Let's talk Trap Speed

[laloosh]

Ok what im looking for here is a civilized discussion. Any statement you make should be followed up by your reasoning.

Problem at hand: Spinning off the line increases trap speed.
What is trap speed: The average of the last 60 feet of the 1320ft track

Bogging: If you bog off the line and fall on your face, you have lost the first 10-15 feet to acc, hence your trap speed will go down.

Acc: I think its safe to assume that the greatest acc. happens in the first 2 gears. If you bog, you not only loose distance to acc, but your wasting your "power gears"

Now spinning: If you spin, you basically not covering as much track as you should, and when u finally catch you begin to acc. Being that you catch when u get traction, just as if u were to leave the line with traction, how does spinning increase trap speed. Think about this and how rpms work. The distance stays the same no matter what.

Slicks: Technically, slicks should increase trap speed, but they almost never do. Why? It cant be that flat tire your draggin in the back 1/8th. With slicks you get to use your first 2 gears to their full advantage and acc. the fastest, as you know going from 0-50 is easier than going from 80-130. So how does spinning increase trap speed and "hooking up" decrease it? I've always wondered about this, ive tried it for myself and maybe its the way i drive, but unless i bog, my trap speed never really changes no matter what. I can get a 2.0 60 and trap 110 and i can get a 2.3 60 spinning out the ass and trap 110. So why are all these claims made?

 

[MS3Chik]

didnt we already go through this..

just say if your tires are spinning more at the line your mph is already up bc your rpms are already up..its really hard to explain..like if you pick a car up from the ground and the tires are spinning then put it down its gunna go really fast..rather than if you just put it down with the wheels stoped..get what im saying..spining at the line isnt always a bad thing

 

[laloosh]

didnt we already go through this..

just say if your tires are spinning more at the line your mph is already up bc your rpms are already up..its really hard to explain..like if you pick a car up from the ground and the tires are spinning then put it down its gunna go really fast..rather than if you just put it down with the wheels stoped..get what im saying..spining at the line isnt always a bad thing

i understand that 100%. However with slicks, you able to bring the rpms up and launch high. When u spin, you dont acc. The only good thing about spinning is like you said, getting the revs up, but like with anything else, too much is not good. With slicks you should be able to launch in the meat of you powerband and use the 1st 2 gears alot better. So why does hooking up lower trapss and spinning suppesdly raises them.

Keep in mind i have yet to inflate my trap by spinning and have been trying for 4 years.

My buddies boosted rsx did an experiment. Hoosier drags at 15psi trapped 112 with a 1.91, He then raised them to 30 psi, and pretty much dumped the clutch, 2.42 60 112 trap.

 

[laloosh]

keep this in mind.

The only way a "spinning tire Run (slow 60ft)" could equate to higher mph is if the spinning tires act as a slipping clutch, allowing the absolute maximum HP the track can take (vs. a non spinning tire run where less than the max HP is utilized).

The concept that it's faster because it has more time to accelerate is silly. Time is funtion of acceleration, (the faster it accelerates the less time it spends on the track) and not the other way round.

 

[SPEED305]

laloosh, what about Top Speed? have you try maxing it out? just curious.

 

[laloosh]

i don't really care about top speed unless top speed is the trap speed, which in my case, its not lol

 

[tru-boost]

i've never understood it either, but it is true from what i have seen. if i bog and run a 13.9 i trap at 100, but with a tire burning launch i trap 104 with the same ET. there has got to be some science behind it, but i sure as hell dont know....

 

[laloosh]

the science part is what i want to know. Where the smart people at. I have a degree in geophysics, but still can't grasp this. Some people claim by spinning ure going slower hence having mroe time to acc without bogging or loosing rpm. To me that sounds stupid. CAuse its stillt he same distance, time doesnt mean much when u have a set distance to work with, in this case 1320 feet.

 

[happy and angry]

I'm a little confused by your problem. Is this a problem of people claiming that more wheel spin at your launch improves trap speed, or you observing that when you spin your wheels your trap speed is better?

Either way, spinning your wheels will be detrimental to both your trap time and trap speed. Tires have a finite level of grip, and you can't get around that. Spinning your wheels means you've exceeded the limits of grip, and once that happens you can't make full use of your tires until your wheels stop spinning. Your trap speed is entirely dependent on how fast you accelerate, which is entirely dependent on your ability to put the power down.

Can you clarify what you're wanting to know? I can probably give you a better explanation if I understand your question better.

 

[driver311]

laloosh Ive been racing for 10 years now. it seems that once you reach that 100mph mark slicks seem to add trap on a fwd. At that power level traction becomes more of an issue and the amount of momentum you lose at first can not be made up in the topend. Now on slicks the amount you gain on the first part more then compensates for any lost up top. MAKE SENSE?

For example my integra type r
On streets 14.7@97
On slicks 14.2@94
this is an example of an underpowered car
For example my srt4 stock
On streets 13.8@100
On slicks 13.2@101
This is an example of a car with more power and traction issue.

This is the best way I can describe it. It only gets worse the farther you go.
My friends stg3 srt
streets 117mph trap
slicks 122mph trap

 

[laloosh]

theory is: Spinning increasing trap speed, Hooking up decreases trap speed.

I dont understand this theory/nor do i agree with it. I want some1 to put some physics behind it. EVery1 cant be wrong, unless some idiot wrote it, every1 read it and believed it.

 

[laloosh]

thx for the experience driver, so technically me running a 26x9.5x16 shoudl increase my trap some. Which is what im looking for.(burnout)

 

[ill_eagle94]

Sometimes you may lose trap on slicks because they balloon at higher speeds. The larger diameter tire is harder to turn.

 

[happy and angry]

It's a pretty bogus theory. It sounds plausible, and you can even do a bunch of runs that generate numbers that seem to report it, but they are misleading.

You have a finite amount of grip AND a finite amount of distance to produce numbers. Period. If you make 100% use of both and hit every shift perfectly, your trap time and trap speed will be "perfect" considering the abilities of your car, where you can get no better.

If, however, you spin your wheels for the first 60 feet (or more), you will be going a bit slower at the end of it than if you'd hooked up perfectly. You will be behind in terms of speed, time, and have to delay upshifting until you're up to speed (or risk bogging on your first shift).

The only way a "spinning tire Run (slow 60ft)" could equate to higher mph is if the spinning tires act as a slipping clutch, allowing the absolute maximum HP the track can take (vs. a non spinning tire run where less than the max HP is utilized).

A non-spinning tire actually provides more grip. The absolute maximum power you can put down is 100% of the traction your tire has without spinning. Once you've managed to generate enough force to get your tires to spin, once you've broken that barrier, it takes LESS force to keep the wheel spinning. This is because you have less grip available on a slipping tire.

It's going to be hard for you to do experiments to prove or disprove this, because it's impossible to establish control variables. There are so many things going on, everything from shift points to throttle control to driver errors to track conditions. If you can generate a run where you run a better trap speed spinning at the launch than you do without, then your launch in the latter run wasn't making full use of the available grip.

 

[Chris Barnett]

I know a couple people know me from neons.org, HAI & SRTforums, but I'm still a noob here, but I'm still going to jump in anyways:


It is actually very simple to explain. Spinning the tires takes time. When you spin the tires, you have more time to accelerate over a given distance. So higher trap speeds, and correspondingly slower ET's are the result. Perfect traction(a misnomer if I've ever heard one), results in quicker acceleration and less time to gain speed.

The examples given above by driver311 are invalid, for one major reason. If you GAIN speed with slicks, you aren't driving the car properly, or its geared wrong(actual gearing + tire diameter).

On street tires you are more likely to spin(obviously), and thus hit the rev limiter in each gear quicker. Most people shift too early. If you do hit the limiter, ride it out for a second, while the actual speed of the car catches up to the wheelspeed. It feels counter productive, but it's the best thing to do if you've already spun that much. Pedaling it will slow you down, and shifting will cause further wheelspin or worse, a bog, which hurts both ET & trap speed. This is a very minimal rundown of how to drive a car at the strip, so please don't over scrutinize it.

One thing to note, particularly on FWD cars, is that when people switch from street tires to slicks, they are changing the overall diameter of the tire in a big way.

22", 24.5", 26", even as small as those 20" MT slicks I ran once. This will have an obvious effect on trap speed, because you just changed the overall gearing in a big way. You can't compare trap speeds on a 26" slick vs a 23" street tire, because it's really a wash.

There are obviously other variables here that effect trap speed, like weight of the rolling stock, overall power, etc. But as a general rule, with all else being equal, a car that has good traction will hit a lower MPH than one that is spinning.

 

[driver311]

thx for the experience driver, so technically me running a 26x9.5x16 shoudl increase my trap some. Which is what im looking for.(burnout)

Id bet money your car will trap higher on 26 slicks than your street tires. No doubt about it. this car is just to short geared to be boosted at high whp levels. Gearing it up will only help.

 

[GS455]

Laloosh,
The taller your tire the more MPH you will run. If you just want to run on the big end go tall and run a lot of air in the rear tires to lower rolling resistance.
I dont know how much height will fit the front wheel wells. Remember the front slicks will grow at speed so dont go too tall.

 

[PeterSellers]

I think it might work sort of like this...

Say you are spinning the tires like crazy at the very start of the track, and you aren't going anywhere. When you're tires do finally grab though (after heating up a bit from spinning, or whatever) you kind of lurch forward since your drivetrain already has a lot of momentum stored up from the engine revving. So in that very instant, you accelerate fairly quickly (or at least more quickly than you would if you were to just slip the clutch off the line). Because you haven't actually gone anywhere on the track yet, you still have the full 1320 (or close to it) to pick up more speed, but you have a slight advantage since you got that little jump at the beginning.

Obviously, this is bad for your ET since while spinning you're just burning down the clock.

I think that might explain it for some cases, although with higher horsepower cars like driver311 was saying just getting traction is probably the most important part.

 

[jbiird317]

i know this is a mazdaspeed3 specific topic, but laloosh, you might get more of a response in the motorsports section, mind if I move it?

 

[happy and angry]

It is actually very simple to explain. Spinning the tires takes time. When you spin the tires, you have more time to accelerate over a given distance. So higher trap speeds, and correspondingly slower ET's are the result. Perfect traction(a misnomer if I've ever heard one), results in quicker acceleration and less time to gain speed.

No.

You have more TIME to accelerate because you are not accelerating as efficiently, but you do not have more TRACK to make up for it. A simple example: a good launch versus a wheel spinning launch. At the end of the first 60 feet, the car with the good launch will be going faster.

You do not cover LESS distance to get up to the same speed in a wheel spinning launch. That would actually mean you are accelerating faster (which you aren't).