Drag Radial/Slick Debate thread

[sneaky98gt]

So what you're saying, its not that wider tires create more friction, its that the wider tire grips the road better in a sense of having more stuff to "grab ahold of and push on", for lack of a better term? The way I'm seeing this is that the rubber tires sink down into the crevices of the road, which i can see how that would increase traction.
However, I was always told that wider tires were "softer" and therefore had a higher (mu). If a person were to create a softer, skinnier tire it would have the exact same amount of traction as a wider one. I knew this was not the case, but I had no alternative solution or explanation.

No, the coefficient of friction is relatively identical for 2 different sized tires (assuming same brand, obviously). What is different is the normal force applied per unit area (i.e. pressure). In theory, if the tire and road were smooth surfaces, the size wouldn't matter because a smaller tire still has the same overall weight on it that the larger tire does; the smaller tire has less area on the road, BUT it has a larger amount of force per unit area than a larger tire, resulting in the same amount of traction.

BUT, because of the reason I explained earlier, that is not true. A wider tire will usually hook better than a narrower one.

The whole power/traction topic is really relative. Like I mentioned before, with my old setup I consistantly went low 1.4's and the car only made 380-390rwhp(depended on bottle psi). The car also ran 11.2-11.4 in the 1/4th. Most cars running that slow and making that little hp dont 60' that well. So saying hp directly relates to 60' or even the type/size of a tire is incorrect.

I think that your weight and steep rear gear ratio (IIRC) has a LOT to do with that. Throw 600-800 pounds of weight and some more typical 3.73 or 4.10 gears on your car, and you'd probably be 60'ing about what most "normal" street cars do (1.5-1.6). Also, your nitrous setup is making a lot more torque than lots of other setups.

I still maintain that if everything else is equal (weight, tire, suspension, gear, etc.), the 60' is directly related to the amount of torque you are putting on the wheels during that time.


While I was at work yesterday, I was actually thinking about this, and thought I'd do some quick torque multiplication calculations just to put what I'm saying in perspective. And to clarify, all I'm saying is that mostly stock automatic Mustangs don't require slicks and/or suspension to hook up at the track, and that there's nothing wrong with 2.0-2.1 60's from those types of cars.

So, car A. It's a 95 Mustang GT, 5-speed, COMPLETELY STOCK, other than 3.73 gears. I started out using a modded car, but even a stock 5 speed more than adequately illustrates my point. It launches at 5000 rpm, where it is making about 250 ft-lbs of torque. Now, let's do the math for the amount of torque it's making on the wheels (which is really what's important). 250 ft-lbs from the motor x 3.35 1st gear ratio in the transmission x 3.73 rear gear ratio. That equals a whopping 3,124 ft-lbs of torque on the wheels! That is very impressive, and certainly makes for some great 60's if you have the traction.

Now, let's move to car B. It's a 95 Mustang GT, AOD-E, a few simple mods like a CAI, underdrive pulleys, offroad H pipe, Flowmasters, and stock 3.08 rear gears. Because of the low stall speed on the stock converter, it can only leave at about 1500 rpm, where it is making 200 ft-lbs of torque (guesstimate). So, 200 ft-lbs from the motor x 2.40 1st gear ratio in the transmission x 3.08 rear gear ratio. That equals a dismal 1,478 ft-lbs of torque on the wheels, NOT EVEN HALF what the 5-speed makes. Does that put it in a little better perspective as to why the stock stalled/rear geared auto doesn't cut good 60' times?!?!? (not directing that at anyone in particular)

Hell, to even further prove my point, I'll use my OWN car (car C), with a positive displacement blower making a lot of torque even off idle, with a steeper 1st gear and rear gear ratio than the old AODs came with. With the stock converter, I've never been able to leave above about 1900 rpm. But for argument's sake, I'd generously guess that I'm making about 300 ft-lbs of torque at an arbitrary 2000 rpm. 300 ft-lbs of torque at the motor x 2.84 1st gear ratio x 3.27 rear gear ratio. That equals 2,786 ft-lbs of torque on the wheels. So in this case, even with the power odds completely stacked against car A, car C (which is a mid 12 second car) is STILL putting down LESS torque on the wheels at the starting line than car A (a mid-14 second car at best).

I hope (seriously) that some of you that don't agree with me now see where I'm coming from. I think a lot of people have been forgetting about the gear multiplication differences in an automatic and 5-speed car, as well has how limited a stock stalled automatic is in getting into it's powerband. So I hope that it is a little clearer why I say it is ridiculous for someone driving car A (or one with MORE power and MORE gear multiplication) to suggest that someone driving car B needs slicks/suspension because car B is half a second slower in the 60' than car A....

@Sneaky, I legally drive my car to the track, who the hell in the right mind drives 2 hours on the highway on slicks?

Exactly my point....

I guess I should rephrase: "I like racing my STREET car in STREET trim..."

 

[97 king cobra]

My rear gears are 3.55's. I ran a 26 inch tire with the spray. No way I could trap much higher with the stock h/c/i.

 

[Rice_slayer]

I understand that too sneaky, but I have access to mounting/balancing equipment all the time at work. Besides, I have 18" wheels and to find a GOOD drag radial in that size will be hard and costly vs. the $300 I paid for my slicks and $20 I paid for the cheap donor rims until I can afford big/littles. I do more street driving than strip driving, BY FAR, and that includes rain, so having a more "street friendly" tire is better for me, everyone uses their stang differently. I like having a fully loaded, semi-quick car that I can drive in comfortably, king cobra has a car that is completely strip, is really fast, but would SUCK to drive to and from work everyday lol.

 

[97 king cobra]

True. This is why my work car is a 1991 honda crx. Mind you im 225lbs and a gym freak. Its like the hulk getting into a smart car. lol But that beast gets 33-39mpg depending how much highway mileage it see's.

 

[Knuckles@Empire]

I understand that too sneaky, but I have access to mounting/balancing equipment all the time at work. Besides, I have 18" wheels and to find a GOOD drag radial in that size will be hard and costly vs. the $300 I paid for my slicks and $20 I paid for the cheap donor rims until I can afford big/littles. I do more street driving than strip driving, BY FAR, and that includes rain, so having a more "street friendly" tire is better for me, everyone uses their stang differently. I like having a fully loaded, semi-quick car that I can drive in comfortably, king cobra has a car that is completely strip, is really fast, but would SUCK to drive to and from work everyday lol.

all i read here is you want to buy my draglites amirite >.< lol

 

[Rice_slayer]

I understand that too sneaky, but I have access to mounting/balancing equipment all the time at work. Besides, I have 18" wheels and to find a GOOD drag radial in that size will be hard and costly vs. the $300 I paid for my slicks and $20 I paid for the cheap donor rims until I can afford big/littles. I do more street driving than strip driving, BY FAR, and that includes rain, so having a more "street friendly" tire is better for me, everyone uses their stang differently. I like having a fully loaded, semi-quick car that I can drive in comfortably, king cobra has a car that is completely strip, is really fast, but would SUCK to drive to and from work everyday lol.

all i read here is you want to buy my draglites amirite >.< lol

Haha read the "no money" part . I have to go to school next month for my next apprentice level, so I have 2 months of getting EI, then back to normal(and higher) paychecks .

 

[justinschmidt1]

No, the coefficient of friction is relatively identical for 2 different sized tires (assuming same brand, obviously). What is different is the normal force applied per unit area (i.e. pressure). In theory, if the tire and road were smooth surfaces, the size wouldn't matter because a smaller tire still has the same overall weight on it that the larger tire does; the smaller tire has less area on the road, BUT it has a larger amount of force per unit area than a larger tire, resulting in the same amount of traction.

BUT, because of the reason I explained earlier, that is not true. A wider tire will usually hook better than a narrower one.




I think that your weight and steep rear gear ratio (IIRC) has a LOT to do with that. Throw 600-800 pounds of weight and some more typical 3.73 or 4.10 gears on your car,and you'd probably be 60'ing about what most "normal" street cars do (1.5-1.6). Also, your nitrous setup is making a lot more torque than lots of other setups.

I still maintain that if everything else is equal (weight, tire, suspension, gear, etc.), the 60' is directly related to the amount of torque you are putting on the wheels during that time.


While I was at work yesterday, I was actually thinking about this, and thought I'd do some quick torque multiplication calculations just to put what I'm saying in perspective. And to clarify, all I'm saying is that mostly stock automatic Mustangs don't require slicks and/or suspension to hook up at the track, and that there's nothing wrong with 2.0-2.1 60's from those types of cars.

So, car A. It's a 95 Mustang GT, 5-speed, COMPLETELY STOCK, other than 3.73 gears. I started out using a modded car, but even a stock 5 speed more than adequately illustrates my point. It launches at 5000 rpm, where it is making about 250 ft-lbs of torque. Now, let's do the math for the amount of torque it's making on the wheels (which is really what's important). 250 ft-lbs from the motor x 3.35 1st gear ratio in the transmission x 3.73 rear gear ratio. That equals a whopping 3,124 ft-lbs of torque on the wheels! That is very impressive, and certainly makes for some great 60's if you have the traction.

Now, let's move to car B. It's a 95 Mustang GT, AOD-E, a few simple mods like a CAI, underdrive pulleys, offroad H pipe, Flowmasters, and stock 3.08 rear gears. Because of the low stall speed on the stock converter, it can only leave at about 1500 rpm, where it is making 200 ft-lbs of torque (guesstimate). So, 200 ft-lbs from the motor x 2.40 1st gear ratio in the transmission x 3.08 rear gear ratio. That equals a dismal 1,478 ft-lbs of torque on the wheels, NOT EVEN HALF what the 5-speed makes. Does that put it in a little better perspective as to why the stock stalled/rear geared auto doesn't cut good 60' times?!?!? (not directing that at anyone in particular)

Hell, to even further prove my point, I'll use my OWN car (car C), with a positive displacement blower making a lot of torque even off idle, with a steeper 1st gear and rear gear ratio than the old AODs came with. With the stock converter, I've never been able to leave above about 1900 rpm. But for argument's sake, I'd generously guess that I'm making about 300 ft-lbs of torque at an arbitrary 2000 rpm. 300 ft-lbs of torque at the motor x 2.84 1st gear ratio x 3.27 rear gear ratio. That equals 2,786 ft-lbs of torque on the wheels. So in this case, even with the power odds completely stacked against car A, car C (which is a mid 12 second car) is STILL putting down LESS torque on the wheels at the starting line than car A (a mid-14 second car at best).

I hope (seriously) that some of you that don't agree with me now see where I'm coming from. I think a lot of people have been forgetting about the gear multiplication differences in an automatic and 5-speed car, as well has how limited a stock stalled automatic is in getting into it's powerband. So I hope that it is a little clearer why I say it is ridiculous for someone driving car A (or one with MORE power and MORE gear multiplication) to suggest that someone driving car B needs slicks/suspension because car B is half a second slower in the 60' than car A....



Exactly my point....

I guess I should rephrase: "I like racing my STREET car in STREET trim..."

Did I just read that most normal street cars 60 foot 1.5-1.6 lol

Theres way too many variables too even begin to calculate these things

 

[Musturd]

I like slicks et streetspersonally I run26x11.50/16 tires are prolly a bit wide for the rim but I cut a best Of 1.62 60ft average 1.6's 1.7's tops launching at 5000rpm stock clutch and Axles full season of runs so prolly a 100 passes on my old 2v4.6. I've yet to run my pushrod sn95

 

[justinschmidt1]

I like slicks et streetspersonally I run26x11.50/16 tires are prolly a bit wide for the rim but I cut a best Of 1.62 60ft average 1.6's 1.7's tops launching at 5000rpm stock clutch and Axles full season of runs so prolly a 100 passes on my old 2v4.6. I've yet to run my pushrod sn95

Thats pretty solid...but I thought ET streets are considered a drag radial? ET Drags are slicks, correct?

 

[duff daddy]

ET Streets are a DOT Slick

 

[Musturd]

Thats pretty solid...but I thought ET streets are considered a drag radial? ET Drags are slicks, correct?

Thanks man
Yea there dot slick like duff daddy said I like em Cus I can still run in regular domestic class on street legal nights
Instead of outlaw. They don't require you to run a loop either but I have one installed. The pair I ran on my car I was told I might get 25 passes out of em I got a full season prolly Cus my car doesn't make alot of power lol

 

[justinschmidt1]

ET Streets are a DOT Slick

Gotcha

 

[sneaky98gt]

Did I just read that most normal street cars 60 foot 1.5-1.6 lol

Theres way too many variables too even begin to calculate these things

Yea, I wasn't exactly clear there. King cobra was saying that he 60ed in the 1/4 range, and while his car is a street car, it is very heavily "geared" (literally, not talking about gears) for the track. I was trying to say that most fast "street" cars, as in built more towards street duty than track duty (good tires, simple all-around suspension stuff [LCAs, UCAs, subframes, etc.], a good driver, and 400ish rwhp with a stick or stalled auto), will 60 in the 1.6 range, occasionally in the 1.5 range.

 

[Rice_slayer]

I was able to cut a 1.8' 60 on a crappy track a few weeks ago with my 26x8.5x15 et drags, but that wasn't going that hard, launched at 3.5/3.7k. My suspension isn't exactly weight transfer friendly either. I have these stupid overly stiff H&R Race springs on it, but it has tokico 5 ways on it, so the fronts are almost as stiff as possible and the rears are set at the softest setting, also have MM rear LCAs. I'm going to try some 4-4.5k launches next time up, see how the car reacts to it. My goal is to cut 1.7/1.6's. Lower would be better but I have to be realistic since I DD the car and don't have the rear end to supper those high rpm launches.

 

[Knuckles@Empire]

oh like you could launch at 5k no worries and cut a 1.6 all night let that car eat!

 

[Musturd]

Yea what knuckles said ! The first time I launched on slicks I let her fly at 4500 it hooked so hard I let off and got scared

 

[duff daddy]

I was able to cut a 1.8' 60 on a crappy track a few weeks ago with my 26x8.5x15 et drags, but that wasn't going that hard, launched at 3.5/3.7k. My suspension isn't exactly weight transfer friendly either. I have these stupid overly stiff H&R Race springs on it, but it has tokico 5 ways on it, so the fronts are almost as stiff as possible and the rears are set at the softest setting, also have MM rear LCAs. I'm going to try some 4-4.5k launches next time up, see how the car reacts to it. My goal is to cut 1.7/1.6's. Lower would be better but I have to be realistic since I DD the car and don't have the rear end to supper those high rpm launches.

Try swapping that I saw better results with the rear on hard and fronts on soft.

 

[justinschmidt1]

Im gonna let her eat when I mount the slicks...hoping for 1.6ish 60 foot.

 

[sneaky98gt]

I wanna hear more about the scooter with Mickey Thompson E/T Drags on it.

I thought I'd revive this thread to inform everyone that there WILL BE A SCOOTER RACE ON NOVEMBER 19th!!!

Official rules: http://www.horsepowerjunkies.com/forums/showthread.php?t=119731

I will be videoing, and we will see exactly how these things 60'.