996tt - how much boost?
Discussion
The way to look at it (apparently) is that a 996TT takes as much boost as is necessary in the conditions to give you 420 bhp. Hence one day booting it in 3rd gear it takes .6 bar and the next day on the same road it will be .5 bar. I say "apparently" because there is a lot of hearsay on this topic :-)
>> Edited by cyrus1971 on Friday 26th May 23:02
>> Edited by cyrus1971 on Friday 26th May 23:02
996tt_stevo said:
If your car is showing 0.6 or 0.9 under full acceleration I would say there is a problem, i.e If you floor it and it reads 0.6, then do another run straight away and it read 0.9 this isn't right!!!
I dont tend to get different readings on the same day. I've noticed over the past few months that on some occasions the reading is higher than on others. The highest reading I've ever had was 0.9 but this has only happened on a couple of occasions and likewise 0.6 is the lowest I've had under full acceleration.
996tt_stevo said:
You can usually see spikes, but this normally equates to 0.1. Is it standard Turbo or x50, has it been chipped/flashed?
Its totally standard. Don't atmospheric conditions and road conditions have a bearing and explain the difference from say readings in the summer vs the winter?
It is perfectly normal for the boost to vary as the engine management will only take what it needs, according to atmospheric conditions.
On a standard TT this is usually between .6 & .8 bar maximum, it shouldn't be any higher than .8 bar, but will occasionally read higher as you lift off at max revs!
If you are consistantly reading over .8 bar on a standard Tutbo then you will likely have a fault developing with the MAF sensor.
More info below (1 bar is atmospheric pressure, so 1.8 bar shows as 0.8 bar in the boost pressure display)...............
Boost pressure is controlled by a joint stroke for the bypass valves masterminded by the engine management. The opening diameter depends on the charge pressure required and is around 1.80 bar at full load, reached at approximately 2700 rpm. Boost pressure is controlled as engine speed increases,and is around 1.65 bar at maximum power. The combination of a high compression ratio (9:4:1) and fast
spooling turbos give the car both a high power out put and fast response to pedal
inputs, minimising lag!
On a standard TT this is usually between .6 & .8 bar maximum, it shouldn't be any higher than .8 bar, but will occasionally read higher as you lift off at max revs!
If you are consistantly reading over .8 bar on a standard Tutbo then you will likely have a fault developing with the MAF sensor.
More info below (1 bar is atmospheric pressure, so 1.8 bar shows as 0.8 bar in the boost pressure display)...............
Boost pressure is controlled by a joint stroke for the bypass valves masterminded by the engine management. The opening diameter depends on the charge pressure required and is around 1.80 bar at full load, reached at approximately 2700 rpm. Boost pressure is controlled as engine speed increases,and is around 1.65 bar at maximum power. The combination of a high compression ratio (9:4:1) and fast
spooling turbos give the car both a high power out put and fast response to pedal
inputs, minimising lag!
Kinda answers the question. This is from the Porsche website, when the 996TT was still on there :
"On the 911 turbo, a maximum boost pressure of 0.8 bar is available from as low as 2,700rpm."
As stated, the ECU will deliver the right amount of boost pressure to ensure 420bhp is achieved. Depending on several factors this will be anything between 0.6 & 0.8.
A standard car should not go above 0.8 on a regular basis. If it does then it should be checked as there could be a fault somewhere (or its been modified & you didn't know)
Judging by the number of ECU upgrades DMS have done (now in the hundreds I believe) there must be a fair few used 996TT's out there with ECU mods that people buy unaware that its been done. I mean I can see why - why spend money putting it back to standard when its almost undetectable ?
R.
"On the 911 turbo, a maximum boost pressure of 0.8 bar is available from as low as 2,700rpm."
As stated, the ECU will deliver the right amount of boost pressure to ensure 420bhp is achieved. Depending on several factors this will be anything between 0.6 & 0.8.
A standard car should not go above 0.8 on a regular basis. If it does then it should be checked as there could be a fault somewhere (or its been modified & you didn't know)
Judging by the number of ECU upgrades DMS have done (now in the hundreds I believe) there must be a fair few used 996TT's out there with ECU mods that people buy unaware that its been done. I mean I can see why - why spend money putting it back to standard when its almost undetectable ?
R.
If the car is standard you should never see 0.9, It has either been flashed, your MAF is starting to play up or even needs cleaned (what kind of filter are you using?) or your wastegates might be adjusted to produce this kind of boost.
What gets me is that you are seeing 0.6 somedays and 0.9 others, I'm telling you now that it should never fluctuate this much!
What gets me is that you are seeing 0.6 somedays and 0.9 others, I'm telling you now that it should never fluctuate this much!
Gassing Station | Porsche General | Top of Page | What's New | My Stuff