X50 / TruboS owners. How much boost do you see if punching it form 2000 to 3000 RPM in 3rd or 4th gear (at 3000 RPM)?

 

0.8 most of the time and 0.9 sometimes.

 

0.9 bar

 

What is peak boost? 0.9? You should see peak boost in 5th/6th gear when starting at 2400rpm or so til whenever you see peak.

What RPM is peak boost? 3000+? I can't imagine you getting much more than 0.6-0.7 if only running it from 2000-3000 in 3rd/4th. The turbos don't have enough time to spool if peak boost is reached at a higher rpm.

 

I tested this out this weekend. I was pulling a steady .8 in 5th gear in the 120+ mph range. brief spike of .9 ran out of room to see what happened in 6th gear. Have '03 X50 with 20K miles.

tmw

 

I can only pull spikes of .8 in 3rd gear, even at high rpm

tmw

 

To be more specific, what's the max boost you get at 3,000 rpm. I guess this more a question about throttle response and lag, as opposed to max boost.

 

Run a higher gear so that the rpms are not climbing too quickly for you to see.

Have everyone start @ 2500rpm in 6th gear and then climb to 3000rpm to see what their boost is at.

 

My peak boost is at 6000 rpm. in any gear.
About .9

2005 ttS coupe/3500 miles

 

Exactly!

 

Just ran 2500 rpm to 3000 rpm in 6th and hit 0.9bar but then i have the stage 4!

 

Doh! There was supposed to be a "not" in there.

"are not climbing so quickly..."

 

the dealer has wiped out my ecu so i've got stock programming right now and some mods (k16/24 hybrids, exhaust, headers, & wastegate adjustments)

in 2nd gear, i can only hit .7 bar most of the time.
in 3rd gear, i can only hit .7/.8 bar until 6000rpm or so, and then it jumps to 1.0 bar (suddenly, car feels like a rocket.)

this seems like very strange behavior to me; i would expect full boost to come on earlier. is the ECU limiting boost in the lower rpm?

(just trying to understand ECU/boost characteristics before i get re-programmed.)

- chuck

 

To answer your question about the ECU limiting boost in lower rpms... Not really. Boost is limited via the load placed on the car and the size of the turbos. The ECU tries to do the same in all gears, actually. 1st-3rd gears (1st and 2nd especially) run out before the turbos have a chance to really stay at a certain RPM and get a measurement. I am sure that there is some lag on the digital reading as well when this happens. What do you pull in 5th/6th?

The problem is that the ECU on the stock TT (with K16s, no clue how the X50 curve looks, but I would assume that it is similar) peaks to ~0.8bar, drops to 0.6 bar, then peaks again at 6000rpm to ~0.7 bar. Getting 1.0 must be a product of the hybrid turbos. As you can see, the boost is ECU controlled.

The stock boost curve (1) is below (remember that it is taken at 1 atm I do believe, so you have to subtract that out in order to get the absolute pressure):

 

well, i get the same behavior if i punch it from 2500rpm in 4th gear.

i should get (close to) maximum load at this rpm point in such a high gear, but it will stick to .7/.8 bar til the higher rpms where it will suddently let go to 1.0 bar.

again, i might have too many variables/mods to really figure out what's going on, but it just seems like odd behavior.

regardless, the re-flashed ecu will be in soon.

- chuck