Diesel more sluggish than gas?

[Mostovi]

New to the site, so hello to everyone. Will be moving into the motor home world soon. I had pretty much settled on DP or large super C, but I've read several posts here where some folks said some diesels are actually more sluggish than gas. Contrary to all I've ever heard. Can those of you with more experience than myself please explain? Thanks!

[willald]

Bruce Brown wrote:
You need to take a new Super Duty for a drive then get back to me on this........

I have, and I agree, those things unloaded, are quick. My BIL has one (fairly new F250 with the 6.7 diesel), and that thing is cool.

However, we're not talking about unloaded pickup trucks with 400 horsepower and 800+ ft-lbs of torque. Thats not what the original poster asked about. The question was if diesel pusher MOTORHOMES are sluggish. And, that's the question I answered.

If you recall what I said previously, I kinda covered the whole unloaded diesel pickup thing:

....No, what I drove was not underpowered, it was just, sluggish accelerating, like most diesel are unless they've been modified, or are totally unloaded (pickup trucks not towing).....

Will

[tinkerer]

Back some years ago I had an older Dodge pickup with a 160 hp Cummins diesel and a Chevy with Vortex V8. The Chevy would take off like a scalded cat empty where the old Dodge Cummins was sluggish from a dead stop empty. Put a trailer behind them and there was no comparison where the Chevy really struggled where the Cummins was night and day ahead especially when there were some grades. There is a reason OTR trucks have 6 cylinder diesels. If you want a drag racers the gasser will be ahead. But I suspect most motorhomes are not purchased for purpose of drag racing.

[ArchHoagland]

The biggest difference, for me anyway, between a gasser and a diesel is not climbing the mountains but rather descending the mountains.

I have a GM 8.1 gas engine and engine braking is almost non existent. A diesel engine will hold back the RV with very little braking action.

The only time I get diesel envy is going down mountains and stopping to get gas with my 75 gallon gas tank. Diesel guys can go forever almost between fuel stops.

[Mr_Mark1]

Will,

You are a good poster as I remember from the past, we just don't agree on this.

Safe travels,
MM.

[Bruce_Brown]

willald wrote:

I've also driven (and rode in) several other diesel powered rigs, not just Motorhomes. And my experience has been the same for all of them - Diesels, in general, are slower to accelerate, because of the very nature of how diesel fuel burns slower than gas. No denying that, really.
Will

You need to take a new Super Duty for a drive then get back to me on this. :W

Or just read this Car & Driver Review to see where an 8300# Crew Cab 4x4 did 0-60 in 6.9 seconds. I'd say that was far from sluggish.

They also tested an F250 gasser that only weighed 6532#. It took 6.7 seconds to hit 60 MPH.

The diesel is over 1700# heavier and only 0.2 seconds behind in 0-60 times. Sluggish? Not in my opinion. :B

(Plus after having a Super Duty gasser, I'm now on my 3rd Super Duty diesel since. Lets just say "never" is a really long time but thats when I plan on buying another Super Duty gasser)

With that said, my baby truck (F150 Crew Cab) has a 2.7 Ecoboost gasser. Seeing as that is nothing more than a car with a box, the little Ecoboost is simply awesome.

For work, buy a diesel. For light transportation a boosted gasser works well.

[gutfelt]

Agreed, I'm not 'dogging' any coaches, at least that wasn't my intention. The original poster asked a specific question, if diesel pushers were sluggish, and I answered that specific question - based on my experience, YES.

I agree, that there is a 'butt for every seat', and diesel pushers definitely have their place and have their advantages. But, they are sluggish compared to a gasser. That is what the original poster asked, and I answered. Thats all.

Will

If you take a new 38-39 ft 3-4 slide 320HP ford Class A MH and loaded for travel and I take my 40 FT pusher with a 425HP Isl and loaded for travel and we take off form a dead stand still I bet you will not get to 60MPH any quicker than I do

[willald]

I will say I 100% believe your seat of the pants evaluation, and here's why; noise sounds and feels fast. Meaning, I think you'll find the V10 isn't as fast as it feels and the diesel isn't as slow as it feels. The excessive noise of the V10 makes it feel fast, the quietness of the diesel makes it feel slow.

Our current MH is actually quick off the line, but you have to pay attention. Diesels are drive-by-wire so there is a slight delay from the time you step on it until it reacts. Once it reacts you're all good.

Good point, and I thought the same thing for a while.

That may be the case with some rigs, but I am one that pays very close attention to acceleration, and I'm here to tell you, my experience is that diesels just do not accelerate the same, they are slower getting up to speed.

Definitely true that once it gets up to speed a diesel is muuuuch better at holding that speed on hills or whatever. No argument there. However, strictly in terms of acceleration and throttle response (which is what the original poster was asking)...Diesels fall flat on their face every time, when you really step on it.

Think of it this way: How many drag racers, where acceleration is most important thing, use diesel?

Oh yeah, your info on the exhaust brake is a bit flawed too. Yes, some only have an exhaust brake, many have a true Jake Brake. Look up the differences.

The gassers only have a transmission brake. The engine itself isn't controlling it, the transmission is.

Actually, your info there is a little flawed, too.

Gassers use vacuum in the intake to slow things down (and compression in the cylinders to some extent). The engine itself is doing the braking. There is no braking done in the tramsmission. Yes, the transmission when in tow/haul mode will down shift more when going down hill, forcing the engine to turn more RPMs, which means the engine generates more stopping power. Bottom line, though, is its the engine doing the braking, not the transmission.

Either way, I'm glad you're happy with yours and it's serving you well.

Ditto. My intention is not to 'dog' anyone else's coach, as someone else implied I was. I was just answering the specific question the original poster asked, based on my experience. That's all, its not anything personal. 🙂

Will

[willald]

gutfelt wrote:

the gasser has much, much better, quicker throttle response. I like that.

If that makes u happy so be it but let me tell you the superior construction,handling, air ride suspension ,engine Brake, overall larger size of a diesel pusher and super quite interior even under acceleration far far far exceeds the one small inconsequential factor of your so called throttle response !! and on a steep loaded mountain climb my 40 ft 450HP ISL will kill your crappy little ford 320HP ford system and I can clearly hear the radio on low volumn LOL

No need to get all 'testy' and boastful.

I don't disagree with any of that (except the last sentence...My Ford has 362 horsepower, not 320, haha).

However, none of what you boasted about there is what the original poster asked about, is it? Original poster specifically asked if diesels were more sluggish, and I specifically answered that question. That's all. 🙂

Will

[willald]

Mr.Mark wrote:
Will, it looks like you have strong feelings about your experience. You drove one diesel coach and now you make that blanket statement?

Noooo, I actually have driven several different ones at various times, because DW really wanted (and still wants) one for the other reasons already discussed. The one I alluded to above, was just the most recent, that I remember the most, because it was a very nice one that we really wanted, but I couldn't get past how sluggish it was, like every other diesel I've driven.

I've also driven (and rode in) several other diesel powered rigs, not just Motorhomes. And my experience has been the same for all of them - Diesels, in general, are slower to accelerate, because of the very nature of how diesel fuel burns slower than gas. No denying that, really.

Mr.Mark wrote:
And I can tell you the motorhome that you drove was UNDERPOWERED! Many times the engine chosen is totally for a price-point.

A 39' coach, 33k GVWR with a Cummins ISL9 engine, 380 horsepower, 1150 ft-lbs of torque (and lists for nearly $300k new) is UNDERPOWERED? Ummm, Really? Good gracious, Mr. Mark, does one have to spend nearly 7 figures and get something with a 500 horsepower Detroit diesel to not have an 'underpowered' diesel pusher? 🙂

No, what I drove was not underpowered, it was just, sluggish accelerating, like most diesel are unless they've been modified, or are totally unloaded (pickup trucks not towing).

If we were talking about a coach this size with the smaller 6.7 ISB engine with only 360 horsepower and 800 ft lbs of torque, I would agree, underpowered. That was not the case, though.

Mr.Mark wrote:
I'm certainly not going to dog a gas coach, all coaches have their place in the RVing world.

Agreed, I'm not 'dogging' any coaches, at least that wasn't my intention. The original poster asked a specific question, if diesel pushers were sluggish, and I answered that specific question - based on my experience, YES.

I agree, that there is a 'butt for every seat', and diesel pushers definitely have their place and have their advantages. But, they are sluggish compared to a gasser. That is what the original poster asked, and I answered. Thats all. 🙂

Will

[DSDP_Don]

Gas engines accelerate, diesel engines gain momentum!

[gutfelt]

the gasser has much, much better, quicker throttle response. I like that.

If that makes u happy so be it but let me tell you the superior construction,handling, air ride suspension ,engine Brake, overall larger size of a diesel pusher and super quite interior even under acceleration far far far exceeds the one small inconsequential factor of your so called throttle response !! and on a steep loaded mountain climb my 40 ft 450HP ISL will kill your crappy little ford 320HP ford system and I can clearly hear the radio on low volumn LOL

[Bruce_Brown]

Will,
I just don't know where to start...

Having OWNED a 350 gasser, a Banks Powered 460, a V10, as well as Cat 3126 and our current Cummins ISL, all I can say is...umm, ok. :B

I will say I 100% believe your seat of the pants evaluation, and here's why; noise sounds and feels fast. Meaning, I think you'll find the V10 isn't as fast as it feels and the diesel isn't as slow as it feels. The excessive noise of the V10 makes it feel fast, the quietness of the diesel makes it feel slow.

Our current MH is actually quick off the line, but you have to pay attention. Diesels are drive-by-wire so there is a slight delay from the time you step on it until it reacts. Once it reacts you're all good.

Once moving there is simply no comparison. Hills that used to bring the V10 to it's knees the diesel just cruises up. The other thing to keep in mind, you said you drove a new one; diesels don't start to wake up until they get some miles on them.

Oh yeah, your info on the exhaust brake is a bit flawed too. Yes, some only have an exhaust brake, many have a true Jake Brake. Look up the differences. The gassers only have a transmission brake. The engine itself isn't controlling it, the transmission is.

Either way, I'm glad you're happy with yours and it's serving you well.

[Mr_Mark1]

Will, it looks like you have strong feelings about your experience. You drove one diesel coach and now you make that blanket statement?

And I can tell you the motorhome that you drove was UNDERPOWERED! Many times the engine chosen is totally for a price-point.

I'm certainly not going to dog a gas coach, all coaches have their place in the RVing world.

Safe travels,
MM.

[willald]

...I know all the diesel owners will disagree, but as one thats driven both....I'm here to tell you, that YES, compared to a fuel injected V10 gas powered motorhome, diesel powered motorhomes are SLLLLLUUUUGGGGIIISSHH.

Last time I drove a diesel pusher Motorhome a year or two ago......I walked away totally unimpresed, and muuuuch happier with how my V10 powered gas Motorhome drives. And, this was NOT an underpowered diesel pusher, it had the Cummins ISL 380 hp/1100 ft-lb torque engine on a 39' coach (and was almost brand new, nothing wrong with it).

I walked away thinking....Man, is THIS what people swear is sooo great, and worth the extra $100k or more that you pay for it? I don't think so, haha.

Yep, I test drove a diesel pusher motorhome with checkbook in hand, and walked away, totally not interested in it. Soo, don't believe that thing about 'don't test drive a diesel pusher with a checkbook in your pocket'. 🙂

Here's the main reason why: When you need to get going quickly with a gasser motorhome, you step on the gas and yes, it gets loud, and it turns some RPMs. However, it gets MOVING. Has great throttle response. You do the same with a diesel powered Motorhome, it grunts, lugs and slooooowly gets up to speed. It can't downshift and get moving quicker like a gasser does, it just has to grunt and lug. Basically, the gasser has much, much better, quicker throttle response. I like that.

Oh, and coming down the hills? Put my Torqueshift tranny in tow/haul mode, it downshits, holds the rig to a comfortable speed very well, without hardly touching the brake. And it does so, without having to choke up the exhaust like diesels do. Gasser engines actually are able to provide that 'engine braking' just the way they are, using vacuum generated in the intake. Diesels cannot do that at all without adding a 'Jake Brake' that closes up the exhaust and slows it down with back pressure. They both accomplish the same thing, but I like the way a gasser engine does it better. Just seems like a more natural, easier, more trouble free way to do it.

Yes, several other aspects make the diesel pusher more attractive (quieter, more torque for climbing hills, can handle much more weight so more options amenities, often comes with air suspension and brakes, etc). However, strictly from a seat of the pants feel when driving.....I'll take my V10 gasser Motorhome over any diesel, any day of the week and twice on Sunday. And, keep a LOT more of my hard earned $$ in my pocket where it belongs. 🙂

[William_B]

I would also add that coming down the hills is much better in a diesel, whether you have an exhaust brake or a Jake, you are in much better control.