Winning BMW Z4 GT3 Car Gets Horsepower Bump In United SportsCar

Illustration for article titled Winning BMW Z4 GT3 Car Gets Horsepower Bump In United SportsCar

IMSA released their Balance of Performance tweaks for the GT classes for the first race of 2015. While all the other proposed restrictor changes for the Rolex 24 at Daytona were 0.3 or 0.6 mm, the Z4 GT3 gets a whopping 19 mm increase. IMSA to Turner Motorsports: "Come back, baby. I didn't mean it."


IMSA uses Balance of Performance mods such as air restrictors and weights to even things out between all the different cars that run in the Tudor United SportsCar Championship series. Restrictor plates are installed to reduce the amount of air that flows into the intake, thus reducing the power an engine can make. The larger the restrictor "size," the bigger the hole is that lets air flow through.

According to Sportscar365, the GTD-class Z4 GT3 will move from a 65 mm restrictor plate to a whopping 84 mm one. For comparison, most GT Daytona cars get a restrictor plate in the 45 to 47 mm range, while the Porsche 911 GT America is the current outlier with a 74 mm restrictor.

Let's not forget that the Z4 GT3 is a car that doesn't really have much connection to its street car in a way unlike many other FIA GT3 cars. The street Z4 doesn't get that marvelous S65 V8 from the E92 M3. Let's also not forget that Turner were running a Z4 GT3 in GTD in advance of the rule change for 2016 that moves the GT Daytona class over to FIA GT3 cars.

Turner's a great squad who would probably find a way to do well in a roundel-clad Radio Flyer, but they did receive a lot of breaks to be able to run this car in TUSC. Then they won the 2014 driver and team championships for the GT Daytona class in Tudor United SportsCar, and...well, why are they allowing the Z4 a bump in horsepower again?

The tinfoil hats are out en force, alleging that it has something to do with Turner's move to a full-time Pirelli World Challenge effort. While Turner hasn't ruled out IMSA for next year, they haven't confirmed any plans, either. The first event of the new season, the Roar Before the 24, is on January 9-11.

Turner is really happy about the switch to PWC, too.

"I really like the fact that we can race the BMW Z4 GT3 as it was intended, with traction control, ABS and the proper aero for the car.," said team owner Will Turner to Racer. "Unlike the GTD rules in IMSA, PWC allows the car to run as it engineered by BMW Motorsport."


Alternately, the restrictor bump could be based more on the performance of the Z4 GT3 teams who are for sure running in United SportsCar instead. Last year's GTD winners are gone, so let's see what the new kids can do.

Or everyone could all just get Z4 GT3s because this change sort of makes it the car to have for Daytona. You need a Z4 GT3. I'm not even running in TUSC, and I need a Z4 GT3. We all need Z4 GT3s.


Speaking of things we need, BMW still needs to give us the Z4M street car that we deserve: one with that M3 V8 and some less boaty suspension, please. Would hoon. Would hoon all day long.

[Edit: We originally misread Sportscar365's numbers in the first version of this article and presented this as if it were a bad thing for anyone running a Z4. Huge oops, but we tracked down the technical bulletin from IMSA to double-check and corrected it now.]


Photo credit: Getty Images



What are the aero differences between the TUSC car and a normal GT3 spec car?