Circuit Racing Rear Wings

[NickR33]

anyone played with the adjustable wing on 33GTR's? mine seems to be adjusted with quite a lot of angle... don't know if it would be all that necessary as corner exit grip is where GTR's shine so they are really just there for high speed stability?

[djr81]

DJR, mine's actually a GTS-t and I don't really have front end grip issues post apex..... usually counter steering if anything..... as I'm interested to see and it's an easy swap over I'll do as Harry suggests...... nd await the howls of laughter from my peers

Fair enough. I am not sure anyone has front end grip problems post apex as it is a power on oversteer issue that characterises the cars handling at this point and aero grip can only do so much to solve it.

I guess what I was trying to say was two fold:

1> Balance is as important as grip.

2> A wing that produces downforce behind the rear wheels will both add grip to the rear & lessen grip at the front.

So a working wing will have the effect of adding understeer to the car. I sort of take the view that getting the car balanced in the mid corner helps your confidence in the car, your apex speed & your ability to apply power. As such I dont reckon a big rear wing will help you. If you watch the good drivers in 2wd cars (particularly low powered 2wd cars) you will be surprised by how 'loose' the car is.

But anyway it isn't a huge effort to bolt it up & see what happens. If all else fails the wing may make a good towell rail or something at a later point.

[Marlin]

lol.... djr, my thoughts exactly, worth giving it a try for the sake of four nuts I guess

If it does make a huge difference and causes understeer, then maybe someone on here may want it that is also working on their front end downforce. (I won't be making any aero changes to mine at the front due to my class of racing)

[benm]

What data logging tools are available and from where?

[djr81]

www.race-technology.com

See the DL1.

[Roy]

Without getting carried away with all the expensive sensors and wiring which just add cost and weight you can get a good enough idea based on corner speeds and lap times to hopefully reinforce seat of the pants

[benm]

So you use the DL1 + suspension sensors to measure the difference in suspension travel caused by varying levels of downforce generated by different front/rear downforce components? Or am I missing something...

[djr81]

So you use the DL1 + suspension sensors to measure the difference in suspension travel caused by varying levels of downforce generated by different front/rear downforce components? Or am I missing something...

No you use the DL1 to measure speed via GPS, accelerations via its own internal accelerometers & such things as rpm, throttle position & steering angle by tapping into the mutlitude of sensors already on the Nissans. Not expensive - you just need an auto sparkie to sort out how to get the sensor outputs configured to work with the DL1.

As far as measuring downforce the wing generates it is far easier to put a strain gauge on the wing supports than trying to find what the suspension is doing. I mean, as (say) 50kg downforce with a rear spring rate of 5kg/mm you are looking for a 5mm deflection (You have 2 springs). Which with bumps etc and only a short time period to find it would be hard.

[boxheadmr]

the DL1 is not really a cheap option, actually owning and setting one up along with the dash it can actually cost quiet a bit factoring in sensors and labour to install + the purchase price of the unit.

Cheaper then some other units though.

Matt

[djr81]

the DL1 is not really a cheap option, actually owning and setting one up along with the dash it can actually cost quiet a bit factoring in sensors and labour to install + the purchase price of the unit.

Cheaper then some other units though.

Matt

You don't have to run the dash you can run the DL1 alone.

As for sensors it depends what you want to run. Most of what is necessary is already present on a Nissan.

Anyway compared to such things as the drift box/performance meter the offer a great deal more functionality for only a small amount of cash.

But if you really want to do it on the cheap you can always use your phone.

[boxheadmr]

You don't have to run the dash you can run the DL1 alone.

As for sensors it depends what you want to run. Most of what is necessary is already present on a Nissan.

Anyway compared to such things as the drift box/performance meter the offer a great deal more functionality for only a small amount of cash.

But if you really want to do it on the cheap you can always use your phone.

I didn't say that you have to run it with the Dash, i did say that it is not a cheap option.

To start to get some good results things like steering angle, pedal travel or brake pressure and perhaps something like looking at the differences in temps across a particular section - for instance the intercooler, you will need additional sensors.

You will need to do a fair bit of stuffing around to plug the factor sensors directly to the DL1 and measure the voltage differences which is a pain, to be honest when you look at it you get good value out of the performnce box unit that has everything done for you and easy to move into and out of different cars.

Coming back to the rear wing Roy's idea sounds the best option,

Matt

[boxheadmr]

Doing a little more reseach as is an area i am interested in it appears that employing some computational fluid dynamics programs would be the best idea to give you real examples of the different effects that adding a Wing and at what angle of attack will give the best amount of downforce with least amount of flow separation.

Aerodynamics of motor cars is really quiet a diffacult area to develop and there is a large amount of varying effects that need to be taken into account, i am reading competition car aerodynamics at the moment and it is mind blowing the different things you need to consider.

For instance in some cases a rear wing can actually give you less drag?

Matt

[Roy]

Matt, let me first say that CFD software was not cheap or acessible when i was doing it around 2000-2001. Dont know these days. But what i can almost guarantee is that irrespective of cost and access these days you need to have a thorough understanding of fluids mechanics if you are to have any hope in hell of being able to do any meaningful CFD.

Reading a book on race aero will give you more understanding then trying to use CFD as a tool. CFD software means the user has to make many base assumptions, which can mean shit in shit out. There are plenty of small level open wheelers manufacturers who with their teams of engineers do CFD only to find that in testing their CFD model was floored by said assumptions. Hell you read the same thing about F1 teams every year having the same problem.

So it can be cool and novel to play with if you have access....but i genuinely believe you need to have an engineering degree with a good comprehension of fluid mechanics combined with several years of industry experience in fluid mechanics if you are to have any hope in hell

LOL, easier to read books and use good practice then substantiate with seat of pants or any data acquisition you may have

[boxheadmr]

Roy, i agree about the cost - not cheap stuff but how are you sure that what you have done is an improvement. The old loud exhaust making the car sound like it is going quicker is a classic and is subjective.

Wool tuffs look to be the most cost effective benifit but you actually have to have what you want to test on the car, i think it comes down to how much you are willing to spend to go quicker and the majority of people are probally better off getting more laps in the car to go faster.

....now where is that ebay vortex generator.

Matt

[Beer Baron]

Roy, i agree about the cost - not cheap stuff but how are you sure that what you have done is an improvement.

lap times.

[BezerkR32]

yeh i thought lap times and general behaviour of the car would be the go

but its obviously a lot more complicated. I guess ill suck t and see. Even if it means borrowing a boot

lid with a wing on it. But if it involves data-logging and sensors i couldnt be assed. ill live with it loose and twitchy, bit like a kart under brakes anyway, just about 12 times heavier and more expensive to fix.

lap times.

[Beer Baron]

yeah a lot of 32s do behave like a kart underbrakes! i've been backing mine into corners for years... dialling out the rear end movement under brakes takes a bit of work. and maybe an adjustment in driving style. for one thing any trail braking usually results in the back of the car trying to overtake you...

[boxheadmr]

yeah a lot of 32s do behave like a kart underbrakes! i've been backing mine into corners for years... dialling out the rear end movement under brakes takes a bit of work. and maybe an adjustment in driving style. for one thing any trail braking usually results in the back of the car trying to overtake you...

driver

[rtune]

Plus if your going to fit a proper rear wing, it has to be attached directly to the body which is quite a modification. Otherwise the boot travel just absorbs most of the downforce the rear wing is making.

That doesn't make any sense.

If you put 20kg on a wing, there is 20kg more on the tire contact patch. Full stop.

Doesn't matter how much the wing or boot lid flexes.. unless it flexes so

much it changes the aerofoil shape (unlikely). or pushes it down & out of the slipstream (impossible)!

[Bowlsclubboy]

Great topic guys, some experienced people in here for sure. Are there many aero rules for australian superlap (time attack) because i'm pretty sure that the splitter on that GTR wouldn't comply with the yank's rules. I'm considering making a wing for my cressida to suit sports sedan regs, but it's more likely it will only ever compete in time attack and sprints so i'd like to know all the info before i start laying up the carbon!

Neil, are you heading to Eastern Creek this weekend? I'll be there crewing for a West so we probably shouldnt discuss aero together!