usccharles

Is it just me that didn't realize this? Have you guys with 991.2 (mine is 4 GTS) checked your boost gauge on Sports and Sports+ mode? The boost is different. I floored it a couple times today and boost maxes out at 15-16 pounds on Sport mode, 18 pounds on Sport +

I thought the different modes only changed throttle response but I guess it actually affects horsepower. anybody have specs on how much horsepower this 2-3 additional pounds of boost equates to?

i'm not sure if it is the nature of the turbo or the gauge itself but I notice its also not very easy to reach 18 pounds of boost even on Sports+ mode. When I try to floor it from second gear to third and fourth, many times it will only spool up to 16 pounds never reaching 18. I have to start from a full stop and do launch control to consistently reach 18 pounds. I find this very odd. and here is my conspiracy theory about this.

Please correct me if my memory is wrong, but from my own experience of playing around with my mitsubishi back in highschool upgrading my turbo and gauge, normally after the initial spool up the turbo will hit max boost and stay there until i shift. in the porsche the turbo, rather than quickly hitting max boost, is constantly spooling up as the engine revs up and just hits a max of 18 pounds at around 6500 rpm and even goes down in boost while i'm still floored to redline. which leads me to believe that if it isn't the gauge thats screwed up, the ECU is somehow controlling the spool up, perhaps bleeding some pressure as it builds up to 18 pounds, while the throttle is even floored, making the car feel more naturally aspirated rather than giving the usual turbo oomph as turbo kicks in. anybody else notice this?

Actually, if what I'm sensing is true, then one can actually hack the ECU so that the turbo spools up to max boost of 18 pounds without any controlled bleeding so that the car is at max boost quicker and longer. this would be more power for the car in the rev range but it wouldn't actually be damaging to the car because youre not messing with the max boost.

also, i find this kind of irritating now that max boost is only on Sport +. I never use Sport + on the street as i'm not comfortable with the shifting. its too rough for normal roads. So its always Sport mode for street and Sport + for track. meaning i have been driving my car, unknowingly, under its full potential, and if I want the full horsepower i have available to me, then I have to deal with the rough, albeit quicker, shifting and the overly aggressive rpm shift point algorithm. I should be able to enjoy full horsepower no matter what driving mode i'm in.

its kind of funny because i made a post while back about how nice it would be if the car was alittle detuned for street use as I can never really make use of all the horsepower to enjoy the full rev range in city road but it looks like porsche is actually doing this.

i wonder what the boost in normal mode is, which i have yet to try.

Mark993TT

I don’t believe these cars are being “detuned ” by Porsche in normal and sport mode to deliver less than their max power/boost.

I cannot verify myself yet, but probably someone else can and will.

TimboCarrera

Just did video of runs in sport and sport plus on my 2017 base. 11 peak boost in sport, 14 peak boost in sport plus. driving in sport + with pdk in manual best of both worlds imo...

eagletangogreen

Yeah well today I did about 10 pulls from 2nd to 4th (991.2 C4S with 2100miles) and it should be boosting to 16psi. However all I saw today was 14psi in all modes once and saw multiple 13psi all day. It boost to 12psi very fast then takes its time to work up to 14psi (temp 40deg). I was in FL last week and saw 15psi for quick sec. My GTR hits max boost fast and stays there, is there something restricting the 991.2 from producing max boost and maintaining it?

TimboCarrera can you share you videos?

TimboCarrera

my vids are bad, handheld phone.
pm an email I'll send the raw however I had to screenshot a frame to accurately see the 14. And 14 was a real crescendo. Worked to get it there.

subshooter

I'm sure you have seen this pic from our manuals but it doesn't mention anything about changing boost when modes are changed.

stout

Really curious about this, too. I was told no change in boost pressure on the launch...

Very interesting.

TimboCarrera

eagletangogreen

I just went out again a did a few runs.. The best I could do was 13 psi in normal and sport mode. When I switched it to sport plus I saw a quick 15psi however its never the same. Looks like there are many other owners experiencing the same issues with boost.

Im going in to get my X51 kit installed with the AWE exhaust and cats this coming Tuesday, this should hold at 18 PSI... We will see.

PCA1983

My recollection is I read that maximum short term boost does increase in Sport Plus in some models.
But it is also a function of your gasoline octane rating.

usccharles

I’m glad to see I’m not the only crazy one experiencing this. FYI My experience is in order to consistently get max boost in each mode is to do launch control. I suggest everyone go out and try for yourselves.

Seeing this has me really considering an aftermarket ECU upgrade after my warranty ends. Clearly these cars are tuned down. A smart shop can probably max out the existing boost levels accross the rev range to gain significant power without even stressing the motor with just max boost increase. Someone should ask Nick to check how the boost increase changes accross the rev range on the GIAC ECU upgrade he tested.

K-A

So....

On 991.2's, we've uncovered that Sport+ cars actually deliver higher power?

usccharles

Actually, Nick’s Video already shows the tune’s difference in the turbo it’s max boost.

usccharles

hmm i'm surprised not so much interest in this as I would have imagined.

I really like my snap crackle pop exhaust of the Sport mode but am now having to drive in Sport + mode even in the city if I want to have full available boost, and hence power, available to me. I may be wrong but I think other members who replied show that Sport + mode indeed generates more boost and power than Sport.

Next time when I'm out of the city and out on some open roads I would like to take video of the boost gauge during launch control for both Sport and Sport +. I have a feeling even the boost buildup of both modes are different and want to see if boost spools up even faster in Sport + before hitting max boost.

arter

This was discussed in another thread already which might be why the lack of response.

What I would like to know is if the 20 second over boost button gives even higher boost levels ( or is it a temporary sport + position).