27 replies to this topic

[Crabash]

Trouble with the tie wrap method is you can never be sure the reading you get is from a bump, the accel, or the downforce no matter how carefull you are. It will still have an effect but less efficient at higher ride height, and to be totally blunt a wing on a road car is also useless as the speed required to make it work effeciently is enough to lose you your driving privileges. Anyway as I said diffusers create the downforce at the other end.

Edited by Crabash, 30 June 2012 - 09:31 AM.

[Nev]

Trouble with the tie wrap method is you can never be sure the reading you get is from a bump, the accel, or the downforce no matter how carefull you are.
It will still have an effect but less efficient at higher ride height, and to be totally blunt a wing on a road car is also useless as the speed required to make it work effeciently is enough to lose you your driving privileges.

Yea, I agree with both those points, the tie wrap measurement is prone to loads of interference from other factors, however it is extremely easy to do in practice and thus viable.

If anyone can genuinely show strong evidence or proof that their diffuser actually does create any sort of decent downforce (at any speed), I'd buy one straight away as the low frontal axel weight of a VX is it biggest bugbear IMO.

Edited by Nev, 30 June 2012 - 03:18 PM.

[Nev]

Here are some figures for you:

OEM diffuser - 1.6 kg of downforce
tat diffuser - 3.2 kg of downforce

Where did those figures get published please, at what speed, and how exactly did they measure it?

Also 3 Kg of downforce is virually worthless (that's not a dig), simply that I don't think I'd notice if I put 3Kg over the front axel and went for a drive. To put that in perspective, if I fit a 70 Kg weight into the psx seat (ie my girlfriend) I still find the front axel weight too low at high speeds, though clearly it does help a lot. So if a 75 KG downforce isn't making enough of a difference, then 3 kg will be a lot less

Edited by Nev, 30 June 2012 - 03:49 PM.

[techieboy]

I think it's a tongue in cheek thing Nev, based on the weight of each item.

[Nev]

Oh! Still, if anyone can show good evidence of one working on a VX I'd buy one.

[Crabash]

I was speaking in terms of how things work, obviously it has to be designed and made correctly, slapping a bit of alluminum or carbon in place of the original does nothing IMO, well appart from the fact that you now have extra weight on the rear axle. I always thought the prob with the vx is not the amount of downforce but the fact that it is not balanced, therefore as speed changes the front - rear balance also changes. What I want is a consistant car. That said I only find that an issue on really fast bends, like 120 plus and even then it's not a spit you off without warning issue.

[danger7]

Hi all, Lets all face it the VX has all the aerodynamic properties of a brick, I seem to recall Winstar played around with an ANSYS model some years ago and confirmed what we already knew. There are several major design flaws in the shape of the VX. For a diffuser to even start working the diffuser would need to extrude something like 600mm. Take modern supercar design the underneath is effectively a tunnel which takes the air to the diffuser at a shallow angle, look under a Ferrari 430 and you'll see real aero at work. Consider the humble VX flat bottom then the short steep rear tray which stalls the air. High mounted wings do generate downforce but also create drag, ok for short twisty circuits but costs speed in extreme cases. I've played around with dive planes on the front to sweep air but pure cosmetic, thought about dropping ride height to a minimum then take a 1" alloy strip and create skirts but the VX needs to be virtually sitting on the tarmac for this to work. So i'm without nowt only what Vauxhall styled lift is bliss Cheers Ian

[fezzasus]

Here are some figures for you:

OEM diffuser - 1.6 kg of downforce
tat diffuser - 3.2 kg of downforce

Where did those figures get published please, at what speed, and how exactly did they measure it?

Also 3 Kg of downforce is virually worthless (that's not a dig), simply that I don't think I'd notice if I put 3Kg over the front axel and went for a drive. To put that in perspective, if I fit a 70 Kg weight into the psx seat (ie my girlfriend) I still find the front axel weight too low at high speeds, though clearly it does help a lot. So if a 75 KG downforce isn't making enough of a difference, then 3 kg will be a lot less

Techieboy's nailed it.

Edited by fezzasus, 01 July 2012 - 10:38 AM.