Greg Field Posted April 25, 2009 Posted April 25, 2009 Well, Dan, as Ratch has said many times he did not have a problem. Therefore the system must work. Despite that, he solved it, anyway. Onward to page 53 of solving a non-problem . . .
dlaing Posted April 25, 2009 Posted April 25, 2009 DAMN my bike must have the only sensor made that works properly in temps from 40c to -5c no hiccups ,no stalling and good mileage, 11500ks without a prob luigi must have had a good day OMG! Then you need RH's solution!
dlaing Posted April 25, 2009 Posted April 25, 2009 You are assuming none of the players have side bets on how long it will last.... Anyone got bets on how long Ratchet's plastic will last?
dlaing Posted April 25, 2009 Posted April 25, 2009 My point is a temp sensor that allows air to flow around it, (plastic and vented as what RH has settled to) it will be quicker to react to head temp. RH's sensor is vented?
dlaing Posted April 25, 2009 Posted April 25, 2009 On this topic I agree with R. What he's done makes perfect sense and parallels what I've experienced on my own machine. You too fixed a "perfectly running" bike that has "head temp sensor body heat soak hot lean-burn feedback loop symptoms" by replacing the brass sensor with a plastic air sensor with "insulating mount and a temp sensor w/ a probe tip sufficiently isolated from the rest of the sensor body, relying upon radiated heat instead of conducted heat (which) would allow for the decreased influence of heat transients while allowing correct sensing of substantive changes in heat output."????? Dude!!!!!!
dlaing Posted April 25, 2009 Posted April 25, 2009 Well, given an insulating mount and a temp sensor w/ a probe tip sufficiently isolated from the rest of the sensor body, relying upon radiated heat instead of conducted heat would allow for the decreased influence of heat transients while allowing correct sensing of substantive changes in heat output. Also, it would mean that since so much less heat was being input to the sensor body, it would remain far more sensitive to slight but consistent changes vs. those too small to overcome its own heat soak. I think ol' Ratch' might just be on the right track w/ his GM sensor kludge... All hail Empiricist Ming! 'er, Hatchracket! er, Hackratchet? Well, whatever his name is... he's empirical! Experimental. Whatever. That's what counts! I like the idea of the insulating mount, and the low mass, but the air gap still comes across as a big negative. The positive effects are lowering the temperature of the sensor so it will last and so that the output matches the ECU map, so that it does not run too lean, or exceed the operating range of the sensor, possibly triggering error codes or faulty reads by the ECU. Perhaps you could elaborate on where these heat transients are coming from? Mexico? According to Dan maximum accuracy or sensitivity of the OEM sensor is at about 80-90C, and according to me it is about 40C, and the accuracy is fine up till over 100C, so you are not going to see it "remain far more sensitive to slight but consistent changes". From RH's chart on the GM sensor, its accuracy or sensitivity should be close to that of the OEM sensor, with the only difference being from a lack of brass creating thermal inertia problems. The problem with the air gap is that air is an insulator. The thermal diffusivity for air is about one fifth that of copper or aluminum. We can't just calculate the air gap here as the conductive, we must also include the air in the chamber, assuming it is not vented,and if it is vented, as Dan suggested, then all bets are off. Having two CCs of air might have diffusivity properties very similar to the mass of brass in the OEM sensor with no air gap!!!! Of course that is not the end of the world, since we all have lived with it for years, but it is not ideal. On the plus side, the low mass of the GM sensor will react more to the radiant thermal energy better than the heavy brass does. What makes it an improvement over the OEM setup or the OEM with Goo setup, has nothing to do with heat transients. It is an improvement over the OEM setup because he has probably cut the thermal diffusivity in half and he has maintained a pretty similar operating temperature for the sensor. The OEM with goo, probably has about the same diffusivity and inertia, but it makes the sensor read too hot (on some bikes), so RH is not likely to see the cold riding fuel improvements of his square wheeled bros in the North. What would work best is a low mass thermistor imbedded in the head, engineered to withstand the heat and have an output close to OEM, adjusted for the hotter condition.
Dan M Posted April 25, 2009 Posted April 25, 2009 Is my timing not once again impecible? Hey Greg can do math! How impressive.
Dan M Posted April 25, 2009 Posted April 25, 2009 RH's sensor is vented? Yes Dave it is. The bottom of the sensor is open to air so the thermistor is exposed. Makes for more accurate measurement of surrounding air. Get it? Funny how you have a strong opinion about a device you don't know much about.
GuzziMoto Posted April 26, 2009 Posted April 26, 2009 Makes for more accurate measurement of surrounding air. And I thought we were trying to measure cylinder head temp accurately. Strange though. In the pics he posted I recall seeing a black plastic piece with three holes, one in each end connecting somewhere in the middle and one for a set screw for the metal rod that was supposed to transfer heat from the cylinder to air inside the plastic piece. If it is vented to outside air it makes even less sense, but I don't think that is the case.
Ray R Posted April 26, 2009 Posted April 26, 2009 GEEEEZUUUUSSSSSS!!!! I just read through this entire thread. There's 4 hours of my life I will never get back! Just doing my part to add to the BQ....being my first post and all.
luhbo Posted April 26, 2009 Posted April 26, 2009 That's some sort of personal bad luck, I'd say. You should have come a bit earlier, like me for instance. Being here for longer than you I had the oportunity to drop a posting also in the GW thread - which is closed now. Well, you can't have everything, but for you: at least the main actors were the same. Hubert
dlaing Posted April 26, 2009 Posted April 26, 2009 Yes Dave it is. The bottom of the sensor is open to air so the thermistor is exposed. Makes for more accurate measurement of surrounding air. Get it? Funny how you have a strong opinion about a device you don't know much about. So, do you mean the thermistor is "vented" to the one or two ccs of air in enclosed plastic chamber or do you mean the plastic chamber is vented to atmosphere (Open air)? Yes, I have a strong opinion that venting to atmosphere would be the wrong approach. I also have a strong opinion that the talk of air gap having superior qualities other than lowering temperature at the thermistor, is irrelevant BS. Funny, huh?
dlaing Posted April 26, 2009 Posted April 26, 2009 On this topic I agree with R. What he's done makes perfect sense and parallels what I've experienced on my own machine. Care to elaborate on your parallel adventures? Did you make a perfect running engine run better?
dlaing Posted April 26, 2009 Posted April 26, 2009 And I thought we were trying to measure cylinder head temp accurately.Strange though. In the pics he posted I recall seeing a black plastic piece with three holes, one in each end connecting somewhere in the middle and one for a set screw for the metal rod that was supposed to transfer heat from the cylinder to air inside the plastic piece. If it is vented to outside air it makes even less sense, but I don't think that is the case. I don't think it is the case either. I think Dan simply means the GM sensor's thermistor is exposed ("vented") to the air in the small enclosed chamber that Ratchet made.
Recommended Posts