Dennis C

I know that there is an overboost function associated with the Sport Chrono Turbo package and an arrow that illuminates in the gauge cluster when overboost is activated.

I have Sport Chrono, but I've never seen the arrow. Today I had the car in sport mode and I ran it all the way up to redline, and I never saw the overboost arrow.

Is my overboost malfunctioning? Does it only activate in certain gears? I'm going to read through the manual, but I thought I'd ask here too.

Thanks!

saabin

You only get the arrow when you mash the throttle..if you are easy on the gas at all, no arrow.. Has nothing to do with what rpm or gear you are at.

aa909

Exactly. You can take to redline and be 3/4 on throttle and never get over boost.

Best what to test it is cruise at 3K-4K rpm in 4th, then floor it. I get over boost 99% of the time when I do that.

Quadcammer

start at 2200rpm in high gear and got WOT. Don't roll onto the throttle, don't be smooth, just slam the pedal down.

Dennis C

Thanks. I'll try tomorrow.

MKIVdan

Doubtful you will see arrow up in 1st or 2nd gear. Higher gears will do the job

Duckstu

The over-boost is mostly an advertising gimmick.

It "allows" an extra 3 psi between 2,000 and 4,100 rpm. However,.. that doesn't mean you'll actually "get" an extra 3 psi for that entire range.

You rarely mash the gas from 1,500 rpm. Probably more like 2,500. And the compressor and turbine wheels in the turbos are heavy enough that you usually don't get full boost until about 3,500 (at least not in the first 3-4 gears). So really it's an extra 3 psi for about 600 rpm worth of the mid-range.

If you really want to see it in action,.. you'll need to go slowly on the freeway,.. select 6th gear,.. and mash the gas from like 1,800 rpm. Of course this is something you'd never do in real life,.. which is why I consider the over-boost thing a gimmick.

The real value of the sport crono is that it adjusts the vanes in the turbos,.. sharpens the throttle response,..and dials back the stability control a bit (and of you have PDK,.. it quickens the shifts and raises the shift points)

MadScience

I actually do just that. It's hardly optimal, and an artifact of driving a manual with stupid amounts of torque in traffic, but I do it.

They up arrow will come on, even if the car won't build build boost for whatever other reason. (I learned that tonight on a car that needs further debugging -- sigh).

RJKflyer

On my PDK, 'kickdown' (of course) brings the arrow on. But/and that's avery aggressive driving only for the right moment.

But people are right that even heavy acceleration at large throttle openings doesn't generally activate it. This is probably the first car I have had where WOT is used infrequently...

I wouldn't classify it as a gimmick - it's an extra 50Nm of torque and it can be felt/noticed in a back-to-back comparative sense (e.g. accelerating from say 60-120 very hard (just not quite o/b) and WOT (o/b on).

Additional to that said, SC also hardens the Dynamic Engine Mounts on the .2 if you have them, and changes the 'moving off' programme of the .1 Tip box. (i.e. uses 1st, not 2nd).

Dennis C

I can definitely feel the difference in sport mode. Maybe my arrow has been illuminated but I'm busy looking at the road and the tach and I miss it.

Quadcammer

its a small arrow for sure.

Marauder1

Good thread as I never noticed my arrow either and I'll try to get the darn thing to light this afternoon!

djillusion

It's also easier to hit in sport plus mode. That's where I get it with a bit more 'ease'.

Igooz

FWIW: Over Boost does come on in 1st. gear - 6th. gear; not sure if you can actually feel the difference or not but the car is rated at 500hp vs. 480hp when you are in over-boost; and you can stay in Over boost up to red line/shift point. To activate you need to have the throttle pressed all the way down to trigger WOT and Sport mode on.

To OP, I actually took the attached photo a few years ago in your home state of CO (I keep some cars there) when this topic came up.
Notice arrow up, and 17psi which is what should happen in a stock 997TT...(5,000 rpm ~85mph, what gear is that?)

caslca

I can get the arrow with ease in my 6mt .2. However, i've never seen anything above 15psi...I only tried in warm weather though(well at least as warm as it gets around Seattle) - not sure how much difference that would make but looking forward to try it in the cold