Boost Spike?

[Steve_Y]

Hi.. Newbie here... Gotta question, What exactly causes boost Spike? I have a A/T 2nd Gen with a ported 16G ANd whenever the car shifts My Boost spikes up to 22-24 psi Waay too much!!!
I currently have the Wastegate piped directly into the soure (no boost controller) But it is still doing it.. Any Ideas fellas?"

[sbiggi]

its caused by your wastegate not flowing enough air to bypass the compressor blades

have you upgraded your exhaust yet?

[Steve_Y]

Ya.. Got 3" turbo to tip However the O2 housing is not ported... Could that be it? The way I understand it, a unported O2 housing causes Boost creep not Boost spikes, Which I am not really suffering from, Correct me if I'm wrong.

[sbiggi]

I believe that the 3" exhaust is causing the boost spikes... one of the other guys should chime in...they'll know

[jmakado]

try hooking up your stock BCS. having the source go directly to the wastegate is like a MBC without any type of bleed hole. it is more prone to spiking.

[DlandryTSI]

What mods do you have? One thing to keep in mind is that A/T's do something similar to "no lift to shift" So basically the driver keeps the gas pedal to the floor and the car shifts automatically. On manual cars the driver releases the accelerator causing the BOV to open.

One thing that could be happening but it should be affecting the boost that much is the turbo is still at a high rate of speed on the high RPM band of the motor. So when the A/T shifts the BOV doesn't open causing less air to go through the motor hence a boost spike.

I havn't personally seen the problem its just speculation....

--Dave

[Steve_Y]

As far as mods go... heres the list: I have a injen Intake With the home made cold induction (A wall made of Rubber flooring) Full 3" Turbo to tip Exhaust, Turbo XS Type RFL BOV Venting to atmosphere ( I know guys, its wrong but I havent got another BOV to allow me to back into the intake). Small 16G turbo ported (ask Marcus the specifics on it, I got it from him) And all the normal free mods. Thats about it I believe... I'll try hooking it back into the BCS and see if that helps.

[sbiggi]

now that I think about it.... my brothers a/t with a 16g used to spike to 20psi and fall to 17/16 psi between every shift

[Steve_Y]

OK I hooked up the BCS... No better... What next?

[POkeyES]

Are you using the 6cm of 7cm ehuast housing?

[Steve_Y]

I believe its a 6CM IIRC.. Id ask marcus to chime in on this one if he's out there.

[POkeyES]

That's the same problem I had when I used a 6cm housing, i thought i would get quicker spool, which it did however the boost spike really high. Switching back to the 7cm Housing it came with put the spikes 2lb above what the MBC was set at.