Big kitty CATs

[tracer]

tracer a junkyard will sell a gauge for $5. A new one should be around $30. It doesn't even need to say "intake press" on it. As long as it goes from 0 to 50 psi. Some 1/8" plastic tubing and brass fittings - $15 maybe less.

Great tip, thanks. There's a large used truck parts place near Windsor, ON on 401. Will ask there.

[Fredog]

Texas Best Diesel Used Trucks and Truck Parts

[Midnight Flyer]

I've seen westbound cattle haulers going down I-40 and they've got a license to fly! I'd venture to guess most are Kenworth W900L's or Pete 389 with at least 600 hp and 18-speeds. One I've seen is a midnight metallic black Pete 379 with chrome out the wazoo! That guy must spend his days off polishing that rig because I've never seen it even close to dirty!

[rank]

It depends on a speed you're traveling. Even windshield wipers affect drag some how, or CB antennas....
And the faster you go, then more is the difference. But in general, I'd guess the difference is around 0.5 mpg average, assuming all other things, are equal...

The number I had in mind was about .25 mpg at ~ 65mph. Even less at 60mph.

[rank]

Tankers and aerodynamics are non existent, don't know why everybody thinks they are.

I never meant to say that tankers were aerodynamic, only that they were shorter than a van and therefore would not benefit from an aero high rise bunk. Put another way, using you as an example, you would see no improvement in mpg's by adding a wind deflector on your bunk.[/quote]

I get the same fuel mileage as a van.....

Have you pulled a van with that truck and got the same fuel mileage as you did pulling a tanker? I'm thinking that the lack of air foil on your bunk would cost you a little due to the extra height of the van but that's just a guess. I have a hard time imagining that a smooth sided tank behind your truck would get the same as a van pulling the same weight.

[rank]

Yes and no. I do know what you mean, but there are other less dramatic factors as well: increased rolling resistance from tires heating up at the higher speed, increased friction in all drive line parts would be the two primary additional factors in actually driving 90 mph.



Rank, if you understand how wind resistance really works, you'll know that the sloped hood means a lot. The overall height of the tractor doesn't mean nearly as much as the "profile" of it. Think of a truck driving down the road as a diver hitting the water from a ten meter board. In diving, one of the main goals is to minimize splash upon entry into the water... the smaller the splash the less the resistance between the diver and the water. What would be the result if a very petite diver hit the water with palms facing the water instead of pointed fingers? Big splash, right? Maybe even a bigger splash than say, a very large diver hitting the water with perfect form and fingers pointed directly toward the water? That hood, as Solo has already said, accounts for quite a bit of mpg improvement.

I'm not sure I buy that.

I still say that a FLD120 flat top with the fairings and mufflers behind the bunk (similar to the ones linkes below) gets the same or better mileage as an identically spec'd high rise aero truck. I know what you're saying about slippery surfaces,but they can only HELP the fat man get in the water. Far better not be fat in the first place.


1995 FREIGHTLINER FLD11242ST Conventional Truck w/ Sleeper For Sale At TruckPaper.com
1994 FREIGHTLINER FLD12062ST Conventional Truck w/ Sleeper For Sale At TruckPaper.com
1991 FREIGHTLINER FLD12064 Conventional Truck w/ Sleeper For Sale At TruckPaper.com

[TomB985]

I'm not sure I buy that.

I still say that a FLD120 flat top with the fairings and mufflers behind the bunk (similar to the ones linkes below) gets the same or better mileage as an identically spec'd high rise aero truck. I know what you're saying about slippery surfaces,but they can only HELP the fat man get in the water. Far better not be fat in the first place.

So, by that logic, a 13.5' x 8.5' block would slide through the air every bit as easy as a wedge that was 13.5' x 8.5' in the very back, but pointed in the front. The wedge would be able to channel air, whereas the block would be like one big, three dimensional sail just pushing it....

I don't buy it.

[rank]

So, by that logic, a 13.5' x 8.5' block would slide through the air every bit as easy as a wedge that was 13.5' x 8.5' in the very back, but pointed in the front.

No, dammit because my block isn't 13.5" high. I don't care how aero dynamic you make a high rise bunk....it's still sticking way the hell up in the air.

[TomB985]

Ah, but that's my point...

For a specific frontal area, you are claiming that aerodynamics don't play a major part. So it's not 13'5" high...maybe 11'6"? 10'? If that were the case, back in the days of sailing ships, it wouldn't have mattered what shape or size object was on the mast, as it would have caught the wind regardless....

Whenever I try to understand a principle, particularly with physics, I take the concept to the extreme. This is why I'm comparing pointed cones with flat sails, of the same frontal area. If a wedge, or a cone, has the same frontal area of a flat surface, such as a sail, it stands to reason that it would move through the air easier than the flat wind catcher...apply this idea to trucks, it stands to reason that for a given sleeper height, some shapes move through the air easer than others.

I'd love to see a study comparing a KW W900L with a T660. Both can be equipped with the exact same sleeper and wheelbase arrangements, only a different front end. Put each trucks, exactly identical with the exception of the nose, through some real world testing...and I'd put some serious cash on the aero for the winner....

[tracer]

Bobtailed 50 miles to the best CAT dealer in the region (Toromont CAT off QEW in Hamilton, ON)... Bruce the Wizard Mechanic once again proved he's worth his weight in gold! I had complained about booming noise in the engine and poor fuel mileage. He plugged in his laptop into my ECM port and we went on a test drive. At one point I was doing 130 km/h - close to 80 MPH ... He said the booming sound was nothing to worry about, he called it 'the pulse', something to do with how fuel was injected in all CAT engines.. However they later did find quite a few leaks (and turbo boost loss) in air-to-air hoses. No wonder my fuel mileage recently has been so poor. After they fixed all the leaks, I noticed a big difference in the truck's performance as I was bobtailing back to our yard in Guelph, ON. I hope I can soon post 7 mpg numbers when loaded

[rank]

For a specific frontal area, you are claiming that aerodynamics don't play a major part......<snip>.... it stands to reason that for a given sleeper height, some shapes move through the air easer than others.

I feel like I am banging my head against a brick wall trying to get this point home to you. I am NOT comparing identical frontal areas, nor am I comparing given sleeper heights. I AM SAYING THAT A LONG HOOD WITH A FLAT TOP BUNK WILL GET THE SAME OR BETTER FUEL MILEAGE THAN AN AERO TRUCK WITH A HIGH RISE BUNK.

I'd love to see a study comparing a KW W900L with a T660. Both can be equipped with the exact same sleeper and wheelbase arrangements, only a different front end. Put each trucks, exactly identical with the exception of the nose, through some real world testing...

W9's don't have side skirts and rear exhaust. Like I said about 10 posts ago. Put Columbias with high rise bunks against the FLD120 flat tops I posted above.

and I'd put some serious cash on the aero for the winner....

I will put same cash on the FLD 120 flat tops.

Everyone bashes the long hoods and all I am trying to suggest that there is more to mileage than the length of the freaking hood. I bet a pencil nosed autocar or 359 with a flat top will get good mileage too.

[TomB985]

Okay, okay...I'll stop arguing now.

Never drove a long nose flattop, so I really can't say much about those. I was more thinking of a comparison between trucks nearly identical in overall height, which was not the point you were trying to make. My mistake!

[Bandit102]

Well, I have 2 T-600's, a Century and a Classic. I don't have governors on any of them, but they all do similar fuel mileage. The Classic, in fact, has the biggest engine - 525 Cummins, 13 speed, 3.58's on Tall 24.5's. It does the best of the whole fleet (all the others are 470 - 475 hp) at 5.8mpg during the last 3 months. Of course, I pull a flat with it, whereas the other 3 pull reefers. The 470 Cummins T-6 and the 460 Cummins Century all get 5.3 to 5.5. The 475 Cat T-6 gets 5.2 or so.

There may be some big difference running at say 60 or 68 mph - I don't know. But running 75 or so, I see no difference. Thing is, when I run the Classic through IL, IN, OH etc. I see NO fuel mileage difference what so ever as opposed to running 75. Different gears and different RPM in the different operating environments may contribute to that.

Of course, everyone else I talk to with trucks spec'd the same as mine always get 2 mpg better than I so go figure.

[rank]

Well, I have 2 T-600's, a Century and a Classic. I don't have governors on any of them, but they all do similar fuel mileage. The Classic, in fact, has the biggest engine - 525 Cummins, 13 speed, 3.58's on Tall 24.5's. It does the best of the whole fleet (all the others are 470 - 475 hp) at 5.8mpg during the last 3 months. Of course, I pull a flat with it, whereas the other 3 pull reefers. The 470 Cummins T-6 and the 460 Cummins Century all get 5.3 to 5.5. The 475 Cat T-6 gets 5.2 or so.

Got a high rise bunk on that classic or a flat top?

[Bandit102]

The classic has the condo sleeper. really tall. So does the century. 1 of the KW's has the standard aero sleeper without the airfoil and the other one has the airfoil on it.