Electronic Blow off Valves

[choppo]

Hi all,

About to install an APEXI boost controller and therefore need an electronic blow off valve.... anyone had good/bad experiences with particular brands.
Note this is a low boost application i.e. from 1psi - 12psi. Any comment would be appreciated..

[Kyle]

Choppo.
The only type of electronic bov Is the ebay gimmick specials they have a speaker and aren?t really a bov?

Boost controllers don?t require you to have a blow off valve at all.

The boost solenoid that comes with your controller should be capable of using the standard wastegates on your turbos also.

[seedyrom]

Thats so funny ... about 15 mins ago I was looking at this:

http://www.mrtrally.com.au/shop/default.asp?Product=musse127h15

An electronic blow off valve (no, not a fake noise generator)

http://www.mrtrally.com.au/shop/images/products/musse127h15.jpg

Cant help though sorry choppo.

a stocker seems fine with my Apexi

[choppo]

Hmmmmm..... think i need to go back to Mechanics 1 oh 1 at TAFE.......

OK guys, just because im new here, ill let you all have a laught at me because this may be the stupid-est thing posted to date (but id still like to know the answer!)

Let me start again. I want to install an APEXI AVC-R boost controller on my TT so i can adjust boost over revs etc etc... i have decided on the APEXI so we can take that out of the equation.....
Now, i thought:confused: that my current blow off valve is a mechanical one, run off boost pressure and some sort of internal spring that shuts off/opens at a pre determined spring tension (say for argument 9psi). To change my boost currently, dont i have to change the spring in the BOV to one that will open/shut at a different pressure. If that is the case (which i am now thinking i am wrong:headbang: ) how does a digital/ electronic controller work???
As above im sure this sufficiently shows im a dick, but, hea..... who cares, thats why i asked here, not 'elsewhere'..

[nirvana]

Hmmmmm..... think i need to go back to Mechanics 1 oh 1 at TAFE.......

OK guys, just because im new here, ill let you all have a laught at me because this may be the stupid-est thing posted to date (but id still like to know the answer!)

Let me start again. I want to install an APEXI AVC-R boost controller on my TT so i can adjust boost over revs etc etc... i have decided on the APEXI so we can take that out of the equation.....
Now, i thought:confused: that my current blow off valve is a mechanical one, run off boost pressure and some sort of internal spring that shuts off/opens at a pre determined spring tension (say for argument 9psi). To change my boost currently, dont i have to change the spring in the BOV to one that will open/shut at a different pressure. If that is the case (which i am now thinking i am wrong:headbang: ) how does a digital/ electronic controller work???
As above im sure this sufficiently shows im a dick, but, hea..... who cares, thats why i asked here, not 'elsewhere'..

ok i'll give it a go but i warn you i don't know much about it.
the different springs for boost is i think in the turbo and that gives you the minimum boost not max.
the boost controller just lets you wind it up or down to the spring pressure.

[seedyrom]

bov's dont control boost, just vent excess pressure when throttle body closes (when you take foot off the gas) - excess pressure is built up cause the turbo is still spinning, and all the plumbing from it, through the intercooler and up to the throttle body is a closed system.
The bov vents the gas to atmosphere, rather than forcing the air back out the way it came (causing turbo impellor to stop and spin the other way - there is conjecture is to whether this causes turbo damage or not).

My old mans turboing his race car, and got a $70 plastic bosch bov, the same as mine funnily enough, so i got to see how it works.

I was blowing as hard as i could through it, and couldn't make any air flow through. My dad then sucked ever so gently on the vacuum hose, and psssshhhht .... seedy vented :D


oh, sorry for getting distracted
the wastegate has the spring in it

[Sonny@AutoWerks]

Hi all,

About to install an APEXI boost controller and therefore need an electronic blow off valve.... anyone had good/bad experiences with particular brands.
Note this is a low boost application i.e. from 1psi - 12psi. Any comment would be appreciated..


Choppo,

U installing the apexi avcr ? if so they are a good piece of equipment as i have installed quite a few,has many features as like boost over rpm,boost over gear,quite etc... a good bit of gear,just make sure you plum the lines with braided teflon line :)

regards sonny

[RedVYIISS]

I want to install an APEXI AVC-R boost controller on my TT so i can adjust boost over revs etc etc... i have decided on the APEXI so we can take that out of the equation.....
Now, i thought:confused: that my current blow off valve is a mechanical one, run off boost pressure and some sort of internal spring that shuts off/opens at a pre determined spring tension (say for argument 9psi). To change my boost currently, dont i have to change the spring in the BOV to one that will open/shut at a different pressure. If that is the case (which i am now thinking i am wrong:headbang: ) how does a digital/ electronic controller work???

Choppo, your level of boost is controlled by your wastegate, not BOV. As Seedy's said, BOV just vents excess pressure when you back off. The wastegate works by directing exhaust gasses either through the turbo exhaust wheel, or when set boost pressure is reached (as determined by wastegate spring), the wastegate dumps exhaust gasses out through it's own internal exhaust port, thereby directing exhaust gasses away from the turbo exhaust wheel (which allows the turbo to slow down and generate less boost)

The wastegate comes supplied with a spring. The set pressure of this spring determins the boost pressure. If you want to be able to adjust boost above the pressure provided by the wastegate spring you need an EBC (electronic boost controller, such as the Apexi-AVCR), though there are 'cheap' mechanical boost controllers available as well (though EBC's are much more versatile than the mechanical boost controllers).

The EBC works by controlling a solenoid valve that bleeds compressed air to or from the wastegate housing, adding air increases the pressure exerted by the wastegate spring, thereby increasing the level of boost (the compressed air comes from the discharge side of your turbo).


I hope that made sense!

[choppo]

Choppo, your level of boost is controlled by your wastegate, not BOV. As Seedy's said, BOV just vents excess pressure when you back off. The wastegate works by directing exhaust gasses either through the turbo exhaust wheel, or when set boost pressure is reached (as determined by wastegate spring), the wastegate dumps exhaust gasses out through it's own internal exhaust port, thereby directing exhaust gasses away from the turbo exhaust wheel (which allows the turbo to slow down and generate less boost)

The wastegate comes supplied with a spring. The set pressure of this spring determins the boost pressure. If you want to be able to adjust boost above the pressure provided by the wastegate spring you need an EBC (electronic boost controller, such as the Apexi-AVCR), though there are 'cheap' mechanical boost controllers available as well (though EBC's are much more versatile than the mechanical boost controllers).

The EBC works by controlling a solenoid valve that bleeds compressed air to or from the wastegate housing, adding air increases the pressure exerted by the wastegate spring, thereby increasing the level of boost (the compressed air comes from the discharge side of your turbo).


I hope that made sense!

Thanks all - clearly i was looking at the wrong thing!
So, based on the above info, i did some net surfing and found 2 articles that (i think) explain this EBC boost pretty well..... i note this is probably not exactly how mine/ours work, however i think it shows the concept pretty well.
The crux of the issue appears to be;
the EBC comes with a solenoid valve that sits 'in line' in the thin boost tube that goes to the turbo waste gate. Buy adjusting the amount of boost (by bleeding off pressure in the thin hose) the waste gate 'sees', it 'tricks' the wastegate into producing or not producing boost....

The article is at;
http://autospeed.drive.com.au/cms/A_2542/article.html
This goes straight to Part 2 but a link to Part 1 is contained within.
Not for the experienced, but for us dumbies, it may be useful.

thanks again

[seedyrom]

Another good article is here (sorry, its a bit lengthy):

http://www.splparts.com/doc/tech/EBC.htm


Reprinted without permission
How does a electronic boost controller work?


First, let us understand how a turbo works. A turbo simply consists of an exhaust wheel and a compressor wheel connected together, exhaust gases from the combustion turns the exhaust wheel which in turn spins the compressor wheel. The compressor wheel then crams more air into the intake, creating boost pressure.



If left alone, a turbo would just keep spinning faster and faster and could result in too much boost, which would cause engine components to fail. To regulate the amount of boost, wastegates are equipped on all turbo-charged cars. The purpose of the wastegate is to divert some of the exhaust away from the turbo (so it won't spin the exhaust wheel). A wastegate is simply a spring loaded valve, this valve opens when the intake pressure reaches a certain pressure and diverts some of the exhaust away from the turbo. Suppose the wastegate is designed to open at 7PSI of boost, then when boost reaches 7.1PSI, the valve opens and the exhaust from the cylinders are diverted away from the turbos, and the turbo starts to slow down. When the boost drops to 6.9PSI, the wastegate closes and the turbo starts to speed up again. This happens rapidly and keeps boost regulated nicely at 7PSI.



The pressure at which the wastegate opens is the base boost pressure, installing a boost controllers will allow you to run higher boost. An electronic boost controller usually works using a solenoid (electronically controlled) valve. A solenoid valve would have 3 ports (sometimes 1 is hidden inside the housing), and 1 port goes to the wastegate, the other port is hooked up to the intake, and the last port is left open to the atmosphere. The solenoid can switch between connecting the wastegate port to the intake port, or connecting the wastegate port to the atmosphere port.



Suppose you want to run 14PSI of boost, then a electronic boost controller should do this -- when the boost reaches 14.1PSI, the solenoid will connect the wastegate to the intake, causing the wastegate to open (since 14PSI is higher than the 7PSI required to open the wastegate)... the turbo will start slowing down, when it drops to 13.9PSI, the boost controller will then switch the solenoid and connect the wastegate to the atmosphere. This causes the wastegate to close since the atmosphere is 0PSI lower than the 7PSI needed to open the wastegate, and the turbo will start speeding up again. This happens rapidly and keeps boost regulated nicely at 14PSI.



Most boost controllers accomplish this by figuring out what percentage (or ratio) of the time the solenoid would connect the wastegate to the atmosphere vs. connecting the wastegate to the intake. This ratio is often known as the DUTY CYCLE, the duty cycle is directly related to the boost level.



Now this is the main function of the boost controller, but there is another benefit to running a electronic boost controller, and that is it will allow the turbos to spool up a little faster. How does it do this? Well, a wastegate might be designed to open at 7PSI, but it usually cracks open a little even before the pressure hits 7PSI. This will slow down spoolup of the turbo, causing it to hit 7PSI a little later. A good electronic boost controller would keep the wastegate shut for as long as possible, by using the solenoid to connect the wastegate to the atmosphere (0PSI) till the turbo gets really close to hitting the boost you want, only then it will start switching the solenoid back and forth according to the duty cycle. To determine how long to keep the wastegate shut, most electronic boost controllers use a number known as GAIN. If the gain is set too high, the boost could spike (the wastegate is held closed a little too long causing overboost), but if the gain is set too low, the spoolup is not as optimal as it could be. Getting the correct gain setting will give the optimal spoolup of your turbos.



Manual mode vs. automatic mode vs. fuzzy logic


Most of the modern higher-end electronic boost controllers have an automatic mode or fuzzy logic, where you simply enter the boost you want to reach, and the boost controller would automatically try to figure out the DUTY CYCLE and/or GAIN. In certain cases (eg. twin-turbo setups), this logic might not work very well, and it would be necessary to use the manual mode.



How to set up an electronic boost controller in manual mode


In manual mode, there are two numbers that has to be determined: DUTY CYCLE (sometimes also labelled as SET) and GAIN. The optimal gain number always depends on the boost level you want to run, if you are running very high boost, then you want the wastegate held closed for a longer time since it takes a longer time to reach the higher boost. So the first step is to determine the duty cycle:



1. Start off with a low DUTY CYCLE and GAIN setting.



2. In a higher gear (3rd or 4th), run the car to see what boost level the duty cycle corresponds to by watching what steady/stable boost level is reached. Increment the DUTY CYCLE with each run till you reach the boost level you want. Fine tune as necessary. If you notice boost spikes, then you have set the gain too high, you do not want spikes at this point since that makes it more difficult to see the steady/stable boost level.



The reason why you should use the higher gears is because in the low gears, things can happen too fast to figure out what the steady/stable boost level is. Now that you have figured out the duty cycle that will give you the boost level you want, the next thing to do is to work out the gain:



3. Make runs in lower gear (1st or 2nd), increment gain with each run till you see boost spikes. Then fine tune it till there is little or no boost spike. This is your optimum gain setting for that boost level.



The reason why you should use the lower gear now is because boost builds much quicker in the lower gears, so there is a higher tendency to boost spike.



When setting your boost controller, always have a passenger set the controller and watch the boost gauge for you, the driver should keep his eyes on the road!



Common problem


Sometimes if the gain is set too high, it may appear to have the same effect as the duty cycle. If you notice (especially in the higher gears) that you initially hit the boost level you want, but then it starts tapering off, then you might have set the gain too high and the duty cycle is not set correctly. Or you might have a boost leak...





Written by Aikmeng Kuah, SPL PARTS INC.

Jan 26 2003

Copyright SPL PARTS INC.

[choppo]

Great find that one - i can now claim im an expert:teach: :lol:
One more question................ what happens if i want a lower boost than the 7psi spring as mentioned in the article? I assume the EBC cant help unless you change the wastegate spring to a 2psi one????

[nirvana]

Great find that one - i can now claim im an expert:teach: :lol:
One more question................ what happens if i want a lower boost than the 7psi spring as mentioned in the article? I assume the EBC cant help unless you change the wastegate spring to a 2psi one????

yep thats right.
but i find 7 psi is perfect for me as an everyday car (around 300rwkw).
when you are in the mood pop in a ac/dc c.d and wind her up. :yep: