Fuel octane rating

Russell · Post by **Russell** » Sun Aug 01, 2010 7:13 am

Finally got my darmah ssd running, spent a small fortune getting there.
One question, what is the best octane rating to run my darmah on, over
here in the u/k we have unleaded 95 ron and super unleaded 97 ron.
Should I be using an octane booster on an engine with a high compression
ratio of 9.5 to 1.

Post by **BevHevSteve** » Sun Aug 01, 2010 8:46 am

Please tell us your cranking compression,....

Russell · Post by **Russell** » Sun Aug 08, 2010 7:06 am

I have checked the compression and the readings are 185psi on the front
cylinder and 186 psi on the rear cylinder. I have had new hardened valve
seats fittedand stainless steel valves. The cylinders have been rebored and new pistons fitted, the bore is now on 86.6mm with forged pistons.

Grover · Post by **Grover** » Sat Aug 14, 2010 1:21 pm

Russ, here in Australia I run my Darmah on BP 98 Octane, where we go up in the mountains I need to put fuel in it to get home and all they have is one of those "no name" servo's that sell supposedly 95 Octane fuel, trust me, after 5klm's it runs like a dog and has no pulling power compared to running BP 98. When we travel around to classic rally's I always look for BP first, followed by Caltex then if I have to I will put Shell in it, but here the 98 Shell product varies way to much for my liking.