PYROMETER - General Notes on interpreting the Information

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1 As a general rule of thumb the following notes are an overview of what type of things to expect or look for in analysing the information that you record with the use of a pyrometer on tyre tread temperatures. Unfortunately this is not the Holy Grail, just a guide, however, some Golden rules to remember before any track work is initiated : 1: Ensure that the basic geometry of the vehicle has been checked and is as intended on initial set up, ie camber, toe, weight split and air pressure 2: Check the batteries of the pyro 3: Ensure the accuracy of the pyro beforehand 4: Ensure you take the recording in the same manner each time to get consistent results that will stand up over time. Some other small items to keep in the back of your thinking are The operating temperature of the tyre is approx 30 F or 13C hotter than when you get to actually record it in pit lane. This is due to the cool down effect between race speeds and coasting to the pits, the tyre will cool down, also another issue to consider is that if the pits is located after a long straight then they will cool even more with the amount of air flowing over the tyre, these are just small things to put into your thinking as you tune the vehicle on the day Optimum operating temperatures vary from brand to brand, but as a guide C is where the majority operate. This naturally will depend on some outside factors ie. amount of downforce the vehicle generates, the ambient on the day, weight split, however, once a general feel for the individual vehicle and its characteristics is gained this will then become the norm so to speak, and not be a factor in the bigger picture. If you have a set up sheet that you record your changes to the vehicle on, ensure there is a place for the pyro readings, afterwards in your debrief or analysis of the days activities you should see the relationship between the readings on the tread face to your adjustments to the car as and when they took place, then the overall relationship between tyre temperature, tyre performance and vehicle speed/ time should become one. As a general rule it would be accepted that the various types of pyrometers available in the marketplace today usually give a different reading on the same surface, this is usually due to the application / use of the pyro more than anything else, while the golden rule is consistent recording to allow a pattern to form on a repeated basis that in turn allows for the transfer of previous recorded information to another day, and its relevance.

2 The various styles / tyres of pyrometers are Probe variety Infra-red Hand Held Infra-red mounted to vehicle The probe type is accepted as the most accurate in a static situation, while the obvious advantage of the vehicle mounted version is that the temperature changes in real time can be recorded. The hand held infra-red are adequate, although they are only giving a surface temperature, as opposed to the probe version which is giving the core carcass temperature, far more accurate but it would depend on the application requirements. The key to the information gathered via any pyrometer system is that it is always carried out in the same manner, therefore the information is relevant from day to day, tyre to tyre. Understanding the information that is recorded can be seen as a black art with car set up changes, although until data recorders, this was the only means of telling the crew what the car was doing as a comparison to the drivers comments. Pyro readings are best collected with the tyre that was considered to be doing the hardest work measured first ( ie right rear on anti-clockwise track), followed by the other corners of the car and usually recorded as seen below with the air pressure included in these recordings (boxed), starting them at 13 front and 14 rear ( cold) Fig

3 From this limited amount of information it is possible to effectively see how the vehicle is behaving in a corner both on entry and exit what effect the driver s style has on the tyres performance effects from changes enacted by the crew Assuming that the car is handing in an acceptable manner, then the pyro readings are telling us the following things: the front tyre pressures could be either 1 psi low or 1 psi high track direction a factor here the rears are either too high as a starting pressure or as a combination, too high then creating a situation where the driver is struggling with power down and has wheel spin on exit therefore exaggerating the problem overall balance is not too bad possibly could use a bit more negative camber or possibly more toe out on the front this is where the drivers feed back becomes very important, it needs to be very simple and clear, one corner at a time to allow the correct adjustments to be made Overall vehicle feel? Good Bad Ugly Does it change of direction easily and as expected? Yes it does no it doesn t Under heavy braking? Stable yes / no chattering locking up vehicle darts around Under light braking? Stable effect on direction vehicle darts a bit Initial turn in? Turns in understeers can not hit apex Will it hit the apex? Yes easily just not in a million years Power down exit Plenty of grip no grip oversteer exit understeer The information that the driver now gives you should allow you to see some form of pattern in the pyro readings you have recorded versus the vehicles overall handling traits

4 If the driver is not experiencing wheel spin on power down exit from corners, then adjust the rear pressures down to 14 psi (hot) Reset the front to 14 psi ( hot), assuming braking was OK, then send the car out for 3-4 laps then back in the check the pyro readings, if this was the problem then the following result should occur Fig You should look for a maximum of a 10 C spread on the tyre temperatures as a rule, therefore with the results as above you would assume that air pressure was the key factor to the excesses you were seeing, the balance should be better and the driver should report better power down, crisper turn in, still good under brakes and overall a better car. If however it came back as in Fig 3 Fig Now the issue to contend with is too much grip on the rear, front pressures are probably OK but the driver will complain of understeer, everywhere, due to rear grip ratio being increased. You would also see wear on the tread face to confirm this reaction. Set the rear tyres to psi ( hot) and the fronts to 14 psi (hot), go out for 2 3 laps then in for a fresh set of readings and it should resemble as in Fig. 2 If however it does not, nothing changes, then this is a clear indication that the problem lies within the set up of the vehicle and not just the tyres.

5 Addressing each area one by one is a solution, however, with time always at a premium the reliance on the driver s feed back really comes into play, allowing you to determine which area is the most critical or possibly that one adjustment you can make to gain the biggest effect from initially, to allow some platform on which to start the tuning process. Using Fig 4. as an example Fig The obvious place to start would be rear bars, shocks, springs, then looking at the camber and toe settings on the front, but start with the shocks and bars, then fine tune with the camber and toe once the rear settles down. There is too much weight transfer in the corner (too soft) and the cambers are reacting due to this transfer and over heating the front tyres inside surface Fig 5. tells us that the rear end is behaving itself, the Front camber or Toe is possibly a bit too much in the negative Fig Not enough negative camber or toe out would produce readings similar to Fig 6

6 Fig There are a thousand and one combinations, the issue is converting the recorded information into something that makes sense, the driver s feed back should re-enforce the information you have in your hands, therefore it should be easier to work through the initial set up issues. The examples in these notes are a guide to the many issues and problems that will face you in this development phase, if you require any further information or specific analysis, please contact us at your convenience For Further Information Please Contact Us Ph: Fax: racing@nttyres.com.au