REFLECTOR: CHT too cool

[Chuck Jensen]

The oil temp is typically 195F-200F in cruise at altitude (7K'-12K').  However, if the engine is already heat soaked or during a long hard climb during warm ambient temps, the oil will nibble at 240F.

Chuck Jensen

Behalf Of Brian Michalk
Sent: Tuesday, June 09, 2009 11:17 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: CHT too cool


What is your oil temp?

Chuck Jensen wrote:
> Cylinder head temp problems are not unusual, but I have a different 
> twist.  My CHT's are too cool.  I can only recall once or twice that a 
> cylinder head ever got to 400F.  Most run 350F to 390F during hot, 
> hard climbs, but at cruise, and running lean of peak, it's not unusual 
> for 2 to be below 300F and the rest just barely over 300F. 
>  
> Now, it well known that engines are most efficient at higher temps and 
> I believe Lyco's recommendation for an IO-540 K1A5 is CHTs in the 375F 
> to 400F temp range.  This would also seem to imply that I'm suffering 
> unnecessary cooling drag from overcooling the CHs.  Oil temps at 
> cruise are 195F-200F but will rise to 240F during long climbs.
>  
> So, my question is, 'is there a way 'adjust' cooling to CHs' that may 
> reduce drag by reducing inflow through the overhead NACAs for 
> downdraft cooling, without sending the CHTs too high during climb or 
> aggravating oil temps during those climbs as well?
>
> Chuck Jensen
>
>      
>
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