Hi all, a question about oem turbo boost levels from Porsche...

What's the factory boost level by specification from Porsche of the 996TT (and 996TT X50)? Any change in the turbos (boost or model of turbos) throughout the 996TT years 2000-2005?
For comparison and interest, I'd like to know also the stock boost levels of the 996 GT2 and 997TT (is there a difference between the 997.1 and 997.2?).

Thank you!

I know these:

996T K16 - .7 BAR
996 T K24 - .8 BAR
996 GT2 - ? there were two output levels over the years

Thanks, anyone else about the other models?
And how do I know if my 996TT has the K16 or the K24 turbos?

If your Car is a 996 TT then you should have K16's unless someone upgraded them. The X50 packaged 996TT and the Turbo "S" as well as the GT2 all have K24's.

Ok thanks,
So a stock 996TT will show a maximum of 0.7 bar boost on the electronic boost gauge?

Yes!

by Porsche 996 The Essential Companion, page 158 all M96/70,70E,70S,70SL,
Maximum factory set boost @ 0.8 bar or 11.6psi

I am pretty sure my stock 996tt k16 did .8 bar max. I have a flash now and am enjoying life at 1.2 bar.

I'll caution you that the electronic boost gauge is not a display of an absolute control parameter.

Boost display will have a bit of variability, due to sensor calibration, air temp and density and operating characteristics.... some days you may see 0.7, other 0.8...one user might see on another a different max. (Which can explain what folks are posting as to what they've seen.)

Just saying...

Is not 1.2 bar too much? maybe your car is showing +0.1bar...

I was asking around here if the k16 can hold 1.2bar and everybody told me that is too much.

Mmh, 1.2 bar gauge pressure on k16....

here is the comp map:






With 1200 mbar gauge pressure, 981 ambient pressure, you are at 2.22 pressure ratio (more than this actually, because the gauge pressure is measured after piping and IC's, so there would be some additional pressure to add because of the pressure drop).
Assuming a VE of 90%, at 5500rpm the turbos are flowing 360cfm each, which is 0.16 liters/second. This means the turbos are working in the 70% efficiency zone, pumping air at 135°C.....
At 6000 rpm they are flowing 0.175 liters/minute, efficiency is near the 65% zone, with air temp 145°C...
This is with ambient temp of 25°C.
So during winter I would say no problem, but I wouldn't run that much boost during summer on k16's....

Boost gauge could be wrong though..

Is the boost reading using data from the ECU?

Nice discussion.

Might I comment that the phrase "I wouldn't run that much boost" is a bit imprecise in that, typically, "you" don't control the boost, but rather you 'observe' the boost- the DME determines, for given conditions, how much boost should be allowed, and that is what you get.

Now if your programming is not well designed, or you are over-riding the DME with an EBC, yes you should "not run 1.2 in the summer".

But by an large most folks (not all) modifying these cars are not in control of the boost, just observers. This becomes an issue where newbs worry "Shouldnt I be running more, how do I change it?" when someone posts "I run X".

Thx

A

Yes, you're right actually.....the driver has no possibility to change desired boost without using an EBC. It has to do with the ECU tune..

1.2 shows up briefly under wot. I just have the standard switzer flash and use 93 octane. Again, stock k16 turbos. I thought pretty much every flash everyone here has will let you hit 1.1 or 1.2 bar? I have not heard this to be a problem in hot or cold weather, although of course cold air is more dense and oxygen rich so you can pack more oxygen into the cylinders for better power and efficiency.

Yes, the gauge readout is just a calculated value by the car, and is not necessarily 100% accurate or precise.