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26 psi HELP (avcr question)

Old 02-01-03, 09:44 PM
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26 psi HELP (avcr question)

Hello all, I installed an AVCR today, and I cannot control the boost. In a nutshell I believe everthing is set correctly, and I need a lighter wastegate spring(have 15 psi spring now). Boosts to 15 psi w/ controller off.
AVCR is;
initiallized
FB is 2 1 1 1 1
boost 1.0 bar
duty cycle 30%
car select 4 4 /
ne points 3000 3500 4000 4500 5000 5500 6000 7000
sensor voltages are correct
turbo is a small TO4 (.60/.85ptrim)
street ported
Can anyone help me with this?
Thanks, Carl Byck
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Old 02-03-03, 12:30 AM
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Solved my problem, the "NO" port was plugged. Anyway, no one seemed to have much input anyway. Later, Carl
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Old 02-03-03, 08:19 AM
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what is an AVCR? I can't keep track of these piggy back boxes names any more. sorry don't use this stuff and don't want to know how they work, since they are not really needed.
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Old 02-03-03, 11:43 AM
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avcr

Actually, the AVCR is an electronis boost controller, not really a piggyback, like a device to control fuel or ignition.
The reason for it is very simple. It is the best, and fastest way to control a turbo.
In a nut shell When you control a turbos boost with a spring the wastgate is always open under boost to a certain degree, concluding when fully open at whatever the max boost the spring is designed for. That means that the turbo is fighting a partially open valve in its quest for your desired boost level(power). Pressure is constantly bleeding off while you are trying to build boost.
With a boost controller, you block that pressure to the wastegate until it reaches your desired boost. At that time it continues to aid you by allowing precisley the right amount of pressure to maintain your boost level.
Real world, first, your turbo will not have to work as hard to hit, and maintain a given boost level so it will last longer. Second you build boost much more quickly since you are not bleeding off any pressure on your way to the final boost level. Third you can maintain a given boost level for longer because more of the turbos energy is usable(not simply overwhelming the wastegate).
For racing this means subtantially more power earlier(probably200-400 rpm earlier), and for a longer time(easily 500rpm added to the max power end ), all while your turbo is working less than it would be without the controller.
This is just the basics since you said you don't want to know how they work
I suppose we don't really need electricity either, but it sure is nice to have
Tim, did you run the Enduro last fall at Thunderhill? What were some of your lap times if you did? I know I have a long way to go, but it would be nice to know just how far that is. Best regards, Carl Byck
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Old 02-03-03, 11:45 AM
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Oh, one last thing, I have an E6K. The AVCR is vastly superior for controlling boost. Carl
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Old 02-03-03, 01:05 PM
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if you are using a quality wastegate the pressure lifting of the wastegate is eliminated. some of the cheep stock setups can have this problem but not a quality race type wastegate(construction of wastegate prevents this problem), so the AVCR is not the"best" it is in essence a piggy back used to fool the stock type wastegate spring. it allows you to dial in any boost pressure as long as it is above the wastegate spring rate. as for the thunderhill enduro I have not raced my own car, but I have crewed for a friend who ran a World Challenge civic in 2001. lap times were slow as the whole race was run in the rain. One day I would like to make the race, but it is expensive and a long tow from LA.
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Old 02-03-03, 01:32 PM
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With all due respect Tim, you are not correct regarding the wastegate spring. First, I use an HKS racing wastgate mounted to an HKS manifold. There is not a better wastegate available to the public that I am aware of. A spring by its very nature is not, and cannot be an on/off switch...At some point you must begin to compress it, and once you do, you are bleeding off pressure. You can change the threshold for this eventuality by changing springs but the fact will remain it is a spring not a switch. A boost controller converts the spring to a switch by putting a comensurate amount of pressure in the head of the wastegate, thus keeping it closed until a specified pressure is reached. Additionally the controller then allows the wastegate to open just enough to prevent boost overshoot(spikes) and maintains that pressure until the turbo reaches its capacity to flow air at which point boost falls. This is not possible to do with a spring, because the spring can only present one range of resistance. You could use a progressive spring, but that would be going in the opposite direction from where you want to be.
The net result of all this is a powerband that is, on the cars I have owned and tuned, in the neighborhood of 800-1000 rpm longer. This coupled with much faster response makes this a great tool for those who wish to utilize its advantages.
I guess the term piggyback implies a bandaid, and that is just what this is. It is a bandaid for the inefficiences of a wastegate controlled by a spring.
Hope all this make sense, I'm just stating the facts, not looking for an argument here. Best regards, Carl
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Old 02-04-03, 09:58 AM
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problem is you are mixing several different percieved problems. the first was
In a nut shell When you control a turbos boost with a spring the wastgate is always open under boost to a certain degree, concluding when fully open at whatever the max boost the spring is designed for. That means that the turbo is fighting a partially open valve in its quest for your desired boost level(power). Pressure is constantly bleeding off while you are trying to build boost.
with the HKS wastegate this is not happening. the design of the valve prevents this from happening. the exhaust gases are pushing the valve closed as it builds pressure. the valve will only start to move once the pressure is greater than the spring pressure, so if the spring is ten pounds then it will not move until 10 pounds is applied. so if anything you may experience momentary pressure increase(this was how Honda and Toyota were cheating the pop off valves in CART, creating higher boost and HP before the pop valve kicked in). by using the solenoid to instantly open the wastegate you can be more precise but all of this does not happen instantly. the box does allow you to easily manipulate the boost pressure. on the stock or OEM flapper type wastegates the phenomenon you made reference to above can happenon some engines. the turbo is trying to open the flapper while the spring is trying to keep it closed, but the spring on the HKS type wastegates is only to open the valve. if the hose came loose it would never bleed any exhaust gases no matter how high the pressure in the exhaust manifold got.
A spring by its very nature is not, and cannot be an on/off switch...At some point you must begin to compress it, and once you do, you are bleeding off pressure.
this is something that will help make things a little smoother. by opening the valve smothly and not violently is always better. I don't want to open and close the wastegate like a light switch. I personally use the HKS wastegate(50mm racegate) and I have never experienced any lower than advertised boost levels. I have run this setup for a couple years on a track only car and I can tell you the boost level at wide open will not move from the spring setting. and finally my own reason for using the wastegate by itself is simplicity. hose from turbo to wastegate end of boost control. no electronics to go bad, no programming to do, and simplified hose system. I think these boxes are useful for someone who wants to change boost settings or program them for different rpm ranges but I don't believe it is going to be any better than a true wastegate. In racing you will find simple is sometimes better.
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