5.4L vs 6.8L in small Class C

[mr61impala]

We have been looking at Class C vehicles in the 24' range typically denoted as 22H, 23C, etc., we will not be towing a "toad".

I see mostly units with the 6.8L V10 but occasionally one pops up with a 5.4L V8.

For many years my parents had a 22' Mini Winnie with 360 Chrysler power and it had plenty of get up and go.

1). Does a modern 5.4L engine have as much grunt as that old 1977 Dodge had?

2). Is there any significant mpg advantage when selecting the 5.4L as opposed to the 6.8L? (Most 6.8L owners claim 7-8 mpg range, I have not seen any reports from owners feeding 2 fewer cylinders).

Over the years I have towed 3 smaller TT with 2 different 1/2 ton pickups and find traveling around 60 mph to be optimal, I don't anticipate traveling any faster in this rig.

[mr61impala]

Healeyman wrote:

mr61impala wrote:
Thanks to all for your thoughtful input!

I am still hoping that an owner or renter of a V8 powered Class C would weigh in with some real life feedback and data.

I gave you 75,000 miles worth of real life experience with a small V8 powered Class C in my post above.

Tim

And I appreciate your input. So you feel the level of power was adequate under most circumstances?

[5Mainecampers]

Another factor regarding any RV besides weight is the wind resistance; it takes more power for a box to cut thru the wind. Furthermore, due to the wind resistance most MH are hard pressed to get more than 10MPG, regardless of the motor.

[Monaco_Montclai]

we have a 29ft Montclair by Monaco.6.8l.before we towed we got 12.6, checked it many times. now the clock is 25k miles.still 12.6. started the tow thing. checked it then. and the numbers are a constant 10 mpg. when climbing any hill, and I need some more speed, I make the tranny shift, and let it wind up and man the power is wow man . now its all happy-camping

[Desert_Captain]

"Depends on what you want.
No gas RV will be great on MPG.... (if you want better gas mileage, the Chevy seems to be about 1-2 MPG better.)"

and you will have less power, they go hand in hand.

"Compare:

Ford 6.8 V10
2 valve version - old version
265 horsepower at 4,250 rpm
425 foot-pounds at 3,450 rpm"

Those are old numbers that only apply to the old V-10's. If your V-10 is 2006 (?) or newer you will have 305 Hp at 4250 and 420# of Torque at 3250 in a 2 valve. Mate this power package to the 5 speed Torque Shift trans (with full Tow Haul), and you will have plenty of power and 9 to 10 mpg in most Class C's (at least anything under 30').

Our 24' C cruises 60-62 at 2100 rpm, 6% grades are 55 - 60 at 3250 rpm (max torque) and once in a blue moon will it down shift to third and wind out to 4,000. We average 9.5 mpg consistently (and that includes some generator time).

As always... YMMV.

:C

[DrewE]

Gene in NE wrote:

Oldme wrote:
Depends on what you want.
No gas RV will be great on MPG.... (if you want better gas mileage, the Chevy seems to be about 1-2 MPG better.)

Compare:

Ford 6.8 V10
2 valve version - old version
265 horsepower at 4,250 rpm
425 foot-pounds at 3,450 rpm

3valve version V10 - new version - only one availabe
Horsepower (SAE net) 362 @ 4750 rpm
Torque 457 lb.-ft. @ 3250 rpm

Ford 5.4 V8
5.4L (330 CID)
Horsepower (SAE net) 255 @ 4500 rpm
Torque 350 lb.-ft. @ 2500 rpm...

It has been reported that the 3 valve V10 is not available in motorhomes. (comment in red added to author's posting)

The three-valve version is not available in the E series chassis (be it a regular cargo/passenger van or a cutaway chassis for a class C motorhome or whatever) due to space limitations—the three valve heads are taller than the two valve heads, and the chassis doesn't have clearance for them. The two-valve version is not currently available on class A motorhomes (and probably most or all truck chassis models), as I understand things.

[rjstractor]

Compared to even the 5.4, the old 360 Dodge (or Ford or Chevy small block from that era) was a turd. Having said that, the V10 compared to the 5.4 will give you better acceleration, faster hill speeds and probably the same mpg as the 5.4. No reason to not get a V10 if you find a motorhome you like with that engine.

[Healeyman]

mr61impala wrote:
Thanks to all for your thoughtful input!

I am still hoping that an owner or renter of a V8 powered Class C would weigh in with some real life feedback and data.

I gave you 75,000 miles worth of real life experience with a small V8 powered Class C in my post above.

Tim

[tpi]

Duplicate

[tpi]

I can see where a smaller/lighter coach with the V10 would be lots of fun shooting past the 31 footers in the mountains.

These things even with the V10 are not that fast. Sure they'll pass 31 footers with V10. But they'll be racing at 4000 to do it. I will test my 11000 pounder at some point but I suspect 0-60 times are in the 16 17 second range. Yes I've passed slower motorhomes, but four cylinder cars routinely blow by me.

Drive it nice and mild let it roll back to 50 on a hill @ about 3100 RPM seems to me like the way to go. Sure they'll run all day at 4000 RPM- but I tend to drive so it stays in the mid 3000s or less. The speed and handling prowess of these motorhomes can be overrepresented on these boards.

Just people happy with their RVs. But there are pluses and minuses.

[tpi]

Alternative view: I don't use tow haul unless in hilly areas and I find a need. I find it to be over the top hyper. Banging off downshifts on brief downhills, racing engine to over 4500 RPM on a hill that will run out imminently. There is no way it can read the terrain as well as a set of eyes. For my tastes it holds gears too long on acceleration as well. Frankly I think as implemented it is of marginal utility. Good for engine braking when needed. But I think a set of paddle shifters would be better-simply select the gear of choice. On acceleration it is an alternative shift program of some usefulness if you feel you want to run out the gears a bit longer.

At least on my 24' I don't see any way towhaul could increase fuel economy. Everything it does points to just the opposite.

At some point a GPS tie in with the towhaul could give a better shift strategy for those who want automatic shifting in all conditions. At least the system would know the hill would run out in a half block.

[Jopops]

pnichols wrote:


This effect will especially be felt if you get a 2005 or later V10 powered motorhome. From 2005 onward Ford mated their V10 truck engine with their superb 5-speed (6 speeds internally) computer controlled TorqShift transmission. Put this transmission into it's Tow/Haul mode and the V10's performance really shines. Tow/Haul mode is meant to be used in V10 powered trucks when a heavy load is being carried .... and since a motorhome is heavily loading the chassis all the time .... many folks just leave their 2005 and later Class C motorhomes in the Tow/Haul mode all the time. Overdrive still works in Tow/Haul mode (plus you get automatic downhill engine braking), so cruising gas mileage is not effected in this mode while enjoying the improved responsivness.

So many people have so many different opinions on this. I always looked at it like you are; an E450 VAN wouldn't really need to run Tow/Haul, but a E450 w/ a house dropped on it would almost certainly constitute HAULING right? Yet so many people only engage Tow/Haul when going up or down hills.

I still don't really get it - I want to leave it in Tow/Haul b/c logically it makes sense to me but so many don't run it there.

[mr61impala]

Thanks to all for your thoughtful input!

I am still hoping that an owner or renter of a V8 powered Class C would weigh in with some real life feedback and data.

I understand that the larger engine (305 hp, not 362 hp) will be more powerful, I am just wondering if the V10 that does such a good job in a #14,500 31 footer with multiple heavy slides is really essential in a #11,500 coach with less storage, smaller tanks and no slide.

I can see where a smaller/lighter coach with the V10 would be lots of fun shooting past the 31 footers in the mountains.

It just seems like a coach that weighs 30% less could somehow get by on 20% less HP, even accounting for the final drive gearing.

[chaeworld]

I own a 2009 E250 cargo van w/5.4L. A 5.4L is great for a 3/4ton cargo van plenty of torque and horsepower to get out of the way. And carry a load. I get 14mpg average.
I would not recommend one for any motor home two different applications.
I have a 2003 Winnie Minnie 29B with a E450, 6.8 V10 I would not want any less of an engine in a RV.
I get 6-8 mpg maybe a little better if I drove easier.

Chae

[leeper]

5.4 will have to work harder than the 6.8 V10. 5.4 will get worst gas mileage than the V10.

[S_NotFree]

I think in a heavy vehicle, always get the larger engine. You will appreciate the extra torque on steep grades and short entry ramps or when you have to pass a farm tractor on a busy 2 way. Also, you will be using more pedal on the smaller engine using as much fuel plus putting more strain thus wear on it. If you ever want to tow anything, even more reason.