Blow Off Valve?

[MazdaSpeeder00]

Ok, Im pretty sure the MSP has a WasteGate and not a Blow Off Valve right? Well naturally Im wanting that loud rush of air when I let off....so what do I do?

[505zoom]

All modern turbo cars have a wastegate. The msp has a BPV(by-pass valve) and not a BOV. This means that instead of blasting that air out into the atmosphere(like the fast and furious1 fake eclipse), the BPV in the msp recirculates the air back into the intake after the maf(mass airflow sensor). If you do not run a recirculating BPV, then you will be venting air that has already been counted by the maf, and you will run too rich because the PCM will add the fuel for the air you vented. This is not real bad, but you will run a high risk of stalling anytime you let the rpm's drop to idle from above 3-4K. You will also run very rich after shifts, not the best considering that the msp is already running very rich(below 10:1 ratios at some points).

If you really want the loud BOV sound, get a greddy type-S and just relearn how to drive it so it doesn't stall.

[MazdaSpeeder00]

LOL, sounds like I better not mess with it seeing as how my mechanical skills a definently lacking..... But hey you have to learn somehow. lol

[505zoom]

Well I have actually come up with a new solution for this one since the last time I posted a month ago. I am now running an open-vent HKS SSQV(blow off valve) in addition to the stock bypass valve. Before I was running just the HKS recirculated. This dual valve setup does 2 things.

1. It cures the stalling issues associated with running just an open-vent BOV. This was just a bonus, I never expected it to work as well as it does.

2. More importantly, it solved the compressor surge that becomes apparent on this car after putting on an injen intake.

So what you do is, get yourself some hardpipes, weld the aftermarket valve of your choice on the IC--->TB pipe, and run the stock BPV like it is now. You won't stall, and you'll get that nice rush of air that you want.

Here are the sound clips that show the difference between the HKS recirculated and the new dual valve setup:

HKS recircualting, no stock valve:
http://www.wpi.edu/~jck15243/MOV00495.MPG
This is also very similar to the sound of the stock BPV.

New setup: HKS open vent, with stock BPV recirculating:
http://www.mazdamp3.com/members/505zoom/mov00533.mpg

[SR20RACER]

^^^ Are you sure those links are listed correctly?
How can the recirculated Blow off valve be louder then the second clip with the same HKS vented into the atmosphere?

[505zoom]

Originally Posted by SR20RACER

^^^ Are you sure those links are listed correctly?
How can the recirculated Blow off valve be louder then the second clip with the same HKS vented into the atmosphere?

Yes they are listed correctly, they are my own vids so I am sure.

The sound that you are hearing in the first clip that has the HKS by itself is called compressor surge. It occurs when you let off the throttle under boost. See what happens is, you let off the gas and the throttle plate closes. The turbo has pressurized the IC core, and all of the piping between the turbo and the throttle body. The pressurized air needs to vent somewhere, so it reflects off of the closed throttle plate and goes backwards through the turbo. This can cause damage to the compressor fins and bearings because the turbo actually wants to reverse itself when the air goes through it backwards. I was having major surge with the HKS recirculating, because it just simply was not venting enough air to get it to function the way it should. Now that I am running 2 valves, there is no surge, and overall less sound.

The surge that you can hear in the first vid is actually similar to what a turbo setup would sound like with no BOV or BPV at all. The sound isn't coming from the valve, it is coming from the turbo and the intake.

Hope that answers your question.

[MetalSpeed]

[quote=505zoom]Yes they are listed correctly, they are my own vids so I am sure.

The sound that you are hearing in the first clip that has the HKS by itself is called compressor surge. It occurs when you let off the throttle under boost. See what happens is, you let off the gas and the throttle plate closes. The turbo has pressurized the IC core, and all of the piping between the turbo and the throttle body. The pressurized air needs to vent somewhere, so it reflects off of the closed throttle plate and goes backwards through the turbo. This can cause damage to the compressor fins and bearings because the turbo actually wants to reverse itself when the air goes through it backwards. I was having major surge with the HKS recirculating, because it just simply was not venting enough air to get it to function the way it should. Now that I am running 2 valves, there is no surge, and overall less sound.

The surge that you can hear in the first vid is actually similar to what a turbo setup would sound like with no BOV or BPV at all. The sound isn't coming from the valve, it is coming from the turbo and the intake.


My Car does the same thing. Do you have a pic that shows the set up of the BOV and the BPV after the welding took place?

[MetalSpeed]

[quote=505zoom]Yes they are listed correctly, they are my own vids so I am sure.

The sound that you are hearing in the first clip that has the HKS by itself is called compressor surge. It occurs when you let off the throttle under boost. See what happens is, you let off the gas and the throttle plate closes. The turbo has pressurized the IC core, and all of the piping between the turbo and the throttle body. The pressurized air needs to vent somewhere, so it reflects off of the closed throttle plate and goes backwards through the turbo. This can cause damage to the compressor fins and bearings because the turbo actually wants to reverse itself when the air goes through it backwards. I was having major surge with the HKS recirculating, because it just simply was not venting enough air to get it to function the way it should. Now that I am running 2 valves, there is no surge, and overall less sound.

The surge that you can hear in the first vid is actually similar to what a turbo setup would sound like with no BOV or BPV at all. The sound isn't coming from the valve, it is coming from the turbo and the intake.

MetalSpeed
My Car does the same thing. Do you have a pic that shows the set up of the BOV and the BPV after the welding took place?

[505zoom]

Originally Posted by MetalSpeed

My Car does the same thing. Do you have a pic that shows the set up of the BOV and the BPV after the welding took place?

Yeah, they all do it. You just don't really hear it untill the stock airbox is out.

Here is an older pic from the prototype install:




The clear tubing is the BPV return line that runs from the BPV to the intake. It was for testing only and I removed it immediatly and replaced it with heater hose after it was a success. I have since upgraded the hose to blue silicone, and it now runs underneath the IC piping so you can't really even see it.

[GWInquisitor14]

Would you recommend the Bypass valve or the blow off valve to someone who is going to turbo their car? I'm also deciding on whether to go w/ the FMAX kit or custom kit...but that is a different post. The FMAX has a bypass valve while if I build my own I'm not sure which I would choice. Id probably go w/ the HKS SSBV if I get a blow off valve
Here is the turbonetics Bypass valve
http://www.turboneticsinc.com/new_product.html
Raptor Valve Kit