Fuel injectors controlled from Arduino

@bmann

I believe that in the design end of things it is the piston speed that is the limiting design factor.  I remember a sport bike I had that dint really make any power till about 8k,   and pulled hard though 12.5k I think the stroke on that engine was around 1.7 inches.

Indeed, piston speed may well be the limiting design factor if RPM is the application design goal, otherwise I don't think that can't be said for any other applications.  Torque is a design goal in many applications too, so I wouldn't think piston speed plays a big part in such a design. 

In my experience, stroke length is the biggest contributor to torque, as it increases the dwell time of the piston at TDC.  I am also aware that a lot of race engine builders use custom length (longer) connecting rods to increase this dwell time at TDC in high RPM engines too, just to get that little bit extra power out of them.

As for the 2 stroke motorcycle, I believe it's the action of the power band that kicks in, ,which actually increases the power, not the piston speed per se, but I'm happy to be corrected if I'm wrong.

@frogandtoad

As for the 2 stroke motorcycle, I believe it's the action of the power band that kicks in, which actually increases the power, not the piston speed per se, but I'm happy to be corrected if I'm wrong.

Couldn't this be attributed to the fact that in a 2 cylinder, 2 stroke engine, ignition occurs twice per revolution but in a 2 cylinder, 4 stroke engine only once per revolution.

@bmann

I was wondering if the relays you are using are having any effect of the oscilloscope trace. I noticed that the signals on the trace show both overshoots on the rising side and undershoots on the falling side of the signals. Surely, in modern engines, the switches will be electronic, e.g. MOSFET transistors perhaps!

@pugwash

As for the 2 stroke motorcycle, I believe it's the action of the power band that kicks in, which actually increases the power, not the piston speed per se, but I'm happy to be corrected if I'm wrong.

Posted by: @pugwash

Couldn't this be attributed to the fact that in a 2 cylinder, 2 stroke engine, ignition occurs twice per revolution but in a 2 cylinder, 4 stroke engine only once per revolution.

My understanding is that the reed valve on 2 stroke engines is what creates the powerband.  You can purchase custom reed valves to either narrow or widen the RPM range of the powerband.