC highway coach (a PD4106), and it was a challenge keeping the RPM's up with only 4 gears (and an A/C that probably pulled close to 35HP). The 4106 was light as highway coaches go (IIRC, it topped out about 35,000lbs), but MCI put 8V71's in big 40' tag axle coaches that could top 50,000lbs.

[GACamper]

BertP wrote:
The 8V71 (or 72) was not used that often in OTR vehicles because it didn't produce enough power. The 8V92, OTOH, was used quite often with a normal power rating of 475HP.

As far as Mr. Lube is concerned, I agree that they can be pulling a fast one. But all I would have to do is have an oil analysis done to prove their wrong doing. I don't think that most dealers would risk the negative publicity that something like that would create. If it would make you happy, I promise to change it myself next time 🙂

Bert

If you go back in time a look you will find that the GMC Cab Over used the Detroit Diesel 8V-71N horsepower ratings of 318 as a over the road truck. That's one I can pull off the top of my head right now.
Having your truck service right and with the right products you would not have to worry about a oil analysis to be sure.
I know a couple here which his wife works with mine that took their Dodge Diesel Dually to a local fast lube place to have service cause they were going on a trip.
Like you said " he didn't have time to do himself" On there way back home the engine burned up do to the oil filter collapsed inside. In the investigation they found that the oil filter which was installed by the Fast Lube was not the correct oil filter. Also the oil they put in the engine was a regular automotive grade oil. The oil filter was the main cause of the engine damage. Their truck had right at 97,000 miles on it. I don't remember the full details but do to the age & miles they were giving a low mileage used motor installed at no cost to them. After the truck was fixed they traded it. Now he when he needs his truck serviced he bring out here to my place. We service the truck and the girls fire take care of the grill.
I'm not saying that this happens all of the time but it does happen. I don't know about where you live but around here it's mostly college kids working part time at the Fast Lube locations.
I know what the recommended specs on the oil filter & fuel filter for my my truck is. I don't use anything less. I can jump in my truck right now and go where ever I want and not worry about anything cause I know everything is done right with the right stuff, Especially on the fuel system. Like the oil filter, not all fuel filters are the same either. I've updated and built my own fuel filter system for my truck. I'm running a Cat 2-micron fuel filter system on my truck. The fuel in my truck runs through have a Baldwin 10-micron fuel filter in the fuel water separator canister then it runs through a Cat 2-micron fuel filter before it enters the injector pump. Injector pumps and injectors are very costly. I try to be picky where I buy fuel but sometimes you have to buy fuel where you can get it when traveling. Dang did I get off track her or what?
Can you tell I'm just a little picky about my truck...:R

[GACamper]

Jarlaxle wrote:

You will not fine a V8 diesel in a over the road truck. Detroit Diesel tried it years ago back in the 70's in the over the road truck. It was ok on flat land but had no pull power at all when it came to pulling in the mountains. Detroit Diesel did not keep that engine long at all before they took it off the market.

It was on the market (8V71 and 8V92) for over twenty years. (V6 versions were also built & used widely, especially in buses.) It was only dropped (with the rest of the venerable 2-strokes) after 1992 due to what was basically a 1930's design not meeting new emission standards. For its time, it was as good as any other engine...and an 8V92TA is a powerhouse even today, easily topping 450HP.

Here is a little history for you on the V6 & V8 Diesels.
Dodge was using Cummins engines long before the 5.9L B-Series engine showed up in the '89 pickup. The 60s vintage NH-220 Cummins displaced 743 ci (12.2L) and cranked out 220 hp and 605 lb-ft of torque. Keep in mind, these engines were naturally aspirated, which helps explains why the current 6.7L Cummins puts out more power and it's only half the size.
In 1960, diesel popularity risen to the point where one in four heavy-duty truck sold was diesel-powered. Cummins was the diesel-engine provider for these new trucks, and Dodge offered four inline-six-cylinder engines with ratings from 175 hp and 405 lb-ft of torque to 220 hp and 605 lb-ft of torque.
In 1963, Dodge offered this 354ci, six-cylinder, Perkins diesel rated at 131 hp and 284 lb-ft of torque in its medium-duty trucks up to 36,000 pounds.
Cummins diesels were offered for the L-series tilt cab trucks for 1965. The standard 785ci (12.9L) VBE-235 V-8 engine produced 235 hp and 568 lb-ft of torque. An optional 785 developed 265 hp and 600 lb-ft of torque.
There was also a 195hp, 450-lb-ft, 588ci (9.6L), V6E-196, V-6 engine. This smaller unit was used in the 65,000-70,000 gross combined weight rating trucks.
1966 saw the launch of Chrysler's Warren Assembly Plant #2. Twelve trucks per shift were capable of being produced. Additionally, Caterpillar and Detroit Diesel power plants were added to the Cummins brand for a broader power range.
Dodge continued to push its heavy-duty line in 1969. The L-series tilt cabs continued to offer six- and eight-cylinder diesel mills. The Cummins turbocharged six-cylinder NTC-280 and 335 engines were offered as options. Then Detroit Diesel added its 8V-71N in two horsepower ratings: 260 and 318.

[BertP]

The 8V71 (or 72) was not used that often in OTR vehicles because it didn't produce enough power. The 8V92, OTOH, was used quite often with a normal power rating of 475HP.

As far as Mr. Lube is concerned, I agree that they can be pulling a fast one. But all I would have to do is have an oil analysis done to prove their wrong doing. I don't think that most dealers would risk the negative publicity that something like that would create. If it would make you happy, I promise to change it myself next time 🙂

Bert