350 HP ICE vs. 350 HP Diesel?

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

The Turbo helps at high altitude. Diesel by its self is actually worse than gas at high altitude.

A turbo on a gas engine would make a very nice RV engine, as long as they can get the cooling worked out. That allows for a smaller engine which will be more efficient, but still have the power when needed. That and turbos tend to have a very flat power curve over a very broad RPM band. Between running direct injection, which prevents detonation under higher compression, as well as variable valve timing, so you can get rid of the throttle plate, all add up to greater efficiencies.

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.

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

Daveinet wrote:
Quick Google search shows its pretty common to run the 502 to 5 grand which is approximate redline. Apparently the outdrives are 1.5 or 2.0 ratio.

I just looked at the Torque curve of that 502. That is a NICE engine!

I would say the Ford Ecoboost has shown us what is in the future. It appears they have been able to design a turbo charger that can be used successfully with a gas engine.

If they are able to pass this on to a 6-7 liter V8 then the current diesels will have some serious competition.

The main thing that gives the current diesels the performance edge is the turbo charger. Remove the turbo charger and you would not see very many diesels is use in the light and medium trucks.

A Chevy 8.1 with current injector technology and a turbo charger would give more power than any current motorhome would ever need.

Quick Google search shows its pretty common to run the 502 to 5 grand which is approximate redline. Apparently the outdrives are 1.5 or 2.0 ratio.

Boat engines run wide open but they do it at 3000 RPM or so. Big difference in longevity between running wide open all day at 3000 and running wide open all day at 6000 RPM. The latter might turn out to be a short day.

JumboJet wrote:
You just cannot comprehend what you read. Apples to apples except for fuel type. That means 3.73 diff in both trucks, 35 gallon fuel tanks both trucks. 25,000 lbs. GVW both trucks. The cruise set at 65 mph - the gasoline would downshift trying to maintain the 65 mpg until the operator just tired of the engine screaming at 5-6,000 RPM. ...

True comparison requires that both engines are operated at their DESIGNED RPM range. Requiring each truck to use the same gearing makes no sense. No manufacturer designs the same gearing when running diesel or gas. Look at what is commonly used in both chassis. The manufacture is always going to optimize gearing based on load requirements. Gearing that I have suggested has been within the typical existing chassis designs. (not some radical skew to favor one fuel type) The purpose of the discussion is to compare what a manufacturer would do in a typical chassis design.

Slightly off topic, I've not suggested running my engine wide open for the purpose of comparison, but my engine is unique in that it is built to run wide open all the time, because it was originally designed as a boat engine. In boats, they do tend to run this engine wide open constantly, and it does hold up.

hardtobe wrote:
To the two gas freaks on here I just cant wait till I see my first 410HP hemi powered 40+ft 4 slide 38K pusher Motor home.I bet tiffin and Sparton will get right on it after reading your most knowledgable posts.
Dave I almost laughed myself off my chair when I read u claimed your going 80MPH up the hill in 2nd and 3rd gear

I do love a gas engine. I'm not ashamed to say it. I've driven and owned both and I am not so foolish to claim there is not an upside to a diesel powerplant. However, I would love to get a gas powered 40' coach when it is time for us to retire. I'm hoping that the industry swings that way by then. I would rather have about 500 hp or so though for that size.

Spartan already IS getting on it by the way. They are promising Q3 or Q4 for the 8.8l based Chasis. It may not do well but we'll see.
it's a different world this decade man: Gas engines aren't what they used to be and neither are diesels.

I keep telling you not to ridicule Dave. His 502 looks to be on steroids. He could easily be at 500+ HP at the crank. At only 18,000 lbs, you would also be blown off your seat by the wind when he dusts you and whatever coach you are driving. I see no reason he couldn't haul that thing up a 6% at 80mph. You show a moderate level of ignorance in your constant ridiculing.

To the two gas freaks on here I just cant wait till I see my first 410HP hemi powered 40+ft 4 slide 38K pusher Motor home.I bet tiffin and Sparton will get right on it after reading your most knowledgable posts.
Dave I almost laughed myself off my chair when I read u claimed your going 80MPH up the hill in 2nd and 3rd gear