R/C Tech Forums - View Single Post - What is the difference in short stoke to long stoke motor?
Old 12-28-2009, 02:33 AM
Tech Champion
Roelof's Avatar
Join Date: Aug 2007
Location: Holland
Posts: 8,873

True but not the reason with 2-stroke I think.

In my eyes it has to do wit the combustion stroke. The combustion stroke is actually from the top down to the moment the exhaust opens. Buggy engines have a lower exhaust port compared with onroad giving a longer combustion stroke which is giving the torque. In the search for more RPM (RPM = Horsepower) you do need to make the exhaust port higher and that means shortening the combustion stroke.
With a longer stroke you have room to make the exhaust higher without shortening the combustion stroke you normally have with square stroke.

In most cases going from 16.4mm to 16.8mm means the exhaust can be made 0.4mm higher and that is a lot while the diameter from 16.4 to 16.2 is almost nothing.

Funny thing is that the RB WS7 models are square stroke and in theory they should perform less in an offroad compared with a long stroke and yet the WS7 models are the most used engines with many victories.
Roelof is offline