Compression

Hi, I just broke in my" new" b series engine and my compression is 13.1:1 , my question is, do I need to run it on race fuel? In my country we only have 95 or 98 octane gasoline!

Thank you

You only need to run race fuel if you want to get all the power that compression ratio can produce. You will be probably be knock limited without using a higher octane fuel.

If you are planning to actually race this car, many tracks have fuel pumps with race fuel available. Or search for fuel distributors, you will often find that race fuel is available in 5 gallon and 55 gallon drums. Check with Powersports (Motorcycles, ATV, etc) dealers as well, they often sell high octane fuels for off-road vehicles.

I don't have a definitive answer but I have chosen to run my 12.5:1 cr b18c on E85 to be safe. Do you have a knock sensor? If not maybe run octane booster with 98. I was knock limited on 98.

Depending on the camshafts, quench, and other aspects you may be able to get away with close to optimal timing.

Anti-knock additives have been mentioned and I would recommend using a knock sensor in case the additive is a bit diluted.

There are a couple of other things that will give a little more lee-way - using a cold air induction setup that keeps the air temperature as low as practical, and running the engine temperature a little lower - if you use a thermostat, you may be able to find an 82C one that fits - as that will help pull heat out of the charge under compression.

I am a little puzzled why you built the engine with that high a compression ratio, if you didn't have the fuel for it, though - is that an actual measured and calculated value?

Knock sensor seems to be kind of hard to adjust in this od engines

I guess it was kind of a beginners mistake, I was aiming for high compression but wasn't aware of the knock problem...the cams im running tho are skunk2 pro1+.

The thermostat is q great point and I will find one with a lower opening temp for sure, as for the octane boosters , I've heard so much about them "good and bad" do you think is something I should do? Thanks everyone for the help by the way

My personal view is that while they are a band-aid, rather than a cure, they do have their place. My main concern is that if one isn't careful, or runs out, the fuel will be diluted and this could cause issues. S you say, the quality does seem to be variable - there are several comparison/reviews of the different brands available on-line, which I would suggest checking out.

You may wish to try one, or at least carry a bottle or two in the boot (trunk) in case you get some bad petrol (gasoline) somewhere.