Getting ready to break down and buy a Digatron 30 series and need some advice. I never ran one of these when I was racing so I need some advice. What is better for a Mac EGT or CHT?
Komet K78?
Thanks in advance.
I think most will say EGT...CHT is about 5 seconds to late...LOL
specially on a foreign motor
GW is right. EGT is: Shut it off NOW! CHT is, OOPS, too late! TJ
That was a great way to get your point across Gary. I'm still laughing. So the next logical question would be what is the max EGT for a 101 on gas?
Foreign?
I use CHT on my Mac engines and highly recommend it. The "speed" of the EGT refers to the fact that it has a faster response time than the CHT because the EGT reads the temp of a small probe while the CHT reads the temp of the interface between the spark plug and the head. The small probe will heat up much faster and it will cool down much faster when the throttle is closed. Accordingly, the EGT is very sensitive to the throttle position and loads placed on the engine which means the readouts are highly correlated with the driver inputs. On the other hand, the CHT doesn't heat up as fast or cool off as fast so it will produce a more consistent reading over a range of driving inputs.
A real world example works like this... I take my Leopard powered TAG kart out and dial it in and drive it hard and I will see EGT readings in the 1050 - 1100 range. If I hand the kart over to a less skilled driver that runs two seconds a lap slower the data system will never record a temp over 950. The jetting is the same and the power output is the same so why the change in readings and which one is right? It's simple.... the readings directly correlate to the amount of time the driver is off the throttle as the probe can cool as much as 300 degrees by simply lifting off the throttle for a couple seconds. With the EGT on a sprint kart the instrument will always generate the highest temp at the end of the longest continuous segment of wide open throttle, not necessarily at the end of the longest straight. If the driver starts out on cold tires and has to lift in a corner that connects two long sections of wide open throttle the peak temp he will see will be much lower than he will see a few laps later when the tires reach maximum grip and the kart can take the same corner wide open. The higher temp may scare the driver into increasing the jet settings to "control" the temp that he is causing by his ability to take the key turn faster.... clearly not a reliable indicator of the correct a/f ratio. Many tout the "speed" of the EGT as a big advantage and it might be if the driver happens to be looking at it right when some major event occurs with the engine. However, we drivers are supposed to be looking at the road when we drive and since the EGT will always produce the high temp at the end of the longest WOT run the driver rarely sees the high temp because the end of the longest WOT throttle run is usually a spot on the track that requires serious attention from the driver! The CHT will react slower so it allows the driver to select a few key points on the track where he can look at the gauge at places on the track where his visual attention can shift from driving momentarily without affecting his performance or safety. Another thing to consider about EGT... the gauge will generally generate higher temp readings as the a/f ratio is leaned down to produce max performance. However, it is well documented that the EGT will begin to generate lower temps if the mixture is leaned out beyond the ratio that provides peak power so it is easy to get fooled by the EGT if you get on the wrong side of the peak with your A/F ratio. CHT will just keep rising the leaner the mixture and the rate of climb will increase as the mixture is moved closer to the critical limit.
Steve O'Hara
Steve if you ever decide to get out of karting we are going to be in big trouble. Your knowledge and experience is greatly appreciated.
(08-07-2018, 06:41 AM)tom dandes Wrote: [ -> ]Steve if you ever decide to get out of karting we are going to be in big trouble. Your knowledge and experience is greatly appreciated.
gw
(08-07-2018, 07:25 AM)Gary Wlodarsky Wrote: [ -> ] (08-07-2018, 06:41 AM)tom dandes Wrote: [ -> ]Steve if you ever decide to get out of karting we are going to be in big trouble. Your knowledge and experience is greatly appreciated.
to..each his own...
I guess for the experienced driver the CHT is prolly a good way to go, while the inexperienced driver is "" picking his point"" he has already lost an engine,,,,,
two sides to everything
its been good,,see ya ..
gw
And I'm not that experienced with kart electronics so it's good to here both sides and why.
I noticed that nobody volunteered their max CHT, so I will. I try to keep my Mac 91B1 around 370 max. I'm curious what other guys are running.
(08-07-2018, 04:18 PM)Bill Peck Wrote: [ -> ]I noticed that nobody volunteered their max CHT, so I will. I try to keep my Mac 91B1 around 370 max. I'm curious what other guys are running.
pretty close 360 is about my limit
gw