johne

Peckster,
Maybe because it is additional pluming? Or they didn't think about it? Or maybe reliablity. I would like to find a piece that is automotive grade.

John

Songzzz

My guess is that the additional lag may come from the extra pluming.. turbulance and also another possible source of boost leak?

At the point, when throttle is opened, there should be enough air between the compressor -> (IC) -> intake... no?

johne

Andrew,
Well if you plumb it properly then when the car is off boost there will be very little plumbing involved. Air filter->maf->1way valve->throttle body. Then when the car is on boost there will be very little additional volume to the intake track because of the 1 way valve.

About the possible boost leak, well you would just have to figure out the maintenance interval of the valve and replace it at that interval.

To answer your questions, yes there is a lot of air between the compressor and intake valves. But when you floor it at 2000 rpm there is a vacuum created between the two and the engine has to suck its air through the turbos compressor which is not turning fast enough to create any pressure. The compressor blade is effectively acting as a blockage in the intake track. This device allows you to bypass that until there is enough exhaust gas flowing to power the turbo.

Good thinking though. It’s always good to analyze a piece as much as possible to try and figure out all of its flaws so that you can improve on the piece and make it even better. That’s what engineering is all about right?

Regards,
John

DanG

Hey guys, I was gone for the weekend, just remembered to check this thread.

Trying to clear up the MAP vs. MAF comparison... as long as this check valve is plumbed AFTER the MAF, then your engine management will still know exactly how much extra air you're sucking in. So with either kind of managment, the order of airflow goes like this...

Filter
MAF (if so equipped)
Route A - Turbo -> IC -> Throttlebody
Route B - Check Valve -> Throttlebody

So as you can see, all the air goes through the Filter and MAF, so its all clean and accounted for.

Also, if there really is a question about boost leaks or life of the valve, you could simply plumb two in series. They have negligible resistance in the correct direction of flow, so you'd have a redundant valve for safety.


J Chen - Since you're overseas, I'm guessing you might not have access to the same kind of building supplies that we have in the US. If your valve doesn't work out like expected, let me know and I can send you one at cost, maybe only $15-20 USD shipped to you in Taiwan.


And BTW, I can't throw stones at that guys welding until I get a little more practice under my belt.

J Chen

Hi Dan,
Thanks for the offer but I think
the check valve that I found is
much better than the one that
you posted. It's for high air
pressure usage. I was told that
it can handle more than 25psi of
pressure.
O.K lets get back to the MAP vs
MAF question. For the Check valve
to be effective, you got to plumb
it right on the IC pipe that connects
to the TB. Now, for MAP it's not a
problem cause it measures air in
the manifold so the computer will
account for excess air but when
using MAF it is not accounted for cause
air is measured by the Hot Wire
Sensor which in all cases is mounted
at the intake of the turbo. So if the
check valve is mounted on the IC pipe
that connects to the TB, that excess
air will not be registered by the MAF &
that will cause a lean out of the A/F ratio.
I would imagine that the Check Valve
would be operating at the vacinity of
1800-2500rpm depending on the type
of turbo that is being used. Maybe, just
maybe I could richen that area a little
with my ARC. Well, guess I would still
have to give it a try & see what happens.

Thanks again Dan

DanG

I may be confusing a bit of terminology, and again, I'm truely unfamiliar with the 951 layout.

Here's a translation of what I've been trying to type...

MAF = Mass Air Flow (sensor)
MAP = Manifold Air Pressure (sensor)

then there's the...

AFM = Air Flow Meter

I was using "MAF" as a direct substitute for "AFM". I think that is ok, but maybe not specific enough. My understanding is that anything that "counts" air can either be called a MAF or AFM. But it seems the convention is to call the stock Porsche "swing" or "barn door" style air flow sensor an "AFM" and perhaps the aftermarket hot-wire sensors are called "MAF".

Whichever combination of the letters "A", "F", and "M" you use, the routing should be the same. Make all the air flow through the filter and the "sensor" first, then provide it the choice of paths strait through the valve to the TB or into the turbo inlet. This ensures that all of the air has been "counted" and you will not see a lean condition.

J Chen,
Your valve sounds like it is good quality, I'd always prefer metal parts to plastic for something like this. Keep in mind that the spring in your valve will cause it to close before reaching 1 atm absolute, how much is determined by the strength of the spring force.


I attached a diagram of what the intake paths should look like. Yes, I have too much free time on my hands.

J Chen

Aaah Dan, now I understand what
you're saying.
Thank you, will give it a try.
BTW connecting it this way will safe
me the hassle of looking for an air filter
for the check valve. If it works, the next
thing to do will be to modify the Check
Valve with adjustable spring tension.

Ben Z.

Dan- It's good to see that somebody made a diagram, I think that should clear up some confusion here. That is exactly what I was thinking. Thanks.

J Chen

Right, silly me. Why did'nt I look
at it from this angle.

Thanks again Dan

BoostSciences

I have seen this idea somewhere else before, but they used a vacuum actuated gate valve. And apparently they saw very positive results. Unfortunately at the time it was of no interest to us, darn I wish I would have saved the link.

Anyway, we have an old design somewhere, that is essentially a spring adjustable one way valve, just like this flapper valve. Except that it is all aluminum, has a piston and an adjustable spring rate feature.

Lets see how the tests go, and maybe we will build a free prototype for whoever is doing the testing. All in the name of Science......Boost Science that is !!

Sounds exciting.

Regards

J Chen

Hey BoostSciences,
Can I have it ?. I was thinking that
if it works, I'll might custom a giant
reliable boost using a ping pong
ball as the valve with spring tension
adjustment just like the reliaboost
that I'm using. Why a ball ? Smoother
air flow

BoostSciences

J Chen:

I hope you really do not mean a ping pong ball. You want something durable. The unit we designed uses a piston with a lapped valve seat. Much more robust and reliable. The last thing you want is parts failing in such an application. Ping pong ***** are not meant for valves

Lets see how things work with the flapper and based on that we'll see if its worth everyones time on the board to pursue this idea further.

It does seem interesting though.

J Chen

Thought I'd get your attention
BoostSciences. Not a pingpong
pong ball but something similar
in dimension but much stronger.
Yes it is a very simple, logical &
interesting idea.

TonyG

This is pretty funny thead...

The operation of the "anti-lag" device is exctly like the factory recirculation valve. Is it not? (which is why it's called a compressor bypass valve.. not a blow-off valve).

hahah


TonyG

NZ951

Link have two antilag devices that can be used with their system, I think one involves a solenoid at the TB... should do some research on it.