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Author Topic: what is squish in the cylinder and head  (Read 1078 times)

Offline evaneyeball

what is squish in the cylinder and head
« on: May 26, 2020, 08:01:17 PM »
i am not a engine builder and i dont plan on doing anything crazy and am having mine built by someone else and am just wondering what squish in the head and piston is and how it effects performance. i dont think that this is crucial information but think if its not then i would like to know. i might be wrong on that part.
LED built 86 trx 350 CEO
81 ATC250r
Zero finesse and alot of throttle

Offline Langbolt

Re: what is squish in the cylinder and head
« Reply #1 on: May 27, 2020, 08:41:33 AM »
Squish is the gap between the outer edge of the Piston and the Cylinder head. Squish Band is the Width of the band in the cylinder head that holds this squish. There is a MINIMUM as rod stretch would allow the Piston to hit the Cylinder head if there isn't enough.....Also if it's too thin and you are burning low octane fuel you will experience pre-ignition....Narrow Squish bands are used for high revving high output motors and wide squish bands are more for lower revving high torque motors. Squish Velocity is a whole different animal...it's the speed at which the fuel or burnt mixture travels across the Squish band and top of the piston. This too has a maximum as it can cause excessive heat and therefore pre-ignition.

OEM engines have large Squish values as they don't want their engines to fail....simply going to a thinner head gasket or machining the head gets you to where you need to be for your personal set up.

:)


 

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