JB3 and long term reliability

[adc]

Originally Posted by gargoyal

So you are saying that above the increase in airflow that is needed to reach standard boost at altitude the N54 engine adjusts for the base atmospheric pressure at altitudes ?

That's my understanding anyway. Even so, there can be some debate as to the fact that if you spin the turbos to those levels but at sea level, they will be working harder than they would at altitude because the air is more dense. :iono:

There should be a stock dyno available from someone in Colorado, over at e90post...

[mad chemist]

adc,

Surely if your running at lower altitudes (denser air, i.e more air molecules per unit volume) the turbo's compressor will not need to run half as quickly to reach the same boost level compared to running at higher altitudes. I also read that modern turbo cars drop far less hp at evelated altitudes due to being able to run the same boost at altitude (but of course much higher turbine speeds are needed to reach the same boost level when compared to lower altitudes).

Just my 10$ worth.

Mad.

[adc]

Originally Posted by mad chemist

Surely if your running at lower altitudes (denser air, i.e more air molecules per unit volume) the turbo's compressor will not need to run half as quickly to reach the same boost level compared to running at higher altitudes.

Yes, you are right - although I haven't seen anything conclusive either way. I personally think that running a tune that peaks at 11-12 PSI should not reduce the engine's useful lifespan significantly. Perhaps the turbos might need to be replaced at a later time, but the engine should be ok to well over 150k.


I had a ride in a modified B5 S4 running K04's and other gadgets for over 400BHP - and it had 184k miles on the original engine.