[StealthFish]

Hi all,

I am trying to learn a few things about the N54 motor. I have a few questions in regards to the engine.

1) What is the compression ratio of the N54 motor?

2) a. What is the max boost (PSI) that we are getting from the stock ECU?

b. I am currently running the Cobb Accessport Stage 1 Aggressive, what is the max boost (PSI) that I should be getting?

This is what I got today but I was not flooring the car nor driving it hard, approx. 16.4 at highest so far:
http://img.photobucket.com/albums/v7...222_082155.jpg

[3.1L Z]

Stock PSI is 8.8, if I recall correctly. 16.4 is where the Stage 1 should max out at in the 4000 rpm range and decrease as rpms increase.

[3.1L Z]

Use the data log feature and download the entire run to your pc.

[straightcashhomie]

theres a sticky right at the top of general forums....

http://www.e90post.com/forums/showthread.php?t=38856

[marv85]

Compression is 10.2 if I remember correctly.

Max boost depends on your environment(load based), mine is usually around 7.5psi. I've seen 8.5psi when the elevation increase.
same goes with COBB stage1 agg, it depends on your environment. I've seen no more than low 15's.
Make sure you are not looking a the boost spike as well...

[StealthFish]

I saw a max boost of 17.1 today. That's what it read in my AP. One the wrx that I used to have, I would get a max of 14.5 max. But that was 8:1 compression. If I'm running 8+, I'm scared it's not good for my car. Could it be because I'm running the aggressive map? Should I switch to the sport map?

[ErvGotti]

Originally Posted by StealthFish

I saw a max boost of 17.1 today. That's what it read in my AP. One the wrx that I used to have, I would get a max of 14.5 max. But that was 8:1 compression. If I'm running 8+, I'm scared it's not good for my car. Could it be because I'm running the aggressive map? Should I switch to the sport map?

Is it 17.1 sustained or spike. You need to data log in order for anyone to help you. Typically Stage 1 aggressive should run 15.5-16 PSI sustained from about 2400 RPM to about 5200 PRM with it tapering down towards redline.

The reason these engines can tun high PSI with high compression is due to direct injection and it's cooling effect on the combustion chamber.

[a7med606]

compression is 10.4.1

[StealthFish]

Originally Posted by ErvGotti

Is it 17.1 sustained or spike. You need to data log in order for anyone to help you. Typically Stage 1 aggressive should run 15.5-16 PSI sustained from about 2400 RPM to about 5200 PRM with it tapering down towards redline.

The reason these engines can tun high PSI with high compression is due to direct injection and it's cooling effect on the combustion chamber.

Thanks everyone, I have not taken the data log yet as I am not driving my car until I get back home but I think it is a boost spike. 10.4.1 compression is in between 8:1 and 11:1, what I was thinking of, thanks.