iTTaliano

Well since my APR 3+ kit has been installed I have been racking my brain trying to eliminate my turbo surging and spiking issues(spike to 30psi down to 20psi back up to 24psi).
Here is what I tried:

1. Boost machine in its standard installation (pressure side in, back to the bottom of N75)Well that would have cured the surging, but by the time I made the increases where it took control over the N75 my spiking in 1st and 2nd gear was far into the danger zone.

2. Turbo XS MBC in a parallel configuration that is used for over boost issues. Well this set-up did stop the spiking, but the turbo lag was substantial. Butt dyno told me there was plenty of power being lost. Not to mention the mess of hoses and plastic connectors under the hood looked horrible

http://www.boostvalve.com/overboost.html

3. ECS N75 race valve. This actually cured the surging and spiking. The only problem I had with this set-up was I was now only getting 23PSI. APR says I should be at 25psi-26psi. So for the money I spent on the kit, that didn't make me very happy.

4. ECS N75 race valve with Turbo XS MBC in line between the side of the N75 and the wastegate. When I finally got this dialed in for steady boost in 3rd and 4th gear I was getting crazy over boost in 1st and 2nd gear!

5. Finally my winning set-up. Boost Machine in line with the side of the N75 and back into the wastegate. I really took my time between adjusting the boost setting on this. Well I am 6 turns on the Boost Machine and 0 on the onset (no onset needed in my opinion with the laggy big turbo)I am now holding consistent boost in all gears. 26psi in 1st and 2nd gear and 25psi in 3rd and 4th....can't wait 'till 5th and 6th!
;-)


Hope this can help someone with an APR 3+ kit or another big turbo kit.

Thanks again Steve!

nikhil

that kit should work right out of the box with no other boost-regulating parts.

step 1: remove the additional parts
step 2: talk to APR.

TTschwing

Probably there is no need for the onset because the APR logs 've seen keep the N75 at 100% duty cycle for a good period of time (Full diversion to the intake and NO pressure to the Wastegate). Most programming starts out at 96% (4% bleed to the wastegate, which is where the onset comes in handy)..

Actually I'm surprised at the difference you got ecause mechanically there should be no difference in placing the BM either ahead or after the N75. Must be the duty cycle programming

Glad it worked!

TTschwing

I believe a new MAF mitigated his..

kodeTT

i'm glad it worked out regardless.

ar design

2nd

iTTaliano

Everything on my car has checked out perfectly. APR suggested trying the N75 race valve on the car in the first place.My mechanic who is certified to do the APR turbo upgrade kit told me to try different set-ups. Every car reacts a little differently to APR kit. As long as all data logging looks good its fine to do some fine tuning while staying within APR's suggested parameters.

petervan

shouldn't need all that tinkering. something not right...call apr/tuner

petervan

my thoughts exactly.

petervan

kits can make an already weak component (Maf, etc) go belly up fast...or become more noticeable. But as the end user you should not need to add pcs to make a kit effective.