Exhaust Temp Gauge?

[snow_rider]

I recently had the motor on my 08 overheat and destroy itself because a stud came through the front exchanger. Since there's no coolant level sensor, only a coolant temp sensor, there was no indication/warning of the situation when all the coolant ran out as I was driving, as the coolant temp sensor cannot 'sense' the 'air' temperature inside the motor when the coolant was gone, hence the destruction of my motor...

Going forward, I want to devise a sensor that will prevent this from occurring again. I'm even going to try and tie it into the ignition kill switch to automatically shut down the engine when an overheat condition is detected. Something, in my opinion, YAMAHA should have designed into the machine to begin with! Not that I'm bitter...

I was thinking that a exhaust temp gauge might be the best option? As a surface probe somewhere on the motor might not react fast enough to the internal engine temp, where I would think exhaust temp should rise fairly quickly and proportionally to engine operating temp?

So, I was wondering if anyone has installed one, or has anybody devised something else that is more effective at detecting actual motor (not coolant) operating temperature?

Any replies will be appreciated!

snowrider

 

[Beenba]

An EGT probe placed 1-2" away from the motor on one of the exhaust runners should do the trick. Just drill the hole and weld the bung in.

As far as building a control system to automatically shut the sled off, it IS do-able but it depends on your level of programming. Most EGTs give a 0-5v analog signal, so assuming you want to shut the motor down at 1500F (that's pretty darn hot - even for a boosted motor) your EGT will give out 4v lets say at that temp. You then take the logic board and write a simple programming if statement so that if the voltage coming from EGT rises greater than 4v for more than 1 second, it triggers a pin going to a relay to kill the ignition.

IMO it would just be easier to wire in a float switch with a LED on your dash. Put the float into the coolant overflow bottle, and if it ever turns on you know your sled is eating or loosing coolant. However with this method hitting bumps etc may cause the float to act up...


Hope this gives you some ideas..

 

[cannondale27]

Why not use a pressure switch?If no coolant there would be no pressure.Could probably tie it into the oil pressure switch for warning at least.

 

[LSXM3]

Why not use a pressure switch?If no coolant there would be no pressure.Could probably tie it into the oil pressure switch for warning at least.

there is 0psi in the cooling system when cold so until the engine reaches full operating temp the warning would be going off the whole warm up!

 

[arteeex]

A flow meter in the coolant line or a temp sensor for the oil would get you there too.

 

[grizztracks]

I'm not sure if an engine oil sensor would detect the problem quick enough. The Ski doo e-tec engine uses a exhaust temperature sensor for oil injection purposes. It may be worth looking into how that sensor works. A coolant pressure sensor that would not be active unless the exhaust temperature is at a high enough level that liquid cooling would be needed might work. If you can find the proper sensors this would be easy to do with a relay and no programing involved. The easy solution is to not run a studded track but if you think it's a must a prestudded track is a good alternative.

 

[snow_rider]

Thanks for all the input!

I think I'm going to go the EGT route, I think it will have the fastest reaction time/heat rise ratio. As for the auto shutdown, I have a buddy who's an EE that might be able to help me out. For now though, I will simply keep an eye on the gauge.

Beenba, mentioned that 1500 degrees is a 'hot' temperature, is that the reading one should consider there being an issue?

Has anyone installed a gauge to see what the mean running temp is?

snowrider

 

[Beenba]

I also thought of the pressure sensor idea, but like others have said the light will be on during start-up and until the sled is warmed up and thermostat opens. It could work though. Oil temp will not respond fast enough. A flow switch in the coolant is the best idea, but can get complex and expensive/custom IMO.

I agree, you don't necessary need a fancy programmed code to run the auto shutoff, but the 1 second delay is what is important. From my experiences with my turbo car, the EGT or AFR often give random spikes (noise) and this 1 second delay will filter out the noise....aka your sled isnt going to shut off and make you crap your pants when really there wasn't an issue.

As far as the specific temp goes, that was just an approximation. My 500whp boosted civic runs around 1100F cruising, and after I do a good WOT pull 2-4th gear I'm just under 1500. I would install the gauge first, get to know the max temp you see after some good hard WOT pulls, and then write your code with your EE friend from there.