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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, oversees the daily updating of news stories and assigns, edits and contributes feature material for
  • Wil Vincent
    Contributing writer

    Wil is a 25 year old student, town planner, and sim racing commentator, most well known for his work as the lead commentator for GlacierTV. Wil got into commentating through his college student radio, where he also worked as a journalist and interviewer, covering gigs and festivals within the UK, and joined GlacierTV in February 2012, becoming lead commentator a month later. His work culminated in him commentating on the 2013 World Championship Grand Prix Series, iRacing Indy 500, and iRacing All Star Race. When he gets in the virtual cockpit, you'll normally see will taking on the thrill of IndyCar Oval racing, or trying his hand in GT action

    Outside of iRacing, Wil's an avid IndyCar fan, having watched the sport since the late 1990s, and always looks forward to the Month of May. He also enjoys watching NASCAR, Formula 1, and V8 Supercars.

  • Jeff Jacobs

    Jeff Jacobs started autocrossing with the SCCA in 1990 while a student at the University of Florida. He has competed in the SCCA's National Tour and ProSolo series since 1995, winning a ProSolo National Championship in H-Stock in 2011 driving a 2010 MINI Cooper. Jeff completed his SCCA Club Racing drivers' school in 2012 at Roebling Road in a Spec Miata. He currently writes a column for the SCCA's Northeast Division in SportsCar Magazine and is the Region Executive of the Philadelphia Region SCCA.

    Jeff joined iRacing in October 2012. After starting with the MX-5 and SRF cars, he has been concentrating on the Ford Mustang FR500S, competing in the Mustang Cup series and the Continental Endurance Sports Car Series.

  • Cam Stark
    contributing writer

    I began taking sim racing seriously about a year ago, but have loved motorsports from a young age. I began following Formula One first, then realized there are a huge variety of motorsports to watch. iRacing has opened my eyes even more to the diversity and volume of “real world” motorsports, let alone on the sim itself. With the huge varieties of series to choose from, you're spoiled for choice!

    Ever since I began iRacing, I wanted to improve on my ability, be it road or oval. Having not really heard about oval racing prior to November last year (blame the UK press), my mentality towards it has totally changed from what it would have initially been - it's awesome! I recently began road racing again - in the Star Mazda - and have been having a blast ever since. On top of racing the series I have the privilege of writing the articles for iRacing News.

    In all honesty I have surprised myself on iRacing. From being a fairly casual gamer/racer, it's been a world of difference, but it has far exceeded my expectations. I had a very brief stint driving in rFactor leagues, but I found my place of sim racing on this service, and I can't see myself stopping anytime soon.

  • Justin Sutton
    series contributor

    Justin is 29 and lives in Texas with his girlfriend and three dogs. Although always a fan of road racing growing up, Sutton never got the chance to participate in Sim-Racing until 2012 and didn't join iRacing until 2013. The son of a writer, and former resident of Connecticut and Philadelphia, his interests vary. Currently Sutton is a co-owner of YouTube channel focused on racing games and simulators and more specifically Formula One along with his partner Mikko from Finland (BoxBoxBoxGaming). Currently Sutton writes the Skip Barber F2000 and Lotus 49 articles (and the occasional F1 article) for iRacing News, and doesn't get nearly enough time to race the cars he writes about.

    Gaming is a big part of Sutton's life as well as he is both viewer and broadcaster on Twitch along with his girlfriend of seven years. In addition to being an aspiring writer he is a skilled speaker with a focus on commentary of races and hopes one day to do commentary for road racing of some kind.

  • Matt Holden

    Matt Holden began his involvement in motorsports at an early age, moving to Charlotte, NC when he was 6 months old. Growing up next door to a NASCAR TV personality, racing has always been a major part of his life. Currently studying Mechanical Engineering at UNC Charlotte, Matt works for US Legend Cars International as a technical inspector and race official at local tracks such as Charlotte Motor Speedway and Concord Speedway. Within iRacing, Matt is the Crew Chief for Gale Force Racing's #05 car in the NASCAR Peak Antifreeze Series, as well as Chassis Engineer for the team's R&D program.

  • Paul Slavonik
    iRacingNews Series Writer

    For all intents and purposes, Paul Slavonik was a late-bloomer to racing. Growing up watching NASCAR drivers such as Davey Allison and Earnhardt Sr. was the furthest extent of Paul’s racing aspirations at the time. Fast forwarding 20 years, Paul began watching the UK show Top Gear and thus ensued a fascination with all things fast. Soon after, Paul stumbled upon and has been hooked on racing ever since.
    A United States Army Veteran, Certified Audio Engineer and aspiring author, Paul spends his time hanging out with his wife and working on his first book. Currently residing in Dallas/Fort Worth (DFW), TX, his favorite racing series is the Australian V8 Supercars (go FPR!) and he has recently joined a local ChumpCar racing team. Paul began writing news stories for iRacingNews in January of 2014 and currently covers the GT3 Challenge Series and the V8 Supercars Series.

  • Thiago Izequiel

    Born in 1985 in the city of Rio de Janeiro, Thiago Izequiel is a graphic and web designer, go kart racer, aiming to get a career in motorsports. He started racing in 2007 and joined iRacing in 2010. Thiago lives in Maricá, a little town located in Rio de Janeiro state, around 60km far away from Rio de Janeiro city. In 2014 he started to write for iRacing News and also started to design layouts for racing cars.

    Working as a freelancer today, he started working as a designer in 2006. After a few years working in web design agencies, Thiago decided to follow his dreams and quit his job to work with a racing driver named Suzane Carvalho in 2011, on her driver's school. Things didn't worked out as expected and Thiago, after getting jobs as a front-end developer and social media content developer, went back to the dream path as a freelancer so he could have more time to focus on his driving career.

  • David Moulthrop
    NASCAR Contributor

    David Moulthrop is an award winning motorsports photo journalist and has covered auto racing since the mid-seventies. While he is most well known for his NASCARimages he has also covered F1, American Road Racing, and IndyCar on a regular basis. He has been published in numerous magazines, newspapers and online news sites including, National Speed Sport News, Area Auto Racing News, Auto Racing USA, Stock Car Magazine, Sprint Cup Dateline, and Jayski. David joined the iRacing team in 2004 as a contract photographer and became iRacing's Laser Scan Project Manager in 2005.

  • Jack Davidson
    Staff Videographer

    Jack is a recent grad from Boston University with a passion for filmmaking as well as racing. He grew up playing games such as the Need For Speed series, Gran Turismo, and more recently, the GRID and DIRT franchises.

  • Jason Lofing Series Writer
    Jason is 21 years old and was born and raised in Elk Grove. California. A big time NASCAR fan, he hasn’t missed a race on Sunday in years. Lofing is also a huge San Fransisco Giants fan and tries to take in at least a couple games a year. Other than sim racing, his biggest (and far more expensive!) hobby is photography. Although he is rather new to sim racing, Lofing has already accomplished some pretty impressive results, qualifying for the 2011 iRacing Oval Pro Series in Season 1, 2011, winning the inaugural Landon Cassill Qualifying Challenge and finishing runner-up in the second one.
  • Katier Scott
    Contributing Writer
    I am a veteran sim racer who first started racing way back in 1993 on the SPRTSIMS section of Compuserve with a league who can trace themselves all the way to the present. Within that league I act as Chief Steward and try to bring the unique viewpoint that this experience gives me into my articles.
    I have a BA (Hons) in Journalism and Editorial design and have been writing for seven years and currently cover the Lotus 79 CTC and Radical series alongside my freelance work. Living in the UK, as well as motorsports I love Photography, Arts and Crafts and reading.
  • David Ifeguni
    Contributing Writer
    I was born in New Haven, Connecticut in 1988 and moved to Midland, Michigan when I was two years old. I stayed there until third grade when I moved to Farmington Hills, Michigan and now I currently live in Naperville, IL where I'm attending Metea Valley High School as a 9th grader. In the past, I have participated in soccer and this year I plan on joining swimming or water polo. My family includes my 15 year old sister, a 7 year old sister and my mom and dad. I have been writing since 6th grade and have participated in many writing contests in my school and have received several awards for writing.
    My fascination for motorsports began when I was nine. The first NASCAR race I watched on TV was the 2009 Toyota/Save Mart 350 at Infineon Raceway, won by Kasey Kahne. My favorite NASCAR drivers are Kyle Busch, Dale Earnhardt Jr, and Jimmie Johnson. I have watched all the races in the NASCAR Sprint Cup, Nationwide and Camping World Truck Series since 2010. I currently have three wins on iRacing, two of them in the Nationwide car at Daytona and one in the Street stocks at Charlotte. My favorite car and type of track on iRacing is the Nationwide Series (B Class) car and superspeedways.

iRacing’s Corvette: Good Enough is Not Good Enough

by Ian Berwick, Vehicle Dynamic Engineer, on January 8th, 2010

We’ve gotten approval to build the Pratt & Miller Corvette C6.R GT1 car!  SWEEEEET!  OK, what’s first?  Hmmmm. Dyno sheets.  That’s the most important thing, right?  That beautiful sounding motor, deep and rumbling, with earth-moving torque and acceleration.  Now that sounds like fun! Corvette C6.R: Sound like -- and is -- fun.'s Corvette C6.R: Sounds like (and is) fun.

Getting the power to the ground is next, so what gearbox does it use?  What are the various gear ratios?  How many options of gear ratio, and what’s the layout and the inertia of all the components?  Xtrac builds the box, and my friends at Xtrac USA have been exceptionally helpful with data for component inertias in the past, maybe they’ll provide me with additional values…

And it’s got wings, well, one, and it’s HUGE.  That must make a TON of downforce.  But then there’s none on the front, and they’re not allowed to use an enormous splitter or multiple diveplanes, so how much of that rear wing can they actually use?  I guess get the front end to work, and balance it with whatever wing position works, then.

I’ve also heard this car generates a ton of downforce.  I just read an article in Racecar Engineering that said it made as much as 1800lbs of it, so 0.9 tons actually!  I’d say that’s BARELY an exaggeration, then.

Oh, but it’s supposed to handle amazingly well too, so I guess we need all the suspension motion data.  Camber gain, spring rates, wheel rates . . . all that stuff.  I guess damping rates are needed as well, since we have springs that need to be controlled.

From ? to virtual C6.R, a cmobination of ?, ? and ?

From WinGeo3 to virtual C6.R, a combination of precise data, painstaking calculations and educated assumptions.

But what are the sprung and unsprung masses?  What are these items you ask?  Sprung mass is anything that the springs hold off the ground.  Unsprung is anything that follows the road surface, like the wheels (with tires) and the suspension (well half of it anyway, the ends that are attached to the wheel).  And now that we’re worrying about masses, that leads us to inertias.  How much inertia for the sprung mass vs the inertia for the whole vehicle?  Does that data exist?  How was it determined?  If it doesn’t exist, I get to break the car down into smaller individual components and take my best shot at calculating it all.  Fortunately, most of the bigger teams/manufacturers have a good handle on the inertias so this time it’s pretty easy.  No more than a few hours to get the numbers laid out with a variable fuel load.

What about the masses and inertias in the engine and driveline?  Thanks to Xtrac USA, the gearbox is easy.  The engine?  Not quite so simple.  General Motors  is not going to give me those numbers.  Not a chance.  So now I get to calculate all the inertias for all the moving parts within the engine.

Exhibit A: C6.R by Pratt & Miller or (See below)

Exhibit A: C6.R by Pratt & Miller or (See below)

So how much does a 7.0 liter engine crankshaft weigh?  Thanks to Google (a wonderful source of arcane information), it appears that a Chevy 427 crankshaft weighs approximately 53-57 lbs.  How much lighter than that is the factory race version?   I figure it doesn’t rev very high, and with all that torque it needs to be tractable, so super light isn’t really necessary, so let’s go on the high side of the range at 56 lbs.  And that crankshaft is tough to calculate.  Draw a crankshaft, break it down into all the individual sections that are symmetrical and try to get a rough estimate to work using the material density and mass, and you’ve got a decent approximation.  But that’s still just a guess.  An educated one, but still a guess… Con (connecting) rods are fairly well documented (online) at approximately 480 grams.  Pistons?  540 grams there…

What about chassis and suspension component inertias?  Yup, I get to calculate those too, but this time Pratt & Miller have provided the masses of the individual components and a total inertia for several assemblies, as well as the whole vehicle from their own shaker rig testing and CAD data.  That makes it much easier to be within the 2-3% error I’ll accept.  (Much more than that, and I have to dig deeper to try to locate any assumptions that may not be correct or outright miscalculations.  It’s happened before, and it’ll happen again, but that’s the challenge!)

Exhibit B: C6.R by Pratt & Miller or (See below)

Exhibit B: C6.R by Pratt & Miller or

What about aerodynamics and downforce now? What’s the “perfect” ride height and rake to maximize downforce and minimize drag?  How about lift to drag ratio?  Is that what we want to optimize?  Or is this thing stout enough that it’ll overcome most any bit of drag with all its torque and just go regardless?  If that’s the case, balancing the downforce front-to-rear is really the key.  With the rear wing trimmed out to the available minimum, there’s less than a 10% drop in drag, so clearly most of the drag is in the body, and the body lines are quite clean, with a very smooth underbody helping to keep it nice and slick.  That means a relatively small difference in top speed from min to max rear wing with this car.  But min rear wing also means the aero balance shifts forwards making the car quite loose.  Sounds exciting in a video game…not a good scenario at 190 mph in real life!  As long as that front-rear aero imbalance gets adjusted, then it’s fine and it’ll gain you about 5mph at top speed.  Like I said, it’s small at roughly a 2.6% increase in top speed, but you trade-out 6% of your downforce.  Is that a worthwhile trade?  How long is the straight at this track you’re racing on?  Are you going to get anywhere near absolute top speed?

(Seeing as I have the benefit of seeing the aero equations, and a few setups straight from the manufacturer, I can clue you in to the rough setups.  2.5 to 3 inch front ride height, and 0.5 to 0.75 inch rake with fairly stiff springs to control ride height and pitch are what seem to work well.)

Exhibit C: C6.R by Pratt & Miller or (See below)

Exhibit C: C6.R by Pratt & Miller or

This is all well and good, but what is the MOST important element of any car?  The tires!  Let me just pick up my phone and call Michelin.  They don’t recognize my name?  And they won’t give me all their tire data?  Why not!?!  It’s only years of data they’ve developed and paid for with their research budgets.  Now what?  All that’s left is trial and error testing of the tires that no one has much information on.  Sure, I might be able to get some vertical spring rates, and maybe some cornering stiffness numbers, but longitudinal and lateral stiffness are critical to the way a tire responds, let alone absolute grip.  And is it a Pacejka-based tire model, or a Magic Formula Tyre model, or one of the many other derivations out there?  There are so many nuances that those models don’t effectively quantify, but they at least offer a starting point.  Ultimately it comes down to getting as much feedback as possible from real-world racers, and applying what we know about tires to what knowledge they can share with us.

So how long does this process take?  How much do I get to start with?  The more data I get, the faster some stuff gets done, but that can also delay the process.  If the wind tunnel data has one data point that’s not coincident with the equation, if the car has rubber bushings in the suspension, if the track performance isn’t in line with what the data is saying . . .  Or say there’s NO DATA.  Where do you start then?  Contract to have CFD data done?  Maybe you can find some dyno numbers and an established top speed, so you can get a drag number figured out.

Exhibit D: C6.R by Pratt & Miller or  (See below)

Exhibit D: C6.R by Pratt & Miller or

How long?  For a car like the Solstice, the Spec Racer Ford or the Legends car — you know something with limited aero –  it’s a fast three weeks or maybe a little more to establish performance limits before a public rollout.  For a car with limited aero, likely five-six weeks, just to make sure the downforce numbers are reasonable outside the “normal” ranges.  Aero dependent cars like the Dallara?  Eight-twelve weeks might be necessary, just to verify that all the individual pieces are working as intended, and the handling is correct.

The big thing is, no matter how good the product is, it can always be made better.  So keep your ears open, listen to what everyone says, and never settle for “good enough.”

*                                                           *                                                             *

A & C – Pratt & Miller (images by Wikipedia and Corvette Racing); B & D – (screenshots by Matt Orr and Bryan Heitkotter)

23 Comments or Trackbacks

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  1. Sean Siff
    January 8th, 2010 at 6:39 pm

    Awesome article Ian! I learned a lot from reading about the process! Keep up the good work.

  2. Sam Hazim
    January 8th, 2010 at 9:06 pm

    Fantastic insight, thanks Ian – this wasn’t prepared in 30 seconds and I appreciate that.

    I think this is just the sort of insight we all could hope for when the notion of a development blog was banded about a while back.

  3. Aaron Devaney
    January 8th, 2010 at 10:50 pm

    Great insight into the making of the cars. Thanks for taking the time to write an article. it makes you really appreciate the attention to detail.

  4. Daniel Buck
    January 9th, 2010 at 12:41 am

    AWESOME ONE, MAN! especially for the pictures!! great stuff right here everyone!!

  5. Marcus Caton
    January 9th, 2010 at 5:05 am

    Great read

    BTW keep up the good work and feel free to post more Optimum info
    maybe the COT next *prepares notpad*

  6. MM
    January 9th, 2010 at 8:08 am

    Thanks Ian, very cool to know a little more how things work to build a car in iRacing! :)

  7. Ray Bryden
    January 9th, 2010 at 3:00 pm

    Wonderful glimpse into the process – Great job, Ian!

  8. George Kuyumji
    January 9th, 2010 at 11:51 pm

    Great article. More of this stuff please

  9. Byron Forbes
    January 10th, 2010 at 2:55 am

    Fantastic – good to see you guys earning your money! :D

  10. Iain Mabbott
    January 10th, 2010 at 8:01 am

    Very interesting article Ian, thanks for sharing that with us.

  11. eddiespag
    January 11th, 2010 at 3:47 am

    Say… in that one screenshot where the Vettes are shown from the back, is that the new future build with all the redone track surface and environmental lighting?

  12. Lincoln Miner
    January 11th, 2010 at 5:17 am

    Thanks Ian! Great article!

  13. Don
    January 11th, 2010 at 8:41 am

    So basically lots of guessing are still involved! Anyway thanks for sharing!

  14. John Prather
    January 11th, 2010 at 12:18 pm

    Fantastic Article.

  15. James Andrew
    January 11th, 2010 at 12:33 pm

    Fascinating read!

  16. Ian Berwick
    January 11th, 2010 at 6:44 pm

    Thanks guys! I’m more accustomed to technical reports than news articles, so it was a little tough to make it not quite so impersonal and… boring.

    Don — I prefer to think they are EDUCATED guesses…

  17. m
    January 11th, 2010 at 11:22 pm

    You cheated with B – it has DOF (depth of field) – iRacing doesn’t (yet). Photoshopping is cheating! ;)

  18. Matt Orr
    January 12th, 2010 at 4:43 am

    Hey hey hey………

    I put in a lot more than just some DOF when I was editing that Screenie. I’m fairly sure that D also has some treatment done to it also. Heck, I could care less what the article said, I’m just amazed that I actually have a little tiny image that I did on this page.

    But I did read the article, and wow…. Out on track you don’t really think about the small little things, but man, the detail they do is outstanding.

  19. Matt Orr
    January 12th, 2010 at 5:35 am

    Sorry, forgot to answer a question directly.

    Eddiespag – Nope, that was taken week one @ VIR in a practice session. Just photoshopped heavily as are most of my other screenies. Think I used a orange-ish Lighting Effect, shifted the Hue and Saturation to give it a more “Fall” look if your interested in knowing. Except for DOF, I could legitimately see iRacing looking like that if that is your thing.

    I don’t think iRacing will let me touch the secretive stuff. lol

  20. Ben Styles
    January 22nd, 2010 at 1:05 am


    I love and appreciate your work.

    Please keep a developer blog for the Williams F1 car…would be SO INTERESTING!

  21. Bob
    February 9th, 2010 at 11:50 am

    This isn’t the same Corvette we already have? Same pic at the top of the pages…

  22. Merrill Geant
    November 8th, 2010 at 7:18 pm

    I’d be inclined to clinch the deal with you on this. Which is not something I typically do! I really like reading a post that will make people think. Also, thanks for allowing me to speak my mind!

    November 11th, 2010 at 5:16 am

    Hi there,

    I have a inquiry for the webmaster/admin here at

    May I use some of the information from this blog post above if I give a link back to your website?