Bike build: air gas hybrid

Discussion in 'OT Driven' started by saxman, Mar 9, 2010.

  1. saxman

    saxman Burninating the peasants

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    So I'm working on a build for my senior engineering project. Figured I'd post up the starts to the blog I'm writing, and update here as I go.

    http://crecca.wordpress.com/


    cliffs: Making a hybrid bike, posting here because it'll get interesting
     
  2. AVengeance

    AVengeance Active Member

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    I don't get it. You turn a 2cyl into a 1cyl, make the 2nd cyl. pump air into a holding take (further robbing the remaining cylinder of power) then use the compressed air to power the bike?

    It doesn't matter how you go about robbing Peter to pay Paul. You still won't win. You could use an electric supercharger, and the engine would have to work harder to power a larger electric generator (or have a heavier battery to use the e-charger in short accelleration spurts). You can hook up a turbocharger to the exhaust, generating backpressure (resistance). You can hook up a belt-driven supercharger (increased engine load via pulley). The supercharger (belt-driven air compressor) is close to this idea, although the supercharger feeds the air directly, rather than into an air tank to be used later. Since the supercharger's output is based on RPM, and the need of the engine is also based on RPM, it's probably the most efficient way, and closest to your idea of turning one cylinder into an air pump.

    No matter what you do, you make efficiency go down from the simple, efficient, 2cyl naturally aspirated engine you started with.
     
  3. saxman

    saxman Burninating the peasants

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    You're thinking about it in too closed of a perspective. If the cylinder only pumped air over, sure, efficiency would suffer, but this offers a lot of benefits. Throttle response becomes almost instantaneous. No need to wait to build boost. Torque curves become very flat as peak boost is available at 0 rpm. Because you're pumping air into a tank, the motor can store up energy when it's not otherwise being used. Engine braking becomes a source of energy that would otherwise be lost. What you're doing is reclaiming a lot of otherwise wasted energy, exactly like a gas electric hybrid. The difference is only in the state of energy storage.
     
  4. saxman

    saxman Burninating the peasants

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    Went out for milk... bike is here
    [​IMG]
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  5. mrduke

    mrduke OT Supporter

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  6. AVengeance

    AVengeance Active Member

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    You're right about it being another kind of hybrid. Seems like it would be easier to just hook up an extra battery and replace the current generator with a true alternator (an electric motor also capable of generating electricity). Any way you do it, it's going to have its ups and downs. For a highway cruiser, it would net a loss, not a gain. Around town or on steep hills, an electric or pneumatic "hybrid" might net you a tiny gain, assuming you weren't losing too much with the added weight of the system.
     
  7. saxman

    saxman Burninating the peasants

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    For a highway cruiser, it shouldn't net a loss. That's a great opportunity to run with the compressor deactivated, significantly reducing internal losses. Same idea as all of the cars out there that safe fuel with displacement on demand.

    Setting up an electric hybrid would require significantly more weight, far more difficult controls, etc.

    Remember with superchargers and turbochargers that they produce a lot more power than what they add. If a vehicle makes 100 hp stock, the supercharger may make another 100 hp, however, requires 50 hp to operate, showing a net gain of only 50 hp. Losses can be 40-50% here. Turbos usually are closer to 30%. In this set up, those losses are taken care of through waste energy... braking, cruising, etc, so that when the power is needed, the net increase in power is much higher, as the losses are already eliminated. You're robbing from Peter when he has too much, saving it, and giving it when it's needed.
     
  8. GammaRadiation

    GammaRadiation Active Member

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    That's cool and all. And I'm sure you've taken thermo, but you've got to see there are better ways of doing this. For instance, all you're really doing is heating up the air because the two cylinders are the same size. If you had one smaller cylinder driving a larger cylender THEN you would be netting energy storage.
     
  9. saxman

    saxman Burninating the peasants

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    Remember, 4 stroke versus 2 stroke. The compressor cylinder compresses twice for every combustion cycle, netting a gain. Also, work that would otherwise be converted to heat energy is being stored as pressurized air.

    As for heating the air, I'm looking into the possibility of using an intercooler as an air storage device. Should help that out a bit.

    This isn't a new concept... it's been done before and works.




    On a side note, got the bike running today.
     
  10. sickmonkey44

    sickmonkey44 01

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  11. saxman

    saxman Burninating the peasants

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  12. saxman

    saxman Burninating the peasants

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    Spent a while this weekend working on getting the garage all set up so that I could have a good designated work area. Thanks to craigslist, a new workbench has found its way to the garage for the huge price of free. Got the extra motor up on the bench with the reed valve and carbs to start getting an idea exactly where things are going to go.

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    For the compressor design, reed valves are going to be used. They seem to fit perfectly on the exhaust side with how the polaris boot is designed. Almost like it was meant to be.
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    I will have to verify on the bike for frame clearance before machining the halve housings(probably next week over spring break).

    On the intake side, the valve will be replacing one of the carbs. Should fit nicely, as it's about the same size as one of the carbs.
    [​IMG]

    On the carb note, it looks like the left cylinder will be the one becoming the compressor, as the right carb has all the controls on it. The carbs are set up so the right one has the throttle hooked up to it, etc, and via levers and such, controls the left one. Makes it much easier to ditch the left carb than the right carb, and as the bike is pretty much symmetrical, there shouldn't be any other issues.
    [​IMG]

    I still haven't decided if I'm going to even stay with a carb set up, but I'll certainly plan for the option there, as doing a fuel injection system would require the same work, left or right.

    To finish off the compressor, I'll need to get rid of the stock valves.
    [​IMG]

    I may be able to remove just the valve itself, and leave all of the springs and such in place. After taking the valve cover off the motor, the valve channels seem to be sealed up nice and tight, so it would make life really easy if the valve train would still operate with the valve itself removed.

    [​IMG]

    In addition to this work, I installed new tires on the bike, along with new brake pads. Now just to rejet the carbs(parts are in the mail) and it'll be ready to ride to start getting some baseline fuel economy figures.
     
    Last edited: Apr 4, 2010
  13. Insert Tokens

    Insert Tokens Making Cancer My Bitch OT Supporter

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    My monitor just overflowed.
     
  14. igotyofire

    igotyofire New Member

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    what is an air gas hybrid?
     
  15. saxman

    saxman Burninating the peasants

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    pressurized air is being used as an energy storage means, versus an electric gas hybrid where a battery is being used to store energy
     
  16. AVengeance

    AVengeance Active Member

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    :bigthumb:
    Simple and direct. That's pretty much it.
    I still think you'd have better fortune with a gas / electric hybrid. Maybe when the wife tires of her Eliminator 125, I'll convert it to a hybrid.
     
  17. igotyofire

    igotyofire New Member

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    yea but....pressurized air needs to spin a turbine of some sort to be utilized?
     
  18. saxman

    saxman Burninating the peasants

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    If it's being converted to an electrical supply, sure. No reason a hybrid has to have an electrical aspect, that's just what most people are used to seeing.
     
  19. saxman

    saxman Burninating the peasants

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    Been a bit busy, but haven't had much to report. Been debating what I wanted to do for the exhaust on the bike, as I need to keep with the visual theme I've got in mind, but wanted something a bit quiet and more subdued. The exhaust on the bike right now is an aftermarket Vance and Hines system that performs well and is very very loud. Wouldn't work. I wanted an exhaust that I could mount under the bike like seen on the Buells and the Yamaha FZ6R, but that requires more money than I wanted to budget towards the exhaust. Fortunately, Craigslist came to the rescue and I found a pair of 2008 CBR600RR exhausts for free in Santa Cruz. I'll probably have to cannibalize both to make one exhaust that'll work, but I like the look, the sound is right, and the price couldn't be argued with. Here's a side by side video showing the sound of the two exhausts.

    [y]cvVOeRYSkSg[/y]

    The 600rr exhaust won't be mounted there, that's just where it happen to end up without cutting the stock pipes. The sound should clean up a little bit as it was leaking exhaust too. Here's a rough idea of where the exhaust will go. I'll have to shorten the pipe a bit and other fun things to get to fit. Ground clearance shouldn't be an issue when it's mounted in it's final position.
    [​IMG]

    In other news, the new forks for the front end are all cleaned up. Painted the bodies to match the frame. Huge improvement over the stock forks with surface rust covering the chrome parts. No good.
    [​IMG]

    On the compressor front, I tore into the extra motor I have laying around. Pulled the head and the cylinders to get a better idea of what I'll need to do. Essentially, I'll need to pull out both valves from one of the two cylinders.
    [​IMG]

    This head will need a lot of work. Didn't even have a headgasket on it. No wonder it wasn't running before. I'm amazed how trashed those valves seem. We'll see if it can be salvaged.

    The cylinder that's going to be used as a compressor is likely to end up with an o ring on the piston instead of traditional piston rings. The amount of pressure it needs to hold is significantly lower than a normal combustion cylinder, the heat it's exposed to is way less than normal, and it's a great opportunity to significantly reduce internal friction. Some numbers suggest that about 30% of the energy from combustion goes to overcoming internal friction, with the piston rings being one of the largest sources of that friction. This is a wonderful opportunity for performance and economy gains. Unfortunately the couple of free o rings I had laying around didn't quite fit. I'm sure I can find somewhere to order some. Now just to figure out how to polish up the inside of one of the cylinders. Perhaps I can get creative with the home honing sets, only with a liberal application of jewler's rouge.
    [​IMG]
     
    Last edited: Apr 4, 2010
  20. deusexaethera

    deusexaethera OT Supporter

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    Maybe you can rig up an exhaust bypass valve to feed exhaust into the second cylinder when appropriate, so when the engine is cruising, instead of just letting the second piston flop around it can be used to gain a little more power from the exhaust expanding in the second cylinder instead of in the muffler.

    You could also add a water injector to the second cylinder so the water spray could flash to steam when it hits the hot exhaust, and turn more of the exhaust's heat into usable energy. Lots of possibilities here. Might want to read up on six-cycle engines if you haven't already.
     
  21. saxman

    saxman Burninating the peasants

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    There are plenty of little things like that I could add to milk out a little more, but going to try to tackle the big parts first
     
  22. saxman

    saxman Burninating the peasants

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    Bit of an update. Finished the valve housings today. Conversion of one of the cylinders to a pump is about 90% there.

    since everyone loves pictures


    How the design started
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    Milled from 4"x4"x3" 6061 billets
    [​IMG]

    Almost finished product
    [​IMG]
    [​IMG]
     
  23. RoblesGT

    RoblesGT [Track Days: 19 ][Crashes: 1] [SuMo Days: 1 ][Cras OT Supporter

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    subscribed, you fucking nerd ass nga ... :coold:
     
  24. saxman

    saxman Burninating the peasants

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    haha, can't say I've been called that before
     
  25. saxman

    saxman Burninating the peasants

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    Spent a while working on the bike project today. Got the new valve housings all bolted up, and the old valves removed.

    I really need to do some cleaning to get all that built up gunk out of there. Any suggestions?

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