posted on January 14, 2013 00:00
2012 BMW M3 GT - Team Rahal Letterman Lanigan
By Khiem Dinh
Khiem Dinh is an engineer for Honeywell Turbo Technologies at the time of this writing. All statements and opinions expressed by Khiem Dinh are solely those of Khiem Dinh and not reflective of Honeywell Turbo Technologies.
Since we last had a look at the car in 2010, it has undergone some aero changes along with a slight change in team name. The team is now called Rahal Letterman Lanigan. For those of you who don't follow road racing, Rahal is for legendary Indycar driver Bobby Rahal. He is now of course a team owner and his son Graham races in IndyCar. Letterman is for David Letterman, yeah, the infamous late night talk show host. Did you know he was a pit reporter for ABC during the 1971 Indy 500? Lanigan is for Mike Lanigan. He ran the family business which happened to be Mi-Jack Construction Equipment which has been a familiar sponsorship name on the side of Indy cars since 1992. The 2012 season was the fourth in ALMS for the RLL team having won the GT title in 2011 with the BMW M3.
|The older fenders up top had these strakes whereas the newer design just has an undercut section of bodywork relative to the full fender width. Behind the front set of wheels look to be the same design AP Racing calipers and two-piece brake rotors. The RAYS forged magnesium wheels are held on by a single nut. The AP Racing caliper is hogged out to remove as much material as possible to reduce caliper weight. Of course, they are still designed to be as stiff as possible. A carbon fiber air duct channels air to the outer-side of the caliper. If you look at the front of the wheel well, you can see the diffuser on the front underbody to improve frontend downforce. It appears the newer car has some vertical strakes added versus the older design. These front wheel well diffusers are getting to be common on high-exotics. I first saw them on a Ferrari F430.
|The rear brakes are also from AP Racing. On the perimeter of the brake rotor is temperature paint to let the mechanics quickly know the ballpark temperature of the rotors. The rear bumper features the same undercut relative to the rear fender as seen on the frontend of the car. This is a change from the 2010 car and we'll look at this more in a bit.
|On the brake calipers themselves is temperature tape. These read up to 250C and give the mechanics a quick reference to see if the brakes are running too hot.
Monday, January 14, 2013 8:25 AM
As you stated, the big ducts feeding in the back are probably to help fill in the base area behind the car to reduce drag. If you look at its competitors, even in race trim the M3 has a lot more frontal area than, say, the Corvettes or the 458s. There'd been a lot of talk about how many waivers the Z4 would need because of the V8 and so on, but these days in racing when a manufacturer wants it enough...
Monday, January 14, 2013 9:43 AM
Bet they got rid of that berm.
Monday, January 14, 2013 12:27 PM
When do we get a similar piece on the Z4?
Monday, January 14, 2013 10:50 PM
@Kenku, yeah, it was like the GTR racing in FIA GT1 vs all the low slung cars like Lambos and Ferraris. The GTR was a whole foot taller.
In racing, throw enough money at an organization and they'll give you the waivers. They equalize out performance with the air restrictors anyways. I remember those Caddys racing in World Challenge with the firewall moved back a good amount, engine moved back and lowered, etc.
Tuesday, January 15, 2013 8:13 AM
It's funny looking at the FIA GT classes... early adopters like the Corvettes started with almost no waivers - thus the destroked 5.5L engine. Then the 458 came in with none at all, but OEM a lot in design that made everyone else need waivers to upgrade to keep up. Now the Viper came in with a waiver for its engine capacity, which GM is possibly kicking themselves for, and now the Z4 which doesn't even share the engine of the production version.
I'm not holding anything against the manufacturers here - more I think it's just a little sad that the market is such that nobody can justify making homologation specials anymore.
Tuesday, January 15, 2013 9:20 AM
Porsche and Ferrari could... haha. But not many are going to buy a $250k homogolated BMW or Corvette. And corporations are all about the bottom line now.
Monday, January 21, 2013 9:41 PM
On page 2, bottom picture are 2x ¾”-ish lines running to the cowl with red caps.. what are these for? Force feeding water to the cooling system under pressure? If so, that would run to the coolant reservoir… what else needs quick filling besides fuel? Oil…?
Friday, January 25, 2013 3:09 PM
What is the brand that make that clotch tape on the wiring page 6 second picture from the top?
Saturday, January 26, 2013 10:53 AM
Just a small correction. It is likely that the damper position sensors are not LVDT but likely just normal potentiometer spec. While with the BMW's system which is a Pi Research LJB (Lightweight junction box), which can do LVDT with no extra hardware, it is not normally done. The LVDT requires a sinusoidal excitation and 2 inputs. Most competitors just utilize single ended 0-5v sensors. This includes differentials being mated to amplifiers because many systems maximize their flexibility and inputs by offering configurable ones.
If you want differential, then many times you will have to use 2 signals and then they become instead of +sig and + sig you will then have sig + and sig -. Taking 2 x 0-5v single ended inputs and changing them to 1 differential.
the LVDT goes one step further. Our system for example, internally will do an AC excitation, but you then take what was 2 x excitations and convert them into excite + and excite - so to speak.
I just wanted to chime in as it reminded me of the debate on the corvette dampers from last year where everyone stated they were the penske adjustable dampers and the plug was the controller. Not true. I will not talk about what it is, but it is not that.
Also one more note. It is likely that the other plugs around a wheel area would either be for TPMS receivers, upright temps, pad wear displacement sensors (specialized for high temp and usually just for endurance series), brake disc temp sensors, tyre temp sensor arrays. Those are just a handful.
Saturday, January 26, 2013 3:01 PM
Oh and I think the lines if we are referring to same ones could be for fluid transfer like for a heater.
Saturday, January 26, 2013 5:48 PM
@Mark, thanks for adding the input!
MotoIQ Proudly Presents Our Partners: