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February 2012

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iRacing TV

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The Team

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  • David Phillips
    Editor and Chief
    David Phillips is a long-time contributor to print and electronic publications in the U.S. and abroad, including Racer, Autosport, AutoWeek, Motor Sport and SPEEDtv.com, oversees the daily updating of news stories and assigns, edits and contributes feature material for inRacingNews.com.
  • Chris Hall
    iRacing.com Series Writer
    Chris Hall has been writing since the nineties and moved into motorsports reporting in 2005, covering series such as ALMS, British GT, FIA GT, Le Mans and 2CV racing for Full Throttle magazine, Motorsport.com, The-Paddock.net, GTGateway.com, L' Endurance and, of course, inRacingNews. During 2008 and 2009, he worked with the RSS Performance Porsche Carrera Cup Team (and former British GT(C) champions) as a data engineer for a variety of drivers and models of 997s.
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    19 years old, Jameson Spies lives in Quartz Hill, California. He grew-up surrounded by racing. His mother raced late models throughout Southern California while his father built and setup the car. Not surprisingly, Jameson began racing go-karts at the age of 13, and is now racing Spec Trucks at Toyota Speedway at Irwindale. He has a passion about all forms of racing and hopes to make a career out of it.
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  • Ray Bryden
    Technical contributor
    Ray grew up in Nova Scotia, which means he’s a hockey nut, but in Nova Scotia’s two non-winter months he had to find other diversions, which meant watching F1 racing on weekends with his dad and brothers. Without the resources to get started in racing, he gravitated to computer versions of racing – first Atari games like Pole Position, followed by PC racing games like Indianapolis 500: The Simulation. Dozens of others came and went, until Grand Prix Legends came along and he decided sim-racing was his official hobby. Years were spent enjoying this both offline and online until a few years of fatherhood took priority. When free-time reappeared he heard about iRacing and signed up in 2008 and became so involved in the service that he wrote one of the first books on the subject of sim-racing, iRacing Paddock. When not writing for inRacingNews.com, his main occupation is as a research associate with Saint-Gobain working on advanced ceramic materials.
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    Patrick Atherton, originally from Adelaide in the state of South Australia, currently resides just outside of Melbourne, Victoria with wife of 17 years and 3 kids. A business manager by profession, but also dabbles with blogging, cartooning and fine art, having been published both as a writer in a short-lived South Australian motorsport yearbook and later as a cartoonist in a niche trade magazine. At the age of 19 he competed in club circuit events in an Austin Healey Sprite, later indulging in sprint karts between 1994 and 2000. Following the move to the State of Victoria he raced Road Race Karts (“Superkarts” as they are known in Australia) in the popular Rotax class, competing at Phillip Island, Oran Park, Mallala, Wakefield Park, Eastern Creek, Calder Park, Sandown and Winton. It was during this time he met former Australian F2 champion and inventor of Australia’s first, and most prolific race simulator rig, Jon Crooke. This culminated in an introduction to Papyrus’ legendary NR2003 simulation, and the subsequent sim racing addiction which brought him to iRacing.
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    Tim Terry, aka the voice of Maritime stock car racing, fell in love with sim racing in 2004 after he joined the Sim Racing Network crew as a pit reporter. From October 2004 to SRNtv’s closure in June 2007, he’s covered prestigious races and leagues such as the Online 500, FLM Fall 400, Real Racing Online and the DMP Racing League – each as the lead broadcaster for the company. At the same time the wheels started to turn in another direction as he began announcing stock car racing locally. Terry became the assistant announcer at Scotia Speedworld in May 2007 and took over full duties in May 2009 when long-time voice Mike Kaplan retired from the track. Terry also became the series voice of the Parts For Trucks Pro Stock Tour in ’09 and continues to hold down both posts in 2011. He has also announced races for the Pro All Stars Series, Atlantic Open Wheel and Maritime League of Legends tours and has called races at six different Atlantic Canadian tracks. Terry can be heard online at WebRacingNetwork.com, RLMtv.com and OLRtv.com covering sim races. He also makes occasional appearances on PSRtv.com. In addition to inRacingNews, his articles and columns can be read on ScotiaSpeedworld.ca, MaritimeProStockTour.com and his own website at timterryonline.com.
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    North Carolina born and raised with over 15 years of computer/IT experience, I combine two of my biggest hobbies -- racing and technology -- here at inRacingNews. In my spare time I run a Nascar fan site and cure my own need for speed riding atvs. If it involves technology or racing I'll be there, but combine the two and I'll be looking a front row seat. Stop by and say hello anytime!
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    Allen was born in West Palm Beach, Florida but grew up in Atlanta and attended Georgia College and State University where he received a BS in Information Systems. Currently a resident of Albany, GA, he started sim racing in 2008 while in college when iRacing was first released to the public. Since then, Krier has been a two time iRacing Pro Series driver (2009 and 2010), picking up one Pro Series win at Daytona in ‘09. Besides sim racing, Allen’s other hobbies include RC Car racing as well as “attending and watching any sporting event that I can including going to the local dirt track.

Second Shift

by Ray Bryden on January 16th, 2010

Alright, I wouldn’t go so far as to call this a retraction, but let’s call it a little clarification of the last article I wrote on the optimum shift RPMs for the Skip Barber car. Based on the calculations of horsepower and RPMs, I put together a prescribed set of shift RPMs for each gear change. But like all theories, it doesn’t hold much value until it is put to the test. The proof is in the puddin’.

So I set out to confirm if my shifting advice would put a driver at an advantage as they scream off the grid towards turn one. To do this I ran a number of starts at the beginning of an 800m long straight stretch and tried to hit a variety of shift RPMs and evaluate what shift technique was quickest to a given distance.

Well, it turned out that the run that was closest to matching my shift recipe was a few milliseconds slower than another run which was slightly off. So I decided to plot all the runs I did and compared them to the fastest run of the experiment. Then I looked at each shift from each run and evaluated whether it gained on the fastest run, or lost to it. I quantified the difference and came up with a much more reliable technique to see which shift RPMs offered the optimum acceleration.

The result is shown in the following graph:

screenhunter_86-jan-13-1450
It was odd how identical full-throttle starts resulted in different launches. It appeared that when the engine was increasing in RPM after the brief drop due to the rev limiter, and was close to 6300 RPM, the result was the optimum launch off the line. This was confirmed when the RPMs were held close to the rev limiter without triggering the rev-limiter. Thus, you could take your chances with a full throttle start, but you may get a slightly more reliable result if you hold it close to the rev limit during the launch into first gear.

The shift from first to second did not seem as critical, since it was changing in RPM so rapidly that the difference in shift points was not pronounced, but the trend did indicate that 6200 RPM was best. Both second to third and third to fourth shifts were optimized when just over 6000 RPM, but the most critical shift point appeared to be the final shift into top gear. Shifting too early is a big disadvantage here and you would need to get close to the 6300 RPM before you lose the advantage.

So the new shift advice for the Skip reads as follows:
Neutral to 1st: 6300 RPM (without triggering the 6400 RPM rev limiter)
1st – 2nd: 6200 RPM … not as critical as the others
2nd – 3rd: 6000 RPM … plus or minus 100 rpm is ok
3rd – 4th : 6000 RPM … plus or minus 100 rpm is ok
4th – 5th: 6200+ RPM … stay well above 6000; shifting lower than 6100 will slow you down a lot compared to people shifting at higher RPMs.

So my old shift points were not that far off the mark, and followed the same trends as was found in the actual testing. Only the second to third upshift was off by about 150 RPM.  Comparing this new routine to someone who starts on the rev limiter and shifts always at 6100 RPM would result in an advantage of about 1.16m after 800m.

But you know how the old saying goes: Even a broken clock is right twice a day.

7 Comments or Trackbacks

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  1. Jose Afonso
    January 17th, 2010 at 12:01 am

    i wish i could see my rev meter when i use realistic FOV on my triple monitor setup :(

  2. Christiaan LeGrand
    January 17th, 2010 at 1:59 am

    I was thinking exactly the same thing as Jose … iSpeed and an iPod help the situation.

  3. CJ Modiano
    January 17th, 2010 at 6:48 am

    wow.. wish I read this before my skip barber race today! Nice to finally know the shifting recipe for this car though. Cool article.

  4. Ken M
    January 28th, 2010 at 4:07 pm

    Another great article Ray. Have you tried plotting the applied torque in each gear vs speed? Depending on the gear ratios and the shape of the engine torque curve it may be better to stay in a lower gear past the intersection of the power curves (as given in the previous article). Unless the torque curve falls off dramatically and/or the gear ratios are quite close, the lower gear can give more applied torque near the rev limit because of the shorter ratio even though the engine power and torque have have dropped somewhat. It’d be interesting to see what shift points the torque curves would suggest.

  5. Ray Bryden
    January 29th, 2010 at 6:47 pm

    Yes, I have that data as well, Ken – as a matter of fact I was plotting some curves of torque v speed last night. And I think when it comes down to it the torque curves are critical for the performance at lower speeds, and the power curves dictate the pace at higher speeds, so really it is important to consider both.
    The procedure above was a nice way to evaluate the optimum shift recipe from a more pragmatic approach.

  6. Ken M
    February 2nd, 2010 at 3:16 pm

    Yeah, some one once told me that power gives top speed and torque gives how quickly you reach top speed. :-)

    Since you have the torque curves and drag/friction losses, shouldn’t it be possible to determine speed and distance over time (acceleration = applied torque-drag)? If you can do that then studying the effect of shift points, wing settings and gear ratios becomes possible without getting into the car. Though that wouldn’t be as much fun. ;-)

  7. Damon Ethakada
    February 23rd, 2010 at 1:24 pm

    The “point” of engine power output is to be a rating of engine performance that considers the effects of both torque and gearing. Were gearshifts instantaneous, you would want to be in the gear that resulted in greater engine power at all times, because this results in the greatest engine torque multiplied by gearing – that is, the highest rear-wheel torque. The only reason that you might want to shift at an engine speed other than the intersection in the power curves is to attain a higher speed before you lose acceleration for a gearshift – something that is more likely to work in a low gear where the rate of acceleration is high.