Revs and Tyres Pressure for Perfect Start

[Jagz]

Hi Guys and Girls,


I'm going to Santa Pod on Sat ND Aug. I drive a 172 with a performance exhaust.

Does anyone one know what i should hold the revs at for the best possible start. I know i need to turn off the TSC (Traction Control System) but is there any other serious tips.

Also running on 205/45/16 tyres. I'm guessing a slightly lower tyre pressure will give me that little bit more grip. Is this correct? If so what tyre pressure should i use?

Thanks

 

[Englebert]

Wrong forum... but in theory lower tyre pressures would give more contact area so more grip. I don't know anything about drag racing but i've seen proper drag cars run very low pressure tyres.

 

[Jagz]

Glad im thinking along the right lines. I thought this would be the right forum as it is about motorsport.

 

[Jagz]

Anyone got any other ideas. Its in 2 days

 

[Keith185]

Trail and error I guess is the only way for finding out how much revs you need for the start (start at say 3k) then work from there.

 

[Jagz]

Cool. I was goin to go striaght out with 4500. I thought someone with launch control might know the answer.

 

[Brown.]

Cool. I was goin to go striaght out with 4500. I thought someone with launch control might know the answer.

launch control dont just set revs.....it adjusts/ limits power to the wheels aswell. . . 5% slip is required according to tiff when doing the 0-60mph record on the twin engined lotus 7......so if its dry try to hold revs, dump cluth churp churp churp of the wheels then floorit........ iirc 4500- 5000rpm in and RS will be be optimal.

 

[Inferno]

My best time at santa pod was somewhere between 4 and 4.5k rpm with the front tyres at 20psi. It was a damn hot day though 32 degrees iirc!

 

[Daz Clio Cup]

Cool. I was goin to go striaght out with 4500. I thought someone with launch control might know the answer.

I've got launch control......however i haven't found the best rev launch yet! lol

It depends on the indivdual car and driver, you need enough revs to stop the engine bogging down, but not too much to stop wheelspin.

You have traction control, why not use it? IMO wheelspin is as bad as the computer cutting power to stop wheelspin............any other views?

 

[Whiteley]

Other views........ yeah flat shift is MINT!!

 

[Daz Clio Cup]

Other views........ yeah flat shift is MINT!!

It is, but sounds a bit like an automatic though ?

 

[Jagz]

i work in a pub and a local who happens to be a car tuning spec and ex racer say just floor it. dont worry about the wheel spin you will be quicker if you wheel spin then if you dont.

20psi. cool i was goin to drop to 25 if know one new.

What is Flat shifting???


Well i dont want a computer to cut out the power coz it takes a second or two to give me full power again. that IMO. i think its great for everyday fdriving infact i have only turned TCS off twice. Save tyres etc. But for track i think i shuld turn it off

 

[Daz Clio Cup]

i work in a pub and a local who happens to be a car tuning spec and ex racer say just floor it. dont worry about the wheel spin you will be quicker if you wheel spin then if you dont.

20psi. cool i was goin to drop to 25 if know one new.

What is Flat shifting???


Well i dont want a computer to cut out the power coz it takes a second or two to give me full power again. that IMO. i think its great for everyday fdriving infact i have only turned TCS off twice. Save tyres etc. But for track i think i shuld turn it off

Quicker if you wheelspin......b*ll*x. If I floor it in mine with normal road tyres, it will just sit there. Don't know what the TCS is like, i have a cup. But you still want as little wheelspin as poss. 20 PSI may be a bit low, experiment is the best answer. take too much air out and you end up only having contact on the outside edges - don't forget road tyres are a long way from drag slicks.
Flat shifting or full throttle gearshift, is a clutch switch which retards the ignition ( to drop the revs) so i can keep the throttle wide open when changing gear

Daz

 

[Keith185]

Quicker if you wheelspin......b*ll*x. If I floor it in mine with normal road tyres, it will just sit there. Don't know what the TCS is like, i have a cup. But you still want as little wheelspin as poss.

From experience of my clio, the standard traction control system gives quite some slip before cutting in. Try with it switched on?

 

[Henry]

brave driver who flat shifts this g'box!:dead: :dead:

 

[Daz Clio Cup]

brave driver who flat shifts this g'box!:dead: :dead:

Nah, it flat shifts fine. Got a 14.1 @102mph with wheelspin off the line. just gotto sort the launch out as launch control failed to do the job!

 

[Dooby]

brave driver who flat shifts this g'box!:dead: :dead:

Nah, it flat shifts fine. Got a 14.1 @102mph with wheelspin off the line. just gotto sort the launch out as launch control failed to do the job!

What have you had done to your car?

I Ran a 14.6 at 96 in a f/f 182 with only exhaust, hill power filter and group n map.

There are cups on here that have run the same time as you with the same mods.

 

[Daz Clio Cup]

Nah, it flat shifts fine. Got a 14.1 @102mph with wheelspin off the line. just gotto sort the launch out as launch control failed to do the job!

What have you had done to your car?

I Ran a 14.6 at 96 in a f/f 182 with only exhaust, hill power filter and group n map.

There are cups on here that have run the same time as you with the same mods.

When it was standard, with just an exhaust and air filter (panel) i did a 14.6 with a near perfect start. that's how i know my starts now are rubbish as i have an extra 65 bhp and 80 kgs less weight!

the main problem is too much power and not able to put it down! lol

I haven't heard of any RS's with the same mods as me, close to but not the same. and as far as mods it's about as close to full race as you can get without being full race(hasn't got race cams/solid lifters or lightened balanced crank/flywheel)

 

[Ex-User (19928)]

IMO Letting pressures down on normal road tyres is going to be more of a hinderance.

Sure, it could give you a bit of help getting off the line... But once you're up to speed, hell, even at 50mph, 20psi road tyres are going to create a bit of drag and slow you down.

Revs... tbh Surely if you own a 172, are registered on CS and are going to SP then you'll have practiced launching before??

Having never driven a 172, I would imagine it's the same as any NA petrol FWD and as most people have said, 3-4k rpm and then it'll be about moderating the throttle.

Another pointer will be to do a standing burnout before you set off (i.e. stop it when there is smoke pouring off the tyres) as this will get them up to temperature. PS Set your air vents to re-circulate whilst doing this, otherwise you'll fill the car with tyre smoke.

 

[Dooby]

What have you had done to your car?

I Ran a 14.6 at 96 in a f/f 182 with only exhaust, hill power filter and group n map.

There are cups on here that have run the same time as you with the same mods.

When it was standard, with just an exhaust and air filter (panel) i did a 14.6 with a near perfect start. that's how i know my starts now are rubbish as i have an extra 65 bhp and 80 kgs less weight!

the main problem is too much power and not able to put it down! lol

I haven't heard of any RS's with the same mods as me, close to but not the same. and as far as mods it's about as close to full race as you can get without being full race(hasn't got race cams/solid lifters or lightened balanced crank/flywheel)

Sorry i ment run the same time as you with just remap, filter and exhaust.

 

[MarkCup]

IMO Letting pressures down on normal road tyres is going to be more of a hinderance.

Sure, it could give you a bit of help getting off the line... But once you're up to speed, hell, even at 50mph, 20psi road tyres are going to create a bit of drag and slow you down.

They did this on Vroom Vroom - with their Astra estate...each week it was run up the strip after a cheap 'mod' i.e. stripping it out one week, big cone filter the next, and upping tyre pressures.

When they pumped the tyres up to something like 40psi I think they took 0.1s or 0.2s off the 1/4 time.

 

[Daz Clio Cup]

IMO Letting pressures down on normal road tyres is going to be more of a hinderance.

Sure, it could give you a bit of help getting off the line... But once you're up to speed, hell, even at 50mph, 20psi road tyres are going to create a bit of drag and slow you down.

They did this on Vroom Vroom - with their Astra estate...each week it was run up the strip after a cheap 'mod' i.e. stripping it out one week, big cone filter the next, and upping tyre pressures.

When they pumped the tyres up to something like 40psi I think they took 0.1s or 0.2s off the 1/4 time.

Mmmm interesting.
Haven't you done pod mark? What tyres do you use? I tried 888's this time but couldn't get enough heat in them

 

[MarkCup]

Nope. 1/4 miling is the past time of Satan.

 

[Jagz]

hi guys i ran a 16.02. standard with exsaust. (Dyno'd the same as standard BHP) Top speed was always the same at 96mph. Ran 20spi in the front and 30psi. Always had a great start. I will get the videos up and the slip times. So if any knows enough to tell what i was doing wrong or right. please let me know so i can improve.

 

[Ex-User (19928)]

^ Probably the 20psi bit if you were using road tyres!

They did this on Vroom Vroom - with their Astra estate...each week it was run up the strip after a cheap 'mod' i.e. stripping it out one week, big cone filter the next, and upping tyre pressures.

When they pumped the tyres up to something like 40psi I think they took 0.1s or 0.2s off the 1/4 time.

Makes sense, especially with a van, traction wouldn't be a big issue and minimising friction on the move would help.

...do a standing burnout before you set off (i.e. stop it when there is smoke pouring off the tyres) as this will get them up to temperature

...I tried 888's this time but couldn't get enough heat in them

If you didn't smoke them then that's why, if you did smoke them, you didn't do it for long enough!

 

[Jagz]

 

[Jagz]

 

[Jagz]

 

[Jagz]

These are my Santa Pod racing slip times in order and there is a line under my car number A632 to show which times are mine.

 

[Jagz]

This is my super concentrating face. lol

 

[Jagz]

 

[Jagz]

 

[Jagz]

 

[Jagz]

Now got the videos up so just click them to watch. Hope you enjoy. I did. had a fantastic time and next year it would be good to get a group of us together.

 

[Jagz]

I have put the race slips times and MPH on to excell and these are my results