Test - Down force vs. Top speed

Sail IC · Dec 3, 2010

When driving, I haven't noticed that much top speed difference when altering down force so I did a "scientific test"

Took two cars to the Nordschleife and drove the long straigt in both directions with max and min downforce, same gearing. Here is the result

ZR-1 RM
Min downforce: 363/357 Km/h
Max downforce: 359/354 Km/h

Lexus IS F Concept:
Min downforce: 309/295 Km/h
Max downforce: 305/290 Km/h

I had expected a higher difference in top speed between Max vs Min downforce than 4-5 Km/h. Knowing this, it seems like you should always tune with Max downforce at the low-grip end of the car and then reduce downforce at the high-grip end until you reached airodynamic balance.

What do you think.

AcceptYourDeath · Dec 3, 2010

I already thougth something like this will turn out if somebody is showing numbers. I always put downforce to maximum at all cars and never felt they became slower.

If the difference is so small on such a high speed I won`t bother to lower downforce at all.

You`ll may be 0.1km/h faster on lower speed ^^

Btw why is your Lexus so slow? I assume they were both set to the same topspeed?

-edit-

Almost forgot - more downforce means more grip and therfore better acceleration. This could compensate air drag to a certain amount.

RacingManiac · Dec 3, 2010

I definitely noticed that. When I setup a RMed Z06 for Le Mans I first did the logical thing of tuning for top speed and running lower downforce. But one time I forgot I changed the setup for a slower track and ran much higher wing level, went back to run the Le Mans track and found that I am maybe 3-4km/h slower top speed but 4-5 sec faster laptime since the car is just better everywhere else...

Seems the drag are not that critical in this game...

nasanu · Dec 3, 2010

Shame, they seem to have to got this wrong. Just another thing to be patched PD!

joetruckv8 · Nov 6, 2011

I did down force checks 2 see if there was a difference and I found nothing, so I believe that GT5 added the PP to give us the power vs down force grip difference. Cars with no wings go faster than cars with wings because to add down force means it cost you pp's

dr_slump · Nov 6, 2011

joetruckv8
I did down force checks 2 see if there was a difference and I found nothing, so I believe that GT5 added the PP to give us the power vs down force grip difference. Cars with no wings go faster than cars with wings because to add down force means it cost you pp's

What?

Forget that PP thing. A wing gives you some downforce, but also increases the wind resistance. If you remove the wing, PP will drop because it would have less grip (less downforce=less grip), but topspeed would be higher because of less wind resistance.

And then theres also the ride height which has a big effect........

XDesperado67 · Nov 6, 2011

While 4-5 KPH doesn't sound like a lot it quickly adds up especially on longer top speed sections of track. You should look at your elapsed time point to point on those top speed tests, I'm betting that the extra 4-5 KPH is good for at least a .10th or two faster times especially at those speeds. A couple tenths is a lot of ground at 200+ MPH.

There is a misconception that max downforce is automatically best, when in reality it is quite possible to have too much downforce. Remember when tuning a car every part needs to be adjusted to balance and compliment the rest and adjustable downforce creates one more variable in your tune. Higher downforce will most likely call for stiffer spring rates, which may require changes in Dampers and anti-roll bars thus changing camber, etc.

If your running in PP restricted events the amount of downforce you use can have a huge impact on total performance as you start balancing the tune trying to find the best combination of available power vs greater downforce. Just my own opinion but personally I find on cars of about 500PP or less I'm generally better going for more power and less downforce in these PP restricted events since the fairly limited speeds generally don't allow much boost in cornering from additional downforce.

savage388 · Nov 6, 2011

XDesperado67
While 4-5 KPH doesn't sound like a lot it quickly adds up especially on longer top speed sections of track. You should look at your elapsed time point to point on those top speed tests, I'm betting that the extra 4-5 KPH is good for at least a .10th or two faster times especially at those speeds. A couple tenths is a lot of ground at 200+ MPH.

There is a misconception that max downforce is automatically best, when in reality it is quite possible to have too much downforce. Remember when tuning a car every part needs to be adjusted to balance and compliment the rest and adjustable downforce creates one more variable in your tune. Higher downforce will most likely call for stiffer spring rates, which may require changes in Dampers and anti-roll bars thus changing camber, etc.

If your running in PP restricted events the amount of downforce you use can have a huge impact on total performance as you start balancing the tune trying to find the best combination of available power vs greater downforce. Just my own opinion but personally I find on cars of about 500PP or less I'm generally better going for more power and less downforce in these PP restricted events since the fairly limited speeds generally don't allow much boost in cornering from additional downforce.

Quite true. Another negative effect of down force in street cars is heavy understeer because only the rear is adjustable. Even when you tune the understeer out at high speed the car is almost always way to loose at low speed. Downforce is most definitely not always good, especially in pp racing. I don't even add a wing to most cars under 550 pp because of the pp it adds which creates a hp penalty. So people need to actually tune downforce like they would anything else, not just put it at min or max.

Weesty · Mar 4, 2012

with any racecar downforce is important to get faster around some corners , quite most corners , but fact is , full downforce not always good ...*
i noticed a few tracks like oval roadcourses with speed corners and heavy braking 60 in stead of 65 on few cars can be really helpful , like almost a second faster onindy roadcourse ... sorry for bad english

Master_gamer438 · Mar 4, 2012

I've tested this on NASCARs berfore they did the tire wear update. But have also tested on nurburg. Anything under 600PP isint worth putting a wing on. Downforce is helpful in slow corners, most of nurburg corners I dont need to go under 60MPH. Technically thats highway speed, and a pretty fast corner. DF should be used on tracks with slow corners. Nurburg has lots of higher speed corners. My CSL no wing, 6'38"1xx and with full aero 6'40. The aero might make someone faster through certain splits. But overall the high speeds you should be able to catch a aero'd car.

dr_slump · Mar 5, 2012

Some cars hit a higher topspeed with downforce.

Johnnypenso · Mar 5, 2012

Master_gamer438
I've tested this on NASCARs berfore they did the tire wear update. But have also tested on nurburg. Anything under 600PP isint worth putting a wing on. Downforce is helpful in slow corners, most of nurburg corners I dont need to go under 60MPH. Technically thats highway speed, and a pretty fast corner. DF should be used on tracks with slow corners. Nurburg has lots of higher speed corners. My CSL no wing, 6'38"1xx and with full aero 6'40. The aero might make someone faster through certain splits. But overall the high speeds you should be able to catch a aero'd car.

My thinking exactly. No street car I have under 600 PP has a wing and some of those at 600PP don't have a wing either. The best road cars to get a wing on are those that also add significant front downforce and running a minimum rear and max front downforce setup is often the quickest way to go at the "handling" tracks because it keeps the HP high and adds significant, balanced, cornering grip at both ends.

Test - Down force vs. Top speed

Sail IC

AcceptYourDeath

RacingManiac

nasanu

joetruckv8

dr_slump

XDesperado67

The Harvey Wallbanger

savage388

Weesty

Master_gamer438

dr_slump

Johnnypenso

Well known double poster

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