[Mk2] [Turbo] My Aerodynamic rework: Giving the MR2 downforce

[dantheman]

Whilst i was hoping to get some data to directly compare with the trackday i did at donington in feb it didnt quite work out that way.

So I did a trackday at Donington again on Sunday and collected more data. This time it was directly comparable to the data I collected previous to the aero changes. Both events took place near the end of feb, both had air temps below 10 degrees, same tires, brakes, weight, boost levels, the lot. Only the aero changed between the two (and potentially experience but at the one in november I didnt push very hard cos it was wet)

Here is the data summed up.




As you can see from the speed trace, the fastest laps from both trackdays are very different.

Noticable differences:

-The 3rd corner (first left hander) was taken with significantly more speed. This is because the car felt much more stable and was not sliding as much. Speed here is 96 mph, enough for aero to be working.
-The long left under the bridge was taken much faster, again because the car was not sliding, speeds here in the mid 80's and above.
-The 90 degree right was taken a whopping 10 mph faster, partly because the car was more stable under braking whilst slightly turning left
-Chicane was taken faster due to being better on the brakes
-Final hairpin shows dramatic improvement in traction

This led to a time increase of over 5 seconds per lap! This was consistently shown throughout all sessions. I have no doubt that the modifications worked, showing significant improvement.

[ashley]

the one in november I didnt push very hard cos it was wet)

So the first track day was wet, was the second one dry?

[dantheman]

Feb 2012 - Dry, No aero
Nov 2012 - Wet, Aero
Mar 2013 - Dry, Aero

Data compared in that post is from Feb '12 and March '13

[ashley]

Ahh- gotcha, so definately some learning curve effects in there as well then....good effort!

[KarlBristol]

The more track days you do (to a degree) the more confident you will get at speeds and with cornering, and so naturally your lap times should drop anyway... I don't think that lap times is a decent measure of aerodynamic work - there are far to many variables there especially if there were other cars on the track!

There are far to many counter arguments to the data you have posted - less cars, humidity, temperatures, exact weather conditions, etc...

All you've done is prove you don't drive as bad as the last time you were on a track

You need some way of actually measuring downforce if you want to prove this works...

Ie standard mr2 in a wind tunnel
Your mr2 in a wind tunnel

Ascertain what can be done to streamline the improvements or vary them
I would like to see wind tunnel results

[dantheman]

This is not my first trackday, its not even my 10th. I have not improved by 5 seconds in 3 trackdays, one of which was wet and so I was taking it easy.

Humidity will make negligible difference, temperatures were about the same and a few degrees will not come close to 5 seconds difference, and to state that these factors would shows nievity. Hell even day to day personal variation accounting for 5 seconds is rediculous. I was consistently lapping 5 seconds a lap quicker, and thats not a small amount. Even beyond that, stability under braking is very noticable and the combined grip limit has improved.

Its enough for me to believe the aerodynamics is the cause. If you dont wish to believe it Karl thats up to you. But if you would like to stump up 10 grand so i can do some wind tunnel testing and prove it to you I will gladly take you up on that.

[KarlBristol]

I think we will have to agree to disagree here.

If you read my post properly you will see that I am not being negative. Its not that I disagree with the fact that your alterations may have had an effect on the aerodynamics of your car. Track times simply cant be used prove that, and have no constant measurable bearing on aerodynamics as there are far too many variables involved in a track day - especially when other people are also using the track.

When I mentioned things like humidity it was to give an example. A culmination of varying small differences add up to a big difference. All I was stating is that its never going to be the same circumstances and even small differences are differences nonetheless which can vary results.

If you want to measure results of aerodynamics the only proper way is by an air tunnel or similar. Otherwise its just finger in the air stuff...

I personally would be keen to see exactly what differences your alterations have caused. It would be interesting to see what does and doesnt help with the MR2 shape. I would just like to see it done in a properly measurable way.

I wonder if you could position sensors in the car to measure down pressure at certain speeds


Oh and Im not nieve regarding driving at speeds and how conditions alter this. I am a fully trained Police advanced driver. My job is response runs and pursuits so I drive, fully trained, at speed daily. Probably best not to comment on how "nieve" people are if you dont know their background

[KarlBristol]

Out of interest - what are future plans regarding the car?
More aerodynamic work or going to aim for engine mods etc...?

Have you considered getting rid of the passenger wing mirror all together and changing the driver one for a more aerodynamic version?

Any plans for a different front bumper as well to help get the air over the top of the car? It all adds up

[niks]

Just a thought: If you really want to quantify the effects of running your aero mods without breaking the bank, the thing to do is run an A-B-A test. Next time you enter a trackday, first do a couple of fast stints with your aero mods on, then simply remove them where possible(might take some effort!) and run again. Finally, bolt everything back on and repeat the initial test to be able to track lap time delta due to track evolution, ambient conditions etc.

Another point to think about: your laptime gain might not simply be due to an increase in down force, but possibly an improvement in car balance giving you more confidence to attack corners and carry speed in.

Anyway definitely an A for effort there mate!

What data logging are you running?

[Peter Gidden]

Another point to think about: your laptime gain might not simply be due to an increase in down force, but possibly an improvement in car balance giving you more confidence to attack corners and carry speed in.

Highly likely. The creation of downforce by passive devices almost always can only be achieved at the cost of increased aerodynamic drag. An increase in aerodynamic drag will make the car slower, thereby requiring an increase in torque just to achieve the same lap speed.

[dantheman]

Track times simply cant be used prove that, and have no constant measurable bearing on aerodynamics as there are far too many variables involved in a track day

If you want to measure results of aerodynamics the only proper way is by an air tunnel or similar. Otherwise its just finger in the air stuff...

Oh and Im not nieve regarding driving at speeds and how conditions alter this. I am a fully trained Police advanced driver.

If you follow F1 you will hear regularly that teams see discrepancies between their track laptimes and what their wind tunnel says. Whilst the wind tunnel is typically more reliable, even the best ones to not represent the real world with 100% realism.

And at which point during your training did they teach you about extensively about aerodynamics, the quantifyable effects of weather on lap time and experimental measurements and data analysis?

Out of interest - what are future plans regarding the car?
More aerodynamic work or going to aim for engine mods etc...?

Have you considered getting rid of the passenger wing mirror all together and changing the driver one for a more aerodynamic version?

Any plans for a different front bumper as well to help get the air over the top of the car? It all adds up

I want a set of semi slicks and then I'm done. No interest in engine work, its plenty powerful. No interest in further aero work. Im keeping the wing mirror as I drive the car on the road. I'm sure it all adds up but I cant afford those things and they are bad on a cost benefit analysis.

run an A-B-A test. Next time you enter a trackday, first do a couple of fast stints with your aero mods on, then simply remove them where possible(might take some effort!) and run again. Finally, bolt everything back on and repeat the initial test to be able to track lap time delta due to track evolution, ambient conditions etc.

Another point to think about: your laptime gain might not simply be due to an increase in down force, but possibly an improvement in car balance giving you more confidence to attack corners and carry speed in.

Anyway definitely an A for effort there mate!

What data logging are you running?

Thats certainly an idea and yes that would show a good back to back reference. But considering to do as you have suggested would take about 4 hours, which is 4 hours of wasted track time, thats not gonna happen.

In fairness I never said anything about downforce. I never actually thought my modifications would add any significant downforce, rather that they would remove the lift the car creates due to its bad design. Aerodynamics is as much about balance as it is downforce. If the balance has improved then the aerodynamic mods work, where the aim was to improve laptime, not downforce levels.

Thanks, i'm using a racelogic driftbox.

Highly likely. The creation of downforce by passive devices almost always can only be achieved at the cost of increased aerodynamic drag. An increase in aerodynamic drag will make the car slower, thereby requiring an increase in torque just to achieve the same lap speed.

Not entirely true. The venturi effect is a near drag-less effect. This is what is seen on the underside of the car. Also the modifications I have done will have streamlined the car in certain areas. The post radiator modification, the flat floor, diffuser and the engine lid all make the car less draggy. The front lip, canards and rear wing make it more draggy. The weightings of each are hard to know.

Also if the aerodynamics facilitate faster cornering speeds then the speed achieved at the end of the following straight is often higher.

[Rogue]

I saw you at Donington, looked like you were having fun.

We were shaking down one of our new MR2 Championship cars ahead of the season opener in a couple of weeks.

[Ren0W]

Here's a look at the underside of our race car:

Image Replaced With URL For Quote [url]http://farm9.staticflickr.com/8436/8011897797_8df3c6991f.jpg[/url]
Rogue Motorsport / Forza 4 - Toyota MR2 - Britcar 24 Hours 2012 by Trackside70, on Flickr

There are some compromises purely to get around other components so I'm aware it's not an ideal setup.

Heya mate.
It's time to change those tires. No profile left on them anymore.

[niks]

Thats certainly an idea and yes that would show a good back to back reference. But considering to do as you have suggested would take about 4 hours, which is 4 hours of wasted track time, thats not gonna happen.

In fairness I never said anything about downforce. I never actually thought my modifications would add any significant downforce, rather that they would remove the lift the car creates due to its bad design. Aerodynamics is as much about balance as it is downforce. If the balance has improved then the aerodynamic mods work, where the aim was to improve laptime, not downforce levels.

4 hours seems like quite a lot, isn't the rear wing and flat floor bolted (& possibly bonded) on? Even so, I imagine 4 hours to justify the effects of all those mods is a fair trade.

You're sort of contradicting yourself there...If your aim was to remove lift, then your intention was to try and create negative lift (i.e. downforce) from your modifications, which would reduce the overall magnitude of lift...

You've clearly read some literature, and you've started off on the right foot, but you don't seem to keen on justifying your mods, which ultimately is the only way you can understand and improve a car...

[ashley]

4 hours seems like quite a lot, isn't the rear wing and flat floor bolted (& possibly bonded) on? Even so, I imagine 4 hours to justify the effects of all those mods is a fair trade.

You're sort of contradicting yourself there...If your aim was to remove lift, then your intention was to try and create negative lift (i.e. downforce) from your modifications, which would reduce the overall magnitude of lift...

You've clearly read some literature, and you've started off on the right foot, but you don't seem to keen on justifying your mods, which ultimately is the only way you can understand and improve a car...

But at the same time he doesn't need to prove anything does he? He's made some mods to his car, and for whatever reason he's now lapping faster at the track and enjoying his track time more.

Does it matter whether this is because he's developed some genius aero mods, or simply because Patrick was at the track bringing with him a cosmic heightened motorsport force that improved everyone's driving that day?

We should be encouraging the attitude of trying out modifications- it's one of the reasons us Brits are the best at motorsport development in the world

Kudos for having a go, and keep it up- lets see what you come up with next...who knows, it might just be the next big break through

[dantheman]

I saw you at Donington, looked like you were having fun.

We were shaking down one of our new MR2 Championship cars ahead of the season opener in a couple of weeks.

I got told that when I ordered new brake pads from you guys earlier in the week. What colour car were you driving? I meant to come find you, I spoke to the 2 guys in the MR2 championship cars (one was blue and yellow, the other white) and got a passenger ride with them, twas them who made me want a set of semi slicks. The difference in grip between their cars and mine was crazy.

4 hours seems like quite a lot, isn't the rear wing and flat floor bolted (& possibly bonded) on? Even so, I imagine 4 hours to justify the effects of all those mods is a fair trade.

If your aim was to remove lift, then your intention was to try and create negative lift

But at the same time he doesn't need to prove anything does he? He's made some mods to his car, and for whatever reason he's now lapping faster at the track and enjoying his track time more.

4 hours is accurate i think. I would need to put the car up on stands and down again 3 times. The floor takes forever to take off, its held on by about 40 bolts, some in hard to reach places. The wing is bolted down by about 20 bolts. The engine lid is very tricky to put back on. And im not paying £150 quid a trackday ticket to spend half of it in the garage, when I have what I believe to be fairly conclusive track data.

This is fundamentally a track car, designed for the purpose of having fun on uncompetitive trackdays. I did the mods as a bit of fun, I have no reason to put extra cost into it when its already working great.

And no i've hardly read any literature. I have however studied a module on aerodynamics at uni, which was taught by the former chief aerodynamicist of Benetton. Ive made modifications to a Jaguar XF over about 20 runs in the MIRA wind tunnel. I made modifications based on my knowledge, implemented them, tested them and collected what I believe is conclusive track data justifying that my mods work.

[niks]

This is fundamentally a track car, designed for the purpose of having fun on uncompetitive trackdays. I did the mods as a bit of fun, I have no reason to put extra cost into it when its already working great.

That's all it is at the end of the day, a little fun, and I don't blame you for not taking it apart to quantify the mods. I merely stated in my first post that if you REALLY wanted to justify the gains, you'd run an A B A test rather than putting it into a windtunnel...

And no i've hardly read any literature. I have however studied a module on aerodynamics at uni, which was taught by the former chief aerodynamicist of Benetton. Ive made modifications to a Jaguar XF over about 20 runs in the MIRA wind tunnel. I made modifications based on my knowledge, implemented them, tested them and collected what I believe is conclusive track data justifying that my mods work

Whilst learning a module is a good place to start, remember that this is an extremely vast subject, which only increases in complexity once you've added vehicle dynamics and driver inputs into the mix. I thought I'd share my thoughts as I deal with this on a day to day basis...and do work with chief F1 aerodynamicists, and correlate windtunnel data to simulator data and circuit data, and quantify aero updates and give the windtunnel performance metrics and direction to focus efforts.

Anyway by the sounds of it you don't seem to need any advice, so well done for the effort again and good luck racing.

[Danbob]

Sorry for dredging up an old post, just redirected to it from OP's newest update.


Just wanted to say I have massive respect for the OP and his way of going about things! Whether this modification has reduced net lift, introduced net downforce or only added weight at least he's gone out and done it, done it himself and has done it based on sound engineering theory!

I'd have far less respect for somebody who turns up at a tuner with a huge wedge of cash and leaves with ££££'s worth of pretty carbon fibre bolted to their car having learned nothing and put in zero effort!

If you look at the majority of cars competing in (non top level) UK motorsport, they are not perfect show cars!

The OP has explained the theory around each of the modifications and has shown he understands why he is implementing them - This is a refreshing change from most internet posts!

And on a side note many of the aero mods are close to the aero mod's of Toyota's SW20 GT300 car, he's using it on track at high speed circuits, so why not optimise it for high speed track use for the cost of less than one set of R888's?

[Torero]

Just wanted to say I have massive respect for the OP and his way of going about things! Whether this modification has reduced net lift, introduced net downforce or only added weight at least he's gone out and done it, done it himself and has done it based on sound engineering theory!

The OP has explained the theory around each of the modifications and has shown he understands why he is implementing them - This is a refreshing change from most internet posts!

+1

I completely admire your attitude and philosphy on this Dan, it is spot on. I did several modules on fluid dynamics and as mentioned it is a vast subject area so the only thing an individual can do is to pick the areas that matter to them and have a go and enjoy it in the process.

I can't stress enough how much I've enjoyed reading this buddy, if we listened to others who didn't want to push the envelope we'd still think the world was flat.

Good on yer!!!

[ads]

Absolutely, respect due.

Peter Gidden made an interesting point somewhere re. venting the front wings to alleviate pressure - has anyone had significant benefit from doing this on a standard bodied 2 ?