Psssssssssssssh

[R-Audi]

Re: Psssssssssssssh

Besides the performance aspect which it sounds like you have figured out, the sound would be my next biggest concern.. I really dislike the Psshht sound from most of the valves... I had a Greddy re-circulated on my 1.8T and it made noise...

[The_Jerbel]

Re: Psssssssssssssh

I love our debates, DJ

I definitely understand what you're trying to describe, but my physics background disagrees with your physics background.

1. The air is being vented into the intake air stream, not at the junction between intake and atmosphere. It would have to force it's way past the slightly pressurized intake air in order to exit the air filter. Most of the air will follow the path into the sucking turbo, while some will definitely force its way out the air filter, but it would be a very small amount, IMO. Air behaves as a liquid, if you release pressurized air into an area of less pressure, it will diffuse into the less pressurized area. If you truly wanted to isolate the vented air, and make sure that it only follows the path into the turbo, and not out the air filter, you could install a low-tension one-way valve between the DV and the MAF housing.

2. The vented air is not spooling the turbo. It is simply allowing the exhaust gas to spool the turbo a little easier. Venting the charge air is providing the siphon effect, regardless of where you vent that air to. Imagine a turbo setup where the compressed air was cycled directly back into the intake side- 100% from compressor side to intake side. The vented charge air would provide the siphon effect, and the decrease in pressure differential in the intake side would decrease the work that the turbo must do in order to overcome the force of resistance. The turbo would spool very easily

At the end of the day, we can debate theory and physics all we want. The proof is in the pudding, and I'm interested in seeing the logs of your car's turbo spool with/without the splitters. If I'm wrong, I'm wrong. And IF that's the case, then I'll have to modify my understanding of physics in order to make sense of it. But I don't think I'm wrong

[aliencurv]

Re: Psssssssssssssh

Besides the performance aspect which it sounds like you have figured out, the sound would be my next biggest concern.. I really dislike the Psshht sound from most of the valves... I had a Greddy re-circulated on my 1.8T and it made noise...

it'll make a lot of noise on the 1.8 because u only have one, venting 20 psi or what ever. so on the s4 with 2, you barely hear it. i can't hear it inside the cab with the windows up.

i'll show u tonight. it sounds nice and quiet.

[aliencurv]

Re: Psssssssssssssh

I love our debates, DJ

1. The air is being vented into the intake air stream, not at the junction between intake and atmosphere. It would have to force it's way past the slightly pressurized intake air in order to exit the air filter.

2. The vented air is not spooling the turbo. It is simply allowing the exhaust gas to spool the turbo a little easier. Imagine a turbo setup where the compressed air was cycled directly back into the intake side- 100% from compressor side to intake side. The turbo would spool very easily

are u coming to the meeting tonight? because i'm bringing a pad and paper and we're gonna hack this out until we're red in the face lol

[The_Jerbel]

Re: Psssssssssssssh

LOL! No, unfortunately I have an MCAT prep course every Tues and Thurs evening from 6-9pm. I'm actually studying for my class tonight, as I type this. The class is on intermediate-level mechanical and hydrodynamic physics

Also, I edited my post above to add some detail.

[aliencurv]

Re: Psssssssssssssh

LOL! No, unfortunately I have an MCAT prep course every Tues and Thurs evening from 6-9pm. I'm actually studying for my class tonight as I type this. The class is on intermediate-level mechanical and hydrodynamic physics

Also, I edited my post above to add some detail.

a majority of the air in your divertor valve setup goes right out the intake air filter. tell me it doesn't.

[The_Jerbel]

Re: Psssssssssssssh

It doesn't

[Red90]

Re: Psssssssssssssh

....but because it's only a few percent of the actual air....

a majority of the air in your divertor valve setup goes right out the intake air filter. tell me it doesn't.

Small percent or majority? Which one?

[aliencurv]

Re: Psssssssssssssh

Small percent or majority? Which one?

re-read.

1) i said a small percentage goes to atmosphere from a splitter.

2) a large percentage of air from your recirculating setup goes out the intake filter

i don't understand how you guys can't grasp this concept. maybe we need to start from the beginning again.

are you aware that an atmospheric BOV is more effecient and beneficial then a recirculate valve on a MAP based ecu and why?

[The_Jerbel]

Re: Psssssssssssssh

re-read.

1) i said a small percentage goes to atmosphere from a splitter.

2) a large percentage of air from your recirculating setup goes out the intake filter

i don't understand how you guys can't grasp this concept. maybe we need to start from the beginning again.

are you aware that an atmospheric BOV is more effecient and beneficial then a recirculate valve on a MAP based ecu and why?

Supposedly, you're saying that only the air that is typically lost out the air filter using a DV is what is being vented to atmosphere using a splitter, so if a large percentage of air from the recirc. is being lost out the intake, then that same large percentage should be vented into atmos. by the splitter. This isn't the reality of the matter.

To answer your question- yes, I'm aware. It's simpler and easier to build and design a system based on atmospheric vent when using a MAP-based system.

[aliencurv]

Re: Psssssssssssssh

Supposedly, you're saying that only the air that is typically lost out the air filter using a DV is what is being vented to atmosphere using a splitter, so if a large percentage of air from the recirc. is being lost out the intake, then that same large percentage should be vented into atmos. by the splitter. This isn't the reality of the matter.

To answer your question- yes, I'm aware. It's simpler and easier to build and design a system based on atmospheric vent when using a MAP-based system.

lol now ur just argueing for the sake of argument now. if you re-read my last post and look at the original pics, you'll understand my next statement.

the Splitter has a very tiny hole to vent to atmosphere compared to the large hole that vents to intake.

ONLY the ammount of air that can't fit in the intake is vented to atmosphere.

i know the hatred behind bov's on maf setups. but this is a new concept and is becoming more popular because of the benefit. this isn't a bov, it's a splitter .. it's to be called a splitter and requires a new understanding. albiet, a bit more complicated of an understanding because you combine the two haha

[aliencurv]

Re: Psssssssssssssh

To answer your question- yes, I'm aware. It's simpler and easier to build and design a system based on atmospheric vent when using a MAP-based system.

that's not why bov's are installed :P .. bov's are used because they maintain the turbine speed, or sometimes increase the turbine speed if venting high psi.

In order of effeciency and performance for MAF based system (lowest to highest):

1) bov's are more effecient then recirculating valves for turbo spool. but cause a rich condition in a MAF based system.

2) recirculating valves somewhat maintain measured air (Even though most of it is pushed out the intake filter) on MAF based systems.

3) splitter valve vents ~70% of it's air to intake, and ~30% to atmosphere. or, only the ammount of air that can fit in the intake up to a percentage of back pressure, in which the rest of the air is vented to atmosphere. maintaining turbo spool, and not causing reverse flow of air in intake.

In order of effeciency and performance for MAP based system (lowest to highest):

1) bov

[The_Jerbel]

Re: Psssssssssssssh

I know what you mean, DJ, but you're telling me that the splitter tells the charge air to only go into the intake piping, and if any of that charge air tries to disobey, it gets vented to atmosphere? haha

Like I said, air flows with the path of least resistance. Regardless of the atmospheric vent pin-hole in the splitter, any air that gets re-circulated is going to follow the path of least resistance (which is the air filter, based on what you're telling me). How do you ensure that the recirc. air flows into the intake path, instead of out the air filter? A one-way valve is the only way to guarantee that all the recirc. air goes into the intake path, if you ask me, although I believe a large majority of that air already does go into the intake path (even with a DV).

[aliencurv]

Re: Psssssssssssssh

I know what you mean, DJ, but you're telling me that the splitter tells the charge air to only go into the intake piping, and if any of that charge air tries to disobey, it gets vented to atmosphere? haha

Like I said, air flows with the path of least resistance. Regardless of the atmospheric vent pin-hole in the splitter, any air that gets re-circulated is going to follow the path of least resistance (which is the air filter, based on what you're telling me). How do you ensure that the recirc. air flows into the intake path, instead of out the air filter? A one-way valve is the only way to guarantee that all the recirc. air goes into the intake path, if you ask me, although I believe a large majority of that air already does go into the intake path (even with a DV).

well, that's controlled by the size of the venting holes in the shaft. also, as the piston opens, it begins venting to intake before atmosphere, because of the layout of the holes.

symantecs, but i was the one that said air flows in the path of least resistance, i.e. towards lowest pressure zone . and that can be controlled with valve sizing (i.e. vent hole sizes).

if one of the exit paths is 30% less pressure but has a 30% smaller hole, then you can imagine that the rest will go towards the large hole with it's exit having 40% less pressure

it's not 100%. but it sure is better.

and wether u like it or not, these valves are going on a lot of high performance cars and race engines. it's been quite popular over the past year and growing.

the strage thing is, it's even going on a few MAP based systems. cam tried explaining it to me. he uses software for fluid dynamics when designing airflow. but it involves exit angles and recirculate positioning, etc. that's something we can't control in our engine bays lol

Edit: look at my svtf piping in the engine bay sometime. it was actually "flowed" when designed. which explains some of the long bends and ammount of space the pipes are taking. airflow can make a substancial percentage more power if planned correctly. intake manifolds are flow specified to valve speed and max displacement of 1 cylinder (tuning lingo).

also, many cars have dual stage or variable length runner intake manifolds. my SVTF has a cosworth variable length intake manifold

[The_Jerbel]

Re: Psssssssssssssh

symantecs, but i was the one that said air flows in the path of least resistance, i.e. towards lowest pressure zone

We still can't seem to agree on the fact that the lowest pressure differential is toward the turbo, not the air filter. The air flow is toward the turbo, so the pressure is constantly negative on the turbo-side of the DV hose (on the Y-pipe coupler), and positive on the air-filter side of the hose. Air will flow from positive to negative pressure zones.

If the DV hose was RIGHT at the junction between the air box and the MAF housing, then yes, the air would flow into the immediate negative-pressure zone of the atmosphere outside of the air filter.