Saving a Scuderia

And yes the GT3 fenders are wider to accomodate the 10 inch wheels. I suspect if you can get your offsets measured precisely for full clearance inside and out, you might be able to get away with a 10 inch wheel on factory fenders. But your measurements better be on point.

 

I thought about it some more. I can certainly see your point where you experienced less downforce. I suspect, if a car is low enough or a front splitter protrudes out far enough, during nose dive situations before cornering (when you need downforce the most), the splitter angles downward making it difficult for air to pass underneath the car. It is either blocking airflow or causing turbulent air flow causing aerodynamic downforce effects to either stall, as you mentioned, or simply decrease the air velocity as air struggles to get through. Yes, you might feel some downforce pressure in the front as the splitter is now angled during a nose dive, but the car as a whole has stalled. The tunnel opening in the front helps keep the airflow more consistent in all situations as well as provide increased air velocity. Keeping the entire car effective as a wing is key.

 

Let's also not forget that the bottom of the bumper is wedged shaped which helps to get air flow going underneath the car and more importantly, enough of it to reach the venturi rear diffuser for better downforce.
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I believe you

By the way, the skirts being that close to the ground is actually a very, very positive thing. It improves "ground effect", preventing the turbulent, slower air along the sides from flowing and interrupting the faster air speeding through the bottom of the car.
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i am rolling on stock shocks w novitec race springs.

at that specific moment, I was probably doing 90-100mph, on a downhill left-hander (Turn 6, Sonoma Raceway).

i'll go get some measurements and report back.

 

Have you found the cure for non aero-understeer? I have tried bigger front tires on stock rims (245/35-19), upgraded to MOTON 3-way dampers with 100-130% stiffer springs and played with rake, camber, toe etc. But the understeer is still there. I think that the only real cure is to put almost equally large wheels in front as at the rear. Trying to fit 9" rims front and keep 10" at the rear with 265 front and 285 at the would be interesting to try...

 

If aero setup matters to you then this is the only way to get the data to solve the problem and set the car up correctly.

Data Capture.
You need some damper linear pots (fairly cheap now) or ride height sensors and a simple data logger (eg DL1). You can then in a good day build yourself an aero map of ride height and pitch - any straight flat road will do.


Front Splitter
Plywood is best, as when it hits the ground or the curbs it just wears away a bit and cheap to replace.
The step in the middle is to keep air flowing when you brake - the ride height is often set in the reg to 50 to 75mm for Open GT and you want to ensure the air keeps flowing even if the nose hits the ground - downforce does wonders for braking performance.

Rule of thumb....
1" = a little bit of front balance
2" = 60-70% of what's available
+3" = will need support ties to hold it and your up to 80-90%
>4" = if you don't fix it proper to the car and have support ties it will get torn off.
yes it really will gen that much downforce. in the order of >200kgs

Add on dive planes and closed splitter end plates and you will be getting nearly all that's available.

Do a much of runs for varying ride heights, rakes and rear wing settings.


Warning ! (and you can guess how i know)
If you put too much on the front with no travel limit (right size bump stop and spring rate) the front can be pushed down at high speed such that it touches the tarmac and stops the air flow under the car.

This is highly funny/dangerous condition.
As the front will start to cycle through a bouncing cycle, air cuts off - nose lifts, front aero kicks in nose hits ground, cuts of air and nose lifts.
The onset can be so violent that your vision will blur and you could lose control of the car.
But if this happens you really will know you have found the force.


Once you have the map, you can easily decide how to balance the car either with ride height, rake, wing or with size of splitter.

Once the straight line stuff sorted - you can start work on how the aero map changes when in corners - but then it turns in to a black hole of setup/track time.

But there is nothing on earth like pulling 2.5g in a corner. or braking from 170 to 30 in 50m - it physically hurts, it's better than sex and more addictive than heroine.

 

Happy you found it help full.

Please tell me more on the engine bits ... I'm a total sucker for upgrades.

I'm having a flywheel done by MD Clutches that is billet CM and should be 1kg under OEM, which is for road use, so not going for extreme race spec.

 

Rear Wing / Rear Spring.

If the rear wing can generate big numbers efficiently eg >400kg then an interest trick, that can work but is hard to set up is.....

Choosing the rear spring rate, such that the downforce as speed picks up - starts to compress the rear - as the rear compresses the rake reduces and the rear wing pitch reduces. So the amount of D/F+drag that would have otherwise just kept climbing as speed went up actually levels out.

The trick is to choose a setup that gives you enough downforce at the speeds you want for the corners, but speeds above that just squashes the bum and bleeds off much of the further increase.

We ran surprising soft rear spring rates and big bump stops, the softer rear also made it rather good at launching out of slow corners too.

 

How about also coupling that soft spring rate w a flexi-wing? So at higher speeds (such as hauling down a straight) the wing leans back / wing angle decreases thereby reducing drag.

 

In our case, the wing and it's mounting were already a done deal,
and flexi-materials seems like a lot of work and a bit risky.

I have lost a wing at high speed and it was not fun. Tyre de-laminated at a 168mph and promptly chopped the wing to bits, 1 lap from the end of a race I was leading. The resulting accident is one I won't forget.
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=O

 

What followed that pic was a number of violent spins, a wall and a fire in that order. Along with the expected fire marshals running away - leaving me to put the fire out myself.
Happy days.

 

oh!!!
i put 275 front and 275 rear

that oversteer is killing me

don't go that route, im turning back to 235-245 front

 

What happened when you went for 275 front and rear? I was hoping for 265 front and 285 rear...

 

How did you get 275 in the front arches ?



It's becoming more and more common on GT3 cars to go huge on the front in search of front end grip. The Camaro GT3 was same front/back.

Due to the huge tires on the Z06-GT3 we ran, the wheel bearings would need replaced every 6hrs of track time. But that's largely due to GM's **** design.

 

What rim size did you use wen you did this? 9.5" front and 10" rear? Rim size plays a big part here as well...

 

2006 Ferrari F430 GT developed in conjunction with Michelotti had
front tires Pirelli 305/645/18
rear tires Pirelli 305/705/18

I see no reason for equal size front and rear not to work...

 

I'm putting on some aero bits as well, hopefully there'll be a no sound limit day at sonoma soon so I can try them out.

Custom front carbon splitter modeled after the gt3 car, carbon front canards & 16M carbon skirts Still going to try to avoid putting a rear wing.