Premixing Fuels on Rotary Engines - increased danger of knock / preignition?

Hi @ all!

First of all i would like to compliment Andrew as i really enjoy the webinars!

As i learned that oil contamination can increase the risk of knock i am asking myself if the premixing of fuel with 2 stroke Oil in rotary applications will contribute to a higher chance of knock occurring.

With alcohol based fuel like E85 we often use castor oil due to its better mixing capabilities with alcohol.

As premixing is a very common thing with rotary engine, does it matter that much? Should the mixing ration should be kept to a certain minimum?

How would you go about premixing in drag applications?

Thanks for your input!

Greetings from Germany :)

Yes using very high pre mix ratios can increase the chances of detonation. Regardless whether the oil is added as a pre mix or via the factory oil metering pump, some oil is required for the rotary engine in order to properly lubricate the seals so it's a necessary evil. Generally I would suggest following the advice of your engine builder about pre mix ratios.