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New GTS boost pressure?

11570 Views 24 Replies 15 Participants Last post by  purekoryo, 
E
I am familiar with the break-in debate, and consider myself part of the 'break-in-is-not-necessary' group.

I have however noticed that during the first few hundred miles, there is a difference between the boost pressure on my 718 base and my 718 GTS. I know that the technical specifications show the boost pressure for the base 718 to be 1.4bar, and the GTS to be 1.3bar. At 150 miles or so, the base 718 indeed was pushing 1.4bar.

After 400 miles, the GTS is still pushing max 1bar, and I am left wondering if this is part of the mystical software break-in period.

Any ideas? Any similar experiences?
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ZuffenHouseRules
epapp said:
After 400 miles, the GTS is still pushing max 1bar.
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What is the max. PSI you observe under WOT run starting at low-revs in 2nd gear in Sport mode? Also, what are ambient conditions (humidity, temp, elevation) where you are?

I'm unable to coax more than 11 psi (observed) out of my S -- in situation above -- yet it feels to be pulling hard and strong consistently and the ECU is not throwing off any codes. I'm at 7400 miles so clearly nothing to do with break-in. I'm thinking the ECU is simply not calling up higher boost in this case because it is able to achieve its optimal state (combination of boost, back-pressure, turbo-flow, temps) with the lower boost. Perhaps because the ambient air is relatively dry, cool and sea-level -- all contributing to highest density -- to begin with.

Because you're seeing lower max. boost with the GTS versus the 2.0 (in similar ambient conditions presumably), I'm also thinking VTG factors in here. Although somewhat counter-intuitive, possibly improved flow with reduced back-pressure from the large VTG turbo can achieve programmed objectives for peak power with *less than* max. boost. Certainly this is true at the top of the rev band -- maybe it can be true everywhere on the rev band under ideal ambient conditions....
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E
Thats a good point - I had thought VTG could be playing games here, but the technical specs from Porsche make me think otherwise, i.e. 1.3bar should be 1.3bar under *ideal* conditions with WOT at low RPMS, but like I said, low range RPM pull, WOT, max pressure is 1 bar. :(
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ZuffenHouseRules
epapp said:
Thats a good point - I had thought VTG could be playing games here, but the technical specs from Porsche make me think otherwise, i.e. 1.3bar should be 1.3bar under *ideal* conditions with WOT at low RPMS, but like I said, low range RPM pull, WOT, max pressure is 1 bar. :(
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Oh I just now saw that you're in the Bay Area so we have same octane and ambient air pressure. Do you display bar rather than psi on your boost gauge? Your 1 bar (14.5 psi) is a lot higher than my 11 psi but your GTS has the larger compressor and higher max. boost than my S.

In any case, interesting that we are both seeing significantly *less* than our respective factory-stated max. boost. I suspect it's the nature of this engine -- the VTG turbo is 'over-engineered' relative to the factory-set power curve programmed into the ECU, so it only calls up max. boost in exceptional conditions (of extreme load; sub-optimal ambient air?).
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Car 718 CGTS MT
Track Sebring
90 degrees and 85% humidity

Finally got the CGTS to Sebring and had a chance to wring its neck. Water temps didn't rise at all and oil temp peaked at 235 degrees.
Boost pressure under full throttle in 3rd and 4th gear were observed to be 19 to 20 psi and did not decrease during the sessions which were 5 to 7 laps. That is all I do at a time as after that the tires are roasted. No sign of heat soak based on boost pressures and observed top speed into turn 17.

Peter
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ZuffenHouseRules
85Gold said:
Car 718 CGTS MT
Track Sebring
90 degrees and 85% humidity

Finally got the CGTS to Sebring and had a chance to wring its neck. Water temps didn't rise at all and oil temp peaked at 235 degrees.
Boost pressure under full throttle in 3rd and 4th gear were observed to be 19 to 20 psi and did not decrease during the sessions which were 5 to 7 laps. That is all I do at a time as after that the tires are roasted. No sign of heat soak based on boost pressures and observed top speed into turn 17.

Peter
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Nice resistance to heat-soak, in tough conditions, by the low-temp coolant system/ICAC. Thanks for the data Peter.

That oil temp is 20-30 degrees higher than I'm observing in Sport mode with non-track but sustained high-rpm sport driving. (local afternoon conditions near the coast, after the fog burns off, around 60% RH, temps 60s-70s).

So if our difference in ambient conditions translates to as much as 30 degrees difference in oil temps, I reckon there is a proportionate difference in IAT and with that, the whole equation of air temp/pressure/charge density/power. Enough to account for our N. Calif. cars' DME calling up less than max. boost under WOT, where others are observing factory-stated max.?

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ZuffenHouseRules said:
Nice resistance to heat-soak, in tough conditions, by the low-temp coolant system/ICAC. Thanks for the data Peter.

That oil temp is 20-30 degrees higher than I'm observing in Sport mode with non-track but sustained high-rpm sport driving. (local afternoon conditions near the coast, after the fog burns off, around 60% RH, temps 60s-70s).

So if our difference in ambient conditions translates to as much as 30 degrees difference in oil temps, I reckon there is a proportionate difference in IAT and with that, the whole equation of air temp/pressure/charge density/power. Enough to account for our N. Calif. cars' DME calling up less than max. boost under WOT, where others are observing factory-stated max.?
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I will be at NCM Motorsports Park in Bowling Green, KY the end of Sept. Weather should be much cooler than Sebring so it will be interesting to see how the max boost pressure changes.

As for the oil temps I was very pleased with them being no more than 235 degrees. On my GT350 I would see upwards of 270 degrees under the same conditions.

The other observation was how good the PSM has gotten over the last some years. Normally I would climb in a car and turn all the Nannies off and have at it. A friend who has a 991.1 GT3 RS with over 10,000 track miles told me to try leaving them on as they don't interfere unless you are really stupid. Lesson learned as I never felt them intervene, though I could see the PSM light flashing, it was very seamless. I know I wasn't overdriving the car as the rear brakes weren't smoking hot when I came off track. For AutoX I do turn everything off as they do interfere with the abrupt inputs required.

Peter
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OldJedi
85Gold said:
I will be at NCM Motorsports Park in Bowling Green, KY the end of Sept. Weather should be much cooler than Sebring so it will be interesting to see how the max boost pressure changes.

As for the oil temps I was very pleased with them being no more than 235 degrees. On my GT350 I would see upwards of 270 degrees under the same conditions.

The other observation was how good the PSM has gotten over the last some years. Normally I would climb in a car and turn all the Nannies off and have at it. A friend who has a 991.1 GT3 RS with over 10,000 track miles told me to try leaving them on as they don't interfere unless you are really stupid. Lesson learned as I never felt them intervene, though I could see the PSM light flashing, it was very seamless. I know I wasn't overdriving the car as the rear brakes weren't smoking hot when I came off track. For AutoX I do turn everything off as they do interfere with the abrupt inputs required.

Peter
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Thanks Peter, I have driven Sebring several times in my ZL1 Camaro. I will do Sebring in the GTS after it reaches 2000 miles. Thankfully it came with Michelin’s. What were your starting track tire pressures? Did you change to DOT4 fluid? Any other preparations for track use? Thanks for the help.
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OldJedi said:
Thanks Peter, I have driven Sebring several times in my ZL1 Camaro. I will do Sebring in the GTS after it reaches 2000 miles. Thankfully it came with Michelin’s. What were your starting track tire pressures? Did you change to DOT4 fluid? Any other preparations for track use? Thanks for the help.
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Started PS4S at 30 psi and shoot for max 36psi hot. They will squeal like a stuck pig in the turns. Yes RBF 660 and Ferodo DS1.11 pads. Front maxed out camber at -1.5 and 0 toe. Rear camber -1.8 and .10 toe in each side. Tire wear was fairly even. Car was a little pushy but manageable. Best lap was a 2:28.07.

Peter
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E
After almost 1500 miles, I certainly noticed a difference in the way boost pressure was applied throughout the RPM range. Now at almost 9000 miles and 6 months of ownership, its almost time to trade for the next one: targa 4s
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TEST DRyVer
epapp said:
I am familiar with the break-in debate, and consider myself part of the 'break-in-is-not-necessary' group.

I have however noticed that during the first few hundred miles, there is a difference between the boost pressure on my 718 base and my 718 GTS. I know that the technical specifications show the boost pressure for the base 718 to be 1.4bar, and the GTS to be 1.3bar. At 150 miles or so, the base 718 indeed was pushing 1.4bar.

After 400 miles, the GTS is still pushing max 1bar, and I am left wondering if this is part of the mystical software break-in period.

Any ideas? Any similar experiences?
Click to expand...
The base 718 is targeted to achieve 19 - 20.5 psi (depending on the several variables)

The 718S is targeted to achieve 14.5 - 16 psi (depending on several variables)

The GTS, I'm not sure, but I believe it's targeted to achieve slightly lower boost than an S, due to a slightly larger turbo

I'm not sure where you're able to see bar on your car, but I'm almost positive my car shows psi only. What I don't like about my base model boost gauge is that it maxes out at 20psi! What if I run too much boost? (I have a stage 2 tune, so I'm definitely running a bit more boost, but I'll never know just how much because my guage is maxed at 20).
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TEST DRyVer said:
I'm not sure where you're able to see bar on your car, but I'm almost positive my car shows psi only. What I don't like about my base model boost gauge is that it maxes out at 20psi! What if I run too much boost? (I have a stage 2 tune, so I'm definitely running a bit more boost, but I'll never know just how much because my guage is maxed at 20).
Click to expand...

Is bar vs psi part of the same settings as km vs mph maybe?
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Chris NZ
rsmith said:
Is bar vs psi part of the same settings as km vs mph maybe?
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That was my thought too. If the display is set to display bar units it would pretty much be 0, 1, 2 and therefore pretty meaningless. Watching Nick Murray's videos his 911 display is in PSI and you can see it moving up and down quite a bit. Surely it is just a set up change?

My current car has a vacuum boost sensor calibrated in mbar and even displays negative numbers when the engine is drawing in air faster than it is being supplied. Maybe Renaultsport are a bit more geeky about this kind of stuff.
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TEST DRyVer
Chris NZ said:
That was my thought too. If the display is set to display bar units it would pretty much be 0, 1, 2 and therefore pretty meaningless. Watching Nick Murray's videos his 911 display is in PSI and you can see it moving up and down quite a bit. Surely it is just a set up change?

My current car has a vacuum boost sensor calibrated in mbar and even displays negative numbers when the engine is drawing in air faster than it is being supplied. Maybe Renaultsport are a bit more geeky about this kind of stuff.
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No, that sounds right! I've owned previous cars that had a bar boost gauge (dial type) and it also read when the turbo was in vacume (the negative number you were talking about). I had this from the factory on a 2005 Subaru WRX STi and various other cars, some of which had an aftermarket boost gauge to always let you know if you were pushing less boost than usual, or peaking higher than normal (boost spike).
You also might be right that it's attached to kph vs mph. Maybe when your car is set to the US standards with mph instead of kph, it reads psi instead of bar.
Last I recall, 1 bar = 14.5 psi of boost pressure. I do like reading psi more than bar because it seems more accurate and quicker to determine you actual boost without you having to do math =)
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RGM718
I saw 235 degrees oil temp when I ran my 981 at Sebring a couple years back.......in March. Not apples to apples but just a comment that probably reinforces the thoughts about heat soak or lack thereof from the turbo.
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don
235 does seem kind of low.

Our old E91 335i with an N54 motor would regularly operate around 240 to 250 F depending on the day. I thought it was a bit high but this was common amongst other owners.
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TEST DRyVer
don said:
235 does seem kind of low.

Our old E91 335i with an N54 motor would regularly operate around 240 to 250 F depending on the day. I thought it was a bit high but this was common amongst other owners.
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I run oil temps around 240-250F in my wife's modded 2015 N55 EWG BMW 335i M-sport. That's a complete Stage 2 with a massive front mount intercooler. Before the intercooler, I would run 250-260+, and this is not on a track. This is just a long and spirited drive home from work (around 50 miles). I've never kept an eye on the oil temps for the 718, but since you guys bring it up, I'll start. Especially since I just had a bench flash tune to the 718 ECU.
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TEST DRyVer said:
Especially since I just had a bench flash tune to the 718 ECU.
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I think a base 718 6sp with a tune sounds like a great value. What is your expectation for warranty support post tune?
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TEST DRyVer
Kingmota said:
I think a base 718 6sp with a tune sounds like a great value. What is your expectation for warranty support post tune?
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This is a trick question. I work for a Porsche Dealership, I'm a Sales Ambassador for the brand. I've spoken to the Service Advisor (he's been with Porsche for 25 years) and the Master Tech. Both stated the same thing on separate occasions:
If the mod is not directly related to the problem (if you had a potential warranty issue or claim because of a failing part), and they can't prove that the mod is 100% contributing to the failure of a part, they have to warranty it.
Keep in mind that where I work is mod-friendly and we have several highly modified cars that we service, and we rarely have a problem covering the fault under warranty. They recently flagged and cancelled a clients warranty because he was running NOS (nitrous) on his Turbo S. Another guy was denied warranty because he's running a massive wide body kit on his Panamera, and he's had constant suspension issues. Of course with the wide body, he's running a very aggressive suspension setup that would allow his wheels to be flush with the wide body. I think both of these situations are completely understandable!
That being said, our other local Porsche dealer will not warranty claim issues on cars that have aftermarket performance parts. So it's important to find out which dealer you have. You can ask your Service Advisor point blank: would you mind if I had my car tuned and added a high quality aftermarket exhaust (just an example). He will give you his or her disclaimer of course that nothing is guaranteed when it's modified, but then he will tell you exactly what you need to hear, good or bad. He'll tell you at their dealership, it's simply unacceptable, or he'll say if the aftermarket parts didnt effect the problem, you're ok. Then you know which dealership you have...
In short! No, I'm not worried about the ECU tune on my car, not because I work there (because they will not break any rules to help me), but because my dealership is mod-friendly.
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Viffermike
TEST DRyVer said:
This is a trick question. I work for a Porsche Dealership, I'm a Sales Ambassador for the brand. I've spoken to the Service Advisor (he's been with Porsche for 25 years) and the Master Tech. Both stated the same thing on separate occasions:
If the mod is not directly related to the problem (if you had a potential warranty issue or claim because of a failing part), and they can't prove that the mod is 100% contributing to the failure of a part, they have to warranty it.
Keep in mind that where I work is mod-friendly and we have several highly modified cars that we service, and we rarely have a problem covering the fault under warranty. They recently flagged and cancelled a clients warranty because he was running NOS (nitrous) on his Turbo S. Another guy was denied warranty because he's running a massive wide body kit on his Panamera, and he's had constant suspension issues. Of course with the wide body, he's running a very aggressive suspension setup that would allow his wheels to be flush with the wide body. I think both of these situations are completely understandable!
That being said, our other local Porsche dealer will not warranty claim issues on cars that have aftermarket performance parts. So it's important to find out which dealer you have. You can ask your Service Advisor point blank: would you mind if I had my car tuned and added a high quality aftermarket exhaust (just an example). He will give you his or her disclaimer of course that nothing is guaranteed when it's modified, but then he will tell you exactly what you need to hear, good or bad. He'll tell you at their dealership, it's simply unacceptable, or he'll say if the aftermarket parts didnt effect the problem, you're ok. Then you know which dealership you have...
In short! No, I'm not worried about the ECU tune on my car, not because I work there (because they will not break any rules to help me), but because my dealership is mod-friendly.
Click to expand...
Really well said.
@Kingmota, Federal law dictates that on vehicle warranties, warranty coverage cannot be denied if the claim involves an OEM part or assembly that is not considered a wear item (or, if a wear item, does not demonstrate unusual or accelerated wear due to manufacturing defect) or has not been modified in any way by the operator, either directly or indirectly.

The key word is 'indirectly', which is open to interpretation by both car manufacturers and the service departments that handle warranty claims by that car manufacturer. That's why, if you have a modified vehicle, the two most important factors in warranty coverage are:
1). The willingness of your dealer to enable and enforce the warranty on modified cars, and
2). The relationship you have individually with that dealer.

ECU 'tunes' are one of the biggest issues regarding interpretation. For instance:
Scenario 1: Can a tune ruin a valve? Absolutely.
Scenario 2: Can a tune ruin a catalytic converter? Yes, it can, but likely only over time.
Scenario 3: Can a tune ruin a transmission? Sure can, but it's difficult to prove mechanically because there are so many parts, and so many other variables, between the ECU and the gearbox.

There are dealers who will warranty all three scenarios. There are dealers who will not warranty all three scenarios. And there are dealers who will warranty every permutation in between those extremes.
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