<VV> EGT Temp

[Dale Gillilan]

On May 27, 2008, at 4:48 PM, virtualvairs-request at corvair.org wrote:

> Craig replies:
> You da man, Mike! I've wanted to do this for years but never got  
> around to
> it. The stock carbs are jetted rich - I've often wondered about  
> folks who
> put in #53 jets "for more power" since the stock calibration is  
> already at
> the "max-power" AFR.  FWIW, 14-15 AFR isn't "Lean" except in  
> relation to
> stock.  15.5 (or even 16.5) is considered the AFR for "Max economy"  
> and
> beyond that is considered "lean". EGT (and NOx) goes ballistic  
> somewhwere
> above 14:1 so above that point it pays to monitor EGT with a  
> pyrometer.
> 1250-deg F. is considered the max for a diesel engine. Does anyone  
> know what
> the limit is for a gas engine?  Are you doing these adjustments on the
> "high-swirl" engine you built a few years ago?  If so, it should  
> tolerate
> 15.5 or more AFR. What size jet are you down to, 48?  Are you using  
> a 65-6
> power-valve carburetor so max power isn't compromised?
>
> Great work - you're a pioneer now!
> Regards, Craig

Craig,

I use to fly small planes, and had several.  We always tuned the  
mixture with EGT, and would adjust it "on the fly" (sorry for the  
pun...) whenever we made significant altitude changes.  If I remember  
correctly 1250 F was about the target temp for the engines I ran  
(converted VW in a homebuilt, and air-cooled Lycoming).  We would  
lean it for peak temp, then bring it back down 50-100 degrees,  
depending upon what the manual said.  We didn't want it at max temp  
(max lean), but we didn't want to enrichen it too much, either,  
because the plugs would foul.  I'm sure the other pilots might be  
able to answer more precisely.

Dale