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10 Psi Boost With One Peice Hose To Actuator On Std Skyline

cosworth1971
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bilbo117 Rising Star

bilbo117

Posted
Posted
If you put a different hose running from your intercooler pipe to the actuator you are running more boost because there is less pressure going to the actuator so the wastegate doesn't open and keeps building boost. The standard vac line that runs to the actuator has a restrictor in it that reduces the diameter inside the hose. A smaller diameter means higher pressure - higher pressure means wastegate opens earlier creating less boost. Imagine it like having a pea shooter - with the thin pipe it will shoot quite far due to the greater pressure but if you had a large diameter pipe with a pea in it it wouldn't go very far. - hope that makes sense :)

That coupled with your new exhaust.

Dude that sounds so wrong.

the smaller pipe will not give you a higher pressure. are you saying that the air pressure in my intercooler piping could be say, 10psi, and because my piping to the actuator is smaller, the pressure inside here will be around 15psi? It doesnt work like that. use common sense.

In actual fact, because an actuator has little air flow to it, the restrictor wont do alot other then slow movement and proberbly make boosting smoother on the standard setup.

Where is everyone taking there actuator tap from? my problem has been fixed, i moved it to the piping immediatly after the turbo and fitted new BIGGER hose straight to the actuator.

R33silverS2 Mentor

R33silverS2

Posted
Posted
Dude that sounds so wrong.

the smaller pipe will not give you a higher pressure. are you saying that the air pressure in my intercooler piping could be say, 10psi, and because my piping to the actuator is smaller, the pressure inside here will be around 15psi? It doesnt work like that. use common sense.

In actual fact, because an actuator has little air flow to it, the restrictor wont do alot other then slow movement and proberbly make boosting smoother on the standard setup.

Where is everyone taking there actuator tap from? my problem has been fixed, i moved it to the piping immediatly after the turbo and fitted new BIGGER hose straight to the actuator.

It doesn't sound wrong at all Dude.... It is common sense. Reducing the diametre of a hose increases the pressure inside the hose. Hence why do you think taking the restrictor out of a gtr or an s15 for example ups the boost when replaced with a generic piece of fuel line or silicon hose... Because the pressure to the actuator is reduced hence the turbo creates more boost as the wastgate doesn't open as early or as much.

Cheers 'dude'

R33silverS2 Mentor

R33silverS2

Posted
Posted (edited)

Btw 'slowing airflow to the actuator :huh: ' is not going to make boost come on 'smoother' If anything it would ramp up faster and harder because the wastegate is not opening as much.

Which is why that is Not what it is doing in the stock setup.

Edited by R33silverS2
bilbo117 Rising Star

bilbo117

Posted
Posted
It doesn't sound wrong at all Dude.... It is common sense. Reducing the diametre of a hose increases the pressure inside the hose. Hence why do you think taking the restrictor out of a gtr or an s15 for example ups the boost when replaced with a generic piece of fuel line or silicon hose... Because the pressure to the actuator is reduced hence the turbo creates more boost as the wastgate doesn't open as early or as much.

Cheers 'dude'

Your analogy is completely wrong. As i said before.

You seem to not understand the relationship between pressure and flow. are you saying if i block off a pipe, and plug the other end into a compresser, that as the pipe gets smaller and smaller it will have higher pressure until it reachs the end? You cannot deny the fact that when flow ceases pressure will equalise on both sides of a restriction. For this reason, I don't see how having a smaller pipe will give you less boost.

can anyone else clarify? perhaps with some more in depth arguements?

bilbo117 Rising Star

bilbo117

Posted
Posted

LMAO

Because the pipe going to my boost gauge is really small, MAYBE, just MAYBE i am reading a much higher boost then i am actually running.

DEAR GOD

the problem is solved, maybe we have different boost gauge piping!

what size is the pipe running to your boost gauge R33silverS2? :huh:

R33silverS2 Mentor

R33silverS2

Posted
Posted (edited)

Your boost gauge is calibrated to run off a certain diameter hose. Go plug in a bigger one than it came with and see how you go....

Also please give us your expert analysis on why boost increases when the restrictor hose is removed... >_<

Also enlighten us to what the brass restrictor is for...

Edited by R33silverS2
R33silverS2 Mentor

R33silverS2

Posted
Posted
LMAO

Because the pipe going to my boost gauge is really small, MAYBE, just MAYBE i am reading a much higher boost then i am actually running.

DEAR GOD

the problem is solved, maybe we have different boost gauge piping!

what size is the pipe running to your boost gauge R33silverS2? >_<

>_<

  • 3 weeks later...
bilbo117 Rising Star

bilbo117

Posted
Posted
Your boost gauge is calibrated to run off a certain diameter hose. Go plug in a bigger one than it came with and see how you go....

Also please give us your expert analysis on why boost increases when the restrictor hose is removed... :laugh:

Also enlighten us to what the brass restrictor is for...

heres what I've figured so far.

Ive been talking to some pneumatic gurus at work and you are WRONG. smaller diameter in the pipe does NOT mean there is greater pressure. in actual fact, the pressure remains very much the same. Flow only increases. Because of this, and we all know the restrictor lowers boost, the guys believe that the restrictor is in place to keep the gate open longer, after pressure is removed from the actuator side. This means that the wastegate, once fully opened, takes a while to close again, meaning that the boost pressure is kept lower. There is NO such thing as a restrictor to increase pressure, it simply holds pressure at the diaphram for longer. (unlike what R33silverS2 has stated several times, pressure does not increase as the pipe gets smaller)

I fitted a restrictor to my car last week (went and bout 2 inchs of copper tube that fitted my vaccum hose) and my boost has dropped to around 8 pound consistently. The restrictor does work. Obviously, the most efficient way to control boost is electronically. Because of the restrictor, the wastegate also takes longer to open and this means it would be easier to have 'boost spiking' present.

Hope this clears a few things up.

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