Possiible Retro fit direct injection

Discussion in '2-Stroke Engines' started by crgintx, Dec 3, 2008.

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  1. crgintx

    crgintx Guest

  2. bluegoatwoods

    bluegoatwoods Well-Known Member

    It was an interesting article, but I'm not sure I understand what's to be accomplished.

    It seems to be a fuel injection conversion. And will this make these engines burn cleaner?
  3. crgintx

    crgintx Guest

    Absolutely! Direct fuel injection will likely become the norm for all street driven internal combustion engines as it eliminates 99.9% of all unburned fuel in the exhaust. The fuel is injected with high pressure during the compression stroke with zero valve timing overlap. A properly designed two-cylinder two stroke will make the same peak power as four-cylinder four stroke twice it's displacement size because they make they same number of power strokes per crank revolution. What's really exciting is that with electronically actuated valves, ICE of the future may be able to switch between two and four cycle operation. Four stroke cycle mode for low rpm torque and cruising and two cycle mode for acceleration and top end. Even the best street two strokes currently are extremely dirty emission wise. With direct injection and pressurized oil lubrication, a two stroke will run as clean as any four-stroke engine out there.
  4. bluegoatwoods

    bluegoatwoods Well-Known Member

    I'm in a bit over my head here, but it's difficult to imagine and engine with intake and exhuast valves operating as a two-stroke. And in the case of a two-stroke engine it would seem as if the compression stroke clearing out the exhaust would push out unburnt fuel whether it was carbureted or injected.

    Sorry. I don't really mean to drag you down into a long explanation for my benefit. But maybe it will become more clear to me when some more give and take occurs in this thread. I'll keep my eyes on it.
  5. crgintx

    crgintx Guest

    Most big rig diesel are two strokes but they are using a positve displacement super or turbo charger to force fresh air into the engine. Naturally aspirated gas two strokes use negative displacement to clear the cylinder. The pressure on the exhaust stroke inside the chamber is higher than outside pressure in the exhaust, so as it escapes though the exhaust port(s), it creates a vacuum that draws the fuel air mixture from the intake port(s) into the cylinder. The timing overlap is much greater than a four stroke and some raw unburned fuel and air is always sucked into the exhaust. Throw in some two stroke motor oil for lubrication and you have some serious HC emissions. You should do a search on the posts for two stroke tuning. There's some links that explain the cycle much better than I can.
  6. Skyliner70cc

    Skyliner70cc Active Member

    Not most, but some are 2 stroke engines...detroit diesel being the big one that has had many 2 stroke diesel engines for big rigs.
  7. QuadManiac

    QuadManiac Member

    But the real question is what does this have to do with MB 2-strokes?

    The investment to convert to DI on an HT or other small 2-stroke (unless somebody, someday, makes a readily availble, mass produced, off the shelf conversion kit) will be more than your car is worth, let alone your motorized bike.

    Nice idea... long way from practical in our application.
  8. crgintx

    crgintx Guest

    Quad, my friend the answer to that one is simple: Emissions standards! If the greenies in the new admin and Congress get their way, all two-strokes will be illegal on public roads regardless of when it made unless it passes a much stricter emissions standard. Even relatively regulation free Texas there is now a gross car pollution hot line and in Houston,DFW, Austin and El Paso, the police can hand you a ticket for gross pollution whether your vehicle has a current emissions/safety inspection sticker or not! Yes, a motored bike delivers more than 3-4 times the gas mileage of the best cars right now but it dumps 25x as much pollutants per gallon of fuel than does the car. The People's Republic of Kalifornia is working as hard as it can to ban all two-strokes and most 4-stroke engines that don't pass the same standard as cars.

    The days of free and open roads are nearly over. The eco-nazi's have already developed a mobile emissions tester that is hand-held and the fuzz will simply put it in your tailpipe when he pulls you over for riding in a 'suspicious' manner. State and local gov't love the idea because it will generate massive amounts of cash for them. In case you haven't noticed, we now live in a police state. The insurance companies are already subpoenaing the black box in all cars equipped in any accident before they payout and are trying to get legislation passed that all cars must be equipped with a GPS that has a built in memory or they won't have to ensure them or they will charge you a massive premium for the pleasure of driving privately.
  9. QuadManiac

    QuadManiac Member

    All true crg, my friend. BUT, if several thousand dollars (or more as i suspect) is required in order to integrate DI into a MB engine (again, unless somebody makes an affordable off the shelf solution) then the topic really is moot. The majority of us will go away or just ride illegally. Nobody's going to retrofit at that cost... they'll just buy a commercial scooter that DOES meet emission standards.

    In order for someone to make an affordable system for MB's there has to be 'economy of scale'. They can't do it (and stay in business) just to meet the needs of the few MB'ers here in the states. NOW, if China were to require such for their own populace, the numbers are there and we might see something that would do the job at a reasonable cost. Don't hold your breath.

    I expect 2-strokes will just be outlawed eventually, and we will have to transition to EPA approved 4-strokes. I don't like it, but as you imply, there may not be an alternative that IS affordable.

    We, as MB'ers, are 'tinkerers'... doing this more as a hobby (or insanity as you state) than as a necessity (of course there are some to whom this is a necessity). As such, we have been finding ways to make things 'legal', but just barely. As the laws get tighter, we'll have to adapt. I don't think we have enough of a voting base among us to enact legislative change, but that doesn't mean we shouldn't try. We'll continue to find ways that allow us to ride and, hopefully, won't cost us an arm and a leg for the privelege.

    Good luck and good riding!
    Last edited: Dec 5, 2008
  10. crgintx

    crgintx Guest

    Saw this in the SAE International magazine

    This company has developed a bolt-on EFI system for small motors. They're hoping to get it out the door for about $50 per unit. This looks like a pretty serious attempt at a true carb replacement system.

  11. BSA

    BSA Guest

    does anyone know about them computer controlled carbs that were popular in the 80's.

  12. QuadManiac

    QuadManiac Member

    Now this is an interesting development, assuming they do reach the market. Looks like they do have some product out there - "Supplier to motorcycles for the 2008 Bejing Olympics."

    One to watch!