do gassers offer anything like the DP engine brake

[kgard1225]

Hi, looking for a class A but will be in mountainous areas a lot and want to see if there is any type of extra braking available on the gassers. I searched the diesel vs gas posts but see no mention of this big plus on the diesels. Thanks, Ken

[SuperGewl]

I recently finished a cross country trip in my rig and yes the F53 chassis does very well up and down the grades while towing. I must admit that Ford did a good job on the Tow/Haul (Grade Brake) programming. If you use it in conjunction with cruise control you will be very happy. There will be a few times when you have to use the brakes to help the program be more aggressive when necessary.

Add a 5 Star Tune and it's even better.

[RayChez]

Holstein, Nice Newmar Kin Aire, but the picture shows it with a hump on the roof. It is not like that, is it? I think maybe it is just a bad camera shot.

[holstein13]

kgard1225 wrote:
Thanks for all the replies. I wasn't sure if the engine rpms would get too high going down a steep descent keeping in a low gear. All of the late model gassers I have been looking at had Ford chassis with the V-10. What is redline on these motors ?

I looked into this one time and read that the Ford V-10 doesn't have a redline because the computer won't let it over-rev. That has also been my experience. My old engine upshifted when the grade declined forcing me to hit the brakes to get to a slower speed where the transmission would stay in a lower gear.

I'll also add my vote of confidence in the V-10s engine braking abilities. It's not perfect, but certainly works well enough for the vast majority of the mountains I've crossed on the Eastern and Western parts of the country. I've only had to hit the service brakes a few times to slow down.

[Terryallan]

zman-az wrote:
I don't know what year the tow/haul mode was introduced into rv's, but I would not buy one without it. It makes a huge difference descending grades. I got a dp now but had a 2011 f53 and that tow/haul mode is awesome and just as effective or better that a exhaust brake.

Even before Tow Haul. Gas engines had GREAT braking when down shifted. My 04 150 does not have tow haul. But all I have to do to slow down the vehicle. Is pull it back to 2nd, or 1st. It will make you fall forward against the seatbelts

[phnguyk]

Fords newer torqueshift.

[DanTheRVMan]

Weeding thru the bias and misinformation on this thread is difficult IMO

I would still like to see quantitative values based on weight/hp. Sorry but I have had too many physics and engineering courses to ignore these type of analysis.

But lacking that and other good information I would have to say BOTH go down hill safely IF you do not go faster than the system can handle.

[willald]

Bottom line is this: Don't let concerns over braking on steep hills affect your decision one way or the other, when it comes to gas vs. diesel.

Its been debated many times, the differences between the two. Gasser engines naturally provide braking by virtue of suction created at the top end when closing the throttle valve. Diesels on their own have no engine braking, but adding an exhaust brake that plugs up the exhaust give them that braking. In the end, both do a good job of slowing things down when they need to, but do so in different ways.

Its not really accurate to suggest that diesels offer engine braking and gassers do not, when the reality is the exact opposite - Gassers provide braking naturally without having to add anything, diesels do not, and only get such by adding an exhaust brake that plugs up the exhaust.

Ultimately, though, since both accomplish the same basic thing when it comes to braking...There are much, much more important factors to consider when chosing between the two drivetrains.

[Old-Biscuit]

rgatijnet1 wrote:
redguard just sent me this as a PM in reference to my post where I said that gasser RV's have no problems in the mountains with either the climb or the descent.

"you obviously have not driven a larger A gasser loaded in the rockies etc as this statement is pure bunk simply put UNTRUE "

I'll let those of you that have driven their gassers in the mountains respond. I have never had a problem with my Monaco gas coach in the Rockies, but I also never had a problem with the diesel coaches I've owned in the mountains.
Apparently he wanted to call me liar in private. Oh well! :B

As the above posts already seem to indicate, gas RV's do fine in the mountains.

redguard is a troll

[zman-az]

I don't know what year the tow/haul mode was introduced into rv's, but I would not buy one without it. It makes a huge difference descending grades. I got a dp now but had a 2011 f53 and that tow/haul mode is awesome and just as effective or better that a exhaust brake.

[carringb]

lostdog wrote:

kgard1225 wrote:
Thanks for all the replies. I wasn't sure if the engine rpms would get too high going down a steep descent keeping in a low gear. All of the late model gassers I have been looking at had Ford chassis with the V-10. What is redline on these motors ?

There is no redline for these motors. The computer will not let you hurt that motor. I've seen 5000 plus RPM on our rig when going down a very steep grade but the V10 was holding speed just fine. I use a combination of Cruise Control and Tow/Haul.

Well, technically they do have a redline. You just would never reach it with the stock programming. I have raised my shift points to 5200 RPM and the fuel cut to 5400. So far so good at 394,000 miles except I can now hear some occasional timing chain slap (worn guides I'm sure). Would the guides have lasted longer without so much time spent north of 5,000 RPM? I don't know, but doing a timing chain job every 400,000 isn't exactly going to break the bank, and I sure like the extra power on tap.

[Terryallan]

MrWizard wrote:
the new Allison trans with braking..for gassers is truly a wonderful piece of engineering

but..some facts about diesels and gassers are getting misconstrued
diesels have such good compression braking because.they are HIGH compression engines..like 20:1 much higher than gas engines
shut the fuel to a minimum and restrict the exhaust and it take a lot of energy to force that engine to rotate

diesel engines are "free breathers" ..the fuel is controlled NOT the air intake

gas engines both fuel and air are controlled..
BUT the air intake is restricted only when there is no throttle.. the gas engine does NOT have naturally occurring engine braking as some have suggested
restricting air intake..throttle body or carb flaps only reduces air into the take..(like suction).. it does not do anything to increase compression and reduce engine speed other than reducing combustion of fuel in the engine

diesel or gas ..tis all about low gears and good driving and Knowing how to use whats available

In truth. Diesels only have high compression on the front side. They have o on the back side. With out a exhaust brake. A diesel just free wheels.

[lostdog]

kgard1225 wrote:
Thanks for all the replies. I wasn't sure if the engine rpms would get too high going down a steep descent keeping in a low gear. All of the late model gassers I have been looking at had Ford chassis with the V-10. What is redline on these motors ?

There is no redline for these motors. The computer will not let you hurt that motor. I've seen 5000 plus RPM on our rig when going down a very steep grade but the V10 was holding speed just fine. I use a combination of Cruise Control and Tow/Haul.

[mowermech]

Welll, guys, all I know is what I have observed.
Gas engines have compression braking, even those old 7:1 compression ratio Model A 4 bangers. It is just the nature of the beast.
Diesel engines (at least the Cummins in my old Dodge 3500 and the little 4 banger in my older Datsun pickup) have negligible compression braking. The Dodge/Cummins however, had a Jacobs Rambrake installed on the engine, and when it was engaged there was a LOT of braking power! Since there was NO intake vacuum, it had a vacuum pump installed to supply vacuum to the cruise control, the Jake Brake, and the power brakes.
As for the throttle plate discussion, I have tried starting gas engines of various sizes by pushing or rolling down hills, and even with the throttle open there is a LOT of compression braking until the engine starts running (if it starts!).
My old Datsun diesel pickup had a throttle plate and venturi (the venturi created vacuum to control the injection pump via a diaphragm). With the throttle plate closed, it still had negligible compression braking.
I have no idea what the technical explanation of all this is, and don't really care. The observations are factual.

Oh, yeah, to answer the original quesation: No, there is no Jake brake or similar unit for gas engines. They don't need them. the inherent compression braking does the job just fine.

[JimM68]

Mr. Wizard, you got things a little backwards....

Gas engine DO have natural engine braking, closing the throttle restricts the airflow through the engine, causing it to resist turning (engine braking)

Diesels have no natural engine braking at all (because there is no throttle plate to restrict airflow)take your foot off the gas (cuts fuel only) and it just freewheels.

Diesels get an addon engine brake (usually a pacbrake, which is a valve that closes off the exhaust, or these days with variable vane turbos, the brake is built into the turbo) to provide the engine braking that gassers get naturally (and a lot more of it usually)

In all cases, managing the transmission (manually is fine, or automatically with a tow/haul. Diesels have transmission management built into the pacbrake system)helps keep the speeds down.