Bypass valve 15 PSI

[biondos1]

is it true that stock bypass valve can hold 15 psi, i read about it on a post but it really wasn't confirmed. also, to what bypass valve can i upgrade to and still keep the turkey alive, does anyone have the turboxs h25, how do you like it. thanks guys

[biondos1]

sorry my computer froze, i didn;t mean to post three times

[Kansei]

Whoa whoa.. be careful there, 15psi WILL blow chunks of your engine block all over the state! Get some forged internals before you think about going above 8psi if you want the car to last.

[biondos1]

Whoa whoa.. be careful there, 15psi WILL blow chunks of your engine block all over the state! Get some forged internals before you think about going above 8psi if you want the car to last.


yeah i have forged internals, i just started up my car this weekend. ive been working on it for the past two months. i have the mpnick turbo upgrade, will the stock bpv hold 15psi, or what can i upgrade to and retain the turkey sound.

[orlandomsp]

There's allways the Forge OEM-style replacement.

[Kansei]

yeah i have forged internals, i just started up my car this weekend. ive been working on it for the past two months. i have the mpnick turbo upgrade, will the stock bpv hold 15psi, or what can i upgrade to and retain the turkey sound.

last I checked, the turkey sound was compressor surge.. I'd try to eliminate that as much as possible.

[Doodsmack]

an upgrade would consist of eliminating the turkey, since the turkey is bad for the turbo.

[orng1]

Try the Bosch it'll hold the PSI and still have some turkey.

[Kansei]

I'd recommend the HKS SSQV with the recirc fitting (a cheap accessory for it last I checked). That being said, I haven't actually used my HKS SSQV yet, but it sure looks/feels nice.

[arlsmazdaspeed]

Let us know what shes does on the dyno and or track... Whats your set-up consist of?

[low_psi]

Just pressure test your pipes and check to see if its leaking. No sense in replacing a part that works. I've run 14psi+ on mine and its held pressure, but yours might not.

[biondos1]

Let us know what shes does on the dyno and or track... Whats your set-up consist of?

right now i have:

built block
mpnick turbo upgrade (gt28rs turbine wheel in t25r)
ghl 3" downpipe
begi fmic
injen cai
awr front and rear motor mounts
exedy stage 1 clutch
kartboy bushings
b&m short throw

in 2 months i will have

mpnick tuner (tuned at 8 psi and 14psi)
dual stage boost controller
3" electric cutout
AEM wideband
upgraded bpv(?)

[biondos1]

last I checked, the turkey sound was compressor surge.. I'd try to eliminate that as much as possible.

sorry i never heard of compressor surge, can you explain please....

[bazooka joe]

I'd recommend the HKS SSQV with the recirc fitting (a cheap accessory for it last I checked). That being said, I haven't actually used my HKS SSQV yet, but it sure looks/feels nice.

haha "looks and feels nice" i love it!! :)

[Kansei]

sorry i never heard of compressor surge, can you explain please....

video:

http://video.google.com/videoplay?docid=-1497995499942132309&q=compressor+surge

they demonstrate the sound of compressor surge in the vid by disconnecting their BOV

[osu1steve]

sorry i never heard of compressor surge, can you explain please....

Your turbo is supposed to pump air through the engine. Two things can happen if you are off the operating line of the compressor.
1. Stall - air stops flowing
2. Surge - air actually goes the opposite direction in the flow circuit

Both are undesirable in the sense that it's a transient loading on the compressor - the sudden loss of loading on the blades.

[BOOSTR]

What is compressor surge?
The surge region, located on the left-hand side of the compressor map (known as the surge line), is an area of flow instability typically caused by compressor inducer stall. The turbo should be sized so that the engine does not operate in the surge range. When turbochargers operate in surge for long periods of time, bearing failures may occur. When referencing a compressor map, the surge line is the line bordering the islands on their far left side.
Compressor surge is when the air pressure after the compressor is actually higher than what the compressor itself can physically maintain. This condition causes the airflow in the compressor wheel to back up, build pressure, and sometimes stall. In cases of extreme surge, the thrust bearings of the turbo can be destroyed, and will sometimes even lead to mechanical failure of the compressor wheel itself.
Common conditions that result in compressor surge on turbocharger gasoline engines are:

A compressor bypass valve is not integrated into the intake plumbing between the compressor outlet and throttle body
The outlet plumbing for the bypass valve is too small or restrictive
The turbo is too big for the applicationPersonally, I do not think that is what the sound is. The turkey sound is barely audible with the stock airbox on. At least thats how mine was. I never even noticed it until I took off my Injen right before going to the dealer for the flash. With the CAI, I only get it when I am driving/shifting aggressively.

As far as the BPV, I too have run up to 14psi and had no problems with it holding boost.

[osu1steve]

Personally, I do not think that is what the sound is.

I agree with this ... Everyone seems to agree it's surge, but it sounds more like a valve flutter to me. Compressor surge sounds a lot more violent than this turkey sound - surge sounds more like a machine gun.

[Kansei]

definitely, definitely not valve flutter though

[biondos1]

so basically i should stick with the stock bypass valve till it leaks

[Kansei]

Yeah if it isn't leaking and it's evacuating the air well enough, might as well stick with it.

[igdrasil]

video:

http://video.google.com/videoplay?docid=-1497995499942132309&q=compressor+surge

they demonstrate the sound of compressor surge in the vid by disconnecting their BOV

Still had surge. I think theres no real benefit over the hks except for the amount of flow (possibly, we dont know how much air it flows)

[MSpeed2397]

Valve looks nice, but in the vid, like igdrasil said...still sounds like surge is goin' on.

[orng1]

I haven't heard too many cars sound like this, I'm not sure if it is compresure surge or the BPV is too small. I have a Bosch BPV and a T3 turbo and it still has the turkey, all that and I'm also using a dual set up it's not as bad anymore but its still there.

[osu1steve]

definitely, definitely not valve flutter though

Why not? You don't dispute that it's not compressor surge - so if it's not that, and it isn't some sort of valve flutter in the BPV, what else do you think it could be?

[Kansei]

oh you meant valve flutter in the BPV.. yeah maybe, I haven't seen the stock MSP BPV in person.

Oh and that video.. yeah I'm not too sure about that BOV either. It looks cool, I like how fast it actuates, and with the nonscientific piece of paper to show airflow it looks like it lets a lot out. Who knows if it lets out enough for larger engines though. I hear that it is coming out in January, we'll see then. I still can't believe that the HKS actuates that slowly, it must be because it wasn't actually hooked up to the charge air at all, just placed near the charge pipe.

[bazooka joe]

oh you meant valve flutter in the BPV.. yeah maybe, I haven't seen the stock MSP BPV in person.

Oh and that video.. yeah I'm not too sure about that BOV either. It looks cool, I like how fast it actuates, and with the nonscientific piece of paper to show airflow it looks like it lets a lot out. Who knows if it lets out enough for larger engines though. I hear that it is coming out in January, we'll see then. I still can't believe that the HKS actuates that slowly, it must be because it wasn't actually hooked up to the charge air at all, just placed near the charge pipe.

i was thinking the same thing...it wasn't really a true side by side comp?

[jeffmsp]

i had my forge Blow off valve working great and i had no surge at all. just relocate your maf so you dont run rich from the air loss.

i also once had a dual setup where i used the forge bov and the stock bpv so that a bit recirculated but that was because i did not relocate the maf with that setup so i recirced half of the air to keep from stalling.

[Doodsmack]

the turkey is most definitely compressor surge. there are a bunch of threads on how to recirculate the air (using bov plus bpv) so that the surge goes away.

[MSP608]

yea when i was redoing my vac lines i decided to mess around with them n what not. i unplugged the bpv line and it made the exact same sound as when i had it working. so, its not the bpv making the noise. its compressor surge.
http://videos.streetfire.net/video/wm/bebc860e-570b-4382-9672-0e614a8c5ceb.htm

[Velocifero]

I am not calling you a liar just not sure what you did when you disconnected your BPV but when I did mine and only ran the BOV I really had compressor surge and it sounds way worse than the "turkey"

I am still in agreement that it is valve flutter.

[Doodsmack]

http://www.msprotege.com/vbb230/showthread.php?s=&threadid=39433.

http://www.msprotege.com/vbb230/showthread.php?t=47267&highlight=compressor+surge

http://msprotege.com/vbb225/showthread.php?s=&threadid=40956

[MSP608]

I am not calling you a liar just not sure what you did when you disconnected your BPV but when I did mine and only ran the BOV I really had compressor surge and it sounds way worse than the "turkey"

I am still in agreement that it is valve flutter.

i mean i unplugged the bov and the bpv, and put a screw in each vac line. it sounded just like my video except the actual 'turkey' sound lasted longer.

i think 505zoom said it, its like when you talk into a fan you hear how the sound is distorted. i would imagine thats what youre hearing, the air in the intercooler pipes rushing back on the spinning compressor.

[Velocifero]

I run a dual set up with no turkey at all normally, only time I turkey is under very low boost. I run the BOV just tight enough to not leak, does that mean my stock BPV can't handle the 3 psi of pressure? Would they run the same on Mitsu Evos, they have a softer turkey, but it is still there?

[osu1steve]

I believe the turkey sound always existed on the MSP, even completely stock. When I first bought my car, I could barely hear a strange noise when I shift - had to pay close attension to hear it (sounded kinda like a pheasant!). My first mod was a CAI, and suddenly I have a turkey. The CAI alone isn't gonna cause compressor surge, and so I thought all that happened was the stock air box and all the plastic piping attenuated this noise that always existed. That would mean that Mazda designed a turbo car that always operated with compressor surge??

[MSP608]

I believe the turkey sound always existed on the MSP, even completely stock. When I first bought my car, I could barely hear a strange noise when I shift - had to pay close attension to hear it (sounded kinda like a pheasant!). My first mod was a CAI, and suddenly I have a turkey. The CAI alone isn't gonna cause compressor surge, and so I thought all that happened was the stock air box and all the plastic piping attenuated this noise that always existed. That would mean that Mazda designed a turbo car that always operated with compressor surge??

or they selected a bpv that was insufficient for the needs of this car and doesnt release enough pressure.

[osu1steve]

I've just never been sold on the idea that it's compressor surge ...

If the bypass valve is insufficient for the required flow, then a better BPV / BOV would fix it, and that's not the case. Also ... I have a friend with an SRT-4 - he's very familiar with the turkey!! I drove his car and was able to make his car generate the turkey sound - he was in denial for a while!! Hehehe ... but, the conditions that create the turkey noise on his car is blowing off a VERY VERY low boost pressure. In fact, it will make a turkey noise nearly identical to that of the MSP if bleeding air from 0 psi to idle vacuum! There is no way that the compressor is surging, but it's sounds just like the protege turkey.

[igdrasil]

I've just never been sold on the idea that it's compressor surge ...

If the bypass valve is insufficient for the required flow, then a better BPV / BOV would fix it, and that's not the case. Also ... I have a friend with an SRT-4 - he's very familiar with the turkey!! I drove his car and was able to make his car generate the turkey sound - he was in denial for a while!! Hehehe ... but, the conditions that create the turkey noise on his car is blowing off a VERY VERY low boost pressure. In fact, it will make a turkey noise nearly identical to that of the MSP if bleeding air from 0 psi to idle vacuum! There is no way that the compressor is surging, but it's sounds just like the protege turkey.

It IS compressor surge.

[osu1steve]

It IS compressor surge.

WHY? Just because no one has come up with a better answer? Just because the majority of members of this forum say it is doesn't make it a fact. So discharging 0.0123 psi through the compressor is enough to reverse flow direction and compressor wheel rotation?

[MSP608]

i dont see how the compressor could reverse direction, doesnt that mean the turbine would then push exhaust gas back into the engine? i thought compressor surge was just the air pushing back on the compressor making a noise similar to when you talk into a fan.

[Blake]

Its more or less blowing the air back through the turbine, which when in reverse direction the air puts alot of pressure back on the turbo. But no the turbo never reverses direction. The exhaust will most the time always be more than the compressor side.

[Rogue]

i dont see how the compressor could reverse direction, doesnt that mean the turbine would then push exhaust gas back into the engine? i thought compressor surge was just the air pushing back on the compressor making a noise similar to when you talk into a fan.that's what I was thinking. Wouldn't that cause some other issues as the piston is going up to push exhaust gas out and the compressor is spinning backward pushing exhaust gas in.

[Blake]

The MSP Turkeys, due to compressor surge, the only reason people say it sounds more violent is because, When Plugged up the Stock BPV releases a little bit of air. When unlplugged that air is no longer vented causeing the "more violent" turkey sound.

[Blake]

The turbo never reverses direction.

[Rogue]

so what is compression surge? if it's a bad thing, why would it be in a WRC car?
http://www.suzuki-wrc.com/e/pv.html

[Blake]

I think it was said best earlier in this thread. Its like blowing air back into a fan, listen and you will hear that chopping noise. Now make that fan a 1300 dollar peice of equipment and make that air alot more. Your putting unnecessary stress on the turbo. WRC cars change out turbos like underwear. Dont quote me but the only thing I can think of for not venting the air, would be to reduce lag and boost build time.

[Rogue]

where does the air go?

throttle opens > turbo spools > positve pressure builds > throttle shuts > positive pressure has to go somewhere, so it goes through the BPV > air goes back into intake > air goes into turbo making noise > where does it go from here?

[Blake]

What happens, is when the throttle body shuts, the air that is still flowing is forced back through the compressor. Creating the chopping, or turkey sound. The BPV does not release all the pressure.

[Rogue]

so the sound comes from the turbo, not the BPV

[Rogue]

the BPV recirculates the air back into the intake since it's already been metered by the MAF, but there's still pressure in the pipes... how is that pressure released?

[Kansei]

I would think out the intake, it's the only place it could get out with the throttle plate closed. Glad I won't be dealing with this "recirc" business :)

[Rogue]

so, the air goes back through the MAF?

[orng1]

The way I see it the BPV recirculates it back into the intake ahead of the turbo and the air keeps going back until the turbo has slowed down enough to not presurise it anymore. This way the turbo will still maintain speed for when you get back on the gas you'll get instant boost.

[Rogue]

the turbine speed is determined by exhaust flow, not intake

[MSP608]

the air doesnt escape thru the intake when it is recirculated, the turbo simply sucks in the air it just sucked in again instead of fresh air. as for the rally car you posted, ive heard before that its some form of antilag. has to do with igniting gasoline somewhere in the system to keep the boost pressure up. no idea if thats what that is tho, just a guess.

[Rogue]

anti-lag is something different. it injects extra fuel during the exhaust stroke. the gas hits the hot turbine blades and explodes, causing it to keep spinning.

sounds cool: http://video.google.com/videoplay?docid=-6933030243990164610&q=anti-lag

[Kansei]

omg I want ALS so much hehe that's a cool way to keep the compressor spinning. I doubt with my GT25 I have much to worry about though :P

[Rogue]

it's hell for your turbo

[jeffmsp]

system like haltech retard the timing and run the fuel pig rich so unburn fuel goes out on the exhaust stroke and hits the manifold walls and turbine causing the turbo to be spooled by the explosion. Another primitive WRC method was to have an injector mounted in the exhaust manifold specifically for als. some cars in europe like the escort cosworth come with als from the factory. it is limited to 30 second stints and the turbocharger is especially designed toput up wth the extra abuse from the als.

find a escort cossie turbocharger on the net and find a way to get a manifold made for your msp, add haltech and you have als msp. prespool 12psi and drop it in 2nd gear. should be either mountains of fun or broken con rod city lol with a build motor and trans this would be sex

[jeffmsp]

http://video.google.ca/videosearch?q=escort+als