4 stroke engine understanding test.

-
TrailBeast

TrailBeast

AKA Mopars4us on Youtube
Joined
Mar 11, 2011
Messages
22,412
Reaction score
11,891
Location
Arizona
During one 360 degree turn of the crankshaft of an 8 cylinder four stroke engine, how many cylinders fire on the compression stroke? :D

So if you got that answer, then how is it that engine RPM's are counted?
By 2 360 degree turns of the crank or one?
Isn't one 360 degree turn one RPM?

Keep in mind that in a four stroke engine the cylinder only fires every other time the piston comes to TDC which would take two 360 degree turns of the crank for each cylinder to fire on a compression stroke.

Good luck. :D
 
Each revolution of the crankshaft fires 4 of the 8 cylinders.

RPM is strictly related to crankshaft revolutions. 1 RPM is the crankshaft turning at the rate of once per minute.

At 6,000 rpm, you would have 24,000 total "compressions" (in a 4 stroke 8 cylinder engine) per minute, and 48,000 total occurrences of a piston at TDC.

Did I get it right?
 
TrailBeast said:
During one 360 degree turn of the crankshaft of an 8 cylinder four stroke engine, how many cylinders fire on the compression stroke? :D
Click to expand...
Four, assuming you don't have a Ford with bad ignition coils.
TrailBeast said:
So if you got that answer, then how is it that engine RPM's are counted?
By 2 360 degree turns of the crank or one?
Isn't one 360 degree turn one RPM?
Click to expand...
One revolution of the crank is one revolution anywhere. Except maybe in South America. Revolutions in that area are erratic.

Besides which, if a four-stroke cycle engine was counted as two revolutions per revolution, then a four-stroke cycle engine running the same speed as a two-stroke cycle engine would be at different RPM. Which is to say, 2 would equal 1. But it ain't. Or don't. Whatever.
 
If a V8 is confusing, imagine a radial anything...............Or a Harley V-Twin.............or a Triple 2-stroke, or a Sterling, Or here's a newbe killer; how does the overlap period constitute a fifth element to the 4-stroke system?
 
Not sure what rpm has to do with spark plugs. Some engines even fire twice on compression. Not only that, an engine doesn't even need spark plugs to have rpm. Some engines fire at compression, have rpm and no plugs at all.

And of course there are the 4-6-8 engines.
 
You must log in or register to reply here.
-

Back
Top