Gas engine and Diesel of same specs.Pull the same.

I'm going to try one more time to explain why a turbocharged engine works better in a tow vehicle. Say there is very steep hill of a known incline and a heavy rv also wit a known weight. Say the calculation is correctly done and it reveals that the HP required to go up the said hill with said rv at 20 mph is 400 HP at the crankshaft.

Let's say a turbo diesel is set up to put out 400 HP @ 2500 rpm and geared such that its 6 speed transmission will allow the truck to move 20 mph in 1st gear @ 2500 rpm....the truck is run up the hill and low and behold it does 20 mph.

If a gasser is set up to make 400 HP at 5000 rpm and has a rear axle ratio double that of the diesel it too will run up the hill at 20 mph.

When cruising down the highway at 70 mph the diesel will run in 6th at 1600 rpm where as the gasser will be running 3200 rpm.

Because 3200 rpm is too fast for a cruising rpm in even a gasoline engine it can be said that if the non turbo engine is going to compete with a turbo charged engine in a tow vehicle it will need more gears.

rhagfo wrote:

Taco wrote:
Yes they have the same pulling capability. They will go the same speed over the same terrain. The gas will do it at a higher rpm and consume more fuel.

I seriously don't buy it that a diesel engine is any longer lasting or more reliable for the engines they put in a light duty truck. The engines they put in light duty pickups are not the same they put in class 8 trucks, container ships, locomotives, bulldozers, or any other commercial application. Just because the engine in a class 8 truck lasts a certain number of miles doesn't mean because it uses the same type of fuel, the light duty pickup engine will do the same.

The diesel heads of this site regularly do the folks who come on here looking for advice a disservice. They tell them they need a diesel, so the person goes and spends 9k more for the diesel being assured they need it and it will last forever. When it will last no better and a gas engine will do the job also.

Just a few minutes ago a diesel owner made a post that his diesel truck only lasted 100k and he was led to believe they lasted a long time. Could have probably saved himself enough cash on that diesel purchase that even if he got a gas engine and even if it failed he could have bought a new engine.

100K diesel death must have been a Ford 6.0. That is not the norm I still pull 11,000# 5er at 260,000 miles. I expect another 260,000out of it.

Actually, it's a Duramax.

As to the cost of diesel, gas at $3.50 and diesel $4.00 gas 8 mpg and diesel 12 mpg. That places the diesel at 15% more than gas, but getting 50% better mileage! I will stick with the diesel, most gassers that slam diesels have never towed with one if they did they would understand why we like our diesels.

I have towed with diesels, I drive a diesel every day...and I will never own another one. Diesel has jumped the shark.

transamz9 wrote:

RPM does not scare me what's so ever and have no problem doing it when it's needed to do what I want to do. When I say that my car shifts at that RPM, it is not loafing by no means. Loafing it shifts at about 12-1400 just like my truck does. I'm not "irrational" about this I just know what I like in a tow vehicle. I drive a lot of trucks day in and day out and usually towing something or at least loaded. I will tell you this. Using all of the RPM your truck has to offer to make it to the top of the hill does not always give you the best results.

As far as the 454 remark, you know what I'm talking about. It was a towing machine compared to the other options in the same years. OH! I forget, you are one of those that like to come apples to oranges just like the post right above this one where you say that your little ole 5.4 will run circles around you "1995" turbo Cummins. So I guess your little ole 5.4 would run circles around my 2005 Cummins also. LOL! Dream on!

OH, BTW thanks for the English lesson, you really look smarter to me now.

If you're Corvette (if you really have one) shifts below 2500rpm under heavy throttle, something is wrong with it.
Using the rpm available when necessary has always giving me the best results both gas and diesel. If the hill requires peak hp rpm, then that's what's used.
The 454 as well as the Cummins was thought to be a towing machine in '95. Both are slugs compared to current Cummins Rams as well as small block gassers. Therefor, todays small block gassers are towing machines. And they're reliable and issue free.
Never said my 5.4L grocery getter would run circles around your little car engine '05 Cummins. That was your assertion, not mine. Not dreaming. We're loading up to go camping this week.
Tenga un buen dia!

I wrote:

It takes torque to keep the vehicle speed up. RPMs measure engine speed, which can easily be increased by downshifting in the transmission.

transamz9 wrote:

The RPM's I'm referring to is at the rear wheels (on the ground where it counts). This is what I've been talking about. These motors are TUNED to run their best at their intended use RPM's.

Well I won't dispute the tuning, which I think was your point. But even in the sentence above you're mixing wheel RPM and engine RPM.

My point was that the role of gearing is to convert an engine's torque/RPM combination (aka power) to whatever torque/RPM combination you want at the wheels. That's different than tuning the engine for sure, but when it comes to determining how well it will perform in a vehicle, selecting the proper drivetrain is as important as the engine itself.

-- Rob

Hannibal wrote:

transamz9 wrote:

The RPM's I'm referring to is at the rear wheels (on the ground where it counts). This is what I've been talking about. These motors are TUNED to run their best at their intended use RPM's. That RPM in vehicles is 1500-2000 give or take. Marine engines (gas) 5000-6000 in must cases. Lawn mowers is 3500-3800. So on and so on. My Corvette has no problem running around in the 1500-2000 range. Even on take off it shifts at or before 2000 rpm's.

It would be different if they would build truck engines like they use to. Now they just use the same engine and tune it differently. The old 454 such use to just be able to lug right on up a hill.

RPM is already plural. Revolutions is the plural. It's per minute, not per minutes.
My truck running 70mph is turning the exact same wheel rpm as a diesel powered duplicate F250.
The intended use rpm in my truck is from 650~rpm to 5k~rpm. To say otherwise really makes no sense. Because it scares you doesn't mean it's hurting the engine. It simply means you're irrational and don't understand anything beyond your perception of what you think it should sound like.
Put your foot into your Corvette. It'll pin you back as it shifts at 5k rpm or more. My truck shifts at 2k rpm or less when I'm loafing around town too. The old 454 is a turd compared to the new small blocks. You shouldn't lug any engine gas or diesel. Especially when there's free rpm to let gear reduction do the work and reduce the load on the engine which in turn reduces wear on the bottom end.

RPM does not scare me what's so ever and have no problem doing it when it's needed to do what I want to do. When I say that my car shifts at that RPM, it is not loafing by no means. Loafing it shifts at about 12-1400 just like my truck does. I'm not "irrational" about this I just know what I like in a tow vehicle. I drive a lot of trucks day in and day out and usually towing something or at least loaded. I will tell you this. Using all of the RPM your truck has to offer to make it to the top of the hill does not always give you the best results.

As far as the 454 remark, you know what I'm talking about. It was a towing machine compared to the other options in the same years. OH! I forget, you are one of those that like to come apples to oranges just like the post right above this one where you say that your little ole 5.4 will run circles around you "1995" turbo Cummins. So I guess your little ole 5.4 would run circles around my 2005 Cummins also. LOL! Dream on!

OH, BTW thanks for the English lesson, you really look smarter to me now.

My lowly 5.4L would run circles around my '95 turbo charged Cummins Ram towing or not. It was cool but man what a slug it was.

rhagfo wrote:

wilber1 wrote:
When it comes to power, the biggest difference between the 8.1 and the diesel is the turbocharger, not the fact one is diesel and the other gas. Take the turbocharger off a DMAX, PS or Cummins and the 8.1 will eat their lunch. A 6.0 will eat their lunch. Turbo diesels are great for towing but you couldn't give me a normally aspirated diesel.

Yep, take that 8.1 down to 5.9 and see how it does, might get better fuel mileage but wouldn't tow near as much!

Bet a GM 6.0 gas a Ford 6.2 gas or a Mopar 6.4 gas would whip their diesel cousins if the diesel's turbochargers were removed.

Modern 6 speed and future 8+ speed transmissions are also much better at putting torque to the ground enabling gassers to make the most of what they have.

No way they would get better mileage though, quite the contrary. But then how could they get better mileage when they would be putting out twice the horsepower of the normally aspirated diesels.

wilber1 wrote:
When it comes to power, the biggest difference between the 8.1 and the diesel is the turbocharger, not the fact one is diesel and the other gas. Take the turbocharger off a DMAX, PS or Cummins and the 8.1 will eat their lunch. A 6.0 will eat their lunch. Turbo diesels are great for towing but you couldn't give me a normally aspirated diesel.

Yep, take that 8.1 down to 5.9 and see how it does, might get better fuel mileage but wouldn't tow near as much!

transamz9 wrote:

The RPM's I'm referring to is at the rear wheels (on the ground where it counts). This is what I've been talking about. These motors are TUNED to run their best at their intended use RPM's. That RPM in vehicles is 1500-2000 give or take. Marine engines (gas) 5000-6000 in must cases. Lawn mowers is 3500-3800. So on and so on. My Corvette has no problem running around in the 1500-2000 range. Even on take off it shifts at or before 2000 rpm's.

It would be different if they would build truck engines like they use to. Now they just use the same engine and tune it differently. The old 454 such use to just be able to lug right on up a hill.

RPM is already plural. Revolutions is the plural. It's per minute, not per minutes.
My truck running 70mph is turning the exact same wheel rpm as a diesel powered duplicate F250.
The intended use rpm in my truck is from 650~rpm to 5k~rpm. To say otherwise really makes no sense. Because it scares you doesn't mean it's hurting the engine. It simply means you're irrational and don't understand anything beyond your perception of what you think it should sound like.
Put your foot into your Corvette. It'll pin you back as it shifts at 5k rpm or more. My truck shifts at 2k rpm or less when I'm loafing around town too. The old 454 is a turd compared to the new small blocks. You shouldn't lug any engine gas or diesel. Especially when there's free rpm to let gear reduction do the work and reduce the load on the engine which in turn reduces wear on the bottom end.

Why not say 5mpg for the gasser and 17mpg for the diesel. I get 8.5~ mpg with the gassers and 10.5~mpg with the diesels towing over the same routes at the same speeds.

For the cost of a ticking fuel injection system on a newer diesel, I can toss in a new long block and transmission so the cost savings is a gamble in the long run. The 100k mile warranty goes poof at around four years with me.

Not to forget the cost of DEF, fuel filters and special fuel conditioners for the delicate HPFP.

I haven't been banned from buying my 7th diesel. As it is, the only real practical benefit I see is 30% lower rpm. And that's only if you're erroneously afraid of a gas engine running in it's normal rpm range. 3800rpm is peak torque rpm with my wheezing 5.4L grocery getter. It can run there all day under load if it ever needs to without worry. As it is, it's only an occasional sprint at that rpm. On flat ground we run 2k rpm in O/D and 2600~rpm against any breeze or slight incline. Not a problem.:B

Why do people gear their diesels like a gasser so it'll run like a diesel? Why not a 3.08 rear ratio to put it at it's 1600rpm torque peak?