Anyone running 9:1 or higher on the street? Options

[-JR-]

I'm still hashing over compression ratios. I've been reading online that these motors don't or won't run compressions as high as 9:1 without taking extra steps. Like aluminum cylinders or electronic fuel injection. Mainly just because of the heat involved.

Has anyone "got away" with running higher compressions like this on stock cylinders?

*** IF anyone has any feedback on what fuel grade they are running at their higher compression and if they are getting any knocks ect... I would also greatly appreciate that information too.

Thanks everyone!

James

[Brett W]

AAAAHHHH the urban legend is back. Compression does not equate heat. The problem with running very low compression ratio is that it is very inefficient. All of the fuel air mixture does not burn inside the cylinder where it makes the most power. Some of that unburned mixture escapes from the cylinder and continues to burn on its way out the exhaust. This is what raises the head temps. If you run higher compression ratios then more of the mixture is burned inside the cylinder. Power is made through heat. The more heat you can keep inside the combustion chamber the more efficient the engine will be.

Higher compression = better fuel mileage, better throttle response, more power
Low Compression = Poor gas mileage, poor engine efficiency

With a higher compression ratio and proper camshaft design you can run much higher compression. Your car will be much more fun to drive.

This is one take on the situation.
http://www.theoldone.com/articles/The%5FSo...%5FHead%5F1999/

I ran 8.9:1 on 89 octane without any problems. My engine ran better on 89 than 93. I am building a 2056 right now that has 9.5:1, should have no problems running on 89.