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

[robna]

Ive driven both the old 5.9 ctd and the new 6.7 and have to say I still prefer my hemi I do agree towing with a diesel is better. The diesels are great tow rigs but my hemi does both fine and enjoy leaving you diesels behind me at a light no trailer of course and yes I have beaten the new 6.7 beat him by 4 truck lengths. Happy trails to all!!!

[dubdub07]

GACamper wrote:
It's no secret that most large commercial trucks and some heavy-duty trucks have diesel engines. Why? Diesel engines generate more torque. Since a diesel engine doesn't have spark plugs and uses compressed air to ignite fuel, the piston has to travel a longer distance to compress enough air for ignition. This cylinder travel distance is called stroke, and more stroke means more torque.
Look at the differences between two truck engines. A Dodge Ram truck with a 6.7-liter Cummins Turbo Diesel engine has 350 horsepower and 650 pounds-feet of torque. The same truck with a 5.7-liter Hemi gasoline V8 engine, on the other hand, has 383 horsepower and 400 pounds-feet of torque. While the gasoline engine has a little more power, the diesel's torque completely blows it away.
While the two trucks have very similar towing capacities --15,650 pounds for the gasoline engine and 16,350 pounds for the diesel all that low-end power means the diesel engine will have an easier time towing things.
Keep in mind that the Cummins Diesel engine gets that much torque at only 1,500 rpm, which is just above idle. With a diesel engine, you won't have to rev the more up to start towing because the power already exists.
Because you're using more energy-laden diesel fuel, diesel engines get better mileage than gasoline ones, so you'll also be able to tow heavier loads easier and longer without stopping. At the same time, a truck with a gasoline engine is going to have a cheaper base price. Diesel engines almost always cost more than gas ones because they are built to withstand greater forces from a more potent fuel. Typically, the bigger the towing job, the larger displacement engine you will need. Towing puts a lot of stress on the engine, so more torque will reduce wear and tear on the vehicle.
All of the evidence points to torque as being more important than horsepower when it comes to towing. Why? The power at low-end rpm provided by high levels of torque lets you move huge loads without much effort. As stated before, some diesel trucks produce twice as much torque as they do horsepower at near-idle RPM levels -- meaning that they can start pulling something like a Camper, Rv or a boat with ease.

Horsepower is important because it allows a car to move faster on the highway and at high rpm. However, if you can't get that RV off the line, all the horsepower in the world won't help you.

Now this is a smart dude! You must drive a Dodge!

[dubdub07]

Hannibal wrote:
Torque, in our application, is measured on an engine dyno and multiplied by rpm, then devided by the constant 5252. On a chassis dyno, you measure horsepower. There's no way to "measure" flywheel torque on a chassis dyno. To many multiplications in the way. Horsepower is linear, torque is not. Acceleration of the drum against it's electrical resistance is measured and "if" you connect the necessary means of interring engine rpm into the dyno's computer, you'll only get a horsepower at road speed readout, not torque. Torque is the calculated number then using hp/rpm X 5252. It's horsepower. The little pickup truck diesels make it at 30% lower rpm.
The Hemi Screaming? 2000rpm with the diesels is 33revs per second. Hardly loafing along. A Formula One race car turning 19,000 rpm is what I call screaming. My 2500rpm towing cruise is a lot closer to the diesels rpm in comparison. Once again, perception trumps reality to most drivers. My Hemi powered duplicate of my '03 SO Cummins Ram easily out tows the 250hp/460ftlbs Cummins with 100more hp and 100ft/lbs less torque.
Torque is a twisting force, not a leverage force. Two different animals. The axle is an idler on a steam locomotive. The axle does not twist the wheel. The arm pushes the wheel. That's not torque.

You are trying to justify why you tow with a hemi, and of course, you are wrong. I have never owned a motor that "twists", they rotate around and axis, like the arm attached to a piston, whether it gas or diesel or steam.

[Madhatter1]

Heres my real world experience. The stock 6.7 is a hotrod compared to the stock 5.9. Ever get "mad" at traffic and floor your way around things? When you floor the 5.9 it goes good but not crazy. My 5.9 is a SRW and the tires never break loose. The 6.7 on the other hand better be respected. Things happen in a big hurry and the dually tires will spin. Don't get me wrong, I am a big 5.9 fan and it pulls a load as well as the 6.7. They can do dyno tests all they want but how it works in the real world is what matters most. BTW I did modify my 98 5.9 up to 900 lbs torque and that is to date the most powerfull Diesel I have ever driven. It twists the frame so much it swerves when you let off. Fun factor: off the chart! Now that I think about it a HUGE atvantage of Diesel over gas is the cheap big HP upgrades. On a diesel you can add a tuner and fuel set up for $1800 and get 50% more power. To get 50% more power out of gas would be big $$$ and bye bye to any fuel economy.

[GACamper]

Madhatter1 wrote:
not true. My 08 6.7 will run away from my 05 5.9 unloaded with all that Hp in the high RPMs but hooked up to my trailer the only difference in performance is from the new 6 speed tranny. High RPM HP is useless for towing big loads. OK, beat me up now.

Madhatter1,
Here is the article I was telling you about. I was surprised myself when I read it.
The article was in Diesel Power
5.9L VS. 6.7L On The Dyno We wanted to see how the 6.7L stacks up next to the proven 5.9L, so we rounded up two stock Dodge trucks equipped with four-wheel drive and automatic transmissions. The 5.9L Cummins truck was an '06 Quad Cab shortbed, and the 6.7L Cummins was an '07 Mega Cab. We began by putting both trucks on Flash Auto's chassis dyno in Albuquerque, New Mexico, to see how the real world power figures compare to Dodge's advertised numbers. As we were generating power numbers, the differences in emissions controls became immediately obvious. The 5.9L made plenty of smoke under load, even in stock form. By contrast, the 6.7L was squeaky clean during our dyno pulls. Advantage: 6.7L Cummins

Stock Power Numbers The 5.9L-powered truck put down 269 hp at 2,550 rpm and 594 lb-ft of torque at 2,300 rpm; and the 6.7L-equipped Dodge put down 259 hp at 2,850 rpm and 487 lb-ft at 2,750 rpm. Runs were made in direct drive for both trucks-however it should be noted that the 5.9L Cummins was backed by the 48RE four-speed automatic transmission and the 6.7L used the new 68RE six-speed automatic. Unfortunately, the 5.9L Dodge used in our test had 35-inch Toyo tires on 20-inch Eagle Alloy rims. In order to limit the variables between the two trucks, the stock tires and wheels from the 6.7L truck were swapped onto the 5.9L truck, resulting in 10 additional peak hp and 10 lb-ft of torque. Advantage: 5.9L Cummins

Plug-In Performance Modules After installing the intakes, we added Edge's Juice with Attitude to both engines while the hoods were still up (5.9L P/N 30106 and 6.7L P/N 30107). The Juice module is a reliable and well-known product in the diesel market, and Edge was quick to bring the Juice to the market for the new 6.7L engine. The Juice module install on both trucks, placed between the ECU and the wiring harness with factory-style connectors, provides altered injector timing and duration for improved mileage and power. Both units were very similar, and installation was plug-and-play, the only difference being the location of the MAP sensor. While Edge didn't include the same detailed color instructions that S&B did, high-resolution photos and installation instructions were found in PDF format on Edge's Web site. Edge is currently expanding its installation video library for these products, and is planning to include an instructional CD with every purchase by the time you read this. Advantage: Tie

Edge Attitude Monitor The Attitude in-cab monitor works in conjunction with the Juice performance modules to allow five different power settings that can be selected on the fly. The Attitude display monitors boost, exhaust gas temperatures (EGT), transmission temperature, and a variety of other user-selected functions. The Attitude also has the ability to reduce power when excessive EGT or transmission slippage is sensed, making it smarter than many competing products. On the 6.7L trucks, the Attitude can also display the critical diesel particulate filter (DPF) regeneration status. This is a feature we have yet to see offered from other manufacturers, but it provides a great sense of security when modifying a new emissions-equipped diesel truck.
Advantage: 6.7L Cummins

EGT Probe Install In order to monitor the exhaust gas temperature (EGT), a pyrometer was added to the exhaust manifolds on both trucks. This was a relatively simple process for the 5.9L engine, but we could hardly even see the exhaust manifold on the 6.7L Cummins! We returned to Flash Auto and let its staff of experts perform the task. The money spent was well worth it when we drove away without any skinned knuckles. Advantage: 5.9L Cummins

Exhaust System Install While the S&B intakes and Edge modules were very similar for both trucks, the Silverline exhausts were dramatically different. Both exhaust systems are constructed from mandrel-bent T304 stainless steel and come with a limited lifetime warranty (5.9L P/N DS105 and 6.7L P/N DS109). Some other exhaust manufacturers can make these same claims, but it was the details that really set Silverline apart from the pack. Welded hangers, easy fitment, polished exhaust tips, bolt-on construction, and excellent packaging were included with both Silverline exhaust kits. While the construction was the same between the 5.9L and 6.7L systems, there were a few differences. The 5.9L system was 4 inches in diameter from the turbo back and used a polished 6-inch muffler with internal louvers. By contrast, the Silverline 6.7L exhaust started behind the DPF (by law all aftermarket exhaust systems must be this way) and used 5-inch diameter tubing with no muffler. We were nervous about running the daily-driven Mega Cab without a muffler, but the exhaust catalyst and DPF provided plenty of muffling-both trucks are scarcely louder than stock. While the noise did not change significantly, the fuel economy increased on each truck and the EGTs decreased. We were very surprised by the improvements offered by the DPF-back exhaust on the 6.7L. Advantage: Tie

Intake and ExhaustDyno Numbers We went back to Flash Auto to quantify the changes on the chassis dyno, particularly to see if the horsepower gains on the 6.7L would be as great as the 5.9L since it did not benefit from a full exhaust upgrade. With the Edge Juice in the Stock setting, the 5.9L gained 38 hp and 117 lb-ft of torque, and the horsepower peak rose 300 rpm. The 6.7L was even more impressive, gaining 64 hp and 158 lb-ft of torque with just the intake and exhaust. Clearly there are restrictions on the 6.7L besides the DPF and exhaust catalyst, since they were retained.
Advantage: 6.7L Cummins

Performance Module Dyno Numbers Turning the Edge Juice up to the Tow setting netted another 44 hp and 127 lb-ft for the 5.9L and knocked the horsepower peak down to a stump-pulling 2,200 rpm. The 6.7L gained 30 hp and 96 lb-ft of torque from the Juice's Tow setting. Turning the Juice up to the Extreme setting gained another 35 hp and 106 lb-ft of torque for the 5.9L, and 23 hp and 51 lb-ft of torque for the 6.7L. Advantage: 5.9L Cummins

Fuel Economy The 5.9L truck was equipped with a 4-inch suspension lift and 35-inch tires on heavy 20-inch rims, and the owner was only getting 13 mpg in mixed highway and city driving. After the intake and Edge module were installed, mileage improved slightly to 14.5 mpg. When the Silverline exhaust was added, mileage improved to 16.5 mpg. "I had never been able to get 500 miles out of a tank of fuel before the exhaust was installed, but now I can," reported the 5.9L Cummins owner.
The owner of the 6.7L truck was not as scientific about recording his mileage, but he did experience a notable increase in mileage after the intake and module were installed. There also seemed to be another increase in fuel economy from the exhaust. The 6.7L owner was pleasantly surprised by the difference the exhaust made, considering that the factory diesel particulate filter and catalyst were both retained. Advantage: Tie

Conclusion The 6.7L Cummins didn't show the same power potential as the 5.9L, but that's no surprise considering that it's saddled with so many emissions controls. What is surprising was that even with an increased stroke length (4.88 inches versus 4.72 inches), the 6.7L made peak horsepower at a significantly higher rpm than the 5.9L Cummins. The fact that we were able to get so much out of the 6.7L without affecting the DPF or throwing any codes spoke volumes about the quality of parts that S&B, Edge, and Silverline are producing.
As more 6.7L Cummins-equipped trucks hit the roads, we expect even more products to become available for them in the future, closing the gap between the new 6.7L and the trusty 5.9L. While the displacement may have changed, the Cummins B-series engine is still alive and well.

[Hannibal]

Just for gits and shiggles, I can't find the torque value. I did find a horsepower paragraph at the bottom of the page.
http://www.steamlocomotive.com/misc/largest.shtml

[Hannibal]

Madhatter1 wrote:
So the 2 Cummins you had were outperformed towing by the Hemi?

Odd but true. The SO Cummins towed in O/D on the flats and mild rolling hills at 2000-2100rpm. It needed direct drive for the steeper uphills. It had the torque but not the rpm. So in order to downshift to direct, we would first have to bog to 58mph so as not to over rev the engine where the PCM would allow a downshift to direct. Through transmission gearing, the Cummins' 460ft/lbs of torque was reduced by 31% by the O/D gear ratio. So I was working with 317ft/lbs of advertised torque to the tailshaft of the transmission. The Hemi, towing in direct not having it's lesser flywheel torque reduced through an overdrive gear ratio, is putting it's advertised 340~ft/lbs of torque to the tailshaft of the transmission. On the steeper uphills where the SO Cummins needed to bog to 58mph so it could shift to direct where it could deliver it's full 460ft/lbs of advertised torque to the tailshaft, The Hemi is able to downshift to 2nd at 65mph 4400rpm with the 3.73 ratio and multiply it's flywheel torque by 1.67 for 626ft/lbs of torque to the tailshaft where it will easily accelerate to over 70mph if you don't mind 5k rpm. It's not that it can't do it. It can and does. It's that most folks don't want to hear 4400rpm on the uphills or pay for the fuel consumption or plan on a worn out engine at 200k miles.
I haven't towed yet with the 4.56 ratio ring and pinion. Overall gear ratio including the transmission and rear end will be very close using O/D and direct as the 3.73 was using direct and 2nd.
I've owned four Cummins Rams. The '95 160hp/400ft/lb Cummins was a real mutt.

[GACamper]

Madhatter1 wrote:
My 08 6.7 will run away from my 05 5.9 unloaded with all that Hp in the high RPMs but hooked up to my trailer the only difference in performance is from the new 6 speed tranny. High RPM HP is useless for towing big loads. OK, beat me up now.

How you put the two trucks side by side. Both the 5.9 & 6.7 were Dino tested. Both engines stock from the factory showed that the 5.9 out performs the 6.7 do to the emissions added to the 6.7. The emissions hold the 6.7 back so it can't make it's make power.
If I can find the article I'll post it for you.

[Madhatter1]

GAcamper is saying what I am saying. No one is saying that diesel is always better than gas. For lighter loads or less frequent towing the expense of a Diesel does not make sense. It laways seems when we talk about a Diesel better performance someone needs to try to shoot down the discussion by saying that with the right gearing a gas can do as much as a Diesel. If you get the right gearing a weed whacker could power a truck and trailer. It would struggle on this hills and drop from 1/2 MPH to .01 MPH. I would have to admit it "could" be done. I will stick to Diesel for my 14.5K trailer, thanks.

[GACamper]

It's no secret that most large commercial trucks and some heavy-duty trucks have diesel engines. Why? Diesel engines generate more torque. Since a diesel engine doesn't have spark plugs and uses compressed air to ignite fuel, the piston has to travel a longer distance to compress enough air for ignition. This cylinder travel distance is called stroke, and more stroke means more torque.
Look at the differences between two truck engines. A Dodge Ram truck with a 6.7-liter Cummins Turbo Diesel engine has 350 horsepower and 650 pounds-feet of torque. The same truck with a 5.7-liter Hemi gasoline V8 engine, on the other hand, has 383 horsepower and 400 pounds-feet of torque. While the gasoline engine has a little more power, the diesel's torque completely blows it away.
While the two trucks have very similar towing capacities --15,650 pounds for the gasoline engine and 16,350 pounds for the diesel all that low-end power means the diesel engine will have an easier time towing things.
Keep in mind that the Cummins Diesel engine gets that much torque at only 1,500 rpm, which is just above idle. With a diesel engine, you won't have to rev the more up to start towing because the power already exists.
Because you're using more energy-laden diesel fuel, diesel engines get better mileage than gasoline ones, so you'll also be able to tow heavier loads easier and longer without stopping. At the same time, a truck with a gasoline engine is going to have a cheaper base price. Diesel engines almost always cost more than gas ones because they are built to withstand greater forces from a more potent fuel. Typically, the bigger the towing job, the larger displacement engine you will need. Towing puts a lot of stress on the engine, so more torque will reduce wear and tear on the vehicle.
All of the evidence points to torque as being more important than horsepower when it comes to towing. Why? The power at low-end rpm provided by high levels of torque lets you move huge loads without much effort. As stated before, some diesel trucks produce twice as much torque as they do horsepower at near-idle RPM levels -- meaning that they can start pulling something like a Camper, Rv or a boat with ease.

Horsepower is important because it allows a car to move faster on the highway and at high rpm. However, if you can't get that RV off the line, all the horsepower in the world won't help you.

[Madhatter1]

Good if your converting the truck into a trawler.

[Ace_]

Anyone ever run a Perkins diesel with much luck? I'm thinking about swapping it in my 2005 F250 V10, good idea, or bad?

[Madhatter1]

So the 2 Cummins you had were outperformed towing by the Hemi?

[Hannibal]

Torque, in our application, is measured on an engine dyno and multiplied by rpm, then devided by the constant 5252. On a chassis dyno, you measure horsepower. There's no way to "measure" flywheel torque on a chassis dyno. To many multiplications in the way. Horsepower is linear, torque is not. Acceleration of the drum against it's electrical resistance is measured and "if" you connect the necessary means of interring engine rpm into the dyno's computer, you'll only get a horsepower at road speed readout, not torque. Torque is the calculated number then using hp/rpm X 5252. It's horsepower. The little pickup truck diesels make it at 30% lower rpm.
The Hemi Screaming? 2000rpm with the diesels is 33revs per second. Hardly loafing along. A Formula One race car turning 19,000 rpm is what I call screaming. My 2500rpm towing cruise is a lot closer to the diesels rpm in comparison. Once again, perception trumps reality to most drivers. My Hemi powered duplicate of my '03 SO Cummins Ram easily out tows the 250hp/460ftlbs Cummins with 100more hp and 100ft/lbs less torque.
Torque is a twisting force, not a leverage force. Two different animals. The axle is an idler on a steam locomotive. The axle does not twist the wheel. The arm pushes the wheel. That's not torque.

[Madhatter1]

I forgot to add that my favorite gas truck engine was my 1990 Ford 300CI inline six and my least favorite was my screaming 1987 Ford 351 HO. I can't count my Chevy 305 because it was in a van. The 300 Ford pulled my boat better through the hill than the 351 could ever dream of. I remember the sound of the factory Holley four barrel, The sound of high RPMs on the down shift, and the speedo needle still dropping. So sad.