REFLECTOR: Egt

Grover McNair grover at mcnairperformance.com
Sat May 12 15:41:43 CDT 2012


Do you guys not have EGT guages?
I would highly recommend one. It will allow you to run lean of peak which gives the best fuel economy and cools efficiently as well.
Peak EGT will vary depending on things like altitude, temperature and humidity. With a guage you simply find peak and adjust from there.
Grover McNair

Sent from my iPhone

On May 12, 2012, at 1:58 PM, Mike Dawson <medawson250 at yahoo.com> wrote:

> Kurt,
> 
> The exhaust are light grey perfect but I suspect that is from the TCP changing lead to white powder. Like I said, the plugs are carbon ed so you are right more lean will clean them up. Wish Dave would pipe in but I'll give it a try!
> 
> Mike
> 
> From: "nmflyer1 at aol.com" <nmflyer1 at aol.com>
> To: reflector at tvbf.org 
> Sent: Saturday, May 12, 2012 7:23 AM
> Subject: Re: REFLECTOR: Egt
> 
> Michael, 
> 
> Seems to me like you are running rich. If the plugs and exhaust are sooty, that would confirm it. Not sure what altitude you cruise at, but 15GPH sounds high at cruise as well. 
> All engines have a "sweet spot" where they make power at an acceptable fuel burn (relatively speaking). Go above that, and sure they run fine and will make more power, but the fuel burn curve steepens (sometimes dramatically). Chevys are no different and that sweet spot is very fine. 
> 
> 3500 and 21" sounds pretty good, but the 1300 sounds like you are just wasting fuel. Specially considering that you are using 100LL. That fuel should not make a difference in your richness setting, but it will provide a higher safety margin against detonation at higher temps. 
> IF the spec sheet or cylinder head numbers say that 1400 is good, I would go with that. 
> 
> You can clean the plugs and exhaust tips, then go for a flight at 1400 and recheck. As long as the plugs do not show signs of running to hot or lean, you should be fine. I would bet that your fuel burn goes down noticeably as well. 
> 
> Hopefully Dave will pipe in with his experience. Mine is based on my years of engine building and work, but not actually flying my V-6 yet. 
> I usually fly my other aircraft at 1400, but it is an old Lyco 540. 
> 
> Kurt 
> 
> 
> -----Original Message-----
> From: Mike Dawson <medawson250 at yahoo.com>
> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> Sent: Sat, May 12, 2012 12:49 am
> Subject: Re: REFLECTOR: Egt
> 
> They are a little black but I am running 100 LL cuz of the auto gas thing. I hope Dave sees this.
> Everything I have found online, although it is about racing, says 1400 is hot if if left too long.
> I do have iconel valves so they are ok. 
> 
> Michael E Dawson
> ATCI CFII
> 
> 
> On May 11, 2012, at 9:33 PM, nmflyer1 at aol.com wrote:
> 
>> 1400 sounds about right for cruise to me. I'd like to hear what Dave says. 1300 sounds like you are running too rich (What do your plugs look like after that?).
>> 
>> Kurt
>> 
>> Alum. V-6
>> 
>> 
>> 
>> -----Original Message-----
>> From: Mike Dawson <medawson250 at yahoo.com>
>> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
>> Sent: Fri, May 11, 2012 10:07 pm
>> Subject: REFLECTOR: Egt
>> 
>> David Bertram,
>> Since we have the same engine, I was wondering if you could give me an idea what 
>> egt you lean to. Len's spec sheet show 1350F for max power and 1400F for cruise. 
>> Seems a little hot!
>> So far 3500 engine RPM, 21.5 manifold and 1300F EGT seems to be about 62% power 
>> and around 15 Gph. You concur?
>> Thanks,
>> 
>> Michael E Dawson
>> ATCI CFII
>> 
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