Race Weekend Central

IMSA Gives the Porsche 911 GT3 R Help with BoP

On Thursday, IMSA released two more technical bulletins for the WeatherTech SportsCar Championship.  These bulletins concern rule changes ahead of the Lone Star Le Mans at Circuit of the Americas.  Unlike the last round at VIRginia International Raceway, there are some substantial changes.

As you’ve seen here at Frontstretch, one of the biggest stories in IMSA recently has been the unhappiness of Porsche teams with Balance of Performance.  The anger led Alex Job Racing‘s WeatherTech-sponsored No. 22 to withdraw from the series and move to Pirelli World Challenge for the last two races (the first of which is a direct clash with COTA), along with Park Place Motorsportsdecision to skip VIR.

For COTA, the Porsche 911 GT3 R gets some help in the form of a new air restrictor that is two millimeters larger.  This will allow the Flat-6 engine to generate more power.  The Porsche also gets one more liter of fuel capacity and a one millimeter larger fuel flow restrictor for the fuel rig.  The aforementioned Park Place Porsche (pictured above) will be back in Austin, so Patrick Lindsey and Jörg Bergmeister may be able to make good use of the extra power.

The class leading Ferrari 488 GT3 gets new, larger boost ratios throughout the RPM range.  Similar to the Porsche, the Ferrari also gets one more liter of fuel capacity, increasing capacity in their case up to 95 liters.  However, they must also install a new restrictor on their refueling rig that is half a millimeter smaller, restricting fuel flow and slowing stops.

The BMW M6 GT3 and Lamborghini Huracan GT3 each get one millimeter larger fuel flow restrictors like the Porsche.  The Dodge Viper GT3-R, like the Ferrari, must make do with a half-millimeter cut in their fuel flow restrictor.  The Audi R8 LMS GT3 and the Aston Martin Vantage GT3 were unchanged.

The Prototype teams saw lesser changes.  The Ligier JS P2-Honda, campaigned by Michael Shank Racing with Curb-Agajanian, gets a 10-kilogram weight break.  The Lola B11/80 that is raced by Mazda Motorsports gets a one-millimeter bigger fuel flow restrictor.  Finally, the DeltaWing DWC13 Coupe gets a .039 bar increase in turbo boost all the way up to 10300 RPM.  Beyond that, there is no change.

In GT Le Mans, BMW Team RLL‘s BMW M6 GTLM’s will get a ten kilogram (~22 pound) weight break next weekend.  In addition, they will get a half-millimeter larger fuel flow restrictor to work with.  The Ferrari 488 GTE gets increased boost ratios throughout its RPM range and a similar fuel flow restrictor increase as the BMW.  The only other change is a one-millimeter cut in the fuel flow restrictor for the Ford GT’s.

Since Prototype Challenge is a spec class, there are no Balance of Performance changes there.  However, there was a minor clarification on wheel nuts in which it was stated that the first thread must be no more than four-millimeters from the rear of the nut.

The Lone Star Le Mans is a 160-minute sprint race that will be held on Sep. 17.  The race will air live on FOX Sports 2 at 12:30 p.m. EDT.


About the author

Phil Allaway has three primary roles at Frontstretch. He's the manager of the site's FREE e-mail newsletter that publishes Monday-Friday and occasionally on weekends. He keeps TV broadcasters honest with weekly editions of Couch Potato Tuesday and serves as the site's Sports Car racing editor.

Outside of Frontstretch, Phil is the press officer for Lebanon Valley Speedway in West Lebanon, N.Y. He covers all the action on the high-banked dirt track from regular DIRTcar Modified racing to occasional visits from touring series such as the Super DIRTcar Series.

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