Koso installation manual has a base setting of 5" (or was it 6"?) but says to verify with manufacturer for recommended EGT sensor location. I've searched and others have installed them at 110 mm, 150 mm, 5" all from face of piston. Anyone have the latest info or care to weigh in?
Thanks.
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MC21R9N track
MC18R2J track
CBR954
CR250

4.5-5" from piston face is a good start. The gas temperature is quite consistent at this position, and is the temperature I use as data for pipe design.

6"+ will show a higher temperature for the same setting.

It depends if you're designing pipes using specific software that requires the temp at a certain point, or setting the jetting, in which case you're after a constant number that you can work to.

You're looking for the temperature that suits your engine. this will be just below it's peak figure. Then you look to jet for that number.

If you don't reach the number then you're too rich, beyond is too lean.

If the temp rises beyond and then starts to drop back, there's a good chance that it's detonating and best to shut the engine off before it destroys itself.

Advancing the ignition will increase combustion chamber temperature, but EGT will drop.

Retarding the ignition will reduce combustion chamber temperature, but EGT will rise.

Thanks Matt. Very helpful.

Bought the EGT for jetting purposes. Getting closer to ideal jetting. Ran it at an open test day Thursday. Jetting needs a minor tweak. And am curious to see how air temperature affects EGT and need to rejet as it gets colder this Fall.
_________________
MC21R9N track
MC18R2J track
CBR954
CR250

Jetting is a breeze with EGT gauges.

But, it's important that you have a base setting temperature to work to. This can be done on the dyno, or if you get a nice setting on the track that's fast and reliable then be sure to make a note of the temp.

For a given main jet, the engine will run lean as the ambient temperature decreases. Due primarily to the air density increasing, so more oxygen for a given volume of air. This will show as an increase in EGT.

If you're really looking for an edge, then consider that hot and cold conditions not only require different jetting, but you can also gain by altering other things.

For example, lets say you set everything in your engine for the average temperature. Setting #1.

As the ambient temperature rises and the air density decreases you would normally just lower the main jet. This will work up to a point where the engine geometry becomes inefficient and the torque loss is severe. Some of this can be claimed back with an increase in the secondary compression ratio (reduction in volume) and/or advancing the ignition timing.

The opposite should be considered when the ambient temperature decreases.

Cheers,

Matt.

My temperature readings approach 1200 degrees at the end of the straight but when i close the throttle the temperature rises upwards of 40-50 degrees. It seems to me only proper for the temperature to rise after throttle is shut down as there is an abrupt absense of fuel to cause cooling and temperature has been building quite rapidly. Is this theory correct? Am i tuning to full throttle (WOT) temperature? Or maximum temperture readings on KOSO EGT gauge (after throttle is closed)?
_________________
MC21R9N track
MC18R2J track
CBR954
CR250