Never Really understood the break down and the significance of the compression ratio numbers(8:5:1,8:8:1,etc). Also to which sercumstances do your run high or low compression ratios and what would be the pros and cons of such. And how do you go about choosing the best set up for your goals/boundrys.
Thanks
Joshua.

 

theres more to it but to make it simple, lower ratios around 8 or 9 to 1 would be better for boosted aplications, higher ratios like 10 or 11 to 1 is better for n/a

 

but all the baller pro people run 10-11:1

 

Would anyone be able to supply a link/book/article that would elaborate. Though there is "more to it" I would really like to have a good understanding of this topic as to better my knowledge and understanding not just this is this, that is that. Hopefully I will be able to decide in the end what is best for my set up. Knowledge is Power...horsepower .

 

compression ratio is the volume of the combustion chamber when it is all the way at the bottom of the engine (bottom dead center) compared to the volume of the chamber when it is at top dead center.

more compression = more torque and better fuel mileage. if your compression is too high, you run into detonation (the charge being ignited before the plug fires) because compressing gasses heats up, in this situation to a temperature high enough to ignite them.

higher compression usually = more power, unless you run a lower compression ratio and more boost.

thats how i understand it anyway, some of that may be a bit off....gl

 

they also have to run race gas all the time or low boost, for an all out race car that is built right and for the track a higher ratio and high boost with race gas can make the most power but for daily driver dsm street cars on pump gas a 9/1 and around 20psi will get you safe and good results

 

heh...knowledge is power, power is horsepower, horsepower is going to rip apart your dsm from the inside out. but you will have a blast on the way.

i dont know of any links, but maybe try howstuffworks.com look up compression ratio and see what pops up

nevermind i looked and found this Compression Ratio - Page 1

 

I was going to put some of that but i didnt want to type that much at work

 

GSt racer very good link . Very very informative. There was a couple things I never knew. On the funny side the formulas they used looked similar to the ideal gas law. High school does have a purpose jk. Thanks guys for the info.