dlaing Posted June 6, 2009 Share Posted June 6, 2009 snip Kudos! You got rid of most of the thermal inertia! I was wondering where they put that thermistor! Since Marelli has two models of varying length on the spec sheet, I figured it must be embedded higher up than some were suggesting. Our's probes in 27 mm while the optional one probes in 18mm. The thermistor must be about 12mm from the sensor body (27 - 15 = 12) How did you trim the brass without destroying the thermistor? Do you have X-ray vision, or were you just very patient? So, now you have over a 15mm air gap? Link to comment Share on other sites More sharing options...
Velf 2003 Posted June 6, 2009 Share Posted June 6, 2009 Any chance you could post any photo's of your modifications of the OE sensor? Please be patient with me. Since party-season has arrived and work takes up most of the rest of my (spare? hahahaha) time it`s not bound to happen anywhere between now and let`s say two weeks. But I`m more than happy to share my attempt to make the original fluid sensor into an air sensor. I did the adjustment with the use of a Dremel-tool, gently taken a layer off, agan and again. Pictures will be taken when I dismantle the cylindertempassembly obviously. Guzzigreetz, Velf2003 I can resist anything, but temptation (Oscar Wilde) Link to comment Share on other sites More sharing options...
Guest ratchethack Posted June 6, 2009 Share Posted June 6, 2009 Pictures will be taken when I dismantle the cylindertempassembly obviously. TIA, Velf. Link to comment Share on other sites More sharing options...
Dan M Posted June 6, 2009 Author Share Posted June 6, 2009 Good going Velf. I'm glad there are others using the idea. Kudos to Ratchet for being the one to take it from theory to practice. Dave, When testing these sensors the manufacturers show the published ohm spec and give a variance of +/- 10%. Considering this overlap, there is virtually no difference from one manufacturer to the next. Manufacturing variances cause this range. To have them all spec exactly would make for a far more costly part. I still don't think the air gap size is terribly important (within reason) considering the cavity is quite small and not vented. I had the opportunity to take my first extended ride with this set up today. The bike ran great, better than it did all last season with the paste on the old sensor. No more lean hiccup on partial throttle in the 3000 RPM range. I have not checked mileage yet. Link to comment Share on other sites More sharing options...
Guest ratchethack Posted June 8, 2009 Share Posted June 8, 2009 I had the opportunity to take my first extended ride with this set up today. The bike ran great, better than it did all last season with the paste on the old sensor. No more lean hiccup on partial throttle in the 3000 RPM range. I have not checked mileage yet. Say Dan According to the "wisdom" we were all so repeatedly and so relentlessly graced with on the previous thread on this topic, there's obviously SOMETHING WRONG with your Guzzi -- and despite the accusation of the placebo effect, and mileage numbers that you or anyone else might as easily as not make up out o' thin air and post here -- just because you have nothing better to do than make stuff up for your own amusement -- SQUARE WHEELS ain't ever gonna solve your "PROBLEM"! Why, its clear as can be that your valves and guides are as roached-out as every service orifice in a low-rent working girl, rode hard and put away wet so many times as to've forced the old bag into retirement! Though without much question, you've got yourself "boxed-in-by-the-need-to-be-outside-the-box" here, I sincerely b'lieve you actually could be on to something, my friend. . . Back to square wheels. Who will admit to performing this amazing improvement on their bike? Now if we only had someone so inspired as to keep a tally here -- along with the once familiar daily empty ridicule/page count. . . Link to comment Share on other sites More sharing options...
raceboy Posted June 9, 2009 Share Posted June 9, 2009 Good Day folks, Interesting topic and great banter as always, some good experimentation going on. One question............. Can someone explain 'Thermal Inertia'? Just a thought about the 'air gap'; I'm wondering if the air gap is a function time, time to sense / time to react ... the time required to heat the air in the available gap / space / volume of air????? Or should there be an air gap at all. .......... or not! Cheers, Raceboy. Link to comment Share on other sites More sharing options...
Dan M Posted June 10, 2009 Author Share Posted June 10, 2009 Good Day folks, Interesting topic and great banter as always, some good experimentation going on. One question............. Can someone explain 'Thermal Inertia'? Just a thought about the 'air gap'; I'm wondering if the air gap is a function time, time to sense / time to react ... the time required to heat the air in the available gap / space / volume of air????? Or should there be an air gap at all. .......... or not! Cheers, Raceboy. If lively banter is your thing, there is 58 pages of it on this very subject here: http://www.v11lemans.com/forums/index.php?showtopic=11231 It became so lively that dad shut it down because some would not play nice. So pour yourself a beer and start reading! Seriously, there are a couple of opposing opinions going on here. One (mine among a select few others) thinks that MG sensing cylinder head temp on an air cooled engine with a coolant sensor and calling it oil temp sensing was in error. Further, a temp sensor designed to be in moving coolant mounted inside a holder sensing the air temp inside the holder was very slow to react and once hot as in very slow moving traffic would take too long to cool when the motor cooled as speed was picked up. The term "thermal inertia" was used here by others to describe the speed at which a material would change temperature, or more accurately, how long it would hold temperature. In this case the sensor body and mounting holder. With the thermistor located inside a brass casing, and in some cases mounted inside a brass holder, the heat would not dissipate quickly enough. All that metal would heat up OK, it just stays hot too long. Ratchet experimented with a sensor designed to sense air temp (the thermistor is exposed and the body is made of plastic, hence lower thermal inertia) I simply installed mine differently. Following this opinion, the reason for the air gap is to smooth the readings. The temp spikes of an air cooled motor make proper fueling more difficult. The ECU will lean the mixture too much when very hot temp is sensed. The bottom line is we are sensing air temp with an air temp sensor and it has worked well for us. Link to comment Share on other sites More sharing options...
dlaing Posted June 10, 2009 Share Posted June 10, 2009 Good Day folks, Interesting topic and great banter as always, some good experimentation going on. One question............. Can someone explain 'Thermal Inertia'? Just a thought about the 'air gap'; I'm wondering if the air gap is a function time, time to sense / time to react ... the time required to heat the air in the available gap / space / volume of air????? Or should there be an air gap at all. .......... or not! Cheers, Raceboy. Welcome to the par-thai! "The thermal inertia of a material is defined as the square root of the product of the material's bulk thermal conductivity and volumetric heat capacity, where the latter is the product of density and specific heat capacity" http://en.wikipedia.org/wiki/Volumetric_heat_capacity So, according to the formula, high conductivity and high volumetric heat capacitiy results in more thermal inertia. Brass has fairly high conductivity and volumetric heat capacity, so its thermal inertia is high. Air has low conductivity and low volumetric heat capacity so its thermal inertia is low. But IMHO, thermal inertia is not what we want. We want high conductivity and low heat capacity, as long as the sensor does not get too hot. Many forum members have had success raising the conductivity by adding thermal goo or other conductive material to the air gap, but some of us (Dan, Ratchet, myself, and others) found we would get lean running symptoms, because the sensor was getting too hot when conductivity was increased. Ratchet came up with an early solution of adding cooling fins to the sensor body to draw away the excessive heat. The counter argument was that it also reduced the non-excessive heat, and increased mass that needed heating. Dan and Ratchet then came up with the idea of using the air sensor to reduce the heat capacity of the sensor. A fine idea, accept it needs more air gap than the brass sensor in order to run cool enough. The air creates a delay, so it is not a perfect solution, but the reduced mass trumps the increased insulation, so it follows engine temperature better than the OEM configuration. Also, air allows for radiant energy to heat the sensor, so the air sensor with air gap responds to more than just thermal conduction. Ideally, we should have a low mass/ low heat capacity sensor with no air gap and the sensor not getting too hot. I'll be taking a different direction than Dan and Ratchet, by going with OEM sensor in brass housing with zero gap, and eliminating the too hot of a sensor issue by remapping the Engine Temperature Sensor table in the ECU using TuneBoy TuneEdit. Still it is not a perfect solution because of the mass and less than perfect conductance. I may trim the sensor down similar to what Velf did, to reduce the volumetric heat capacity, but then add a copper conduit to transmit the heat to the now shorter sensor tip, creating a faster path for the heat to pass between cylinder head and thermistor. Right now I am using copper conduit and the sensor is running just a little too hot. Once I remap it, I am confident it will run morer betterererer Link to comment Share on other sites More sharing options...
Guest ratchethack Posted June 10, 2009 Share Posted June 10, 2009 Can someone explain 'Thermal Inertia'? RB, please allow me a simple definition and an illustration with a direct comparison of what we're talking about here. Simply put, THERMAL INERTIA is that property of a material that determines its resistance to temperature change. For practical calculation purposes, it’s expressed in units of measure denoting RATE OF TEMPERATURE CHANGE in degrees over time by volume, as Dan noted above. Since the “most vocal few” naysayers had such horrific difficulty with simple heat flow concepts in the previously retired thread, and either could not (or more likely, simply would not) “get it”, I’d come up with a “working definition” for THERMAL INERTIA that I figured would be simple enough, and not too much of a cerebral stress test, so that just about anyone could grasp it. As it happened, for wotever reason, it was still beyond the grasp of the most vocal few naysayers, but in any case, here it is again: NOTE: Those who still don’t (or won't) comprehend the concept of thermal inertia (there are at least 3 hereabouts that we’ve been. . . um, “blessed” to become so repeatedly aware of by their posts) – please do look it up in a credible source (NOTE: Wikipedia IS NOT a credible source) and give it some study. It just might save you further embarrassment here -- not if, but when you’re compelled to post about it as if you knew what you were talking about (again). Without at least a fair to middling grasp of this concept, along with at least an equal comprehension of associated basic principles of heat flow analysis, you haven’t had a glimmer about what’s been discussed here for the last 2 months and 20+ pages, and you’ve been broadcasting naught but your own ignorance. Now for all those who posted earlier who are unable/unwilling to look things up, and/or for whom the concept of “study” is as loathsome and as habitually avoided as a root canal, (you know who you are, and by now, so does everyone reading this thread) here’s a nice word picture for you: Take your 1.4 oz brass body OE sensor, along with a 1 g. GM plastic body sensor, and heat both up to a normal hot day, hard Guzzi riding sensor temp of 100°C. A little swim up to a nice rolling boil in a pot of H2O will do nicely. Fish ‘em out and wait exactly one minute for both to cool. Now suck in your gut, yank open your trousers, and drop both of ‘em down the front of your gauchies. Now which one of the two d’you figure will have you screaming like a schoolgirl and doin’ the Lambada at ludicrous speed until you manage to drop your drawers? HINT: It won’t be the GM sensor. That’s thermal inertia, Binky. Capice? Hope this helps. Link to comment Share on other sites More sharing options...
Dan M Posted June 10, 2009 Author Share Posted June 10, 2009 Take your 1.4 oz brass body OE sensor, along with a 1 g. GM plastic body sensor, and heat both up to a normal hot day, hard Guzzi riding sensor temp of 100°C. A little swim up to a nice rolling boil in a pot of H2O will do nicely. Fish ‘em out and wait exactly one minute for both to cool. Now suck in your gut, yank open your trousers, and drop both of ‘em down the front of your gauchies. Now which one of the two d’you figure will have you screaming like a schoolgirl and doin’ the Lambada at ludicrous speed until you manage to drop your drawers? HINT: It won’t be the GM sensor. That’s thermal inertia, Binky. Capice? Hope this helps. I tried to get them to do a similar experiment in the middle of the last thread involving a pot on a stove so no one would have to buy anything to further their understanding. They didn't bite on that one either... Link to comment Share on other sites More sharing options...
Guest ratchethack Posted June 10, 2009 Share Posted June 10, 2009 . . . They didn't bite on that one either... As an erstwhile student of physiology and neurology (many years ago), I've given this some thought. To reach some people, it seems you've gotta grab 'em in a place where the nerve pathways can complete a full circuit through the spinal cord and fire straight back out to the extremities -- bypassing the cerebral cortex altogether. 'Nother words, there ain't ever much neurological activity wotsoever beyond knee-jerk reflex. . . In such individuals, it seems that when nerve impulses actually DO manage to make it up higher than the pelvic girdle, the spinal cord elevator to the top floor may be slow or not running a-tall. Then, assuming the elevator actually does run all the way to the top floor (not always a valid assumption), and that impulses actually do make it to the cortex, it seems that by the time they get there, more often than not, all the lights are out, nobody's home, all electrical activity has bled off to ground via the stair-well, and the dimmest of wotever's left of any remaining pica-amperes by then simply fall flat and expire on the spot. And then waddayagonna do? Link to comment Share on other sites More sharing options...
dlaing Posted June 11, 2009 Share Posted June 11, 2009 Simply put, THERMAL INERTIA is that property of a material that determines its resistance to temperature change. For practical calculation purposes, it’s expressed in units of measure denoting RATE OF TEMPERATURE CHANGE in degrees over time by volume, as Dan noted above. Credible????? Reads like you are defining Specific Heat Capacity, not Thermal Inertia. I prefer wikipedia, but I still wonder why conductivity and heat capacity aren't inversely proportional. Perhaps Ratchet can go to wikipedia and post how square wheels should be part of the formula????? Here is how the allegedly non-credible Wikipedia defines Thermal Inertia: [quote )Thermal inertia Thermal inertia is a term commonly used by scientists and engineers modelling heat transfers and is a bulk material property related to thermal conductivity and volumetric heat capacity. For example, this material has a high thermal inertia, or thermal inertia plays an important role in this system, which means that dynamic effects are prevalent in a model, so that a steady-state calculation will yield inaccurate results. The term is a scientific analogy, and is not directly related to the mass-and-velocity term used in mechanics, where inertia is that which limits the acceleration of an object. In a similar way, thermal inertia is a measure of the thermal mass and the velocity of the thermal wave which controls the surface temperature of a material. In heat transfer, a higher value of the volumetric heat capacity means a longer time for the system to reach equilibrium. The thermal inertia of a material is defined as the square root of the product of the material's bulk thermal conductivity and volumetric heat capacity, where the latter is the product of density and specific heat capacity: See also Thermal effusivity SI units of thermal inertia are J m − 2 K − 1 s − 1 / 2 also occasionally referred to as Kieffers[2], or more rarely, tiu.[3] For planetary surface materials, thermal inertia is the key property controlling the diurnal and seasonal surface temperature variations and is typically dependent on the physical properties of near-surface geologic materials. In remote sensing applications, thermal inertia represents a complex combination of particle size, rock abundance, bedrock outcropping and the degree of induration. A rough approximation to thermal inertia is sometimes obtained from the amplitude of the diurnal temperature curve (i.e., maximum minus minimum surface temperature). The temperature of a material with low thermal inertia changes significantly during the day, while the temperature of a material with high thermal inertia does not change as drastically. Deriving and understanding the thermal inertia of the surface can help to recognize small-scale features of that surface. In conjunction with other data, thermal inertia can help to characterize surface materials and the geologic processes responsible for forming these materials.(/quote) http://en.wikipedia.org/wiki/Volumetric_heat_capacity Link to comment Share on other sites More sharing options...
docc Posted June 11, 2009 Share Posted June 11, 2009 I continue to feel damn lucky my Guzzi runs at all; let alone my stupid Chrysler product. Growing up on the Left Coast of Florida, I've always thought thermal effusivity should be treated with oysters and Margueritas. Then again, "Wiki . . " never asked me . . . Link to comment Share on other sites More sharing options...
dlaing Posted June 11, 2009 Share Posted June 11, 2009 I continue to feel damn lucky my Guzzi runs at all; let alone my stupid Chrysler product. Growing up on the Left Coast of Florida, I've always thought thermal effusivity should be treated with oysters and Margueritas. Then again, "Wiki . . " never asked me . . . Wiki asks everyone, you just have to listen. Of course if you listen to some people, you'll end up believing Ratchethack and the WSJ are more correct than the "tyrannical" "philistine" "group think" of wikipedia Link to comment Share on other sites More sharing options...
Dan M Posted June 11, 2009 Author Share Posted June 11, 2009 bla,bla,bla... .....bla,bla,bla, bla,bla Well, it looks like we are drifting away from the intent of the thread again. Why does the subject of temperature (cylinder head or climate) always cause such hubbub? Link to comment Share on other sites More sharing options...
Recommended Posts