Oct-04-2012 05:21 PM
Nov-16-2012 11:55 PM
427435 wrote:uncleluap wrote:ed1 wrote:
As an engineer (retired) I'm always amused by the arguments over diesel vs gas torque. The interesting part is that your diesel, generating 800 ft lbs at 1500 RPM, is exactly equivalent to your gasser generating 400 ft lbs at 3000 RPM. Why? Because both engines drive the same size wheels but at different engine speeds, so the gasser has a final gear ratio which is 2X that of the diesel. Guess what the 2:1 gear ratio does?- it multiplies the gasser's engine torque by a factor of 2. So, at the rear wheels, both engines provide the SAME torque.
now to be fair, the diesel is humming in the rear of the coach, while the gas engine is roaring under your feet.
This discussion always reminds me of the specifications for the M1A1 Abrams tank. 135,000 lbs, top speed of 60 mph, able to climb 45% slopes! And all with 270 ft lbs of torque!
How do they do that? They generate the torque at 30,000 RPM, then feed it into a 10:1 reduction gear. So then you've got 2700 ft lbs and 1500 HP at 3000 RPM.
I seriously doubt you are correct on your figures however your never going to see a ford V10 in 40ft 4 slide pusher style Motorhome
The reason being is a V10 ford gas engine does not produce enough torque at any RPM to move 36K+ up hills etc at any where near accepted level,s of speeds and reliability
Again, it's not the torque but the hp (and enough gears) that actually move a MH uphill.
The reason you don't see gassers in bigger MH's is that the people with the money for a 40' MH are also willing to pay the money for an air-ride suspension system and to have the engine/transmission in the back (quieter).
Nov-16-2012 11:48 AM
crappie_fisherman wrote:
...I've driven a 2 valve V10 pulling a 9000# TT (i.e. 17,000#'s combined) all over and I mean ALL over this beautiful country...didn't find any hill that I couldn't climb...did I slow down...sure...did I expect to...sure...
I now drive a 30,000#+++ 4000# toad Class-A with a diesel...in the few trips we've taken since getting it...the 6 speed Allison transmission sure is nice to have...if I had a 6 speed tranny behind my 2V V10...I'm sure that experience would have been easier on me as a driver...driving the 2V V10 loaded to 17,000#'s took driver control and attention to the road and the upcoming road/hills...
Thus far I've found I can simply set the cruise on the coach and the trans has yet to downshift out of 6th...on the SAME roads my V10 would downshift out of 4th...I KNOW that when we head to real hills...I'll use more gears on the coach...but comparing same roads to same roads...the Cat and Ally combo handles them much easier even though were more than twice the overall weight (coach and toad)...HP wise...my 2V V10 had 325HP...my Cat has 350HP...
Nov-16-2012 10:46 AM
Nov-16-2012 10:26 AM
Nov-16-2012 09:35 AM
427435 wrote:michelb wrote:427435 wrote:
...
Again, a 300 hp diesel engine won't climb a hill faster than a 300 hp gas engine moving the same load----------at least at altitudes under 3000 ft. Turbocharged engines (gas or diesel) do have advantages at higher altitudes.
The small gas engine is not irrelevant------------it serves to prove the point about the differences between hp and torque.
I would strongly disagree with this. Our 275HP (might even be 325HP) gasser will not keep up with a 300HP ISB, ISC or CAT 3126E.
Our old 98 Pace Arrow 36B gasser weighs about 20k lbs on the road and is MUCH slower climbing hills than in our 03 Phaeton DP (330HP) even with the DP pulling a toad on a dolly (total weight easily over 30k lbs).
I'm not saying that everyone needs to buy a diesel as the gas engine will get you over the hill and it does what it needs to do but there's a huge difference between a gas engine with 300HP/400 ft.lbs torque and a diesel with 300HP/600 ft. lbs or even 900 ft. lbs of torque.
I suspect you weren't willing to run your gasser at 4000 rpm when climbing a hill. I'll routinely hold my V10 at 4000 to 4500 rpm when climbing hills. Works great.
Nov-15-2012 06:05 PM
Nov-15-2012 03:51 PM
Nov-15-2012 12:16 PM
427435 wrote:michelb wrote:427435 wrote:
...
Again, a 300 hp diesel engine won't climb a hill faster than a 300 hp gas engine moving the same load----------at least at altitudes under 3000 ft. Turbocharged engines (gas or diesel) do have advantages at higher altitudes.
The small gas engine is not irrelevant------------it serves to prove the point about the differences between hp and torque.
I would strongly disagree with this. Our 275HP (might even be 325HP) gasser will not keep up with a 300HP ISB, ISC or CAT 3126E.
Our old 98 Pace Arrow 36B gasser weighs about 20k lbs on the road and is MUCH slower climbing hills than in our 03 Phaeton DP (330HP) even with the DP pulling a toad on a dolly (total weight easily over 30k lbs).
I'm not saying that everyone needs to buy a diesel as the gas engine will get you over the hill and it does what it needs to do but there's a huge difference between a gas engine with 300HP/400 ft.lbs torque and a diesel with 300HP/600 ft. lbs or even 900 ft. lbs of torque.
I suspect you weren't willing to run your gasser at 4000 rpm when climbing a hill. I'll routinely hold my V10 at 4000 to 4500 rpm when climbing hills. Works great.
Nov-15-2012 12:14 PM
VinCee wrote:
If the money equation (aka what can I/you afford?) was not one of the prime deciding factors, I would think 80% or more of class A's on the road would be DP's. However, most of us have to deal with the reality that $$$$$ doesn't grow on trees.
Nov-15-2012 12:01 PM
Nov-15-2012 09:27 AM
Cloud Dancer wrote:
My first MH was one of the original Winnebagos that had a Dodge engine/chassis. The next one had a Ford. Then, I had a couple with big-block GM engines/P-30. Then, another gasser, a nice Vectra on a F-53 chassis. I'm an ole gearhead/racer, and I am NOT opposed to WOT all the way up a hill.
NONE of my gassers could outclimb my present heavy DP which is on a Spartan/8.3 ISC Cummins.
My gassers all had 4 speed trannies, and it was obvious to me they would've done much better with a 6 speed, and even better with a 10 speed (there's a reason Newells have a 10 speed....:B)
Nov-15-2012 09:04 AM
Nov-15-2012 07:48 AM
michelb wrote:427435 wrote:
...
Again, a 300 hp diesel engine won't climb a hill faster than a 300 hp gas engine moving the same load----------at least at altitudes under 3000 ft. Turbocharged engines (gas or diesel) do have advantages at higher altitudes.
The small gas engine is not irrelevant------------it serves to prove the point about the differences between hp and torque.
I would strongly disagree with this. Our 275HP (might even be 325HP) gasser will not keep up with a 300HP ISB, ISC or CAT 3126E.
Our old 98 Pace Arrow 36B gasser weighs about 20k lbs on the road and is MUCH slower climbing hills than in our 03 Phaeton DP (330HP) even with the DP pulling a toad on a dolly (total weight easily over 30k lbs).
I'm not saying that everyone needs to buy a diesel as the gas engine will get you over the hill and it does what it needs to do but there's a huge difference between a gas engine with 300HP/400 ft.lbs torque and a diesel with 300HP/600 ft. lbs or even 900 ft. lbs of torque.
Nov-15-2012 03:28 AM
427435 wrote:
...
Again, a 300 hp diesel engine won't climb a hill faster than a 300 hp gas engine moving the same load----------at least at altitudes under 3000 ft. Turbocharged engines (gas or diesel) do have advantages at higher altitudes.
The small gas engine is not irrelevant------------it serves to prove the point about the differences between hp and torque.
Nov-14-2012 08:32 PM
nevadanick wrote:
Correct me if i am wrong but i was to understand that torque is what moves you and horsepower is what you feel.