R35 Circuit Work And More Power

[LSX-438]

I recently added some more power to my R35, whilst it was great for simple straight line stuff (running 11.1 @ 125mph at WSID) i found that my circuit laps times have actually gone backwards (!).

My conclusion: the extra power is inducing VDC/Traction Control "events" (wheel slip) and pulling power.

Background: If you've ever forgotten to put your R35 in 'R' mode on the circuit, you will have noticed/heard/felt the system working each corner of the car, with the threshold of slip being rather pessimistic. However put the car into 'R' mode - the system then allows a higher degree of slip & yaw, less instrusive & better laps times, and more fun...

Anyway, with the aftermarket tune - say +60rwkw - 'R' mode seems like 'non-R' mode used to! (on the circuit anyway). I think the extra power is overwhelming the delicately tuned 'R' mode thresholds built into the VDC calibration.

So... consider this a heads up! Adding gobbs of power isnt going to immediately translate into quicker lap times. Unless you're comfortable turning VDC off, and driving the thing on your wits alone.

The sprint series i am in doesnt allow aftermmarket tunes, so i need to remove the tune anyway (for this coming weekend) but i thought this might spark some debate on the matter. Perhaps some others have tried adding significsant power to the R35, very interested in your thoughts (in a circuit racing context).

Edited September 6, 2009 by LSX-438

[andrejp]

Driver tuition is your answer to better lap times, not more power!

Edited September 6, 2009 by andrejp

[LSX-438]

Driver tuition is your answer to better lap times, not more power!

Driver training is probably never a bad thing, especially for amateurs like myself. But i dont think that's the primary issue here. It sure is easy/tempting to suggest that though; most people that have not driven the R35 on the track think it drives itself. That's probably true to an extent... up to about 80% of the cars potential.

That extra 10 to 20% isnt a cake walk.

Anyway, with normal power, in R mode, on the track, with RE55's, i don't feel VDC kick in, ever - unless i've made a huge error. However with (significantly) more power, it seems to break loose much more easily. Extra slip isnt necessary a bad thing, in fact i reckon a certain percetage of slip is required for the absolute quickest times (dependig on tyres). However the VDC calibration only allows so much slip. No amount of tuition is going to get around this - it's a hardware/calibration issue.

The answer is, be content with standard power OR be prepared to turn VDC (and your warranty) OFF. It's probably a non-issue, given anyone running a tune probably doesnt have a warranty anyway. This is just a heads up/fyi for R35 owners, and what to expect when you add gobbs of power

Edited September 6, 2009 by LSX-438

[Gibbo_R35]

I actually noticed the increase intervantion of the stability control even with just the Midpipe added. In R mode I am getting it come in more than I did before.

I have not tracked since the mid pipe was installed however I have a day planned in about 3 weeks so I can finish of the Bridgestones before the Dunlops go on.

It is an interesting point you have raised Duncan and I am curious now.

Cheers

[Marlin]

This is a fairly common trait in newer vehicles equiped with stability control (and importantly torque limiting protocols). Adding more power often leads to excessive interuptions, whether it be a tow vehicle or race car, and could possibly lead to a slower lap.

My suggestion would be to switch it all off.

[targa]

This is a fairly common trait in newer vehicles equiped with stability control (and importantly torque limiting protocols). Adding more power often leads to excessive interuptions, whether it be a tow vehicle or race car, and could possibly lead to a slower lap.

My suggestion would be to switch it all off.

You can end up very very sideways with it switched off

Believe me I know

90 degrees to the track at Winton in the sweeper

[Marlin]

lol, come on Jeff, you can end up sideways in anything if you fluff it up mate

We did last year's Tassie Tarmac Challenge (Rally Burnie) with it all off in some real grotty conditions and only took it off road twice

Edited September 7, 2009 by Marlin

[LSX-438]

This leads me to a question i should know the answer for... when you turn VDC off, what exactly is turned off? Is it just the traction control mechnaism? What about torque split (front vs rear) and god know's whatever else is in the system?

[Beer Baron]

yeah turning it off is the only answer. even in R mode with more power you will be cutting in the traction control/stability control often and it will slow your times.

I have driven standard R35 on track and upgraded (exhaust, ecu etc) and prefer VDC to OFF. yes you will find yourself dealing with some power oversteer but its very controlable if you know how to use throttle and opposite lock (and I'm sure you do mate).

it's not like it becomes a scary unbalanced car when you turn VDC off. the chassis is great, it still has loads of grip and the active torque split is still working as it should. just no traction control will cut in no matter how sideways you get it. but I honestly reckon you would have to actually try to spin one off the track. they are very controlable in a slide and you can easily balance the car on the throttle. and it's fun.

[LSX-438]

makes sense, thanks Richard

[Martin Donnon]

Its one thing to sit here and tell you how to drive....but from what I know you already have more than a good handle on that.

The answer lays in something else, and thats the ability of the turbocharger system of the GTR to unbalance the car. If you stand on the throttle at the wrong point of the corner in a GTR its easy to unbalance the car, even slightly step the tail out, and lose time. VDC-R isnt so much the problem, but the ability of the car to change direction and correct for a rapid shift in lateral G-Force really is! The key is to be as smooth and progressive as possible, with the fastest lap times coming to the calmest driver

This is why when I custom tune a GTR for the track I do this -

Notice that the boost curve progressively pulls away from stock and then only by a psi or so from 4200 (thats over an off the shelf Stage II Cobb tune). The key to giving a GTR more power AND improving lap times is by minimising the throttle-on imbalance of the car and keeping the power curve as linear and 'spike free' as possible. This is difficult with an airflow based wastegate duty cycle table (as the GTR has from the factory), so we spend many hours developing wastegate control maps that keep boost spikes out of full throttle upshift and keep the GTR balanced on the exit and transition

This is not saying the way anyone else does it is wrong. There are some out there in Aus that seem to have a good handle on the GTR and reflashing. Just this way is how we do it after spending a few hundred laps trying different things in our own R35

[LSX-438]

interesting Martin. I guess this makes sense.