1.3 Bar is second seems a lot...

[turboguru]

Hi,

I bought a 996 TT about a week ago and now I am getting used to it have opening it up more. It pulls 1.3 bar is second near the red line and 0.9 bar in all gears so seems to have been modified? any thoughts anyone? how do you cars compare?

I posted a similar question a few days ago but that was re the 0.9 bar bit, the fact it is now doing 1.3 bar and the car is really really quick, quicker than I would have thought. So much so I don't see a long relationship lasting with my driving license at this rate.

[domster]

1.3 certainly doesn't sound standard. I'll ask my tech (Andy at AmD) about it when I chat to him next.

[Rocket123]

Air becomes denser as temperature decreases. Effectively you can burn more fuel. Might be why you are seeing a boost in peak power under current climatic conditions. Also intercooler is more efficient

Rocket

[turboguru]

cheers, just seemed a hell of an increase and my mates 996 TT is still running 0.8 max? Domster if you could ask you mate at AMD that would be much appreciated.

[roshambo]

Turboguru...give domster the original numberplate....AMD might well have been the people that tuned it, they can check their database

[GreigM]

As far as I know the max boost you should see for a non-modified car is 1.0, and more normally between 0.6 and 0.8. I think porsche reckoned 1.0 was the maximum safe boost on a non-modified car. 1.3 definitely sounds like the car has been modified somehow.

[ultra violent]

Historically the internal boost gauges were crap on Porsche's and shouldn't be trusted. Not sure about the 996tt ones though....

[t urbo]

1.3bar doesnt seem alot it is alot. Std tt max boost is 0.8bar and X50 is 1.0bar and thats on the rev limiter! How many miles has it done, do you know if it is std or an X50 and is it smoking yet?

[vic cohen]

i confirm the gauges are sometimes very irregular,however John Greasly at G Force once admitted he only used 1.4 for setting grid times in a full race car.............BEWARE .........if it really feels that quick also, then get it checked sharpish or you ll only find out when it goes bang!!!

[nel]

t urbo said:

1.3bar doesnt seem alot it is alot. Std tt max boost is 0.8bar and X50 is 1.0bar and thats on the rev limiter!

I saeem to recall reading in Paul Frere's book that nominally the maximum boost on the 996tt is 0.9 bar, compared to 0.8 bar on the 993tt.

All the talk of cold, humid air giving a higher boost confuses me a bit as the electronically controlled wastegates control the boost pressure by spilling the excess, whatever the state of the inlet charge. I accept that the dense, humid air leads to higher power outputs as it would be cooler through the inetrcooler and so denser into the engine, but the absolute pressure generated should be the same shouldn't it, i.e. waste gate setting?

[domster]

I have just spoken to Andy at AmD.

Their tuned remapped 490bhp 996TT conversion, using standard turbos, is set at 1.0 bar. This is what Rich's car is set at and is a quick piece of kit.

If it is boosting to 1.3 bar, there is likely to be a wastegate problem.

- The gauge is unlikely to be a factor, they tend to underread not overread

- The cold air doesn't create more boost, boost is set by the ECU

- The ECU should open the wastegates at 1.0 bar as an overboost precaution. If 1.3 bar is showing, this could be a physical wastegate malfunction.

* IMPORTANT*

1.3 bar running through standard turbos will kill them quite quickly if you do not sort this out soon. They can only cope with 1.0 bar safely or they will get too hot and the bearings are likely to pack in and then all hell breaks loose. Andy says you need GT2 turbos to cope with 1. 3 bar.

If it's an X50 engine then you will have the bigger turbos, but 1.3 is still higher than an X50 setting and it may have been chipped.

AmD can read the ECU data and check wastegates etc. if you are near Bicester, Oxon. Andy said to give him a call on 07730 989895 if required.

[turboguru]

Cheers Domster, I will keep an eye on it as it just came back from it's major service and because I have only had it a few days it could be something I am doing. It is fine in all other gears and goes to 0.9 bar but I am not concerned about that as it feels fine and max's there. It only hit 1.3 bar once but if it does it again I will get it back down the garage and get the wastegate checked.

Please say thanks to AMD, I will call them when I have some more cash as I want to get it on the rolling road and the ECU remapped to hit 450 bhp which I remember them saying was a safe thing to do and really helped midrange torque for overtaking between 50 and 70 mph.

thanks for everyones help! much appreciated!!

[domster]

No problem. AmD remap them up to 490bhp (not 450bhp) without changing the turbos. Something like 3.5-4k from memory including exhaust and cats.