In talking with a friend about her search for a new car, she implied that she would never purchase our 4-cylinder lovely because of the compression ratio. Is her concern relevant? Is our compression ratio higher than the majority of other cars out there? I would assume that Honda wouldn't produce a car with compression so high that it would be a problem...?

Granted my automotive knowledge could fit on the head of a pin with room left for the unabridged works of Shakespeare, but in all the research I did before buying a new car, compression ratio just wasn't on the list.

Before anyone flames me for asking a potentially painfully stupid question, please consider that I am a female (shameless plug for mercy) with no background in how engines work, although I'm learning more as I go along and this site has been invaluable.

Thanks in advance for any explanations.

Julie

ps. moderators: if this is the wrong forum please relocate.

 

Our compression ratio is definitely on the high end of the scale for road-going cars.
However, the only real disadvantage I can see with higher compression ratio engines is that you generally have to buy higher octane fuel. That'll cost you a couple extra dimes at the pump.

 

Oh cool! I'm the first one, so I get to explain it... don't know how much you know, so I'll start with the basics and hope I don't insult you...

A basic four-stroke engine consists of four cycles: intake, compression, combustion, exhaust. During intake, a valve opens and lets in the fuel into the cylinder while the piston is moving down. Because of fuel injection, this consists of a mixture of gasoline vapor and air (for oxygen). During compression, the piston moves back up, compressing the air/fuel mixture. Combustion occurs very close to top dead center (when the piston is at the top of its stroke), when the spark plug ignites the mixture. The resulting explosion pushes the piston back down. This is the power stroke that gives the power to the drivetrain. Just as the piston begins to come back up, another valve opens to release the exhaust gases left over from combustion, and the cylinder forces the waste gas out the valve. When it reaches top dead center, its ready for another intake cycle.

This probably sounds confusing, but check out http://www.howstuffworks.com for EXCELLENT explanations, complete with animations and everything!

The compression ratio has to do with the volume of the air/fuel mixture in the cylinder compared to the volume under compression (at top dead center). Our engines are 2.0L, meaning the cylinder volume is 0.5L. An 11:1 compression ratio means it squeezes down to 45.5mL before ignition! THAT'S HIGH! Average vehicles run around 9.5:1, with most performance vehicles running 10.3:1 - 10.5:1.

NEVER FEAR THE S2000! Honda built all the supporting components tough enough to take it. In fact, many people here use some sort of forced induction (mostly supercharger) without any issues at all, even after thousands of miles. With an inline four that weighs 2850 lbs that puts 300+hp at the wheels, how can you go wrong!?!?!

 

No think if you got the stroker route, i ve heard that the TODA stroker kit strokes the motor to 2.2 liters and takes the compression up to 14.1 i believe. Damn i want to hear that motor at redline!

 

Thanks, guys. I appreciate the help.

s2k-zonie--nope, not insulted in the least. Great explantion and I understood it. (but don't ask me to explain it to someone else!) Thanks for taking time to answer.

Julie