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Sub 5 sec 0-60 attempt

2K views 60 replies 8 participants last post by  Steve! 
#1 ·
I want to hit a sub 5 sec 0-60 at trax this sunday. Last year i managed a 5.36 at the FCS at Bruntingthorpe. Since then I've saved more weight and have adjustable suspension (raise / stiffen the rear).
The 5.36 run was done on shagged out yokohama a539's that have gone very hard, I still have the yoko's but am unsure on the following, do I

A) get some tyre softener and treat them b4 the weekend

or

B) buy a pair of Toyo R888's?

Any advice or people with experience appreciated. :beer:
 
#6 ·
Cool, not an issue then, just something ive seen other small blocks doing.

They either have too many rpm and light up or not enough and bog down, seems to be harder to launch one just right than a big block motor.
 
#7 ·
CP used to somplain that his 1.4 16v would bog down off the start, but i really can't see that happening, maybe i'll be surprised how much grip a decent set of tyres can generate :confused: But i never launch using many rpm, so i've got plenty spare if the softer tyres need it for a good launch :nod:
 
#8 ·
I think you are slightly missing the point, lol

The problem if you start needing lots of rpm, is that you then light the tyres up or have to slip the clutch like buggery to get away, neither of which is good.
 
#10 ·
Don't worry about your clutch, if it means that much to you to make a good time just fry it. They're not expensive are they?
 
#11 ·
tathan said:
Don't worry about your clutch, if it means that much to you to make a good time just fry it. They're not expensive are they?
Kind of limits the number of attempts you get though if you overheat the clutch and glaze it on your first go lmao
 
#12 ·
chip said:
I think you are slightly missing the point, lol

The problem if you start needing lots of rpm, is that you then light the tyres up or have to slip the clutch like buggery to get away, neither of which is good.
I disagree, If you double the grip at the tyres then you can double the force without breaking traction. Therefore revving higher and producing more force will lead to inreased accel as a=f/m. I don't see the need for lighting up, yes clutch slip will be involved as with any standing start, but no slipping like buggery. If anything reduced slipping as slip is only required to allow the engine to be held at a suitable rpm to prevent 'bog' till the roadwheels are rotating at such a speed that when drive is fully engaged 'bog' is prevented. Since with stickier tyres the accel will be greater the time taken for the vehicles speed to get out of the 'bog' will be less and hence less clutch slip.
Again stand to be corrected, Your thoughts?
 
#14 ·
chip said:
Kind of limits the number of attempts you get though if you overheat the clutch and glaze it on your first go lmao

It's only FWD, it won't get that hot.




Probably ;)
 
#15 ·
dhdev said:
I disagree, If you double the grip at the tyres then you can double the force without breaking traction. Therefore revving higher and producing more force will lead to inreased accel as a=f/m. I don't see the need for lighting up, yes clutch slip will be involved as with any standing start, but no slipping like buggery. If anything reduced slipping as slip is only required to allow the engine to be held at a suitable rpm to prevent 'bog' till the roadwheels are rotating at such a speed that when drive is fully engaged 'bog' is prevented. Since with stickier tyres the accel will be greater the time taken for the vehicles speed to get out of the 'bog' will be less and hence less clutch slip.
Again stand to be corrected, Your thoughts?

I can see EXACTLY where you think you are coming from, it just doenst work like because the increased traction you refer to also increase the rpm at which the engine will bog down in the first place on any given flywheel, so you arent using your extra grip to get to the same engine speed you are using it to get to a higher engine speed, hence slipping for longer.

Obvioulsy it depends GREATLY on your current flywheel wait etc and how sticky you are going on the tyres etc, on the tyres you mention, you are only talking about a relatively moderate increase in grip, so it MAY not be an issue at all.

Try it and see, you may come away thinking "ah, now i know what chip was on about" or you may come away thinking "nope, load of rubbish lighter the flywheel the better" until such time as you come across a better example of what im saying, at which point you will then realise what im on about, LOL



Also worth considering a clutch stop on your car to improve your consistancy, but only if you have time to practice using it first to know where to set it of course!
 
#16 ·
chip said:
I can see EXACTLY where you think you are coming from, it just doenst work like because the increased traction you refer to also increase the rpm at which the engine will bog down in the first place on any given flywheel, so you arent using your extra grip to get to the same engine speed you are using it to get to a higher engine speed, hence slipping for longer.

Is the reason for the increased 'bog' rpm you suggest, because 'bog' is reduced with the harder tyres due to a degree of wheel slip (as opposed to a full spin) allowing for reduced clutch slipping? This is the only way i can make sense of what you've put lmao
 
#17 ·
dhdev said:
Is the reason for the increased 'bog' rpm you suggest, because 'bog' is reduced with the harder tyres due to a degree of wheel slip (as opposed to a full spin) allowing for reduced clutch slipping? This is the only way i can make sense of what you've put lmao
Kind of.

Think of it this way, you have the tyre and you have the mass of the car, from those you work out the absolute maximum rate of acceleration possible within those constraints.

From that you can use your "f=ma" business to see the force required.

Now this force that your engine must match in the speed that you left the clutch up at.
Your engine has two places to get that force from, one is the torque its making at the time, and two is the amount of kinetic energy it currently has stored in the flywheel and crank rotating.

Now the quicker you let the clutch up, the quicker then engine has to supply that amount of force, so if its got more kinetic energy in the flywheel then its going to manage it more quickly.

Hope that makes sense, ive been in the office since 9am this morning and havent gone home yet so it might not, in which case i will clarify in the morning lmao
 
#19 ·
parachute :beer:


One last point, seeing as you seem fairly "physics minded" think of it this way, to get your car up that strip requires and amount of energy, the amount of energy is obviously partially dependant on your terminal speed, but assuming thats the same so is the energy requirement roughly.

The more energy you have in the flywheel at the start of the run the less time it takes the same engien to provide the rest of the energy requirement.

So why dont people have 1 ton flywheels? Ah, thats for the same reason, if you have too much energy in the flywheel then your "light the tyres up speed" decreases just like your bog speed does, and you end up having to slip the clutch like buggery to avoid lighting up for that reason, LOL

Its a complicated process and TBH trial and error is the only way to really know what works best.

I was just mentioning the flywheel as its a part of the equation people often forget, in reality though, probably make very little difference in your case and i apologise for ruining your thread with so much talk about something who's effects are so small.


On the subject of tyres, why not go for the R888's and use some tyre softerner on them?
Or better still use some road legal drag radials?
 
#21 ·
m50 bmw engine do you mean?


The point i'm trying to make is that there is an optimum weight of flywheel for launching any given car on the strip, if you change anything significant about the car (like its power/weight/grip) then that optimum weight for the flywheel also changes.

So without knowing anything about your car i would say that one of the following is true:
a) your car has the perfect weight flywheel now for a quarter mile
b) your flywheel should be lighter
c) your flyhweel should be heavier



Once you have the perfect weight flywheel, take it on a track isntead of a drag strip and its about 99.9% likely its now too heavy.

dont you just hate compromise?


LOL
 
#22 ·
No no, I read on Scoobynet that the lightest flywheel possible makes your in gear times substantially quicker :s



Serious point, tyre softener only softens the very outermost skin of the tyre, you'll be down to fresh rubber after one attempt at heating the tyres. I know someone who used to use it loads on track days, and he barely got sub-1min laps in a light car out of it.
 
#23 ·
chip said:
m50 bmw engine do you mean?


The point i'm trying to make is that there is an optimum weight of flywheel for launching any given car on the strip, if you change anything significant about the car (like its power/weight/grip) then that optimum weight for the flywheel also changes.

So without knowing anything about your car i would say that one of the following is true:
a) your car has the perfect weight flywheel now for a quarter mile
b) your flywheel should be lighter
c) your flyhweel should be heavier



Once you have the perfect weight flywheel, take it on a track isntead of a drag strip and its about 99.9% likely its now too heavy.

dont you just hate compromise?


LOL

So keep it as it is! Its not a track car never will be, never want it to be. I want it to be quick like!
 
#24 ·
Tathan, it does indeed increase your in gear aceleration if you go ligther, thats the main reason why ligther is better on trackdays as you dont launch at all on most trackday but you spend the whole time acceleating and decelerating in gear.

Mind you too light also means the revs drop too low between changes unless you start heal and toeing it too of course.

So much more to flywheels than people normally think about!
 
#25 ·
ZafiraSteve said:
So keep it as it is! Its not a track car never will be, never want it to be. I want it to be quick like!
TBH, if it works well now, dont spend money trying to find out which flywheel is best, its only a small effect we are talking about here anyway and generally its one of the last places to worry about spending on most cars :beer: (v6 vectra being an exception though lmao)
 
#26 ·
It does work well, 0-60 times I GUESStimate at high 6's so far! Im running 200bhp in an E30. Well you drove a 171bhp e30, you know how fast they are! Add another 30bhp to that.......you get the idea, but more to come yet! BBTB and mapping to start.
 
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