Under square, over square or square (Bore and stroke the same number) matters not. Detonation is the ignition event remote from the spark plug AFTER the plug has fired at its normal time.
So, detonation is charge temperate dependent.
Although my driver could detonate the race engine on the way to the false grid and he did observe the rules of detonation by letting the clutch all the way out (Engaged) while at very low speed. Our first gear was good for 70 MPH, (Like starting out in third gear in a street car) So you must slip the clutch a bit and then declutch to clear the engine, then slip some more. But never engage the clutch with any amount of throttle applied.
In normal use it is nearly impossible to detonate a normally aspirated rotary. Large cold combustion with poor squish areas.
This is also why they are hard to start in cold weather. Worse when warn out with low compression.
The fuel air mixture is carried past the plugs at high speed. Like you holding a lighter out the window going one way down the road while your friend passes you in the opposite direction holding a candle out his window.
The chance of the candle lighting is slim indeed.
The engine will run very well on very low octane fuel. In olden times we ran 86 octane (regular) gas with extra motor oil mixed with the fuel so as to reduce the octane further and improve sealing and reduce ware.
Timing at 20 degrees on both leading and trailing plugs.
Later race engines used 27 degrees of advance on both plugs but still regular gas. The ignition system in racers is nearly always a MSD 6AL or better or a Mallory HiFire. My plugs were gaped at .010" NGK R6725-11.5. If a high speed miss developed (Above 9,500 RPM) the plug gap had opened a bit.
The rotary is a popular subject of the boosted folks because it can be boosted without fear of detonation, most of the time.
But remember that charge temperature must be controlled. This means anything that overheats the charge must be controlled. So boosting above 4 or 5 pounds without an intercooler is not done because of "Heat of compression
. Full throttle from idle is not done suddenly. (unless you have control of ignition advance via computer). Ignition advance must be reduced as
boost pressure goes up. Notice that as boost goes up the engine (in effect) is getting bigger in displacement but he combustion chamber is not. So the effect is that the compression ratio going up. And, since flame front travel will be higher, the effect is that you are advancing the timing....ouch.
That is the why of it.....Now the How of it..........Biggest intercooler you can fit in.....Highest octane fuel you can afford. Well rich of peak EGT for take off and climb. Once at cruise, lean to lean of peak until lean stumble, then back a bit. Looking for EGTs around 1600 degrees. Water of coolant about 180. Oil about 180 to 190.
Make one change at a time. Make the change big enough to see which way you are moving. Make a movie of the gages......LEH
In a message dated 7/17/2020 8:10:17 PM Eastern Standard Time, flyrotary@lancaironline.net writes: