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Author Topic: Front spoiler/air dam for mileage  (Read 12649 times)
Chaz
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« on: August 10, 2007, 07:00:47 PM »

Ok guys, my brain has been at it yet again. (sorry, I'm an artist  Grin)

  I seen a semi-truck that they were working on to get the best mileage possible in Australia a few years back and they were stream lining it (tapering it), filling the gap over the fifth wheel, closing wheel well openings AND using an air dam on the front to keep the air from dragging under the truck.
  I was just wondering if any of those concepts -ie. the air dam- would work or help on our beloved buses??  If somebody has any insight, I'd love to know what they think. I like reinventing the mouse trap, if it's at least viable. I hate making mistakes that have been made before.  Angry

  "Airing" on the side of fuel mileage,
        Chaz
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« Reply #1 on: August 10, 2007, 11:50:34 PM »

Hello.

From all the stuff I've read over the years about the various strategies for improving tractor trailer aerodynamics, the percentage improvements are so small that it would make payback pretty much impossible for a busnut.

Removing unneccesary weight, a more gentle use of the throttle pedal, both on acceleration, and in choice of cruise speed, and keeping engine idling to a minimum are the significant things we might do to change fuel consumption.

Or trade in my MC8 for a 4104.....

happy coaching!
buswarrior
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superpickle
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« Reply #2 on: August 11, 2007, 06:05:33 AM »

Well, if you take your Bus and make it in the genral shape of the Space Shuttle, it would do wonders  Wink

Your best bet is to do as buswarrior sais..  Grin

Paul...
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Chaz
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« Reply #3 on: August 11, 2007, 06:39:51 AM »

Thanx guys, but your info helps little. I'm not trying to change the shape of my bus, that was just a statement about what the show was about. OH, and by the way, the design made a HUGE difference in mileage. Expensive to impose? Yes. But all good improvements come from somebody who cares, trying to make things better. (I'm just not somebody who is content on sitting on my a** and letting the past dictate "exactly" what the future needs to be. ie. the wheel sure beats the hell out of a stick dragging on the ground! But I'm sure there were those that thought the person who invented that was wasting time too. Oh, and then there is electricity............etc.)
  My point was and is, just like on a race car, has anyone given any time or thought to decreasing the under vehicle drag on a bus? If no one has, fine. If someone has some insight, I'd love to hear about it. It seems like it could be a viable possibility. But if there is info out there that says it's a moot issue........................ on to the next attempt.

  I'm not trying to be a pr**k here. I just want to help us make things better. I am what is called, a "Creative". And I have a shop that can can build most anything. My philosophy has always been, "If you can, then you should". But most people don't care enough. Sad. So sad.
  So back to "On Topic". Anyone have any insight about this?

    Just trying to help  (with knowledge you already have)
        Chaz
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maria-n-skip
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« Reply #4 on: August 11, 2007, 06:59:08 AM »

Just my observation.

    Front ground effect could look real cool. (but) (little but) Smiley I did one on my Talon. The major issue is that
 to get the front effect to do any real good it needs to be very close to the ground. On the roads around here
 I end up fixing mine at least once a year. So I don't know if it is worth the effort. Just don't use fiberglass
 or you'll be constantly fixing like me.  (maybe a stainless steel cow catcher design would work)


  Skip

 
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Chaz
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« Reply #5 on: August 11, 2007, 07:15:50 AM »

Thanx Skip.
  Yeah, I would also have to keep in mind the airbags going down too. But I was thinking more along the lines of flexible and forgiving.   Wink (something my life usually needs!  Grin )
  I was thinking along the lines of heavy belting (rock quarry stuff) and like heavy spring retainers on the back side.
  The "cool factor", if there actually was one, Wink would just be a by-product.
 
  Thanx for the help tho!!!!
       Chaz
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Kristinsgrandpa
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« Reply #6 on: August 11, 2007, 08:00:14 AM »

Chaz, I think the reason for the air dam is to force the air around the outside of the coach instead of under it where the turbulence/parasitic drag holds back the vehicle. I thought about doing a sheet metal, smooth undercarriage to eliminate that.

Several years ago I bought a 300ZX Nissan it had an engine pan under it to cut down on the turbulence, it extended back to the floor pans, which made it smooth all the way back to the rear axle, which was recessed up inside the cross tunnel.  It was basically smooth underneath.

The wheels also had spokes that were canted/slanted to act as a fan to draw air from underneath the car to eliminate the high pressure.

These things might have added up to a big mileage boost, apparently Nissan thought so.  Maybe it was done for speed, I don't know.

Ed. 
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« Reply #7 on: August 11, 2007, 08:33:33 AM »

Air dams on race cars and the like are more to get rid of lift than they are to help get rid of drag. At high speeds on a light car the air can actually raise the car and make the tires not have a good contact, thus the car becomes unsteady. I don't think we are going to be going fast enough to cause any lift and I don't think the air going under the bus is a major factor in fuel mileage. That big wall we call the front of the bus is what is causing the mileage to go down. Some one joked above about reshaping the front of the bus like the space shuttle - a funny joke, but also true.

I like your creative thinking and agree about trying new things instead of just accepting the old way of doing things. But an air dam wouldn't accomplish what you are looking for since that is not their purpose.
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Chaz
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« Reply #8 on: August 11, 2007, 08:50:37 AM »

Dang.  Tongue But that is a good point Songman. But I still kinda wonder if it wouldn't help. I'm not real versed in aero technology, but it just seems that I remember some info that it "can" help. But maybe not. I do know we don't really need the down force!  Grin lol
  By the way, a biodiesel bus member DOES have an aero front end on his bus!!!!!!! TOTALLY unique. It definitely gets your attention!! I'd bet it helps! I wouldn't mind trying something like that, but I REALLY like the look of my Buffalo the way it is.
  Ed, yeah, there is also something about a smooooooooth bottom pan that I seem to remember hearing that helps. But MAN, That's ALLOT of smoothing!!  Grin

  Still might consider the "Cool Factor".    Wink  lol
        Chaz
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Songman
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« Reply #9 on: August 11, 2007, 09:00:05 AM »

Go for the cool! When I was traveling some with Travis Tritt in the old days, he had neons under his Eagle. Never would have thought I would like it but it did look cool! haha
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TomC
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« Reply #10 on: August 11, 2007, 09:47:42 AM »

Chaz- the biggest contribution to fuel mileage will be the state of tune your engine is in.  The first big question you could answer is what size injectors are you running?  If you want maximum fuel mileage, you want the N55 injectors for 255hp with 675lb/ft torque.  This was the injector of choice for the big bus operators since the engine could be run both flat out and lugged without damage and in most cases not overheat.  With the N55 you should be in the 6.5-8 mpg range. The next best fuel mileage size is the N60 for 280hp and 740lb/ft torque.  You'll have about a .5 mpg reduction.  Then is the N65 with 304hp and 800lb/ft torque.  This is what I had in my bus before my turbo job.  With my car in tow I weigh 34,750lb and would get 4.5-6mpg.  If you want the highest horsepower on a non turbo, you could retime the engine to the A timing with N70's and get a true 318hp with 860lb/ft torque.  Your mileage would be about the same 4.5-6mpg.  After the turbo and air to air intercooling of my engine, I'm getting 375hp and 1125lb/ft torque with 9G75 injectors.  My mileage now is in the 5.5-6.5 range-so an improvement a bit. Detroit went as high a 7G80 injectors for 400hp and 1200lb/ft torque.  Don Fairchild will put in 9G90's for 450hp and 1350lb/ft torque. So you can see that the same engine can produce a wide range of power-a two fold range of torque.

Try unscrewing the two bolts on the lower valve cover to remove it and look for the little round tag on the injectors-the injectors sit in between the four exhaust valves.  Post what the number is on them.  The biggest factor to fuel mileage if you have bigger injectors is driving habits.  Good Luck, TomC
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Chaz
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« Reply #11 on: August 11, 2007, 10:41:13 AM »

Tom,
  I'm hip to the idea of making the engine as efficient as possible, driving styles, etc. but, that is all stuff that is known and done. I am looking for things "I" can do or perfect or improve or build or whatever. "I" want to help the bus community!!!!!!!!!!!!!!!!!!!!!!!! I have got a freaking GREAT deal of info from all you guys and I just want to do what I may be able to to help.
  Sure, I can do all those things to help "ME", but as I said earlier (which most people just don't "truly get", I like to help and my area of expertise is in metal and fabrication. THAT is the info I am trying to glean from this thread.
  But I do appreciate you trying to help me with the fuel mileage thing. I, as well as everyone I know wants to get the best we can. So Thank You so much for that!!!!!!!! I DO appreciate it. BUT, I want to help in the arena that I am familiar with and can possibly do some good in. I know it may not be much, but it's the best I can do.
  By the way, I think I have the color "brown injectors". ( Huh  Is that right? I think that's what I remember) I get about 6.2 mpg and think I could do even better if I could afford to get them pulled and benched. But..............? I understand there are others who get some pretty decent mileage out there. Unfortunately tho, mine is an automatic.

  Thanx again!!!!!!!!!!!!!
     Chaz

   p.s. By the way, if there is something along the lines of "what I can do" that someone knows of, I would love to discuss it and see if we can't make our bus's better.
   Just a thought and an offering.
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« Reply #12 on: August 11, 2007, 11:38:33 AM »

Guys,

I did this with a  car way back when.  I made the air dam a two stage affair.  The first dam was part of the front of the car that I changed out and was aftermarket.   The second was a piece of conveyor belt from a mine.  Very tough stuff!  I used old hack saw blades as stiffners.  I cut the thing to drag on the ground and it wore itself in to the "perfect" length.  I also had strips down the side to max my surface effect and retard air geting back under the car.

Did it work?  I could POP over two lanes at 100 mph and it felt very controled.  Z's are usually bad airplanes and are not prone to imparting any feeling of confidence.  Between the air  dam and whale tail it stayed glued.

Was it effieient?  I made a connon ball run in the am of a XMASS eve.  Drove 26 miles at an ave. of 107 mph and spent a lot of time at 135mph to do it.  My gas milage for the trip was 19 mpg.  Note that the "low speed tail" was a serious drag at speed.  The car normally gave me 30 mpg on the highway at 70 mph cruise and 23 around town.  With the cam and richened carbs the 2.4 liter put out 280 or so hp.

I know an air dam would enhance the MPG of any bus and the hard part is how to deal with the settling.  Maybe put the dam on a frame that would pivot and position the dam in a more horizontal posit when parked or for entering a drive.  Skinning the underside would help a lot and if the panels are small enuff they would not impede access to specific areas for maint or repair.  This would not be high on my list fo pri, to be sure but for someone that simply has to tinker with a project and expexts some return, albeit small, this is a good one.

On a hundred thousand miles, what is .1 mpg increase worth on a vehicle that gets 6 mpg?  Say $800 return?  You could do better, maybe and this isn't your biggest bang for the buck, but it easily is a break even project. 

IMO,

John
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Chaz
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« Reply #13 on: August 12, 2007, 09:08:43 AM »

Quote
On a hundred thousand miles, what is .1 mpg increase worth on a vehicle that gets 6 mpg?  Say $800 return?  You could do better, maybe and this isn't your biggest bang for the buck, but it easily is a break even project. 


 Thanx John. That is the point I'm after. I know most stuff that I can do and can contribute to everyone is small and probably inconsequential, but if I can do enough of those, maybe it can amount to something. And hopefully it will be something that I can design that others can do themselves also.
  The other thing I was thinking about is the back of the bus and if there is a way to reduce the wind drag off the back. Now before I get a bunch of replies on how stupid and irrelevant that would be, I would like to know if anyone has any experience in this. It's just an idea!!!  Roll Eyes

    Keep thinkin,
        Chaz
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maria-n-skip
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« Reply #14 on: August 12, 2007, 09:43:22 AM »

 Chaz,

   Please don't reduce the back end drag. That is what the rest of us count on.
 Drop in behind you for some slip streaming action and reduce our feul costs.

   So you can always lead the pack and we will all be Smiley

   Smiley  Shocked

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