The ultimate in 18 wheeler aerodynamics, -from Walmart?

[Flying W]

ncnewbie: The link below is to the Kenworth fuel efficiency pdf. It lists the % gain for individual tractor items. I read somewhere that these are not cumulative. But they should at least provide some insight as to their effect. Page eight of the Kenworth White Paper states that a low roof results in better aerodynamic performance with a flatbed or tanker. Which then makes me wonder as to the benefit of the other aerodynamic improvements for flatbeds/tankers.

http://www.kenworth.com/brochures/FuelEfficiency.pdf

GMAN, et al: Were loads heavier back then (80k+) with those smaller engines? I'd love to see the mpg results of a modern aerodynamic tractor (chassis improvements, etc) with those smaller engines. It would be interesting to see if there is a mpg improvement or not.

[GMAN]

When I started we were not allowed to carry as much weight as today. Trailers were not as long, either. Most trailers were 45' long. Many of those 238 engines pulled around 80,000 pounds as there are still some on the road today. Those were dependable engines, but fuel economy wasn't so much of a consideration back then. Trucks get better fuel economy today. Modern trucks are also much more comfortable. I don't think we have come very far on fuel economy from 30 years ago. It seems to me as though we could have done much better in improving fuel mileage.

[BanditsCousin]

I think they're more focused on diesel engines burning cleaner at the moment while focusing on mileage 2nd. I think once all the bugs are worked out with EGR and ULSD, the next main focus will be MPG's. Things like aerodynamics should be on the forefront now, as they can be a complete project separate from engine efficiencies.

I think the government grants to drivers (APU units in WI, newer diesel engines in CA) are a good start. Kinda like college grants for disadvantaged students to achieve success, we are no different.

I heard about the old days from my Dad. Things like waking up 2 hrs early to light a BBQ grill under the cabover to get it warmed up enough to start on a cold winter morning make me feel spoiled. My Dads buddy (62 y/o) talked about mixing a little kerosene with diesel because it was a few cents cheaper than diesel helped, having to carry a 55 gal drum of oil (slight exxageration) and the days of spring ride suspension let me know that guys like you (Gman) really paid your dues!

In my last 9 months of being O/O with my semi-largecar, I've learned the best way is to keep the left door shut and stay off the throttle. I have been using Howes every now and then, but my Dad swears by "Power Service" (although I haven't found that yet. He had a nose cone put on his HHG van to help fuel economy and belives the centramatics help tire life and provide a very modest mpg increase. Also, while pricey, aluminum wheels on all 18 help.

How efficent are the sideskirts of the Conway trucload trailers? I wish someone could gove me a number. I'm sure they help. I think I benefit from that advantage, as probably 2% if the members on CAD can crawl under my trailer (present company definitely excluded!)

[kc0rpm]

I think they're more focused on diesel engines burning cleaner at the moment while focusing on mileage 2nd. I think once all the bugs are worked out with EGR and ULSD, the next main focus will be MPG's. Things like aerodynamics should be on the forefront now, as they can be a complete project separate from engine efficiencies.

I think the government grants to drivers (APU units in WI, newer diesel engines in CA) are a good start. Kinda like college grants for disadvantaged students to achieve success, we are no different.

I heard about the old days from my Dad. Things like waking up 2 hrs early to light a BBQ grill under the cabover to get it warmed up enough to start on a cold winter morning make me feel spoiled. My Dads buddy (62 y/o) talked about mixing a little kerosene with diesel because it was a few cents cheaper than diesel helped, having to carry a 55 gal drum of oil (slight exxageration) and the days of spring ride suspension let me know that guys like you (Gman) really paid your dues!

In my last 9 months of being O/O with my semi-largecar, I've learned the best way is to keep the left door shut and stay off the throttle. I have been using Howes every now and then, but my Dad swears by "Power Service" (although I haven't found that yet. He had a nose cone put on his HHG van to help fuel economy and belives the centramatics help tire life and provide a very modest mpg increase. Also, while pricey, aluminum wheels on all 18 help.

How efficent are the sideskirts of the Conway trucload trailers? I wish someone could gove me a number. I'm sure they help. I think I benefit from that advantage, as probably 2% if the members on CAD can crawl under my trailer (present company definitely excluded!)

I dont know how efficient the side skirt are, but we are ripping them all off the trailers now when they go into the shop. They sit too low and if you have to back over a curb, they tend to get damaged.

[allan5oh]

those side skirts are made by freight wing.

[ncnewbie]

Thanks for the link Flying W

Anyone have any experience with the Liberator (or other brand exhaust)? How accurate are their claims of 5-10% improvement?

http://store.getliberator.com/Produc...ctCode=LES-001

[Flying W]

I don't have any experience with the Liberator, and am not an engineer, but the two articles I could find on it make me skeptical at best. The words "under certain circumstances" make the rest of the article doubtful at best to me. Or stating one thing, and then following up with something that sounds good but in reality has absolutely nothing to do with the first statement like the quote below. I'd love to see someone try claiming that their unrealized fuel gain is a "manufacturing defect."

"AET is the only company in the heavy truck muffler industry that makes
specific mileage claims," Bergesen said. "And we are so confident in the
quality of our product that we are offering a lifetime guarantee against
manufacturing defects to original owners."

If the product were as good as it seems there should be plenty of information to fill an article with. I see two articles with very little supporting their claim. Just my $0.02 worth.

http://www.theautochannel.com/news/p...ess030996.html

http://www.theconcreteproducer.com/i...ticleID=589107

[thebobguy]

Great information guys...thanks!

[durango360]

I know its rather complex and will add weight, but perhaps a two speed axle would be the answer like they had in the early days with gasser trucks that were lucky to push much more over 100hp while carrying quadruple their weight. Besides, if BMW can create an excellent car with a direct drive standard transmission, there's no reason KW, Freightliner, Pete or any other truck manufacturer can't do the same with more wind noise.

[Mandilon]

Take a 10 spd overdrive with 3.58 gears, and a 10 spd direct with 2.64 gears. Both behave exactly the same, same startability and shift points. But in the final gear the torque goes right through the direct drive, and has to go through a gearset for the overdrive. This results in a 2-3% or so gain in fuel mileage. Schneider has known this for years, and they always spec direct drive trucks. It's the way of the future. Unfortunately 2.64's are the lowest numerical gearset currently availabe. If one wants to run efficient 22 LP tires, the top speed is very limited. Much like 3.58's with an overdrive transmission with 22 LP tires.

At 70 mph you'd be screaming at 1600 rpms.

With direct drive and fuel efficient tires(22.5 LP's or super singles) you need to run slow. That's why you don't see direct drive transmissions very much.

**Can you overdo TALL gearing?

I recall reading about someone who tried this (of course I can't find the reference now), who was not very happy with the results. The new gearing was so tall that the truck's already slow acceleration became unbearable. He ended up using lower tranny gears longer and more often, and with much more throttle than before, which negated the theoretical fuel economy benefit of the swap.

So is it possible to overdo things exclusively via gearing? Sure. Your OEM final drive was chosen by the engineers to balance fuel economy & performance. Depending on how & where you use your rig, you could easily go too far:

Heavy loads: your OEM gearing / final drive is designed so the engine can handle a full load of cargo. If you regularly carry a lot of weight, changing the final drive could be a problem.

Hills: if you live in a mountainous/hilly area, you may already often be at the "limit" of drive-ability with your stock gearing & final drive.

Clutch wear: changing the final drive may require much more aggressive clutch use to get moving in first gear. If you drive in an area where you regularly have to accelerate briskly to accommodate other drivers, this will reduce clutch life.
Just a thought.

Keep On Trucking