Class 8 Trucks

[jamesqf]

Originally Posted by johnmyster

The whole reason why your gas engine pulls fuel is in order to cool things off in the combustion chamber and prevent precombustion that a "hot mix" could be succeptible to. Um, precombustion isn't an issue in diesels. Forget about it.

Huh? Seems to me the reason the gas engine pulls in fuel is to burn it. Sure, there are some old designs - aircraft engines & two-cycles - that used fuel for cooling, but that's ancient.

Plus, why would you ever want to intake warmer air on a TURBOCHARGED AND INTERCOOLED engine?

Because it might give better fuel economy? As in maybe there's a good reason why those trucks have their air intakes located where they are?

Maybe your computer does something funny, but the basics of Carnot/Rankine cycle dictate that a cooler charge/sink temp is more efficient at harvesting the heat energy from the source. Always.

That's the same thinking that says an engine has to have an A/F ratio around 14:1, and can't possibly run at 21:1 or leaner?

I don't claim to be an automotive engineer. I just know what happens to the mpg display on a cool day, when the ScanGauge shows IAT around 60 degrees, and I hook up the duct that brings warm air off the cat to the intake. The mpg goes up significantly. If I said I knew for sure how or why this works, I'd be lying. I just know it does work.

[jamesqf]

Originally Posted by SmartTrucker

also I forgot to link a photo of a freightliner columbia. This one isn't ours but it's similar it has a larger sleeper though and the exhaust is behind the sleeper like ours should be.

Can't tell from the picture, but it looks like that visor over the windshield might mess up airflow.

Also, if you always haul flatbeds, could you somehow do a taper back from the sleeper to the top of the load?

[roflwaffle]

Originally Posted by jamesqf

I don't claim to be an automotive engineer. I just know what happens to the mpg display on a cool day, when the ScanGauge shows IAT around 60 degrees, and I hook up the duct that brings warm air off the cat to the intake. The mpg goes up significantly. If I said I knew for sure how or why this works, I'd be lying. I just know it does work.

Is this on a gas or diesel engine? Warmer intake air should help out reducing pumping losses on a gasser at part load, but on a diesel w/ no throttle to incur said pumping losses there's no point.

[Big Dave]

"Lean" and "rich" have no meaning to a diesel. Unlike in a spark-ignition engine, where the combustion is of a fuel vapor/air mixture, the diesel combustion event occurs of the surface of the droplets squirted out of the injector. Diesels usually operate in an "excess air" condition. If they don't, they belch black smoke.

Yeah, you might get a little more power from sucking in cold air but that would only matter at max road load.

The increased aero drag from an external air filter more than overwhelms any imagined efficiency gain.

[RH77]

What truckers need is a trailer without wheels aligned in different directions (according to a Cummins study on optimum fuel economy).

I don't know how many intermodal trailer bases I've seen with wheels that looked like a cartoon clown car. Getting wheels that don't wobble and are properly aligned is a good start, but hard/impossible to implement.

Tractor owners often pick up what ever is next on the list. No say in the matter. Paycheck or not. Efficient or not. Alignment is key.

[SmartTrucker]

yes a proper alignment is huge. If you're unaligned it's going to cost mpg and improperly wear our expensive tires.

Bigdave we are almost always loaded to max weight. Also, I'm of course not thinking of putting the air filter outside just possibly pulling the air into our internal air filter from the top side of the hood. Any new drag caused from that would be pretty minimal.

[Big Dave]

Class 7 and 8 tractor-trailer are aero-dogmeat because of the chief virtue of the tractor-trailer setup: flexibility. Class 5 and 6 straight trucks may offer some scope for aero-improvements although most of these are local delivery trucks. However there are the hotshotters.

[ConnClark]

Check out this site for trucking aerodynamic improvements.

SOLUS - Products and Inventions for Fuel Economy

It has a few NASA engineers and PHDs that have applied their knowledge and skills to come up with a few simple cost effective solutions. They have employed computational fluid dynamics and wind tunnel testing as well as on the road testing to verify there methods.

[trikkonceptz]

This is relevant to the topic, unfortunately not a possibility for the application being discussed.

I saw a tractor trailer pass me this morning and its trailer was rather odd. First it had a large dome in front of the trailer to break up the air.
Then after the kingpin and clearing the tractor, the trailer floor dropped to within 1-1/2 feet of the ground and the entire side of the trailer had a side skirt that cleared about 8" off the ground. That lead to the the very small rear wheels on this trailer. By small I mean they were the size of your average suv wheel, no where near the 22.5" I see on standard trailers. It had eight on the back like all other trailers. After the wheels the side skirts sloped up to meet the back of the rig at what looked like an angle between 10 - 15 degrees. And to end it all it has a rounded rear that spanned from top to bottom, I guess the best boattail attempt I have ever seen on a rig that large.

All in all this beast was 48' feet long and I think the tail made it 53, it looked hinged so it could swing out of the way for loading. It was the first time I saw anything that resembled an attempt to help aero on a production scale. Of course the tractor was all smoothed out with the stacks tucked behind the cab, gas tanks were covered and even the rear wheels had full fiberglass covers and skirts. I wish I had my camera handy, it really was a neat thing to see.

Oh and he was hauling ass, I had to do 80 to get near it to notice all of this .. ANd when I did, I experienced a suction effect instead of the normal air pushing me into the next lane, which I thought was kinda cool.

[zenhozen]

Originally Posted by SmartTrucker

Anyone out there that's made and tested fuel savings on class 8 trucks by way of aerodynamic and/or powertrain changes?

Looking forward to hearing any ideas or knowledge people have on the subject

The members of this forum have discussed several solutions to get fuel economy for Class 8 trucks. Here is another, there are currently on the market a fender for class 8 trucks that is certified for the reduction of fuel. This fender is designed and manufactured by Meka Form. These fenders not only reduce your fuel bills, but save you money on your operating cost, and they have a very good return on investment.

Here the link an some photos:

Meka Form Fenders