Bleed Valves and Boost Spikes

[adam 32]

If you are using a bleed valve and are trying to set your boost to say 14psi when do you take this measurement? (given that bleed valves are prone to spiking under certain situations.

would you take it

a) at night (cold) driving uphill in 3rd? (heavy load on car, most likely to spike?)

B) flat road driving during the day (25 degrees ambient temp)

the reason i ask is that i have to set my bleed valve to 14psi, during the day the boost reads 0.9 bar exactly (13.05psi) however at night it will rise up around the 0.95-1bar mark (14-14.5psi)

so what should i be aiming for? spiking to 14psi with a 13-13.5 psi constand pressure

or spiking to 14.5 psi and maintaining a 13.5-14psi constant pressure??

[Black33]

Personally mine is set at the lower value (in your case - 14psi) and spikes up.

I do this cos when it spikes it is only for a short period - for the majority of the time it is at the desired boost!

[Guest DON91E]

Heres a secret...

run 2 bleed valves...

a mate of mine has done this and no matter what gets absolutely no SPIKING wat so ever...

Try it and let me know,

Donnie

[skylark]

I run my stock 32 turbo on a 14.5 spike with it settling to 13.5 on full boost, I acknowledge that this is quite high but so far so good.

With reguards to the twin bleed valve proposal, I though boost spike was to do with the intercooler reaching restriction point? Hence the fact that heat will expand and cold will contract the air density, you can pass more volume at a cooler temperature through any intercooler, this is why your boost increases in cold weather and why I will be decreasing my boost when it gets back to winter time to avoid the turbo huffing and puffing and blowing it's housings in.

Hope I made sense?

Rhys

[adam 32]

my setup is slightly different, im runing a bigger FMIC, to4e turbo, and the bleed valve setup on an external wastegate. therefore i worry mroe about leaning out on boost spikes...

with reference to the 2 bleed valve idea i think id rather save for an EVC than have 2... beside im not convinced that would work, the reason a bleed valve spikes is due to the way in which iit bleeds air away from the actuator line, and under load is unable to accurately control this. how would 2 bleeders solve this?

[Robo]

I Run 2 bleed valves...

When I had my stock intercooler I ran 11 psi constant... (Entire car was stock).

Never once did it spike didn't matter what the temp was.

If you like I can dig around for a photo I took of the set up....

Cheers

Rob

[XrSiSt]

From my understand (which may be wrong),

You stick ur bleed valve between the hose

to increase boost. If you increase the length

of this hose, I assume this will affect the

pressure it holds? ie. can i increase the length

of the hose and expect no drama's or the

opposite?

[Black33]

If you increase the length of the hose - you will get bigger spiking due to the time it takes for the air to fill all the hoses before it begins to bleed off!!

The shorter your hoses the better boost control (and make sure they are all well fixed at ends to stop any leaks)!!!

have fun.

:burnout:

[ix9]

Just _wondering_ how I would go about upping the boost on my R33... Right now the stock boost gauge peaks at 1/2way... so that converts to 7psi right...

What SAFE boost would you recommend on stock coola, ecu, etc ?

I have turbo-back zorst btw.

and I've heard of people running 10psi using small irrigation taps/valves/t-pieces... how is this done ?

when you people are all mentioning bleed valve devices, what are you exactly talking about ? and where can i get them ? DIY jobs ?

-Kym

[XrSiSt]

Strich9ine, here's some info by Grim (who's on these boards also)

http://www.performance-mod.com/nuke/html/m...=article&sid=15

http://www.performance-mod.com/nuke/html/m...=article&sid=16

Hope this is what your lookin for.

Its seem to be 10 psi is recommended.

[XrSiSt]

Originally posted by Black33

If you increase the length of the hose - you will get bigger spiking due to the time it takes for the air to fill all the hoses before it begins to bleed off!!

The shorter your hoses the better boost control (and make sure they are all well fixed at ends to stop any leaks)!!!

have fun.

:burnout:

Oh and thanks Black33

[Guest INASNT]

heres a better idea!

piss the bleed valve off and get a EBC! bleed valves sux