[Fot] EGT gauge installation

[Duncan Charlton]

With a two-stroke aircraft engine I was led to understand that the distance in the exhaust port from the piston skirt to the sensor (equivalent to the distance from the exhaust valve to the sensor on a 4-stroke) was critical due to pressure waves creating local variations in temperature and presumably this is the same in 4-stroke engines.  I don’t recall the recommended distance but the sensor will read a higher temperature than the piston crown will see.  Venolia uses two types of aluminum alloy for their pistons, 2618 (990-1060˚F melting point) and 4032 (1020-1180˚F melting point) alloys.  Pure aluminum melts at 1220˚F.

I seem to remember trying to keep it around 1250˚F or so on my 2-cylinder 2-stroke engine.  On one occasion I saw a brief spike in temperature, likely over 1325˚F, and heard a clinking sound in the exhaust.  The plugs later were found to have tiny shiny aluminum-colored globules on them.  (I’d adjusted the mixture the wrong direction before takeoff, so I quickly realized it was a little on the lean side.  It was an unstable aircraft and I inadvertently dropped the nose while consulting a map, unloading the prop a bit, which raises the EGT.)

Duncan

> On Feb 28, 2019, at 9:56 AM, Tony Drews via Fot <fot at autox.team.net> wrote:
> 
> I've always heard that if you have a balance tube between front and rear carb that you want to run in 1 and 4 so you can better isolate which carb you want to adjust.
> 
> I have mine in 1 and 4 but run webers so no balance tube.  I see up to 1450 F at the end of long straights.  Much more than that and I start to transfer aluminum from the piston to the cylinder walls.  I think there's some variation in temp readings between different probes and gauges, I don't know what the accuracy really is.
> 
> It's a great troubleshooting tool when the car starts to run like crap.  Another helpful tools is a fuel pressure gauge (with isolator so you don't pipe gas into the passenger compartment).  Pressure too high overruns the floats.  To low and you've got something funny with the feed like a regulator / pump going bad or you forgot to put gas in the car.
> 
> - Tony
> 
> On 2/27/2019 6:10 PM, Barr, Scott via Fot wrote:
>> Interesting – why not 1 and 4 or 2 and 3?
>>  
>> Scott (B.)
>>  
>> From: Fot <fot-bounces at autox.team.net> <mailto:fot-bounces at autox.team.net> On Behalf Of Rick Parent via Fot
>> Sent: Wednesday, February 27, 2019 2:20 PM
>> To: John Styduhar <johnstydo at gmail.com> <mailto:johnstydo at gmail.com>; Terry Stetler <tlizzard at msn.com> <mailto:tlizzard at msn.com>
>> Cc: Friends of Triumph <fot at autox.team.net> <mailto:fot at autox.team.net>
>> Subject: Re: [Fot] EGT gauge installation
>>  
>>  
>> If you are using SU's I would use Cylinders 1 and 3 or 2 and 4. If you are using dual Webers I prefer the same as above but any two will do really.
>> On Wednesday, February 27, 2019, 1:00:53 AM EST, Terry Stetler via Fot <fot at autox.team.net <mailto:fot at autox.team.net>> wrote:
>>  
>>  
>> One and Four.  Typically those would run the leaner than Two and Three.
>> 
>>  
>> 
>> Terry Stetler
>> 
>>  
>> 
>> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10
>> 
>>  
>> 
>> From: Fot <fot-bounces at autox.team.net <mailto:fot-bounces at autox.team.net>> on behalf of John Styduhar via Fot <fot at autox.team.net <mailto:fot at autox.team.net>>
>> Sent: Tuesday, February 26, 2019 12:30:15 PM
>> To: Triumph 'Friends of Triumph
>> Subject: [Fot] EGT gauge installation
>>  
>> I need some tips on installation of a dual probe EGT gauge on the TR4 race engine with twin Strombergs-
>> What two cylinder to use for probes.
>> Optimum EG temperature for tuning purposes.
>>  
>>  
>> Thanks 
>>  
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