Quote:
Originally Posted by dlisabeth\";p=\"
Thanks for all of the replies, there is some good info in them. *The information I am most interested in is where everyone is mounting their temp sensors. *I believe two people stated that their fan sensor is located either in the radiator tank near the outlet or in the hose leaving the radiator. *I understand how this would definitely reduce the amount of time the fan is running which is one of my goals. *But wouldn't it also increase the overall temperature of the cooling system which my fan that now runs almost non-stop can hardly control? *Or is the idea to feed the motor coolant which is between 190-200 degrees (or whatever the thermoswitch is designed for) and really not worry about the increased temperature of the coolant as it passes through the motor? *In that case the main concern is cooling the fluid back down to the appropriate temp before it makes its way back in to the motor. *I have a feeling the fan may run just as long but it will probably cycle on and off quite a bit (which I don't mind) with the thermoswitch in this location. * *
Now as far as the location of the temp sensor for the gauge. *It sounds like it should be as near as possible to the thermostat in order to get a reading on the coolant leaving the motor. *Is this correct? *I guess this tells you how hot the coolant entering the radiator is and if the radiator alone can cool it back down to under 200 degrees it will otherwise the fan will kick on to ensure that the coolant being sent back to the motor is cool enough. *
I don't think anyone answered my question in regard to the stock temp sensor. *Is it needed in a sandrail application as a sensor for the ECM or was it only used for the stock bike gauges?
Thanks Again,
Derek
|
Hi Derek, In a properly designed system the fan switch should be mounted in the out going side of the rad. It really doesn't matter if it is tank or hose mounted as long as it is near the out going side. The fan is there to assist the rad (if needed) in cooling the engine so it needs to monitor rad temp not engine temp. If the rad is to small and can't handle the engine's heat output the fan will be running all the time no matter where the switch is mounted. Factory locations for engine temp sensors should be used whenever possible unless you have really modified the engine or it's stock assessory systems (fuel, ignition, exhaust, cooling). If you have engine management systems (fuel ingection/ignition) that require input from a coolant temp sensor to perform their jobs you should have the proper T-stat installed so they do there jobs as originally designed by the factory. Without a T-stat your engine temps will vary more than designed and the engine managment systems will not perform as well as they should.
* The internal engine temp is what is important to the engine not the temp of the rad. If the rad was sending back coolant to the engine that was 100 degrees cooler it wouldn't matter. The T-stat would close down and restrict the flow enough to compensate. It would only allow enough coolant flow through the engine to keep it at the proper operating temp. *The T-stat is the controller of internal engine temps and the rad is there to provide a means to get rid of excess heat. If the rad is oversized the T-stat can compensate for it but if the rad is undersized and can't provide coolant back to the engine at a temp that is lower than the proper operating temp of the engine it will overheat. You must have a radiator that is capable of getting rid of heat faster than the engine can produce it or you will have problems.
* The fan helps the rad do it's job but it also has limits. You can only push so much air through a rad at one time. That amount depends on the size of the rad and the size of the fan but the temperature of that air is a huge variable in how much good it is doing.
* My opinion is that your problems are being caused by a radiator that is undersized. I have no experiance with a Busa engine but from what you are descibing and what others have said here my opinion would be the same no matter what you were running for an engine.
*My suggestions would be to #1 get a bigger rad (I would rather have one that is oversized for the job), #2 install the proper T-stat for your engine, #3 get your bypass line routed into the in coming side of the rad, #4 make sure your factory engine sensors are in the proper place and hooked up, #5 get a fan that is sized to the rad with it's controler switch mounted on the out going side and # 6 try to find a spot for your temp gauge sensor that is as close to the engine side of the T-stat as possible.
* If you are having trouble finding a spot for your gauge sensor there are other options. I have included a pic of a factory Yamaha snowmobile setup that installs the gauge into the bypass line. It would not be my first choice but it will work.
* Good luck, Phil (opsled)