4 stroke vs. 2 stroke

faust /
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the mechanics of the two types of engine are totally different. 2 stroke engines fire on every revolution of the engine. 4 strokes, every other revolution.the revolution of the engine that the engine doesn't fire is used to push out exhaust and draw in the fresh air/fuel mixture. the crankshaft is used to 'pump' the air fuel mix into the cylinder on a 2 stroke and the incoming mixture is used to force the exhaust gas out of the cylinder. this is part of the reason that the shape of the pipe is so important on a 2 stroke. like a musical instrument, it is 'tuned' to help optimize air flow. the 'megaphone' cone shape of the exhaust lets the exhaust charge escape easily. the reverse 'megaphone' shape on the other end of the pipe helps to slow down this same charge to keep the fresh air/fuel mix from just following the exhaust out the exhaust port. the more air/fuel mix in the cylinder with the least exhaust in the same cylinder, means more power.

all this is accomplished with camshaft timing, lift, duration, ect... on a 4 stroke engine. fresh air/fuel mix is drawn in thru the intake port, past the intake valve, as the piston reaches the bottom of the cylinder, the intake valve closes, the mixture is compressed. around 10 to 20 degrees before TDC the spark is fired, pushing the piston down. as the momentum of the piston forces it back on the upswing, the exhaust valve opens forcing the exhaust charge out. the size of the exhaust pipe is more important than the shape for a 4 stroke because it doesn't need the shape to help scavenging. port shape is more important. valve size, cam profile (lift, duration, overlap,...), carb size, ect.

tell some guy with a CB750 you can't build a honda. tell the kid in the civic you can't build a honda... I think they'd reply, " you need to quit smokin' that s#!t, it's bad for you.

2 stokes in general make about 50% more power for their displacement, but they don't burn their mix completely (that's part of the reason they smoke, VOLUMETRIC EFFICIENCY) if they did it would be closer to double.

both can be made to make power, just gotta do like the nascar boys. "you can make any engine go as fast as you want to spend your money."

This single post is part of a larger thread. Start from the top or view this post in context.
Subject Written By Posted
  Honda Metro / Crea Scoopy Un-Restriction & TunTopic by: optionboy optionboy 08/08/02 08:07AM
  Re: Honda Metro / Crea Scoopy Un-Restriction &Re: Chris Rice Chris Rice 08/08/02 11:23AM
  Re: Honda Metro / Crea Scoopy Un-Restriction &Re: dave dave 08/08/02 12:20PM
  Re: Honda Metro / Crea Scoopy Un-Restriction &Re: InfectedBootSector InfectedBootSector 08/08/02 03:51PM
  No 'expansion chambers for 4 strokesRe: Fred Fred 08/08/02 04:11PM
  Re: No 'expansion chambers for 4 strokesRe: InfectedBootSector InfectedBootSector 08/08/02 04:24PM
  Re: Honda Metro / Crea Scoopy Un-Restriction &Re: Asdf Fdsa Asdf Fdsa 08/08/02 06:27PM
  Re: Honda Metro / Crea Scoopy Un-Restriction &Re: InfectedBootSector InfectedBootSector 08/08/02 06:36PM
  Re: Honda Metro / Crea Scoopy Un-Restriction &Re: h/b h/b 08/05/05 08:30PM
  Re: Honda Metro / Crea Scoopy Un-Restriction &Re: Fred Fred 08/08/02 09:37PM
  Re: Honda Metro / Crea Scoopy Un-Restriction &Re: david f martin david f martin 08/08/02 09:55PM
  Re: Honda Metro vs. KymcoRe: Wayne Wayne 08/08/02 10:23PM
  Re: Honda Metro / Crea Scoopy Un-Restriction &Re: Asdf Fdsa Asdf Fdsa 08/09/02 08:10PM
  Re: Honda Metro vs. KymcoRe: david f martin david f martin 08/08/02 10:33PM
  Mini's at the strip.Re: Fred Fred 08/08/02 10:41PM
  hawaiin scoots deluxeRe: Asdf Fdsa Asdf Fdsa 08/09/02 08:32PM
  Re: Mini's at the strip.Re: david f martin david f martin 08/08/02 10:58PM
  4 stroke vs. 2 strokeRe: faust faust 08/09/02 12:06AM
  Re: 4 stroke vs. 2 strokeRe: Fred Fred 08/09/02 12:27AM
  Re: 4 stroke vs. 2 strokeRe: faust faust 08/09/02 12:45AM
  Re: 4 stroke vs. 2 strokeRe: Asdf Fdsa Asdf Fdsa 08/09/02 08:48PM
  street drags????Re: dave dave 08/09/02 10:04PM
  Re: Honda Metro / Crea Scoopy Un-Restriction &Re: david f martin david f martin 08/09/02 08:19PM
  Re: Honda Metro / Crea Scoopy Un-Restriction &Re: Asdf Fdsa Asdf Fdsa 08/09/02 08:49PM
  Re: Honda Metro / Crea Scoopy Un-Restriction &Re: h/b h/b 08/05/05 08:34PM

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