hi,

was running well suported fuel last wkend in the nationals 1/8th ic onroad, and was struggling to tune the engine. its either have low end and no top end or vice versa. Then changed over to bryon gen 2 fuel and problem solved ! The first fuel used castor oil but not sure about bryon....oh this engine was a sirio AAC

hence my question is that oil % (castor or sythetic or mixture of both)....what would be min % for both protection and power ?

Thanks

Min oil % I would say is 8%. Some people like to go a bit lower but 8 is the lowest I like to go. Also, I like to add a bit more castor for AAC motors. It seems to help.

The issue you mentioned sounds like a moisture in the fuel issue more than an oil issue.

I agree that 8% is a safe minimum oil content but......

Most castor oils are thicker than most synthetic oils and castor does not burn compleetly with the combustion. Thats why I think with pure castor based fuels it is easy to go down with the oil content.

Regarding the difficulties in tuning. Because the thickness of the castor oil and it gives a layer of oil inside the engine I do think it will also act as a piston ring, a fill up between piston and sleeve to build up compression. When the engine is near end of life you can notice difficulties to get it reliable running when using some fuels and a perfect running engine with others, the other fuels must have a high content of castor oil.

I have found that 30% caster works well for me 8 - 10 percent oil. and 30% of oil is caster. I have found that the first press thick caster works really well and is cheap, I used degummed before. If you running shorter tracks go with 20% caster, its still safe, longer tracks you can up the caster 30%. If your motor is a little on the old side you can further up the caster content to increase compression 40% to 50% off total oil is caster. How do you find AAC motors?

All the best mate!