Manual Or Electronic Boost

[zebra]

Yeah can never run below the spring pressure

[J'son]

Ahh, i see. That is awesome. I don't totally follow how the boost controller bipasses the actuator and allows for higher boost etc, but it makes sense about the min boost i can run now too. It is also good to know they are easy to remove and that they are exactly as i thought, a device spliced in to the boost lines... but still not 100% clear on it all.

TA!

EDIT: After reading again it makes a bit more sense, even if it seems so primitive... When you say this (below), are you saying the needle valve actually does vent to atmosphere and this is the whole reason these things are not really legal? Or is it still plumbed in properly to the exhaust, cos i still have the stock plumb back waste gate running, and it still sounds awesome...

A Manual boost controller or bleed valve simply reduces the amount of pressure the can receives by bleeding off though a needle valve (if you looks at the bleed valve there will be a little hole in it somewhere) and tricking the diaphragm into thinking there is less pressure there so the spring holds the flapper closed more than normal, allowing more exhaust gas to go through the turbine wheel and thus increasing boost.

Edited November 15, 2011 by J'son

[zebra]

It is basic.

Think of a garden hose with a balloon on one end, you need to inflate the balloon to move an object with is being pushed back from the opposite direction by a spring.

So you blow into the garden hose (boost pressure) the balloon inflates and pushes the object back as it over comes the spring pressure.

now poke a hole in the hose and try to blow it up, you blow the exact same amount of air as the first time, but now because the hose has a hole in it the balloon doesn't inflate as much and doesn't move the object as far because you are loosing pressure through the hole in the hose

Now think of the wastegate being the object you are trying to push, the spring as the spring holding the wastegate shut and the balloon as the diaphragm pushing the spring, and the hose as the vacuum line from the actuator to your intercooler piping.

The excess pressure is simply vented out the hole in the boost controller into the engine bay.

what you are thinking of in part of your post is the blow off or recirculation valve.

What that does is when you close the throttle (let off the loud pedal) all the pressure in the intercooler piping has nowhere to go but back where it came from (back out the turbo) making the "dose" noise or the tu tut tutut utut noise you often here.

Big conjecture as the whether it does any damage to the turbo or not.

So the factories started fitting recirc or blow off valves.

Work similar to a wastegate but backwards, they close up tight under boost and release when the throttle plate is closed.

They too are fed boost, but from the intake manifold only, so they are fed boost to hold the valve closed, plus a spring to hold it closed too and when you back off the throttle because the intake manifold is now under vacuum that same boost feed + the pressure in the intercooler pipes opens the valve to let the excess pressure out, either back into the intake before the turbo (legal) or straight out to atmosphere (not legal) illegal due to the noise plus the air in the intake system is full of oil vapor / fuel vapor etc and might kill some baby seals or some shite.

Also cars fitted with Mass Air Meters (AFM or MAF) like the skyline dont like externally venting blow off valves, because the air flow meter measures the amount of air being sucked in and tells the ECU to add fuel for that amount of air.

Except the engine doesn't receive that air but the computer thinks it does so it throws a whole heap of fuel in thinking all that air is making it into the engine, causes stalling issues and horrid fuel economy.

Where as when plumbed in, you will see it feeds back into the intake between the turbo and the AFM it just gets recirculated back around and reused, so the amount of air the AFM reads is now correct for the amount of air the engine is receiving.

Hope that makes sense, made it as basic as I could

[Manuel Kasko]

These guys are amazing with all the info!

I just read all the posts 2x so it all soaked in

Quiz me go I dare you

[zebra]

These guys are amazing with all the info!

:

nohomo

[Manuel Kasko]

nohomo

*Cough* follow me to my rape dungeon nice house *Cough*

Edited November 15, 2011 by Kasko

[J'son]

Yeah i think i follow all that now, thanks.. Took a moment to get my head round it.

But one of my main points: Is the reason they dont like and it is illegal to have a duel boost controllers, is cos it illegally vents to the atmosphere rather than sending it back into the exhaust (like the legal blow off valves/wastegates?).

Also, what were you referring to as to what can damage the turbos? The multi stage blow offs?

Edited November 16, 2011 by J'son

[zebra]

any aftermarket boost controller is illegal, changes the emissions output of the car by changing the state of tune.

For the damage bit - without a blow off valve, the air coming back out the turbo inlet hammers the bearings inside the turbo as the compressor wheel gets pounded by air going the wrong way...kind like driving along the road and grabbing reverse instead of 5th etc...just not as severe

[Manuel Kasko]

Kind of like punching yourself in the face