[NSRCA-discussion] Engine tuning info

[Karl G. Mueller]

John,

Most of the 2C sport engines to be used with a muffler are timed
at about 145-148º exhaust down time.
On most of the .60 to 1.60 size, to get the benefit of the supercharging
effect from the pipe, I increase the exhaust downtime to 155-158º, without
changing the intake timing, except for some directional porting for better 
scavenging effect. This all will not decrease a reliable idle.
I believe that the pylon engines are ported to 170º exhaust down time and 
on those you are not looking for a reliable low idle. 
Never tried any work on 4 strokes. To get any benefit from a pipe on those
you would have to have overlapping valve timing, which none of our model
4 stroke engines have.

Regards,

Karl G. Mueller
kgamueller at rogers.com

  ----- Original Message ----- 
  From: John Pavlick 
  To: nsrca-discussion at lists.nsrca.org 
  Sent: Thursday, November 06, 2008 5:02 PM
  Subject: [NSRCA-discussion] Engine tuning info


        Has anyone taken the time to measure the port timing of various model airplane 2C engines? Specifically the OS140 and 160? Also, if anyone has cam profiles + index info for the YS 160 and 170 4C motors I'd be interested in that as well.

        John Pavlick 



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