TCS & Drag Racing

[Deuce B]

Does TCS affect quarter mile times and speed much?

I ran my car the other day and had TCS on. I didn't even think about it since it's on when you start the car. Never even considered it until the drive home. For some reason, when thinking back on my runs, I felt that the shifts were mushy and TCS came to mind. Would TCS do that or is it just an old clutch that will need replacing soon?

Anyways, I only made two passes (both with TCS on). They were almost identical. As I remember, the 60" time was 2.225, 1/8th mile speed was 81.5, quarter mile ET was 14.030 @ 101.5MPH.

Would that improve much with the TCS off? I have a stock 91 with headers and Tubi exhaust. The car has just under 40,000 miles.

 

[Carguy!]

You can definately get better times with TCS off, but it requires a little practice to make sure you don't get too much wheel spin. You will probably see .5 to .8 seconds better with a good launch with TCS off.

Good Luck!

 

[Deuce B]

That much?!? WOW!!!

So these cars are capable of going mid 13's basically stock? That's awesome!

My car goes in for 6yr/60,000mi service, timing belt/waterpump, drive belts, & valve adjustment Monday. I'll have to go back to the track this Friday and see how much better I can get that time.

Any suggestions for launching the car with TCS off? RPMs? Dump the clutch or let it slip a little? Any tips?

BTW, the two passes I did make, I only managed a .904 RT. Those lights seem faster when you're actually at the line.

 

[coolnsx]

Deuce, Where do you run your car?

 

[Deuce B]

I ran it at Hawaii Raceway Park.

It's on Oahu in Campbell Industrial Park.

http://www.hawaiiracewaypark.com/
http://www.hrpdragracing.com/index.html

Near 0 altitude.

 

[Brian2by2]

I just ran this weekend and was running consistent 13.5's @ around 103 with 60' times ranging from 1.9-2.1.

I was at full weight: full tank of gas, luggage, my 'show' rims, street tires and spare/tools/etc.

I was just on vacation and someone told me their track is empty on fridays so i went.

I launched from 3,500-5,500 RPMs everytime with the 1.9 60' being my 5,500 drop. Spun a little but its ok. (i have 275/35/18's in the rear, so i get better traction that stock 245s).

TCS definetly does alot...and lower the air pressure in your rear tires quite a bit too in order to get traction.

 

[NSX/MR2]

With the TCS off, you control the spinning by letting the clutch grabs in 1st gear first before you punch it.

 

[nsxtasy]

(i have 275/35/18's in the rear, so i get better traction that stock 245s).

Wrong. The 275/35-18 will not get better traction during acceleration than 245/40-17.

 

[Brian2by2]

oh, they won't? Please school me on how a larger contact space is not beneficial to traction. And then please explain to me why most D/Rs are extremely wide, and why high horsepower/torque cars such as Vipers, Z06s, and Ferraris come with such wide tires in the rear. I'm not being sarcastic Ken, I really was under the impression wider tires help grab (and still am).

I also speak from experience as when I had my stocks on last week, they definetly broke lose much easier than my other tires.

 

[nsxtasy]

Please school me on how a larger contact space is not beneficial to traction.

Well, that's the first misconception right there. Wider tires do not have a larger contact patch than narrower tires. The shape of the patch is different (wider side to side, narrower front to back) but the size depends only on the weight of the car and the amount of pressure in the tires (as long as the inflation in the tires is fully supporting the weight of the car). For example, if you put 40 psi in all the tires of a 3000-pound NSX, the total area of the four contact patches will equal 75 square inches - whether the tires are skinny 205 mm rain tires, or 305 mm racing slicks.

And then please explain to me why most D/Rs are extremely wide, and why high horsepower/torque cars such as Vipers, Z06s, and Ferraris come with such wide tires in the rear.

The primary advantage that is alleged for wider tires - and it is only true up to a certain point, and sometimes not even true at all - is in cornering, where the wider contact patch is an advantage, and not in acceleration or braking.

I also speak from experience as when I had my stocks on last week, they definetly broke lose much easier than my other tires.

There are a lot of things that can change from one session to another, particularly with different tires - everything from the grip of the tire design, to the amount of tread, to the environmental conditions, etc etc.

 

[nsxchi-town]

ken,

man u r the sh*t... i belive u know evething...

glad to me a member and learn from u..thanks for all the wisdom
and insight on our nsx..and for ripping eveyone , when u see fit.


thanks,
i enjoy it very much...

 

[NetViper]

Ken... you should see if you can get a job at The Tire Rack

 

[pach]

Taken from Performance Handling, a pretty
nice book that covers the basics on suspension, aerodynamics, and tires.

Increasing Tire Traction

There are three factors that increase tire traction:

Increasing the friction between the tire and the road. (Ie. Softer compound tires)

Increasing the vertical load on the tire. (ie weight transfered to the tires)

Increasing the number of rubber molecules at the tire contact patch.
(which would involve things like a wider tire w/ the appropriate wider rim, a tire with less grooves in the tread, and proper tire pressure and suspension alignment to maximize the tires contact patch on the road)

 

[Brian2by2]

Taken from Performance Handling, a pretty
nice book that covers the basics on suspension, aerodynamics, and tires.

Increasing Tire Traction

There are three factors that increase tire traction:

Increasing the friction between the tire and the road. (Ie. Softer compound tires)

Increasing the vertical load on the tire. (ie weight transfered to the tires)

Increasing the number of rubber molecules at the tire contact patch.
(which would involve things like a wider tire w/ the appropriate wider rim, a tire with less grooves in the tread, and proper tire pressure and suspension alignment to maximize the tires contact patch on the road)

well, using that as a guide, I would say it also helps gain traction off hte line...

If the wider tire doesn't grip better than why do vipers run 315s in the rear?? they're so expensive and if a 245 would do the same thing, why not use that??

 

[nsxtasy]

Increasing the number of rubber molecules at the tire contact patch.
(which would involve things like a wider tire w/ the appropriate wider rim

That reference is, quite simply, wrong.

For a more knowledgeable reference, click here.

Or, use my example above, and tell me how you can divide 3000 pounds by 40 pounds per square inch and get a number other than 75 square inches.

If the wider tire doesn't grip better than why do vipers run 315s in the rear?? they're so expensive and if a 245 would do the same thing, why not use that??

I guess you didn't read the part I wrote above, about cornering, did you?

 

[Brian2by2]

Great site...thanks for sharing.

Guess its the tire compoundor air pressure of my 245s that allow me to only launch at 3500 w/o spinning while i can launch at 5500 with my 275s

 

[nsxtasy]

Guess its the tire compoundor air pressure of my 245s that allow me to only launch at 3500 w/o spinning while i can launch at 5500 with my 275s

I don't know what kind of tires they are; a difference in the tire compound could indeed increase grip. Reducing air pressure can also greatly affect your grip, because that does increase the size of your contact patch.

 

[SNDSOUL]

Ken, taken from your reference:

This has been found to be almost exactly correct for most tyres (the exceptions being so-called run-flat tyres, or tyres with extremely stiff sidewalls).

Have you ever felt the stiffness of the sidewall on a 275/35/18?? EXTREEMLY STIFF!! Therefore according to YOUR reference, the tires that are in question in this thread would be the exception to the rule and therefore, would give a larger contact patch than a 245/45/18 at the same air pressure on the same car. More tire on the road, more grip.

 

[Macster]

SNDSOUL, I'm thinking run-flat tires and stiff sidewalls reduce the size of the contact patch... as in they don't allow the tires to lay as flat as they normally would.

tires that are in question in this thread would be the exception to the rule and therefore, would give a larger contact patch than a 245/45/18 at the same air pressure on the same car. [/B]

 

[Brian2by2]

Alright, check it. Ken made a great point and linked us to a great article, however, tonight, i pulled into the gas station and there was a puddle i ran through.

On the dry pavement under the neon lights, I could see my tire tracks. The 275 rear end tire tracks were DEFINETLY wider than the entire 245 tire is!!! So I'm going to stand by my belief that wider tires touch more ground than narrower ones unless you can explain to me what my own eyes saw...i might be missing something.

 

[pach]

Dont worry Brian, that article doesnt explain everything.

While it is true that a tires contact patch will distort based on the weight and pressure inside. I.E. a 245mm tire
will have a contact patch of 245mm and a 275mm tire will have one of 275mm, but the 245's tires contact patch will be a little taller(rounder) since it has to support the same amount of weight and deform to a similar amount of surface area. Its based on the assumption that tires are completely elastic and not partially inflexible, it also doesnt take into account that a wider tire has a more rectangular contact patch on the road and will have less tread deformation.

And apparently the head of Bridgestone Motorsport tire development agrees with you too.

What performance advantage would be gained by increasing the contact patch of the tyres? An increased contact patch gives increased grip because there is more rubber in contact with the track surface.

http://www.firestone.co.nz/default.asp?action=abo.longnews&NewsID=71

 

[SNDSOUL]

SNDSOUL, I'm thinking run-flat tires and stiff sidewalls reduce the size of the contact patch... as in they don't allow the tires to lay as flat as they normally would.

I'm thinking the stiffer sidewall tires have a smaller sidewall also, reducing the amount of bulge in the sidewall. The same air pressure would then push the tire surface to the ground instead of pushing the side wall out, thus a larger contact patch. Also a smaller sidewall tire is more likely to be a flatter tire than a larger one.

From the Tire Rack:

The shape of a tire's contact patch or "footprint" greatly influences its performance and is dependent on its profile or "aspect ratio". Low profile tires (most performance tires) have a short and wide contact patch that is effective in converting the driver's input into very responsive handling, cornering stability and traction...especially on dry roads.

 

[Macster]

Your quote from Tire Rack is correct but it is not the same as what you are saying. Stiffer sidewalls will help maintain a a good contact patch while cornering as the tire won't be "rolling" over.

To get the greatest contact patch on a drag car, you want tall, high profile tires, and LOW air pressure. You'll never see low profile tires on a serious drag car.

As Ken stated, tire pressure and vehicle weight are the main factors when determining contact patch SIZE. Since all tires, within a reasonable range, will have roughly the same size contact patch (amount of surface area)...

What matters (for corner carvers like us) is the shape of the contact patch. This can be best explained here.

 

[SNDSOUL]

Ok, well I guess you guys are right, wider tires are just a waste of money and dont serve any real purpose unless you are racing you car in the twistys. I guess all the people that have actually improved their handling and traction by up sizing(myself included) didnt really get better traction, we just thought we did.

I've got two sets of wheels and tires and as soon as my car gets out of the paint shop I will do a test. Say, 3 runs on my 245's and 3 on my 275's at the same tire pressure, on the same day, on the same car, at the same track and I will even use my rev limiter to keep the launch rpms the exact same. I can gaurantee a lower time with the 275's. How do I know---BECAUSE I ALREADY DID IT!!!! My quater mile times improved by 3 10th's consistently, but what do I know?

 

[Gerry Johnson]

I can say with the stock 92 rear wheels on my car I can have the car in third gear @ 60-70mph get into boost and burn the tires like I just left a stop sign, but with my 275/30/19's I can only do this in second. Wider tire = more traction.