- Oct 18, 2003
- Saline Michigan
Two sparkplugs per cylinder with these small combustion chambers and EI is probably excess;If I could take an off the shelf motor and throw money at it I would get a small alloy block 4 cylinder motor and make an aviation specific head for it.
2 spark plug holes per cylinder.
2 valves per cylinder.
Reduction drive shaft running at 2 to 1 with bearings at front and rear to carry prop loads.
Secondary function of shaft is to activate valves.
For a 3 cylinder engine some balance factor built into shaft.
Now for the hard part.There has to be a drive system either belt or gear with some cushioning to drive the secondary shaft.
Two valves per cylinder when the base engine came with four means lots of custom parts. Now if you could get a SOHC four valve per cylinder engine, you would lose some weight while keeping most of the breathing advantages and not having to design and build a new head;
Reduction drive at 2:1 is scary, with all sorts of resonance interactions that you DO NOT WANT;
Balance shaft for a three is usually at engine speed, not the one-half engine speed that camshafts run at;
You will definitely have to build a vibration isolation system into the prop shaft as the big inertia of the prop will not play well with the firing vibrations - resonant frequency of the prop on one end and the whole engine on the other will require a soft enough spring system to drag 1st resonant order down near or below ground idle of this system.