Diesel vs Gas????

[Joe-FL]

Can't really add much to what has been said about choice between gas vs. diesel. Available funds, how much will the RV be used, and how much tow capability is needed I suppose should all factor in to the decision.

[Bob Denman]

Joe,
I see that your Toad is a Harley Trike: Which one??
How do you haul it?

I wonder how many of us RV folks enjoy "wind therapy"?

[Steve70605]

Originally Posted by Chance

Regarding power, 800 pound-feet of torque at 1800 RPM is only 274 Horsepower. No matter how it's geared, it's not going to move a heavy motorhome uphill very fast.

Pulling the toad (2017 Wrangler Unlimited) we weigh in at 40K. Slowest the coach ever slowed down to going up a hill was 57 MPH. Eastern mountains and tall bridges. Not too shabby. I am sure it can be worse on steeper grades.

The Cummins also has 360 HP @ 2300 RPM. Proper gearing and Allison transmission gearing/tuning are also important.

800# of torque beats 462# any way you slice it. Also, 1800 RPM, that is the normal rpm while in sixth gear steady state. In my rig that is about 68 MPH. The chassis is designed to make the best use of torque under steady state. Torque moves loads - not horsepower. Horsepower is a calculation based of of torque and RPM's (T * RPM)/5252. Horsepower is used for acceleration. Give me 40k# vehicle and I will take the diesel over gas any day.

[Bob Denman]

What was it, that Denis Leary said in the Ford commercial?
"Torque is what gets the cap off your beer bottle."

[Chance]

Originally Posted by Steve70605

.....cut.....

800# of torque beats 462# any way you slice it.

.....cut.....

Actually, it doesn't. It is a very simple subject but not as simple as choosing the larger of the two numbers. A torque number by itself means next to nothing on a practical basis.

And for what it's worth, greater engine "power" is what it takes to climb hills faster. A torque number by itself doesn't define how fast a MH can climb; which is why torque numbers are always expressed along with RPMs, which then defines POWER.

With enough gearing a lawn mower engine can move any motorhome uphill by delivering the same torque down driveshaft, but not fast enough to be practical.

A simpler way to look at it is that 800 lb-ft of torque at 3,000 RPM can do work much faster than the same 800 lb-ft of torque at 1,500 RPM.

[Laco]

The torque vs horsepower discussions have been going on for as long as engines have existed. Simple way to differentiate, is, if you have a wrench with a one foot handle, but are unable to move a bolt, and you extend that handle by another foot, now you can move the bolt. You have effectively doubled the torque, but the power remains the same. Because of the one foot extension, you actually will be moving the bolt more slowly, but you will be moving it. Same power, more torque, more force applied, more slowly.

[Travelin' Texans]

I would much rather move my 5er with 800 ft lbs of torque at 1500 rpm than revved up to 3000 rpm, I don't care how fast I can tow it.

[Laco]

Yes and with that 800 pounds of torque at 1500 RPM, if you had more horsepower, you could gear it, so you could pull that grade faster. As Chance said, its not just about the bigger numbers, its all about the laws of physics.

[Chance]

Originally Posted by Laco

The torque vs horsepower discussions have been going on for as long as engines have existed.

.....cut.....

In mechanical engineering school there is really not much to debate on this subject. It is what it is.


Whether an engine powers a boat, airplane, water pump or motorhome, the principles are the same. People can have opinions on what "feels" better to them when driving, but that doesn't change measurable performance. Things like how fast a motorhome can climb can be calculated (estimated) very closely as long as the data is good.

[Chance]

Originally Posted by Laco

Yes and with that 800 pounds of torque at 1500 RPM, if you had more horsepower, you could gear it, so you could pull that grade faster. As Chance said, its not just about the bigger numbers, its all about the laws of physics.

Exactly. That's also why diesels will climb faster at peak HP RPMs than at peak Torque, even though the engine is making less torque. As long as transmission gearing allows it, peak performance comes at peak power, not peak torque.

[Joe-FL]

Originally Posted by Bob Denman

Joe,
I see that your Toad is a Harley Trike: Which one??
How do you haul it?

I wonder how many of us RV folks enjoy "wind therapy"?

Bob, we have a 16 black Tri Glide (FLHTCUTG). Right now I have an Aluma TK1 trike trailer. Harley weighs in about 1200 and the trailer right at 400 with spare, don't even know it is back there when towing.

Will be seriously shopping for DP and 24' enclosed trailer in the next month or so though. Going back on the road full time and want to have the Trike plus our car with us all the time.

What is in your garage?

[Joe-FL]

Bob, I'm an idiot, I didn't read your post down far enough. I see you are riding a Can Am. We were in S. Dakota this summer for the 3rd Trike Rally. There were more Can Am bikes than Harleys out there.

[Bob Denman]

[QUOTE=Joe-FL;86426]Bob, we have a 16 black Tri Glide (FLHTCUTG). Right now I have an Aluma TK1 trike trailer. Harley weighs in about 1200 and the trailer right at 400 with spare, don't even know it is back there when towing.

Will be seriously shopping for DP and 24' enclosed trailer in the next month or so though. Going back on the road full time and want to have the Trike plus our car with us all the time.

What is in your garage?[/QUOTE
]004.jpg

This is the new one that's on order:

This is the old bike:10th Anniversary 01.jpg

Tri-Glides are REALLY comfortable!

[SceneOne4teen]

Originally Posted by Brooks2017

I'm torn between diesel and gas for my next RV purchase. Thoughts on drive ability and power vs maintenance and fuel consumption. I'm moving up from TT so I'm really lost!!!

Same here.. i really like the Thor Outlaw 38KB but not really feeling the gas only option. but with that being said, im not sure that todays diesel engines with DEF is necessarily a "fuel saving" option especially with all the scary stories about parts breaking down.

I seen someone talk about adding a turbo charger or similar ?

anyone own a 38Kb that can share their experiences?

[axis earl]

Originally Posted by SceneOne4teen

Same here.. i really like the Thor Outlaw 38KB but not really feeling the gas only option. but with that being said, im not sure that todays diesel engines with DEF is necessarily a "fuel saving" option especially with all the scary stories about parts breaking down.

I seen someone talk about adding a turbo charger or similar ?

anyone own a 38Kb that can share their experiences?

I think I heard someone on this forum comment that anything over 32 feet warrants diesel power. There may be some truth to that because I have heard several complaints from the 34 foot and above crowd comment about braking issues too, not to mention the thought of towing. 32 feet and under, probably not an issue for the most part.

[mountainsam]

DEF will cost you $1.50- $2 every thousand miles. Fuel economy can be 20% or more better than gas. Gas or diesel will do you a great job. They are all modern state of the art technology.

[SuperD]

I’ve had both and no problems with either. 40 ft diesel got around 8-9 mpg, 30 ft gas around 10 mpg. Service for the diesel is MUCH more expensive, initial cost is about $10,000 more for the diesel and then add in the cost of the diesel generator. I would choose the coach first and engine second, like mountainsam said they are modern engines and both will do just fine.

[EA37TS]

We just went from a Challenger 37 ND (38 foot gas) to an Entegra Accolade 37TS (Diesel Super C) and feel we made the right decision for us.

Maintenance expense - might be a little more expensive based on amount of oil used etc... but with my Super C the labor rate is standard truck rate not motor home bang your head rates. All motor homes require maintenance so it is a wash out as far as I am concerned. Super C gets truck rates Class A diesel pushers get higher motor home rates. Check with your local service center about rates. Also, I no longer have to find a shop that can handle a motorhome to do the service. I can now pull into a Speedco (open 24 hours) or a Loves Service Center along the road and get a service with no appointment necessary plus my local Freightliner dealer is less than 3 miles from the house.

Fuel expense - yes diesel is more expensive than gas. My estimate is 10 gallons (1 tank) of DEF every 2000 miles. Approx DEF cost 30.00 per tank.

Power - My Challenger had 360 HP with about 400 ft lb of torque. The Accolade is 360 HP with 800 ft lb of torque. More get up and go from a stop, more pulling power for the hills. My Jeep Grand Cherokee can push this down the road at 70 MPH all day long and never groan about it.

My suggestion, find a floor plan you like, list the things you want in a motor home and see what you find that is close in either diesel or gas. Bottom line is you will spend more time living in it than you will driving or servicing it. The living area is the important part.

Happy searching and have a safe and Merry Christmas.

[Bob Denman]

For as fast as I drive: our little V-6 diesel does a great job.
It pulls off the line as well as the V-10 that was in our other coach, and it only gives up a little bit on the top-end.

[Chance]

In smaller rigs (like Transit) another minor difference to consider between gas and diesel is that Diesel engines typically weigh more, so remaining payload capacity is usually a little less. Large SuperC-type rigs are not normally available in gas so engine weight comparison doesn’t matter; plus they have plenty of payload capacity anyway.

It’s nothing I would consider because they are way too large, but it will be interesting to see if RV manufacturers offer gasoline versions of SuperCs based on new Ford F-550 and F-600. They will be available with both gas and diesel V8s. Up to now manufacturers haven’t pushed gas, but that may change with new engines. Hard to predict what people will buy. In any case, the 7.3L gas V8 weighs about 700 pounds less than the 6.7L Power Stroke Diesel.

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