Re: The big AeroCarb/AeroInjector thread
Posted: Wed Oct 11, 2017 5:59 pm
sonex1374 wrote:Kerry talked about the tuning process on Episode 7 of SonexFlight, so that might be worth reviewing again for those just joining the conversation.
Interesting: I just listened to that episode and Kerry says (at 32min in):
Once you're at WOT and the EGTs have stabilized ... slowly pull the mixture control back and listen for your RPM to increase and you watch your EGTs and you are looking for an increase in RPM coupled with an increase in about 75-100 degrees. That tells you you're a bit on the rich side for WOT and that's what you want to be.
(my emphasis) He says nothing about the EGTs peaking or the engine starting to run rough. I interpret that statement as meaning you want the full rich EGTs to be 75-100 degrees lower than what they are at peak RPM ie. best power mixture, not 75-100 lower than peak EGT. This actually agrees pretty well with my impression, because peak power EGT is something like 125-150 ROP and full rich then becomes 200-250 ROP. See the plot below, for example.
But that description doesn't sound at all like what I read in the AeroCarb manual, which clearly says to lean until the engine begins running rough.
As for experimental vs not, the Aerovee is an air-cooled, four-stroke, two-valved, fixed-time spark-ignition engine running 100LL. It's similar to a Lycoming or Continental in every fundamental detail. A Rotax has some significant differences, ie liquid cooled heads, but operates on the same physical principles. A two-stroke, or diesel, rotary, or Atkinson cycle engines for that matter, are fundamentally different in their operation and I wouldn't apply any of the ideas here to those. But to say that an Aerovee is different in some way from a certified aircraft engine just isn't true.