Do you all launch at peak boost or peak power?

I launched at peak power last time so im assuming by launching at peak boost i may get better results?

 

I launch at the point where I get the least wheelspin

 

hehe

 

Surely you cannot launch at peak boost? I thought the boost only started building once the engine was under load? (I may be wrong).

 

You can get some boost whilst under no load...just a matter of using full throttle "blips" instead of feathering the throttle and holding the revs.

 

Well if your revving the engine then surely your spooling up?

 

Launching or lunching

Dipster

 

I'm lunching right now

 

ive just finished lunching

 

16vmarc: Get a boost guage and you will see that just because you are reving the engine does not mean you have boost.
To get boost you need load on the engine, hence the use of anti-lag or launch control systems, none of which are recommended for road use or the longveity of your turbo/engine/transmission.

 

Err, yes. It helps...But please bear in mind that your gauge (unless you have a weird install) is connected to the INLET MANIFOLD.

So boost pressure under "revving" conditions is dictated by the throttle and not the turbo. With a closed throttle at high rpm you'll register a vucuum.

You'll only see what the turbo is doing under part/closed throttle positions when you connect the gauge directly to the output side of the turbo

 

To launch a turbo car you do need to generate some wheelspin, or the turbo will come off boost and the car will bog.

Drop the clutch at the point at which it will generate boost, and not bog. This point is learned through trial and error. It is dependent on the turbo itself and the level of grip available. At Elvington, good starts requireing 7,000rpm launches are no uncommon .

Harvey and others are correct, boost comes with load.

Rannoch

 

nowt wrong with mine and steves launches

 

Of course, if you are very rough with the use of the clutch, you can apply some load before the launch. Dont expect clutch to last too long though.

Or get some form of launch control.

 

Stevie,

tricky with a paddle clutch

R

 

What is a paddle clutch?? Does it not have a biting point just on or off?

 

Is that burning clutch I smell?

Best way to get a 4WD off the line if you don't want to kill your transmission is to let the clutch out briskly at low revs then floor it!

You could always use the '7000RPM and dumped clutch' approach, but don't come crying to us when your gearbox explodes!

Best

 

At Crail, I did 1.8 60' times launching at 3500 RPM with very little practice on normal road tyres at normal pressures. But the motor was quite torquey with a short 1st gear and a smallish turbo.

 

That is a very good time John. At the hill climbs, the distance is 64 feet, so to cover 64 feet in 2 secs = 1G accelleration.
It seems easier to pull good starts on road tyres, I can get 2.1's on Toyo's consistantly, on my Kumho's it's much harder to be consistant.
Issue is getting wheelspin down to wheel 'slip'; my Sti spins its rear first and then the front breaks free.
Out of interest maybe, my 911 will pull the same 64 ft times on SO2's as the Impreza on Kumho's.
Pre start tyre warming helps on the Kumhos but does nothing with Toyos.

911

 

Bloody hell. 2.1 on the 1st 64' ! Jeeeezzzzzz

In the Pug 205 I managed a 2.67 which was a bloody good start on road tyres in a FWD car.

Unfortunately when I used to compete in the Impreza split timing wasn't available at the event so I can't compare other than the Pug feels hideously slow off the line in comparison.

My technique used to be 5500 and floor the throttle as the clutch came up. Always got wheelspin off the line but launched bloody well. 1st gear wasn't ever a problem, but ate a few gearboxes over its 2 year hillclimbing life on the Impreza...... oh and several AP Paddle clutches

 

Do a lot of you Double-clutch to launch? Believe someone mentioned this method earlier...

 

2.1 in my class is a bit cr@ppy!

The EVO 5 with full GEMS/460 bhp etc can cut 1.93 on Yoko road tyres........
And the Audi quattro on slicks can cut 1.88!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I think it is interesting that a 911 weighing 1000Kg on 7'' rims and SO2's can match the Scooby in the dry.

911

 

No, engage 1st gear on start line press loud pedal till 5k showing, dump clutch and ignore all mechincal sounds till in second. Quick check in mirror for gearbox and proceed down main straight.

I have on occassions tried less revs and slipping the clutch very slightly but it never works, always bogs down or cooks the clutch.

Mark

 

Way to go!
911

 

Have to add that the majority of my starts are on cold slicks, so initially it's happy to spin the wheels. When the car is shared the second person is in the lucky position of having very sticky slicks and therefore gets a better launch.
My understanding of the sprint rules is that I'm not allowed to do a dummy launch, so the tyres tend to be cool.

If I had the money I'd stick some very sticky slicks on, but then you run the risk of picking up loads of crap on them in the pits/grid

Racing on 23rd October and might try road tyres in the free practise and compare times.

Anyway my 2p worth.

Mark

 

Tell all on the 24th Mark!
On the hills there is a 'spin wheels' area just before the start area, really for warming tyres and getting the stones of the (driven) wheels rather than pelting the start line marshals with a free grit-blast.....
Never really considered that cold (Avons?) will spin when cold so saving the poor gearbox.

911