[mhkm]

Is it OK to install SSTT if you are already a mile high? (altitude, that is!).

[5soko]

YES, Split Second mentioned it is okay a while back when i asked them a question, refering to this

[E30M3Driver]

Originally Posted by 5soko335i

YES, Split Second mentioned it is okay a while back when i asked them a question, refering to this

Yes, but what do you actually get for it? Noone has answered that question. If the car stock is already boosting 10 PSI at 5000 feet due to stock ECU altitude adjustment, is the extra 0.5-1 psi really worth $500?

[Dr_Dirt]

Originally Posted by E30M3Driver

Yes, but what do you actually get for it? Noone has answered that question. If the car stock is already boosting 10 PSI at 5000 feet due to stock ECU altitude adjustment, is the extra 0.5-1 psi really worth $500?

I'm sure Jeff from Eurobahn will chime in....
Its all relative, the actual pressure the MAP sensor sees is still ~stock boost 8.8psi.
For example if your external boost gauge show 10psi when your stock, its a good bet that the MAP sensor is only detecting 8.8psi. Therefore all things being equal the SSTT will just cause the boost to increase the manifold pressure to reach ~11psi... It really sould be similiar gains as you would see at sea level.

[BzzzBom]

Originally Posted by Dr_Dirt

I'm sure Jeff from Eurobahn will chime in....
Its all relative, the actual pressure the MAP sensor sees is still ~stock boost 8.8psi.
For example if your external boost gauge show 10psi when your stock, its a good bet that the MAP sensor is only detecting 8.8psi. Therefore all things being equal the SSTT will just cause the boost to increase the manifold pressure to reach ~11psi... It really sould be similiar gains as you would see at sea level.

If the SSTT has a max boost of 11-12 PSI and atmospheric pressure is approx. 3 PSI less at high altitude compared to sea level, it would seem that the SSTT would have zero net benefit at high altitude.

[Dr_Dirt]

Originally Posted by BzzzBom

If the SSTT has a max boost of 11-12 PSI and atmospheric pressure is approx. 3 PSI less at high altitude compared to sea level, it would seem that the SSTT would have zero net benefit at high altitude.

Its a max boost according to the MAP sensor which as I explained at that altitude on the stock setup still only reads 8.8psi so you still have the same 2-3 psi gain with the SSTT.
So your external boost gauge may show ~14 psi with the SSTT installed when the MAP still reads ~11psi

[Amir87]

Originally Posted by Dr_Dirt

Its a max boost according to the MAP sensor which as I explained at that altitude on the stock setup still only reads 8.8psi so you still have the same 2-3 psi gain with the SSTT.
So your external boost gauge may show ~14 psi with the SSTT installed when the MAP still reads ~11psi

That makes sense.

But one question, I thought the ECU could only compensate boost up to 11.5 PSI for high altitude?

[Dr_Dirt]

Originally Posted by Amir87

That makes sense.

But one question, I thought the ECU could only compensate boost up to 11.5 PSI for high altitude?

The fact of the matter is the ECU tries to reach a boost target for stock which is ~8.8 psi, so it monitors the MAP sensor to make a determination of whether or not the target is reached.
If you were to look at the atmospheric pressure reading of the MAP sensor at sea level it would read ~0. Now take it up 5000ft and it would read ~-2
The MAP sensors know the actual pressure. This is why the car doesn't loose boost pressure at higher altitudes. It simply maintains the 8.8 psi in the manifold.
I don't believe that achieving 11.5 psi at that altitude is an issue unless the turbos can't spin fast enough.

[Jeff@Eurobahn.us]

The only issue we have ever had at altitude was related to automatic cars in auto mode where the extra torque made the trans shift sooner than the owner would have liked!

Jeff
Eurobahn