Tuning boost with EBC

Last sunday I started dialing in the boost with the Greddy E01 EBC. Until now I have been running a direct boost signal from the compressor to the WG.
I found a stretch of deserted road and did repeated WOT runs while datalogging.

To my surprise I saw major boost creep above 6K rpm.
How is this possible with a 38mm external WG and an open dump pipe ?
I mean, this should be a pretty optimal escape route for the boost rather than going trough the turbine.
I found some settings on the E01 where I can shut down all boost when it reaches a boost limit.
Trough the excellent internal data logging and replay function I can se exactly what happens in the EBC display which can graph RPM, boost solenoid and boost.
The boost keeps rising above the limit regardless of the EBC opening the WG 100%.

My first thought was that the SuperTrap muffler was creating back pressure.
That turned out not to be the case as I got the same problem with the silencer of the day after.
The next test was with routing the signal directly from the compressor. Same results only much slower spool.

After some thinking I’ll try the following to cure the problem:

- Replace the 0.8 bar spring with a 0.5 bar spring. Already ordered.
- Reroute the boost signal from the compressor housing to the intake plenum.
- Recheck the piece of s* vacum hose I got from ATurbo for leaks. A crack here will gradually bleed boost. From now on I’ll use fuel lines for vacum/boost.

While over boosting I saw in my logs that I reached 1.45 bar boost peak at one occasion and had several runs on 1.15-1.20 bar.
That’s probably not safe for OEM rods… But the car goes like a rocket. The power compared to the OEM turbo is something else :) . Too bad I have to limit the boost to sub 1 bar to not grenade the engine this year.


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