Discussion in 'Performance Mods' started by militarymonark, Feb 5, 2012.

  1. militarymonark

    militarymonark New Member

  2. militarymonark

    militarymonark New Member

  3. HeadSmess

    HeadSmess Well-Known Member

    the elctric one would be handy as a blower on my forge and nothing else, they cant make pressure.

    the real turbo...thats on my wish list now :)

    but please. on a pitbike, not a bicycle.
  4. militarymonark

    militarymonark New Member

    I'd like to put it on my whizzer
  5. jaguar

    jaguar Well-Known Member

    Turbos that utilize the exhaust on a two stroke are not a good idea because then it would screw up the effect of any expansion chamber you put on it, and I doubt it would give more power than an expansion chamber. The problem with two strokes is not inability to breath, but inability to retain what it has breathed since 20% of it is lost out the exhaust port before being burned. An expansion chamber stuffs that lost 20% back into the cylinder at top rpms for a power boost there.
  6. HeadSmess

    HeadSmess Well-Known Member

    not only that, it also raises crankcase compression, increasing charge loss through the exhaust port with bad transfer designs, increases strain on crank case seals and still doesnt do a thing for the compression ratio, therefore making no affect on performance, if not a major loss in performance...

    ill chaange the pitbike/bicycle statement to

    "on a 4 stroke, not a 2stroke, please"
  7. motorpsycho

    motorpsycho Active Member

    yep an expansion chamber (if set up right and tuned) will give you a supercharger effect. a chamber is a lot cheaper, and a lot easier to install....Just bolt it on.
    i'm afraid that setting up a turbo to actually work on a 2 stroke would be pretty difficult.
    you'd have to beef up the bottom end to handle the boost pressure. as well as install the turbo, make new exhaust, and an intake, plus run an oil line in and an oil line out to the bearings in the turbo. then you'd have to make up some sort of gravity feed oil reservior that woudl not only supply the oil to the turbo bearings, but it woud also have to take in the return oil from the turbo bearings.
    to get free horsepower from a 2 stroke, you need to take advantage of the exhaust and put on a good expansion chamber.
    if you have never ridden a 2 stroke with a properly tuned expansion chamber, you'll be in for a surprise. when the pipe "comes on" it's the same effect as if it had a turbo or a supercharger.

    putting a turbo on a 4 stroke would be easier...such as this:

    a test run:
    Last edited: Feb 21, 2012
  8. HeadSmess

    HeadSmess Well-Known Member

    a two stroke CANNOT be turbocharged.

    exhaust port opens, then the transfers open. air starts pumping out from crankcase.

    piston has covered up intake port so turbos just trying to blow air down a blocked hole.

    any increase in crankcase pressure simply forces charge out and into cylinder faster through transfers.

    transfers closed, but exhaust port is still open. any extra air that somehow made its way into the cylinder to raise pressure, wont. the exhaust ports open.

    therefore youve added a lot of inneficiency for no gain whatsoever, just a loss.

    but **** psycho! that chopped schwinn looks...like it might need rego! :jester:

    with that fleabay turbo that militiary linked it could be made a lot neater :) the closer you can mount a turbo to the ports, the better.
  9. MikeJ

    MikeJ Member

    That's one heck of a unique ride. And a unique crew. The bike ought to be as much fun to ride as it will be to watch it be ridden.

    So turbo chargers are out? So I'm willing to bet some curious person will next ask, "What about a belt-driven centrifugal supercharger, shaped like the pistol-grip hair dryers of long ago?" I'll bet somebody will ask that....
  10. max350

    max350 Member

    Two stroke engine can be turbo charged - snowmobiles for example http://www.tikka.se/default.asp?ID=80&menu_item=80
  11. motorpsycho

    motorpsycho Active Member

    I am by no means an expert on this subject, but i the major difference is that snowmobile engines have reed valves, not transfer ports.
    since the reed valve act like regular valve (such as in a 4 stroke) I could see how a turbo would work on one of these.
    If you think abotu this as well, i have seen 2 stroke diesel engines with turbo's and superchargers together.
    BUT, i think the major difference is the valve arrangemet, which allows you to actually build boost in the cylinders.
  12. motorpsycho

    motorpsycho Active Member

    no, but i've thought about making a dummy centrifugal super charger just for looks.
    Or, maybe a small empty turbo case, bolted up to the intake, and then run the real exhaust through it just for the look.
    hey, sometimes the look is all you need to make a point.
  13. Neon

    Neon Member

    If it's not possible to turbo charge or super charge a two stroke. the maybe you can tell me why Jonsered, Husqvarna and Poulan have been doing it for years. It doesn't give a huge horsepower increase .1hp, It's not really a turbocharger. More like a low grade super charger, but is still forced induction. It's main claim to fame is to keep the air filter cleaner, but still manages to give a slight power boost. The saws certainly sound like something is going on, there is a massive whine that gets worse the more the revs increase.
  14. motorpsycho

    motorpsycho Active Member

    yeah i know what you are talking about.
    but really, on a 2 stroke such as these h.t. ones, a well tuned expansion chamber will give you the same results as if the engine had a turbo or a supercharger, and that would be at a fraction of the cost of a turbo or a supercharger.
    when you have a well tuned pipe, as soon as the engine gets into it's peak working rpm range where the pipe is working, the rpms will just take off like crazy, just like they woudl with anything that builds boost pressure.
    the whine you hear on those chainsaws may just be the chain.
  15. Neon

    Neon Member

    The noise doesn't go away even when the chain is removed. Thought it might have been the auto chain oiler as well. With that gone it's still there. Also have a non-turbo Jonsered. I use it everyday. No whine at all just excellent cutting power. And yes an expansion chamber is still the easiest and cheapest way to go
    Last edited: Feb 23, 2012
  16. HeadSmess

    HeadSmess Well-Known Member

    any two stroke engine, with the exception of the larger DIESEL engines, has transfer ports. regardless of whether the induction is via piston porting, reed valves, or disc/drum valves.

    all twostrokes, excepting the diesels, use crankcase induction. it is a fundamental key to their operation.

    i believe the "forced induction" mentioned with the chainsaws is to do with ventilating/cleaning the airfilter. simply raising the pressure in the air box, reducing the effort needed to suck air in through woodchips and sawdust and bar oil and sap and borer innards and index fingers is always going to improve performance. and blowing a breeze past a fiilter does something for keeping it cleaner than one that just sucks at debris all day...

    more of a leafblower than a performance upgrade?

    a tuned pipe, coupled with correctly shaped and TIMED ports is the ONLY way to go on 2 strokes.

    the design of a 2stroke simply means that any method used to raise INTAKE presure, is useless. people have been working on them for over 100 years, thinking of how to make them run better. noone has yet thought of anything that works as effectively as a tuned pipe.

    there is a fourstroke engine that completes ALL cycles in one revolution, intake compression power and exhaust... technically thats a twostroke... thought id throw that in just to confuse everyone :)

    and to add to the confusion.... by using a tuned pipe in conjunction with some type of intake booster...ie a turbo... they could work. the pipe being there to squeeze everything back into the cylinder...so if the turbo pushed more out into the exhaust, the exhaust has more to push back in... and combined with reed valves that can open whilst the piston sweeps through bdc, unlike other port systems...

    so ill change my statement and outright denial to " 2 strokes cannot be turbocharged EFFECTIVELY with the exception, possibly, of reed valved twostrokes combined with tuned pipes designed for such a system"

    considering the effort required just to design a good pipe, and fabricate one... leave the turbo for the fourstrokers.
    Last edited: Feb 24, 2012
  17. Neon

    Neon Member

    I believe i already had said that.
  18. HeadSmess

    HeadSmess Well-Known Member

    not exactly.... you call it a supercharger and forced induction.... mentioned the fame claim, but still called it a forced induction system, which it is not.
  19. Neon

    Neon Member

    Ok, my bad. Sorry.
  20. machiasmort

    machiasmort Active Member

    In a two-stroke, the exaust is the turbo. When balanced and tuned properly, engine hits given rpm (filling up the exaust pipe), this pressure pushes back on the top of the piston increasing the rpm of the motor, otherwise know as "power band".