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vrracing · 02-26-2012, 06:30 PM

Relevant mods

90 S5 Vert.
JDM Tii
Pineapple Racing street port
BNR Stage1 turbo
Bonez cat-forward. Corksport cat-back with Vibrant UltraQuiet resonator.
RTek Stage2
720/1000cc injectors
Zeitronix w/b
HKS EVC Black Edition

With the EVC off, we were seeing a max of about 4.5psi so I'm assuming the wastegate spring is about 4.5pounds. We set the EVC to 50% and we were expecting about 7psi max (4.5 + (50% * 4.5)) but it went to ten; which was fine.

As you can see in the Zeitronix chart, boost is maxing out at ~10psi at 4700RPM and drops off gently from there.

We are using Aaron Cake's rule of thumb AFR tuning targets

0-4 PSI: 12-12.5
4-8 PSI: high 11s
8 - 15 PSI: mid to low 11s
16 PSI +: high 10s

but obviously the 1000cc secondaries still need to be pulled back some. IIRC we are pulling them back about 3% above 4500RPM.

Is the fact that we're getting too rich after 4500RPM what's causing the boost to fall off or is the wastegate spring at fault?

Thanks, appreciate any guidance yall have.

02-26-2012, 06:30 PM	#1
vrracing Rotating Assembly Join Date: Oct 2008 Location: TX Posts: 102 Rep Power: 17	Boost falling off Relevant mods 90 S5 Vert. JDM Tii Pineapple Racing street port BNR Stage1 turbo Bonez cat-forward. Corksport cat-back with Vibrant UltraQuiet resonator. RTek Stage2 720/1000cc injectors Zeitronix w/b HKS EVC Black Edition With the EVC off, we were seeing a max of about 4.5psi so I'm assuming the wastegate spring is about 4.5pounds. We set the EVC to 50% and we were expecting about 7psi max (4.5 + (50% * 4.5)) but it went to ten; which was fine. As you can see in the Zeitronix chart, boost is maxing out at ~10psi at 4700RPM and drops off gently from there. We are using Aaron Cake's rule of thumb AFR tuning targets 0-4 PSI: 12-12.5 4-8 PSI: high 11s 8 - 15 PSI: mid to low 11s 16 PSI +: high 10s but obviously the 1000cc secondaries still need to be pulled back some. IIRC we are pulling them back about 3% above 4500RPM. Is the fact that we're getting too rich after 4500RPM what's causing the boost to fall off or is the wastegate spring at fault? Thanks, appreciate any guidance yall have. __________________ 90 S5 Vert. JDM Tii with BNR Stage1 turbo. Pineapple Racing street port. Bonez cat-forward. Corksport cat-back with Vibrant UltraQuiet resonator. RTek 2 wZeitronix w/b. HKS EBC. Vis CF Tii hood. 3000GT wing. Ground Control coilover kit with KYB AGX shocks. Red and Black leather RX8 seats. Corksport Odura lip & bumper caps, OEM Tii skirts