Apex13B

*looks in rule books*



All WRC cars have syncromesh, sequtntially shifted gearboxes. The noise you hear IS the turbo. A dogbox would require a complete rebuild after 120+ shifts a driver will execute during a single stage.



All WRC cars must run a "production type" turbo setup, and they are limited to size and trim types, but boost is not limited. The "chirping noise you hear is HARCORE backspin. Remember, the turbo will get rebuilt/ thrown out after every event. I have never heard a WRC car engineer admit to how much boost they run, but since the cars are restricted to "about" 300-350 hp for saftey reasons it cant be much.



IF any of you where observant, you would see during the service stages that the cars do not have blow off valves, as any true racing machine wouldnt have one. IMO they are boost leaks



The popping and banging is the Anti-Lag system that is used, similar to haltech/motec anti-lag setups that dump loads of fuel into the turbo, detonating it and keeping the turbine moving

Baldy

I thought I remember seeing a feature where the host was explaining how one transmission is an h-pattern, yet shifted electronically. This was supposed to be an advantage, for instance if the driver was in 4th, spun out, they wouldn't have to cycle through all the gears to get to R (non-sequential gear box). At least that's how the host explained it.



Also, would a/c really be necessary? Aren't most WRC races just a few minutes long? I don't have any experience, but I would think they would be able to handle 5 minutes in the suit, with the assistance of a breeze in the cabin (from roof scoop?).

rmaiersg

Rallies are usually several kilometers long. Inbetween stages, often times, they have to drive quite a way on regular roads to get to the next stage.

yonner

if u ever hear a motor bike or a car with a seqential ytransmision it squeels its head off trust me. thats why fast rode cars that want quick gearchanges now go with tiptronic

inanimate_object

The whining is not caused because the gearbox is sequential - most motorbikes have sequential boxes and the gearbox makes almost no noise - most of the sequential 'boxes I have seen are usually attached to high revving engines, maybe this is where the confusion is coming from. Further to this the Subaru WRC car has a H-pattern (ie. not sequential) gearbox yet it still makes the same whining noise - this is because like the rest of the rally cars it has straight-cut gears as opposed to synchromesh. The picture below is actually of a rally-type gearbox and you can see the striaght-cut gears in the middle and the synchromesh ones (diagonal looking) on the very left and right hand side of the pic:



Hope this helps,



Mark

j200pruf

yonner, what are you talking about, none of my bikes have squeeling tranmsmisisons, and I have 10 in the garage, not one squeels while going down the road.

yonner

any sewquential car ive been in has squeeeled its head off thats why they dotn realy use em in road cars. thats why tiptronic is so popular

Leetheslacker

YOUR POSTS MAKE MY HEAD A SPLODE.

Robbomaz

A sequential box does not HAVE to be straight cut or dog engaged, but most are

Sequential boxes are not noisy because they are sequential, but because most do not use helical gears. Straight cut gears are stronger but noisier than helical gears. Rally boxes are sequential straight cut units with air or hydraulic shift. Xtrac is one supplier.

Power is limited to 300 hp by a FIA restrictor, but if you consider these engines make 650 Nm of torque it is clear boost must be sky-high (I have heard 2 Bar mentioned in Parc Ferme at Rally Oz). Unrestricted these engines must make 500+hp if they make such high torque since HP is torque x RPM

As said they don't use blow-off valves as that is just wasted energy. The chirp is reversion through the restrictor and wastegate flutter, the banging is the anti-lag.



They have to drive on the public roads to & from the special stages here and they are required to behave themselves but lemme tell ya when an Impreza WRC opens up at 80 kmh it just f@#ks off like nothing I've seen this side of a rail