I'll be going boost on my Z6 equipped crx in the summer, and I've been hearing a lot of compression ratio talk. What does it all mean? 12:1? 8:1? I need someone to explain it to me like a little kid!

btw: I plan on running 5-7lbs. on stock internals w/ a greddy kit.

 

The compression stroke is the upwards movement of the piston in the cylinder with the valves closed following the intake stroke. This upwards motion compresses the fuel air mixture inside the combustion chamber raising the pressure. The difference between the initial volume of the cylinder and the final volume at the top of the compression stroke is known as the compression ratio. Typically this is approximately 9:1 in spark ignition engines and 15:1 for diesel engines. The compression ratio is particularly important in compression fired engines such as diesel engines. The fuel-air mix and compression ratio is critical to avoid pre-ignition which is the abnormal ignition of fuel in the combustion chamber before the combustion stroke. In diesel engines the fuel is injected under high pressure towards the top of the compression stroke. The distribution of fuel before combustion is also of interest because it effects the efficiency of combustion.

 

i'm not flaming anybody but is the number of posts a lie or can it be altered because somebody with that many posts should grasp the idea of compression ratios. Just a thought....

 

No one asked for your opinion. But up to now, I never built up my bottom end or gone FI so thats why I'm asking the question.

 

mamaboy: shutup

RacerBoy: Im pretty glad u asked this because I've been wondering about it too.. kinda thought it'd be over my head if I asked about it though.

GudeH23a: so if I have a 12:1 compression ratio.. that means the piston squeezes 12 times the a/f mixture once its compressed? and how do 8:1 or 10:1 or 12:1 FMU's interact with this?

 

The Piston compresses the A/F mixture to 1/12 its original volume, this also increases the density & pressure 12 times.

FMUs are totally different. when a 12:1 FMU sees 1 lb of boost, it increases fuel pressure by 12 psi.

 

hahahahaha....wow...hahahahaha

 

Hey *******, are you helping anybody here? Most of us know these things but some don't. Everybody has to learn somewhere. WTF do you think this forum is here for?

 

He can post in the other H-T forums and get alot of legitimate posts.

Remember, this isn't just a FI forum. People slowly come to the darkside....

Randy