GTIR Areodynamics

[AJ4]

this post wasn't even aimed at cars with purpose built spoilers for downforce, but Corsa owners who buy some bolt on 747 wing from Halfords and reckon it gives them better traction :lol:

As far as I know the pulsar spoiler ( like most spoilers ) is flowed to reduce drag at the back of the car and make the airflow more laminar, not to generate any appreciable downforce. F1 wings I can understand, but having that little bit of plastic stuck on the roof of a 1250 kg car isn't going to make that much difference, and thats with drive at the back wheels! The back of the Sunny in particular is square and doesn't flow too well as standard, hence the spoiler. Try follwing one up the motorway in heavy rain and you'll see what I mean

 

[geoff pine]

The roof extension spoiler of the pulsar gtir prevents the airflow wrapping around the roof/hatch transition, so reduces drag and lift .Julian Edgar /21st century performance.

 

[Dooie Pop Pop]

so do you think aerodynamicly speaking it would be a good idea to remove the oe backbox heat shield and drill some huge holes along the length of the rear bumper/bar??

 

[gtirneil]

Anyone thought about an undertray ? especially at the rear of the car, as the back bumper acts like a parachute :der:

 

[jpward]

so do you think aerodynamicly speaking it would be a good idea to remove the oe backbox heat shield and drill some huge holes along the length of the rear bumper/bar??

I could be wrong but isnt there a white rally car possibly a Gti with that done? :?

 

[powerfreack]

the awd 10sec gti-r is done like that but is not road legal

 

[azboy]

is saw a test on the escort cossy with the rear wing it did 137 mph without as they were a free option at 1 point they did 148 mph so i would say that it would cause more drag but does its job of holding the car down at speed increasing the handling.

 

[Rishi]

Anyone thought about an undertray ? especially at the rear of the car, as the back bumper acts like a parachute :der:

I've moaned about this for a while now... Its now being taken care of... 8)


Rishi

 

[jpward]

I've moaned about this for a while now... Its now being taken care of... 8)


Rishi

Ohh do tell :-D

 

[Rishi]

Ohh do tell :-D

Basically i've been looking at using 1mm Aluminium sheet... Maybe thicker and having it cut and bolted to form a rear undertray to get rid of that parachute effect and provide better flow...

You could even cut a small amount out the rear bumper to bend the sheet up at the end for a rear defuser...

Looking at both options just now... Will let you know how it goes...



Rishi

 

[jpward]

Basically i've been looking at using 1mm Aluminium sheet... Maybe thicker and having it cut and bolted to form a rear undertray to get rid of that parachute effect and provide better flow...

You could even cut a small amount out the rear bumper to bend the sheet up at the end for a rear defuser...

Looking at both options just now... Will let you know how it goes...



Rishi

Sounds very A-Team :lol: :lol:

Yeah id say you'd have to look at maybe 2.5 or 3mm to stop if flexing like Ralf Harris on speed

The defuser would be a good idea but sounds like a lot of work would be needed to get it right good enough for V-spec's and FQ's good enough for the R ;-)

 

[campbellju]

My old Mk2 MR2 came as standard with a complete undertray. It was only 2mm plastic. Made it a complete pain to work on for some simple jobs but helped with dirt and stuff as well as the aerodynamics

 

[jpward]

My old Mk2 MR2 came as standard with a complete undertray. It was only 2mm plastic. Made it a complete pain to work on for some simple jobs but helped with dirt and stuff as well as the aerodynamics

So there was a good point to the engine being in the rear then after all :lol:

 

[bracpan]

I was told a few years ago by none other than an aerodynamisist who work for an F1 team about undertrays explained angles etc.
Also dont just cut holes as air does not like going thru round holes cut slots, will be having a look at doing an undertray in the near future, will keep you informed.
Cheers
Phil

 

[Dooie Pop Pop]

a proper ally one for the front would be good. not a guard a tray.

thanks for the 'slots' tip;-)

 

[Fast Guy]

What about a rear diffuser as part of, or an add on to an undertray.

Also that front laguna spoiler should help by stopping alot of air going under the car, but the side affect of that on some cars, not sure about ours as I haven't looked, is that it also stops the air getting to the bottom of the sump that helps cool the oil.

A flat bonnet will also help in the aerodynamic stake.

 

[Rishi]

What about a rear diffuser as part of, or an add on to an undertray.

Also that front laguna spoiler should help by stopping alot of air going under the car, but the side affect of that on some cars, not sure about ours as I haven't looked, is that it also stops the air getting to the bottom of the sump that helps cool the oil.

A flat bonnet will also help in the aerodynamic stake.

Read my post Carl... I was on about having the rear undertray made with a rear defuser...

I also have a Turini Bonnet which should help...



Rishi

 

[deslynam]

a proper ally one for the front would be good. not a guard a tray.

thanks for the 'slots' tip;-)

I've had one made up from 2-ply stuff my mechanics use on the BRC cars they maintain. It only cost ~£50 in total but I wanted it to protect anything hanging down whilst driving on the cr*p roads around here.

 

[bracpan]

If you fit a rear undertray you have to make sure it does not collect air and thats a problem when you look under the Pulsar. Idealy it should come from the floor of the car fitting tight with no gabs for air to get behind, but because of the rear diff , drive shafts and supension its not easy. Cutting away or slotting the rear skirt would be a start but not perfect. Will take a bit of thought to get it right.
Cheers
Phil

 

[AJ4]

rather than trying to make a negative into a neutral by covering the hole at the back, it would probably work better if the air was deflected down the way just enough that it cleared the back bumper. That would make a venturii inside that space that would give you a bit of downforce as well.