350 HP ICE vs. 350 HP Diesel?

[RMIGHTY1]

OK, newbie here and aspiring RV'er. What comments can be made about the advantages/disadvantages of a 350 HP internal combustion engine vs. a 350 HP diesel engine in a class A camper (assuming all other variables are equal)?

[sailor_lou]

BillMFl wrote:
You are hard to please. haha I could have said the Eco boost engines are more fuel efficient because they have turbos (some have 2) that squeeze more horsepower out of a smaller displacement engine thus using less fuel while providing good performance. But the key point is that it is the turbo that allows the Eco boost engines to be more fuel efficient while still providing enough HP for good performance. A small engine without a turbo is even more fuel efficient but a dog to drive unless the size/weight of the vehicle is reduced. Lots of variables to consider. Wanna throw in wind resistance/air flow? We can beat this to death!

I'd say this entire thread was beaten to death around page 7 !! 🙂

Lou
05 Travel Supreme Envoy

[mikeintn]

I think when most people talk about "diesel motorhomes" or "gas motorhomes" they are taking in the whole package (length, ride comfort, towing rating which is as much the braking system as the engine pulling it, floor plan, . As stated a few post back, the engine itself is a small part of the whole motorhome experience.

[MikeRP]

Actually Buick came up with a very successful v6 turbo in 1987. The Buick Grand National. Fastest American production car that year.

I think we are circling the wagon on these posts which can be fun.

So, what if we do a advantages/disadvantage list. Kind of incorporate a lot of what has been said?

So Gas IN GENERAL:

1. Comes on less expensive overall Coaches.
2. Used on Coaches that weigh less than 30000 lbs gcvwr.
3. Has less maintenance expenses.
4. The Primary fuel is cheaper per gallon
5. Has Coach's equipped without air ride. Thus they ride rougher.
6. Does not have an exhaust brake
7. Has an engine with less torque than a diesel equipped Coach.
8. Comes equipped in Coaches less than 38 feet.
9. Engine is in the front of the Coach.
10. Major repairs are cheaper.
11. Gasoline is a more consistent quality fuel than diesels across the U.S. This is an important consideration in newer diesels.
12. Engine is considered less durable than diesels. Although this is contested by many with newer engines.

You guys get the idea

[the_silverback]

A whole lot of posts about which engine is best when the engine is not operating over 90% of the time. to me it is floor plan, floor plan, floor plan, then power train, mainly horsepower to weight ratio.

[wolfe10]

Yes, that document makes excellent reading for anyone with a heavy vehicle.

All the HP requirements in the document are AT THE REAR WHEELS, so engine HP must be quite a lot more because of loss to cooling fan, alternator, transmission loss, rear axle loss, etc.

Note especially the HUGE difference in HP required to move a heavy vehicle up a grade compared with the small increase in HP needed by a car.

It also give an excellent perspective on how few MPH more you will get from those 30-50 HP increase devices (like 5 MPH those few times you are on those 6% grades).

[Daveinet]

http://www.rvtechlibrary.com/engine/Cat_RV_Performance.pdf
Please note that when Caterpillar describes the requirement to move a vehicle up a hill, they specify horsepower requirement, NOT TORQUE. They do not specify diesel or gas, just state what the HP requirement is.

BTW: According to the graph on page 5, I should be at 52 to 53 mph with a total weight of 40K lbs.

Updating per Brett's point, since the graph refers to rear wheel HP, typically when dyno testing, drivetrain losses are usually figured at 20% to 25%. Required rear wheel HP is 350 to maintain 45 mph 6% grade. I'm running somewhere between 420 and 440 HP, which puts me pretty much right at the requirement.

[hardtobe]

Daveinet wrote:

JumboJet wrote:
You can build a 900HP 360 c.i. engine that will push that 18,000 lb. motorhome over 100 mph, but it will not last very long.

On flat land, it only takes 420 HP. I've seen 98 3 times, 2 of those times it was towing the same Jeep. It had plenty left, just ran out of open countryside. Lower profile helps on wind resistance.

But none of that matters, what really matters is what is practical to drive. One should note that the stock Workhorse gas chassis has a 30,000 GCWR.

the point is we are talking mountain passes and 38000 lbs not flat land and 14K or 15K.Take your 502 as I have said fifty times and put it in my 38K gross unit and u wont go up that same hill at 45MPH never mind your claim of 80.that's my whole point.!!!

[Daveinet]

JumboJet wrote:
You can build a 900HP 360 c.i. engine that will push that 18,000 lb. motorhome over 100 mph, but it will not last very long.

On flat land, it only takes 420 HP. I've seen 98 3 times, 2 of those times it was towing the same Jeep. It had plenty left, just ran out of open countryside. Lower profile helps on wind resistance.

But none of that matters, what really matters is what is practical to drive. One should note that the stock Workhorse gas chassis has a 30,000 GCWR.

[hardtobe]

JumboJet wrote:

hardtobe wrote:
There are only a few 500 mile Nascar races these days and one 600 mile one and its not because of engines.its more with TV,fans, etc etc
If race is too long you loose your viewing audience etc
and besides what does it have to do with gas verses diesel??

You can build a 900HP 360 c.i. engine that will push that 18,000 lb. motorhome over 100 mph, but it will not last very long.

I have seen many NASCAR engines fail in those races. It did seem there were less engine failures last year though. Mostly broken valve springs.

yes but not up 6+7% grades and like you said would never last
NASCAR engine failures have been very few in last few years compared to the old days.But back then those were not the $100K super engines being used today.Lots of start at the back of the pack because of engine replacement is not neccessarely because it blew up

[JumboJet]

hardtobe wrote:
There are only a few 500 mile Nascar races these days and one 600 mile one and its not because of engines.its more with TV,fans, etc etc
If race is too long you loose your viewing audience etc
and besides what does it have to do with gas verses diesel??

You can build a 900HP 360 c.i. engine that will push that 18,000 lb. motorhome over 100 mph, but it will not last very long.

I have seen many NASCAR engines fail in those races. It did seem there were less engine failures last year though. Mostly broken valve springs.

[BillMFl]

You are hard to please. haha I could have said the Eco boost engines are more fuel efficient because they have turbos (some have 2) that squeeze more horsepower out of a smaller displacement engine thus using less fuel while providing good performance. But the key point is that it is the turbo that allows the Eco boost engines to be more fuel efficient while still providing enough HP for good performance. A small engine without a turbo is even more fuel efficient but a dog to drive unless the size/weight of the vehicle is reduced. Lots of variables to consider. Wanna throw in wind resistance/air flow? We can beat this to death!

[Daveinet]

BillMFl wrote:
Ya I know, but I don't know of any rv gassers with a turbo. And not many diesels out there without a turbo. Interestingly the new "Eco boost" fuel efficient engines in passenger cars are using turbos to squeeze more efficiency out of less fuel. Used to be that turbos in gas engines were mostly used for more horsepower in high performance cars.

Sort of. Technically the turbo does not increase efficiency, but just allows the use of a smaller engine, which is where the efficiency lies - allows it, because it increases HP.

[BillMFl]

OhhWell wrote:

BillMFl wrote:
The diesel also does much better at high altitude than a gas engine, but many rvs seldom make it to the Rockies.

That's the Turbo again, not the fuel type.

Ya I know, but I don't know of any rv gassers with a turbo. And not many diesels out there without a turbo. Interestingly the new "Eco boost" fuel efficient engines in passenger cars are using turbos to squeeze more effiency out of less fuel. Used to be that turbos in gas engines were mostly used for more horsepower in high performance cars.

[hardtobe]

wny_pat wrote:
Original question in this thread:

RMIGHTY1 wrote:
OK, newbie here and aspiring RV'er. What comments can be made about the advantages/disadvantages of a 350 HP internal combustion engine vs. a 350 HP diesel engine in a class A camper (assuming all other variables are equal)?

Good first post which certainly opened Pandora's Box. If you intend on putting on a awfully lot of miles and keeping the rig a very long time, you want a diesel pusher. If you are not going to put mega miles on it and don't plan on keeping it for a long time, you want a gasoline rig. And if you have read all the posts in this thread, you probably now realize that not all 350 HP internal combustion engines are not created the same, and the same with 350 HP diesel engines.

you want diesel pusher(newer not old ones) also if u want quite,nice ride(air) better brakes,better handling and over all better built