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tamar
Posts: 804
Registered: 5-1-1989
Location: Gouda
Member Is Offline
Mood: A new beginning 
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posted on 15-3-2008 at 17:23
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EEC R#2 Merlijn: Weightcalculator, Power & Handicap
Hello Slotters
It seems just yesterday that we left a snow covered Olso, but in fact 6 weeks have past. There are just 2 weeks remaining till we meet again in
Brussels.
In the aftermath of the first round of the EEC there has been a lot dicussions on what went right and what went wrong in Oslo.
Maybe not all remarks were exactly to the point but at least every one managed to post their opinion, and believe me they do matter when ever we
evaluate what steps we need to take to make things better.
But I was happy to see that the general impression was one of a great event, so lets try to copy that for Merlijn.
After examening the data from Oslo 3 points of attention were found
- The actual dimensions of the cars measured in Oslo differed from the data we used to make the weightcalculator.
- Of all the cars measured in Oslo the average body weight was some 9 grams above the required weight.
See the attached exel file
- The new PS 4000-Imca motor seemed to be much more powerfull than the old spec PS4000.
To verify the impressions of Oslo we did some extensive testing with different weights and trackvoltages and checked our findings with Pro Slot. It
has now become clear that the new PS 4000-Imca has much more torque than the old spec motor. The PS 4000-Imca had no problem pulling 220+gr heavy
cars, where as with the old spec motor's anything above the 215gr was a severe handicap.
We also noticed that @ 14,2v lighter cars had problems putting this extra power on the track.
During testing we also discovered that with the new PS 4000 Imca motors the optimum weight for a car was around 205-210gr instead of the 200-205gr we
used as a reference.
Several posts mentioned the apparent dominance of the 88-89 mm wide Maserati MC12, some suggested that limiting the trackwidth would curb their
advantage. So we tested the MC12 at narrower trackwidths and behold...in low grip situations the MC12 was actually faster with a narrower trackwidth.
As a result of these tests the following changes will be implemented for the next rounds of the EEC
Weightcalculator: small adjustments
As the W.C uses the average values of the dimensions of the cars to calculate the weights, we have corrected the reference values to the data we
collected in Oslo.
The total reference weights for both GT1 and GT2 have been raise with approx. 5-6 gram, which means that the lightest cars will be able to run at ±
200gr and the heaviest ± 220gr.
The new values have been added to the online weightcalculator.
Track Voltage/ Power: less because the PS 4000-IMCA has more
During the tests we compared the laptimes of both the old spec PS 4000 and the new PS 4000-Imca motors at different track voltage settings. There we
noticed that @ 13,8 volt the new PS4000-Imca achieved similar lap times of the old spec motor @ 14,2 volts.
So for the remaining rounds of the EEC the cars will be run at this reduced trackvoltage. An added advantage of running 2 13,8-13,6 volt is that even
with heavy cars the motor does not run hot.
Handicap: less power instead of more weight
Much has been said about IMCA's handicap rules, and although this is part of the Sporting rules which are under the authority of IMCA, we did test
what the consequences would be.
As a result of these test we discovered that adding wheight does not handicap all cars evenly, which is a requirement if the system is to work in a
fair way.
However during our test for the motor and the weightcalculator we did discover that lowering the voltage immidiately resulted in higher laptimes.
However the powerband of the PS 4000 IMCA motor is such that a cummulative handicap system would not work.
It has therefore been agreed with IMCA that a handicap of ±0,6 volts will be given to the top three in each class.
Meaning that they will run at 13,0-13,2volts compared to the 13,6-13,8 volts of the cars without a handicap.
During testing a reduction of 0,6volt gave an increase in laptimes of ±0,08 sec on an average laptime of 8,6 sec.
This handicap will be implemented by means of a power reduction/restictor in the Plus wire leading to the controller.
Further details of this device will be posted this week.
Attachment: R1_oslo_weightcalc.xls (240.5kb)
This file has been downloaded 893 times
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