Updated Project /Stability control

pablo · Post by **pablo** » Sat Dec 22, 2007 7:32 pm

How far do people go when it comes to sorting the handling and high speed stability of their cars.

When setting up our car i take into consideration what the air flow around / over the car could do.
We have recently bought a new bonnet for the car with large vents to get rid of hot air. Sitting down and thinking about it I believe that this could potentially have a negative effect on the handling of the car. As the hot air is sucked out of the top of the bonnet it will mix with cooler air this could affect the smooth air flow over the car, which in turn could affect the air flow to the rear wing.
We will put this to the test at our next track day. If my theory is correct then I have a possible solution already thought of. Which is to fit Vortex Fins, as per the EVO MR FQ400. The idea being that this will help to clean up the air flow before it hits the rear wing.

Are my thought correct or am I getting too technical.
P.S. At the moment at speed our 1988 sierra track car is far more stable than my 54 reg MGZT 190.

Post by **Stuart** » Sat Dec 22, 2007 7:51 pm

I think that short of hiring a wind tunnel you'll struggle to measure the actual differences rather than the perceived ones. I would imagine that keeping the engine cooler would be of more benefit than any marginal loss in stability, but then I don't own a wind tunnel for you to check.

I'll get my coat..............

Gerry H · Post by **Gerry H** » Sat Dec 22, 2007 8:09 pm

I've got a vision in my head now of a Matchbox Sierra sitting in an empty loo roll core with a hair dryer up one end

There you go Pablo. Scaled wind tunnel testing. 8)

Bart · Post by **Bart** » Sat Dec 22, 2007 8:35 pm

Gerry H wrote:I've got a vision in my head now of a Matchbox Sierra sitting in an empty loo roll core with a hair dryer up one end

There you go Pablo. Scaled wind tunnel testing. 8)

im on it just got to find my scalextric car,small candle and a piece of tubing ill use the wifes hair dryer.

James Breadvan · Post by **James Breadvan** » Sat Dec 22, 2007 8:39 pm

If the car is going at 100mph there will be a fair bit of cold air hitting the front of your car, I doubt the warm air rising from your vents will make a measurable difference at that speed.

Or so I'd have thought

Get the vortex stabilsor anyway and see if that makes a difference to the way the car handles. If it's good enough for an evo...

ScoobieWRX · Post by **ScoobieWRX** » Sun Dec 23, 2007 1:14 am

Why don't you make lots of dimples on the bonnet and wings of your car like a golfball has so that you travel faster and maintain stability through the air.........

Why don't manufacturers actually do that on cars....just make bodies completely covered in dimples?? Works for Golfballs!! :idea:

duncan · Post by **duncan** » Sun Dec 23, 2007 8:26 am

good question Pablo

The air coming out through the top of the bonnet is still air in my opinion and would not have any noticeable effect.

I would concentrate on the underside of the car, trying to speed up the air flow there with undertrays, diffusers as these have no negative drag effects that upper body aero parts have.

pablo · Post by **pablo** » Sun Dec 23, 2007 11:57 am

Good points gents...Duncan, we have thought about these before but as ever our problem is that these parts are extremely hard to get for car unless you want to pay silly money for ex rally stock.
I think this might be a job for 'A J T Fabrications' (Bart).
:-D

duncan · Post by **duncan** » Sun Dec 23, 2007 12:01 pm

It should be reasonably easy to mock up a template out of cardboard and for guys with your obvious skills making the necessary parts out of GRP or carbon sheet

pablo · Post by **pablo** » Sun Dec 23, 2007 2:01 pm

you know our methods and madness to well :-D