Aerodynamics

[Matt T]

Yes and Supras supposedly top 180mph relatively standard, so i cant see an extra 20mph being any kind of problem

[Digsy]

My personal opinion is that you REALLY don't want a street-car that has positive downforce. It's too danegerous. (Seriously... you don't want it)

 

So that kind of leaves you with less drag. The bumper with the least drag would completely do away with the inlet to the radiator. However, you'll soon find things will warm up fairly quickly without this. So that kind of leaves you with a compromise of sorts. As compromises go, the one that's probably had the most analysis would be the stock set-up (probably not what you want to hear, but that's just how it is) Next I would go for the TRD kit, (as TRD are probably the only company that's selling kits that have the cash to be aero-testing the kit they sell) after that, IMHO with regards to aero efficiency, all the other kits are junk.

 

I also would stay away from anything that has these little canards (Vortex generators), as they can be a very powerful tool, at either generating or destroying drag/downforce. Which it happens to be on these bumpers, is all guess work. They're put on their for cosmetic reasons, with no regard to what they're actually doing to the flow. You can spend many hours in a wind tunnel pissing about with these things trying to get them to work to your benefit. (Believe me the number of these things I've designed that have ended up as scrap is shocking!)

The Supra nosecone isn't held onto the chassis / body strongly enough to transmit any meaningful kind of downforce to the car, anyway.

 

I agree with Tony about the wind tunnel thing. Very unlikey that any real development goes into these parts. Even doing CFD simulation in a computer is more of an art than a science.

[Suprasteve]

and also anything other than a standard nose cone would this really make any different to the top end speed, is it worth it, the money, time and effort.

 

sod it, leav it as it is and stick the right foot down until the needle stops moving and let us all know where that point was.

 

have fun and don't rear end anything !

[Suprasteve]

The Supra nosecone isn't held onto the chassis / body strongly enough to transmit any meaningful kind of downforce to the car, anyway.

 

whats the point of Mr T spending all their research money on the front active spoiler (i don't have one on my car and know very little about these) but surely it must do something ?

[Digsy]

Probably better for Tony to answer that one, but I don't think that the front lip actually creates downforce, rather it prevents lift by stopping air getting under the car?

 

I was just looking at it from a machanical perspective: The nosecone only has four "structural" fixings, and they are 6mm studs at 90 degrees to the direction of force. The rest of the fixings are little plastic clips.

 

I believe that the active front spolier attaches to the stud plates for the stock rubber chin trim, and doesn't attach to the actual car body at all?

[Suprasteve]

Probably better for Tony to answer that one, but I don't think that the front lip actually creates downforce, rather it prevents lift by stopping air getting unfer the car?

 

I was just looking at it from a machanical perspective: The nosecone only has four "structural" fixings, and they are 6mm studs at 90 degrees to the direction of force. The rest of the fixings are little plastic clips.

 

I believe that the active front spolier attaches to the stud plates for the stock rubber chin trim, and doesn't attach to the actual car body at all?

 

fair point about how the front bumper being attached to the car with just a few studs and clips - worring when you think about hey!?

 

If anyone knows what the active front spoiler actually does and if it does a lot then why don't the jap models have um either ? - suppose its the same reason why they don't have air vents in the bonnet too ???

 

sorry for the hijack BTW but it is related to the whole aerodynamics thing.

[JohnA]

whats the point of Mr T spending all their research money on the front active spoiler (i don't have one on my car and know very little about these) but surely it must do something ?

It does a lot mate.

It restricts a lot of air from going under the car, thereby reducing the lift created by the whole body.

It also slightly increases the effectiveness of skirts and the rear spoiler.

The less air under the car, the lower the pressure of the air that does make it down there. That sucks out the hot engine bay air, increasing the efficiency of the radiators (equivalent to having larger front openings)

 

Mr "T" has spent a lot of brainpower for engine bay - overall air management. Some people think that sticking a FMIC and dumping stock ducting (waste of space, eh?) can only be a smart move, an 'improvement'.

Well, think again.

[Alex]

The active spoiler is just there to reduce lift by lowering air pressure behind it.

The effect is to pull the car down rather than push it down...not that you'll actually see it move, it's not that great a change.

 

All the aero features on the car are designed for negative lift, and not to make downforce, inc the rear wing.

[Suprasteve]

cheers alex and Johna thats made it clear in my mind...i think. basically the active spoiler is designed to pull the car to the ground for better stability at high speeds by redirecting airflow whilst drawing the warm air from the rad and engine bay to keep it cool.

 

Sounds like this is more of importance for Whitelightning then a new nose cone ?

 

do you know why it isn't it on all the models ? seems like theres a few corners cut on the jap model i.e. the bonnet vent to name a few. is this purely to keep costs down in the japanese market compared to the uk market ?

[JohnA]

...do you know why it isn't it on all the models ? seems like theres a few corners cut on the jap model

indeed, that's how we fuel the eternal UKvsJSpec theads (good natured fun really... )

i.e. the bonnet vent to name a few. is this purely to keep costs down in the japanese market compared to the uk market ?

The 'vent' is a different thing altogether.

It's not a vent for starters, it's a scoop.

vents are for air exiting, scoops do the opposite.

The scoop was for the European market, where prolonged high-speed operation was deemed as likely (autobahns for example). It directs cool air straight to the hottest part of the cyl head, to stop temps from going out of hand.

 

As for other bits of spec, you have to remember that there is only one UK spec (everything+kitchen sink) while JSpecs vary depending on what the original buyer wanted.

[Suprasteve]

so in a nut shell the jap and uk models differ due to the environment they're supposed to be driven it. horses for courses and all that stuff.

 

i'm off to get my jigsaw out and cut a hole in my bonnet

 

cheers mate

[JohnA]

so in a nut shell the jap and uk models differ due to the environment they're supposed to be driven it.

pretty much yes.

In Japan it is highly unlikely to sustain 150mph for a long time, in fact it's unlikely to sustain even legal UK speeds very often.

So they went for different turbos and gearing, enhancing low-rev performance. Even that they thought of fitting the small brakes reflects what sort of speeds they are expected to reach in the Japanese market.

[TLicense]

all sounds right from my point of view.

 

The bonnet on these cars is a massive aero-device creating loads of lift.

My friends have often said when I've been following them that my bonnet looks like it's open, when it's firmly shut. It's just being sucked against the catches.

The active spoiler is there just to reduce this a little. How effective it is, is anyone's guess but it would bea easily measurable with a load transudcer on one of the wishbones. You could then do one run with it down and one run with it up and see what the difference is. Quite simple really.

I shouldn't worry about the bolts holding the nosecone on, what are they 6mm studs? Well an M6 bolt's double-shear strength, according to Mr Unbrako is 44.1KN (9,920 lbs or 4.5 tonnes) Should be good enough I would think.

 

As far as why some jap cars have it and some don't. Not sure. It may have something to do with the fact that the J-spec cars are limited to 112mph so aren't expected to be doing the "high speed" thing.

[Alex]

WL,

 

I've got the same nose...I want to sort out an Ali undertray for it but when/if I do I was also going to make a couple of removable splitters (if at all practicable). I've heard that a splitter needs to extend 4" infront of the nose to work most effectively creating real high and low pressure spots. Something like this fitted to the Ali undertray you have will probably make high speed runs more stable. Just remove it before going into a built up area, instead of taking peoples ankles off!

 

Also a flat bottom to the car at the rear to "condition" the air before it exits may also reduce drag. Think you've got the TRD wing?? Set it to the flatest position.

[Digsy]

I shouldn't worry about the bolts holding the nosecone on, what are they 6mm studs? Well an M6 bolt's double-shear strength, according to Mr Unbrako is 44.1KN (9,920 lbs or 4.5 tonnes) Should be good enough I would think.

Pah. It's a great big floppy thing and the fasteners are about 10" apart at the back near the wheelarches and the spoilers are at the front.

 

Seriousy, though, that figure looks high. I make it more like 9kN for an 8.8

 

UTS = 800MPa

Shear strength to UTS ratio: 0.58

Shear strength = 464MPa

Core diameter = 5mm

Core area = 19.6mm^2

Area (in m^2) x shear strength = 0.0000196 x 464000000 = 9110N

[Guest Terry S]

WL,

 

I've got the same nose...I want to sort out an Ali undertray for it but when/if I do I was also going to make a couple of removable splitters (if at all practicable). I've heard that a splitter needs to extend 4" infront of the nose to work most effectively creating real high and low pressure spots. Something like this fitted to the Ali undertray you have will probably make high speed runs more stable. Just remove it before going into a built up area, instead of taking peoples ankles off!

 

Also a flat bottom to the car at the rear to "condition" the air before it exits may also reduce drag. Think you've got the TRD wing?? Set it to the flatest position.

 

 

The Purple car already has an Ali undertray on it. Have you ever looked into flat bottoming a Supra! its a Nightmare, I looked briefly and gave up!

[Dave S]

IIRC when IanC's car was used to break the public road speed record they flat bottomed it,removed the door mirrors and rear wing...went well in excess of 200mph...

 

Dave the pirate

[Ian C]

Hmm, the less said about that the better tbh...

[Alex]

The Purple car already has an Ali undertray on it. Have you ever looked into flat bottoming a Supra! its a Nightmare, I looked briefly and gave up!

 

 

Dude I didn't mean do the whole lot!!!

[Guest Terry S]

Dude I didn't mean do the whole lot!!!

 

Oh I did, here is a pic of the undertray I made for the purple car in feb 2002

[Alex]

How did you fix it in place?

 

And did you have to beef up the nose to hold it? And why didn't you do more!

[Guest Terry S]

M6 Gutter bolts

 

No the nose was fine, in fact the undertray gave it a lot more strength.

 

Didnt do anymore as it was a PITA. Leon tried to get me to make him one too, but I couldnt be arsed. He had one made after but its not a patch on that one.

[Guest Terry S]

Out of interest, why do certain fronts have a raised centre part in the lip, like Stillen, Veilside etc, what does this achieve?

[Alex]

Hmmm dunno but the F360 and F430 have a similar arrangement too...(though slightly more wind tunnel developed I'd expect!)

 

On the Ferrari's I'd expect it to be to do with, reducing frontal area and getting the right air in the right condition to the undertray.

 

The Veilside and Stillen etc are probably just styling fads...ie what the designer thought looked good, based on what some supercars were doing at the time.

[Guest Terry S]

Just wondering as I thoght of building a tray for the stillen, but I could keep it flat and somehow utilize the centre section for additional cooling, either brakes or Radiator.

 

Tony??