Nigel S Dobbie's definitive book on Corvette racing

2014 TUDOR Balance of Performance

TUDOR 2014 Balance of Performance

At the beginning of the 2014 season IMSA the Governing body of the TUDOR United Sportscar Championship set the Balance of Performance for all four Classes. I am only interested in what happened in the GTLM Class. So I have based my calculations on the following scenario:

I took all of the published IMSA Timing data available at for the 2014 TUDOR United Sportscar Championship for all of the rounds involving the GTLM Class.

I then filtered it to Green Flag Racing Lap and grouped the data by Brand and Car (I added two new columns to the data Circuit and Brand). I then wanted to find the fastest theoretical lap by Brand and to do this I looked at all of the sector times to calculate the best sector time for every sector regardless of the driver or the car i.e. Sector 1 for Corvette for example might be Antonio Garcia in the #3, then Sector 2 might be Oliver Gavin in the #4 and so on to get the Best Theoretical Lap Time.

For all of the charts below the bars represent the time in seconds for the cumulative theoretical best lap time by brand and is measured in seconds on the left hand axis, the dark red line represent the average time for all the brands (6 at Daytona and 5 for the rest of the rounds as Aston only competed at Daytona). The red line represents the top speed as measured by IMSA at their speed trap, this is the actual best time by brand and is measured in MPH and represented on the right hand axis of the chart. For Daytona I actually added a further line which took out the Aston and the Ferrari and this line is in green.

Race 1 Daytona

Race 1

Race won by Porsche. Aston Martin considerably slower than the Average as was the Ferrari, however the Ferrari data is a little skewed by the fact that only Matteo Malucelli drove the #62 and the other Ferrari the #57 is the Krohn car. BMW, Corvette, Porsche, Viper all below the “average” so taking the Ferrari and Aston out of the equation I created an Adjusted Average of the other 4 manufacturers. This shows how well balanced all of those 4 manufacturers were at Daytona. Viper potentially fastest but less than 2/10th of a second covering all 4 manufacturers. The scale is lap time in seconds for all charts.

14th of February AoP adds 15kgs to the BMW, 15kgs to the Viper and reduces the Aston by -20kgs.

7th of March additional -30kgs for the Aston.

Race 2 Sebring

Race 2

Race won by Porsche. Aston Martin decided not to race so no data available so for the rest of this report there will be just 5 manufacturers shown. Ferrari again significantly slower than the average but again #62 crashed early and #57 the Krohn car more amateur than pro drivers. Potentially fastest car was the Corvette but both cars suffered late race problems so the next fastest car the Porsche won.

Race 3 Long Beach

Race 3

Race won by Corvette. BMW potentially fastest, Porsche right on the average and both the Ferrari and Viper more than 2/10ths slower than the average but also the two fastest cars through the speed trap.

Race 4 Laguna Seca

Race 4

Race won by Corvette. BMW significantly potentially fastest, Porsche also faster than the average by about 2/10ths of a second, Corvette the winners actually slower than the average but within 1/10th. Viper slowest and more than 3/10ths slower than the average. Ferrari also still slower than the Average. Viper fastest through the speed trap.

Race 5 Watkins Glen

Race 5

Race won by Corvette. BMW potentially fastest car, then Viper, Porsche and Ferrari both slower than the average. Viper now running -15kgs and with a bigger restrictor after 20th June AoP adjustment. Corvette running exactly on the Average. BMW lowest top speed but fastest lap time.

Race 6 Canadian Tire Motorsport Park

Race 6

Race won by Corvette. Corvette fastest car and faster than the average by more than 3/10ths of a second. Actually all cars faster than the average apart from the Ferrari which was massively slower than the average by more than ½ second. Corvette fastest through the speed trap.

IMSA makes Adjustment of Performance as follows: (Changes in BOLD)

BMW -15kgs
Corvette +25kgs
Ferrari -30kgs
Porsche +15kgs
Viper -15kgs

Race 7 Indianapolis

Race 7

Viper fastest car and it now appears that the cars are pretty well balanced as all four other manufacturers are all extremely close to the Average except for the Viper. However this is deceptive given the nature of the track when compared with the other tracks to follow and the amount of time under caution.

Race 8 Road America

Race 8

Race won by Ferrari. Porsche and Ferrari both significantly faster than the average. BMW and Corvette both slower than the average. BMW within 2/10th of the Average but Corvette now more than ½ second slower than the Average carrying the extra 25kgs and now 70kgs heavier than the Ferrari.

Porsche which has historically always liked Road America and had the potential fastest lap time, should have won the race.

Race 9 VIR

Race 9

Race won by Ferrari. Ferrari more than ½ second ahead of the Average, Corvette now more than ½ second slower than the Average. BMW about 2/10ths faster than the Average.

Race 10 COTA

BMW +25kgs 1255kgs
Corvette -15kgs 1255kgs
Ferrari -30kgs 1200kgs
Porsche +15kgs 1225kgs
Viper -15kgs 1250kgs

Race won by Viper. AoP applied before the race.

Race 10

Porsche was potentially the fastest borne out by their pole position and should have won the race and would have but for the failure of the driveshaft on the #911 car. Viper was the second fastest car and took full advantage taking the 1-2 in the race. Porsche finished 3rd, Ferrari 4th and Corvette ran to form i.e. last just behind both BMWs who were equally slow with the same weight as the Corvettes. The extra weight massively affected the BMW as it has the Corvette and the smaller restrictor on the Ferrari seems to have had the desired effect i.e. brought them back to the average. Porsche have a huge advantage of 0.7secs compared to the average. Corvette and BMW are both more than 0.5secs over the average. Spread of potential best times now a massive 1.2seconds from best to worst.

Race 11 Petit Le Mans

Race 11

Porsche significantly faster than all the other manufacturers and won the race. All the other four manufacturers were actually closely matched with the spread of potential best lap times covered by just over 0.3secs.

Weight / Wait!

My conclusion to all this is that given this was the first season of TUSC IMSA should have stuck to their guns i.e. left the Balance of Performance alone once it was set at the beginning of the season as they were pretty close to perfect at Daytona (except Aston Martin). Going forward into 2015 IMSA should set the class weight at 1245kgs for all cars AND NOT CHANGE IT EVER!

The fuel tanks for all cars should be the same (except for those running E85 as you need more fuel to get the same performance as E10). The fuel flow should be the same for all fuel rigs as a faster team in the pits shouldn’t be penalized for being better / faster.

If IMSA feel one car is making more power than another then sure they should change the restrictor(s) for the cars… other words lets’ go back to the days of GT1 where the best team with the fastest car won the races.