vmapper

iTrader: (8)

I just purchased a MaxFlow Vortech bypass valve, and to test it I attached a 1/4" vac line from the engine while at idle.
Pulls the valve open no problem.
Now my question / concern is how fast the valve closes after the vacuum is removed.

This seems to sloowly close, a good second. I thought this would SNAP shut.
Can this be adjusted ? Is that the screw set on the top beside the vacuum line?
Is this bypass valve shot?
Or is this normal for operation?

It is used but looks in very good condition, so would peg it as barely used.

Thank you in advance.

vmapper

iTrader: (8)

Does no one know or watch their stuff in action?

2001WS6Vert

The spring pressure is adjustable with the screw. Been awhile since I observed it's operation so I can't Help you there.

vmapper

iTrader: (8)

I was under the impression that the top screw (nut) was to adjust the amount of vacuum required to pull the valve open.
from Vortech:
bypass valve is preset to open at four to five inches of vacuum.

I really need to know if this is fubared or normal before installation as it will not be an easy area to access once all in.

So.jerZ-28

iTrader: (20)

how bout calling vortech? I'd answer ya if I knew. My bosch valve seemed to snap close pretty quick, thats all I could tell ya.

vmapper

iTrader: (8)

I was going to leave calling them long distance further down the list , since, I did pick it up used from here, not from vortech or any authorized dealers.

I was more or less wanting someone to quicky say:

Hey, that means the piston is worn or, thats fine.

thanks everyone.... I guess wait and see how it works. Guess I should have bought a new one to eliminate any possible issues.

5 Liter Eater

iTrader: (5)

I can't remember how my Tial acted when I was testing it but I don't think yours is anything abnormal.

vmapper

iTrader: (8)

Thanks Bill,

One side question, seen you on HPTuners forum many times...(Im thread jacking my thread)

Stoich target (14.680:1) before PE enable. Do you change TPS %, MAP, rpm delay so PE is enabled before there is any boost in the manifold or what is the proper way to set this up ECM wise?

No need for details, just some wise info.

5 Liter Eater

iTrader: (5)

Many PCM's ignore PE Delay RPM. Its mostly trucks that use it but I always set this to 0 as I don't want to keep PE disabled until any certain RPM. The PE Enable MAP is usually set very low anyway (stock for me is 15 kPa) but if not I'd zero that out too.

I have the 2 bar SD OS so I also have a Boost enrich table so when I cross 105 kPa it uses the BE table to ensure I am in PE (BE really but I have PE and BE the same). Without the BE table you'd just have to see where you start making boost at different RPM's and TPS's. You could make a histogram to plot TPS against the PE table and set a filter to only display data when the MAP is >105kPa. Then drive around for a while and set the histo to display the smallest values. This would generate you a PE Enable TPS table that ensures you are in PE when you are in boost. Copy them into the PE Enable TPS table and subtract ~10% from all cells.

Now with a positive displacement blower or especially a turbo this method would not work.

vmapper

iTrader: (8)

Ok, that makes sense. Create a PE TPS enable for all rpms and give a 10% cushion, upper rpms TPS enable obviously can be flat lined 5% or so above lets say, 4500rpm and gather values for everything under 4500rpm.
Going SD does have that nice boost enrichment feature.
my 3000ft elevation change driving habbits though, i wanted to try MAF only first.

Its a CTS-V with a procharger.
I am going to run MAF only. Boost is ~7psi. I will still plot based on Map greater than or = 105kpa. (stock 1 bar map limit i think) with your suggestion.

Your input is gold.
Thank you Bill!

5 Liter Eater

iTrader: (5)

No problem. Lastly, don't increase any values, just decrease. So if the histo says you don't enter boost until 60% TPS at 2000 RPM's but the PE table is set to 45% TPS at 2000 RPM's, leave it at 45%. You may find that the stock PE Enable TPS table is fine.

vmapper

iTrader: (8)

Stock PE TPS % enable is the following:

64% up to 3200rpm
55% at 3600
45% at 4000
36% at 4400
26% at 4800 - 7200

Im sure ill be bringing these values down.

Your advice on this was very clear and appreciated!

9t8z28

iTrader: (19)

the valve closes slowly becuase there is no pressure behind it. In a closed system, the valve will be forced shut by the pressure.

vmapper

iTrader: (8)

That really makes no sense as the pressure would be pushing on the valve.
If your talking about a closed system as in, recirculating, again, it would recurulate to pre-blower (inlet)... and a vacuum would be present on that side.
The valve would be rendered useless if was circulating back to the pressure side of the pipe.

9t8z28

iTrader: (19)

It makes perfect sense. It is a butterfly. It doesn't matter which way it opens or closes, pressure will push up against it and shut it.

Your testing the butterfly by hooking vacuum to it and looking down the barrel. You can't test it this way.

vmapper

iTrader: (8)

???
Its not a butterfly.
its a piston as stated in the first post.
ref:

http://www.vortechsuperchargers.com/product.php?p=25

9t8z28

iTrader: (19)

My bad, your right

stevieturbo

When you physically push the piston to open it by hand, does it close slowly or quickly ?

If quickly, then mechanically it is working fine.

9t8z28

iTrader: (19)

Isn't this technically a blowoff and not a bypass?

vmapper

iTrader: (8)

Actually, if you want to get technical just for info purposes....

A surge valve Surge valve can be recirculated (also known as or called a bypass valve) or vented to atmosphere (or open bypass or called a bypass vented to atmosphere, NOT A BOV! (Blow off valve). This is the misuse of term and is a different valve.
Bypass (Surge ) = Belt driven superchargers
BOV (Blow off Valve) = Turbo

A surge valve is used in supercharged applications. It is open under part throttle conditions and throttle lift-off and closed at WOT. Since a supercharger is always spinning "x" amount of speed vs engine speed no matter the load conditions, the extra air needs to be bypassed or you will have continuous compressor surge and heating of the intake air at part throttle.

The bypass is operated by a vacuum actuator control unit that is normally closed. When vacuum is high (idle-cruising) the actuator opens the bypass valve, equalizing the vacuum pressure throughout the system. When boost is required (accelerating) the vacuum is decreased and the bypass valve instantly closes, causing pressure to increase into the cylinders. This equalized vacuum condition virtually eliminates the normal parasitic power loss of a forced induction system.


A blowoff valve is used in turbo applications only opens at throttle lift off (after boost has been produced). It is closed at part throttle cruising and WOT. A turbo system does not generate boost at part throttle cruising therefore an open bypass valve could possibly ingest ambient (unfiltered) air under cruise conditions.

As you can see, the actual workings of the TWO different types are quite different yet serve a similar purpose. There are reasons why they work differently and that is due to how superchargers (belt driven) differ from Turbo (gas driven).