Apparently, trick exhausts are going to be the hip thing in this season’s FIA Formula 1 World Championship. After Renault’s bold reconfiguration to route the exhaust forward of the floor, McLaren and Mercedes have already stated that they’re working on similar exhaust systems. Red Bull Racing, on the other hand, is utilizing what they believe is a loophole that will allow them to run the exhaust directly into the diffuser through the floor inspite of the FIA’s attempt for prohibit this. Frankly, I’m not sure about the loophole, so I suspect we’ll see more wrangling and arguing in front of the WMSC later this year. Here’s the pertinent section from the 2011 FIA Formula 1 World Championship Technical Regulations:
§3.12.7: No bodywork which is visible from beneath the car and which lies between the rear wheel centre line and a point 350mm rearward of it may be more than 125mm above the reference plane. With the exception of the aperture described below, any intersection of the surfaces in this area with a lateral or longitudinal vertical plane should form one continuous line which is visible from beneath the car.
An aperture for the purpose of allowing access for the device referred to in Article 5.16 is permitted in this surface. However, no such aperture may have an area greater than 3500mm2 when projected onto the surface itself and no point on the aperture may be more than 100mm from any other point on the aperture. Additionally, any bodywork in this area must produce uniform, solid, hard, continuous, rigid (no degree of freedom in relation to the body/chassis unit), impervious surfaces under all circumstances).
Well, you’re not going to exhaust an F1 engine through a single 2.3″ x 2.3″ opening. So, RBR tried something different. They’re venting the exhaust along the outer perimeter of the diffuser in such a way that it exploits an allowed 50mm opening into the outer channels of the diffuser, effectively creating the blown diffuser that the FIA tried to thwart with §3.12.9-10.
§3.12.9: In an area lying 450mm or less from the car centre line, and from 450mm forward of the rear face of the cockpit entry template to 350mm rearward of the rear wheel centre line, any intersection of any bodywork visible from beneath the car with a lateral or longitudinal vertical plane should form one continuous line which is visible from beneath the car. When assessing the compliance of bodywork surfaces in this area the aperture referred to in Article 3.12.7 need not be considered.
§3.12.10: In an area lying 650mm or less from the car centre line, and from 450mm forward of the rear face of the cockpit entry template to 350mm forward of the rear wheel centre line, any intersection of any bodywork visible from beneath the car with a lateral or longitudinal vertical plane should form one continuous line which is visible from beneath the car.
So now the real question (all rules lawyering aside) is which system will produce the best results, Renaults forward exhaust and blown floor, or RBR’s partially blown diffuser? So far it looks as though Renault has the upper hand in pre-season testing with Kubica posting the top time so far in Valencia. It is only testing, and its difficult to know just how much faith to put in these times, but Kubica topping the time sheets is nothing to sneeze at, either.
For a more detailed explanation of this system, Craig Scarborough at ScarbsF1.com has done a VERY nice job illustrating where the exhaust exits and how it engages the diffuser. Check it out, its a very good read.