They aren't, except for hp per cubic inch.quote:
Originally posted by drive it forever:
If two cycles are much more efficient then 4stroke engines,
Given a single cylinder, a 2 stroke engine delivers 1 combustion event per crankshaft rotation, while a 4 stroke delivers 1 combustion event per every other crankshaft rotation. That's why 2 strokes are more powerful. The way a 2 stroke gets fuel to the cylinder is a little messy, though. Basically it goes into the cylinder in the back side of the piston (where it lubes the bearings and cylinder walls), then gets pushed to the front side through a tube as the piston gets pushed down from the combustion event. I don't know all the details, but the result is a less efficient burn than a 4 stroke, resulting in much dirtier exhaust. I believe a big part of the reason is that you have fresh fuel and air mixing with the combustion gasses, which results in less oxygen available for the combustion. You're also burning oil with the fuel, which can lead to smoky exhaust.quote:
Originally posted by XS650:
They aren't, except for hp per cubic inch.quote:
Originally posted by drive it forever:
If two cycles are much more efficient then 4stroke engines,
I agree! My 9-5 Saab isquote:
Originally posted by Drew99GT:
Guys, I'd say that it's a toss up in today's world with modern fuel injection and turbocharging technology. My old turbo car would get unbeatable mileage if I laid out of the boost really hard. Just cruising on the interstate though, the turbo does all the work on steep hills and such; once it spools just a hair, you can lay off the throttle a bit and get amazing gas mileage. Look at the mileage that Saabs get.
Another good comparison would be the two Impreza models with the same displacement engines:quote:
Originally posted by tweeker43:
same car, different motors
subaru impreza 2.5rs (na), 165hp - 23/30 mpg manual, 22/28 mpg auto
subaru impreza wrx (2.0 turbo), 227hp - 20/27 mpg manual, 19/26 mpg auto