By textbook definition, a 13b is a 3.9l anyways...

 

Sure bud...

 

"Howard, why after all these years, you're now saying it's a 1.3L? I thought your mathematics said "2.6L"....."

the distinction is and always has been central to understanding our motors. it is simple but challenging to explain.

once understood it is not open for argument.

if you spin a 13B over for one revolution and measure the air ingested it is 1.3 L.

so that should be simple and worthy of no further discussion.

if you spin a Corvette ZR1 motor over it will ingest 6.162 L.

so speaking purely displacement... 1.3L

the rotary, however, functions similar to a 2 cycle motor.

a 2 cycle piston motor produces a combustive event every time the piston reaches top dead center.

a 4 cycle piston motor produces a combustive event every OTHER time the piston reaches top dead center.

like the 2 cycle piston motor the rotary produces a combustive event every time the combustion chamber reaches top dead center.

if we wish to measure the displacement of the combustive events during one rotary rotation comparative to the 4 cycle piston engine we need to double the displacement to be on even comparative terms.

in some ways this is an advantage because we are getting more power by getting combustion every TDC but it also is a negative as the engine does not benefit from the cooling event every other TDC.

hc

 

Ah, but a Corvette ZR1 motor won't ingest 6.162L in ONE revolution, it will actually only ingest 3.081 L. Each cylinder will only intake every other stroke, meaning that while the swept displacement is 6.162 l, the air intake volume is only the 3L.

 

both ^^ and ^ summed up the discussion well

 

howard, iv been curious about the injector duty %,, if the PFC says its at 50% or 80%, is that only one of the secondarys?(figuring a primary would be much higher) or is that both or what?

 

Like others, I too continue to learn from Howard's posts. I've been attempting to learn the "what does it take to reach XX HP for my FD" reading through all the forums -- and Howard's threads.

This is the first time I have seen comments about injector slippage when they are not running wide open. Don't recall seeing this on maxcooper's web page or other posts.

Something new to add to my "Things to know."

I could not agree more, and I appreciate that you are willing to take the time to share what you know. "Knowledge not shared is energy wasted."

All the greatest thinkers/contributors in the world were criticized. Appears the same has happended to you. Not to worry. Many of us are still listening.

 

criticism just makes you think harder

you can call it a 1.3L or a 2.6L.

the difference is, this is simply not a 4 stroke engine. i consider it a 2 stroke because if you consider just the single face of the rotor compared to a piston you get 1 firing sequence per revolution, no valves to increase stroke procedures.

2 strokes engines still ALL use 4 stroke volumetric principles. so a 4 stroke with the same bore and stroke has the same displacement of a 2 stroke with the same bore and stroke all things equal, but the stroke being the difference and how many times the engine fires with revolutions counted.

that is my opinion.

with that said i give it leeway, Howard is right that all the above said it is acceptably a 1.3L engine. as i said though it is a weighty bulky 1.3L engine. there are many motorcycles that displace more than this engine that are lighter even with transmissions fit to them. i prefer to consider it a 2.6L but if someone gives me lip you can break out those facts and call it a 1.3L if you wish.

 

a 2 stoke piston engine uses 1 rotation of the crank to fire all of its cylinders

a 4 stroke piston engine uses 2 rotations of the crank to fire all of its cylinders

a rotary engine requires THREE rotations of the output shaft to fire all of its chambers.

the rotary engine is a 4 stroke, it has a BDC in the intake, a TDC in compression a BDC in the exhaust stroke and a TDC in the exhaust stroke, unlike a piston engine the rotary does its strokes in different physical locations. so its correct to say that like a 2 stroke it has a power stroke every time a rotor face is near the spark plugs. its also like a normal 2 stroke in that there are no valves.

its nice to compare, but at some point its just not a V8!

 

a stroke is it's path through each cycle, for each rotation of the e-shaft the rotary engine goes through all 4 cycles. half rotation is intake and compression, 2nd half is ignition and exhaust. 2 strokes use the same principle of combined cycles.

a 4 stroke engine takes 2 revolutions of the shaft to do the same.

i consider each chamber irrelevant when compared to firing events. each rotor face is the equivalent to a firing sequence or each cylinder in comparison.

 

from the spark plugs point of view that is right. from the chambers point of view half a turn is only 2/3rds of one stroke!