Causes of spiking?

[MM2death]

Just curious as to what can cause spiking (bleed valves). I notice that when it's colder the more my bleed valve will spike. I've had up to 5psi difference! I've got a turbosmart (cheapest one) and the most i can turn the boost down to is 12psi. Why is this so?

And are all bleed valves the same in performance or are some better than others?

This setup is temporary until i an afford EBC.

Regards,

Scott.

[GTStR32]

i get that aswell, its bad

stupid fuel cut

[MM2death]

Mine spiked from the set 12psi to 16 odd last night (10 degrees ambient).

I just got the cheapest bleed valve (turbosmart boost tee) *sigh*

[unwritten law]

I just bought a 32 gtst this week. It has the same controller. It has been tuned to 10 low 12 high, but with the cool air lately its been spiking to 12-13 and back to 10 on low boost. I dont wanna let it get over 14psi when on high.

[Emre]

Just curious as to what can cause spiking (bleed valves).

Inefficiency of the internal wastegates in stock turbos, as in, not being able to bypass the excess exhaust gasses quickly enough is the most common cause of boost spiking. It will not damage the turbo as it happens in midrange where the turbine speeds are not excessively high. Assuming you have enough fuel to go with it, it should not damage your engine either, but provide you with a stronger midrange. They are more manageable in GTRs as the stock ecu is able to supply enough fuel and keep the AFRs steady.

[Busky2k]

I find with my GFB bleeder I get 1 psi more all round on a really cold night compared to a 30 degree day. It spikes a lil more, spiking from 12-->15psi sometimes on a 5 - 10 degree night, but its low in the revrange and lasts only 1/2 a second or so, so i dont mind. It doesnt worry me too much cos there is no such thing as a spike free bleeder. But i still want an EBC to keep things constant all the time.. No cash atm tho =(

[MM2death]

I figured out my 5psi difference. The actuator hose had worn a hole in it....

Scott.