I've got an early 07' build MCS that's unmodded (to my knowledge!) and it's blow off valve vents to the atmosphere.

Don't take me wrong here, I think it's great! But my mother in laws 09' MCS doesn't have an atmospheric BOV.

What gives? The only difference (aside from year) is the tranny's. Mines a 6 speed, hers is an auto. Could that be the difference?

Thanks!

 

If your car has a blow off valve it's modded

 

Hmmmm..... Very interesting.... Very interesting indeed!

Can you put an aftermarket BOV on the stock setup? I wonder what other goodies my car is hiding!

FYI, Ibe only owned the car for about 2 months, 1 month of which it sat in a collision repair shop cause I was rear ended. That combined with the fact that I've been working some hectic hours equates to very little car time. Hell, I've only washed the poor thing once!

 

There is a sandwich plate Forge makes that goes between the stock diverter valve and the turbo which makes the diverter valve vent to atmosphere instead of recirculating the air. I run this part on my '09 Clubman. There could also be a more standard VTA BOV installed somewhere in your piping. It would be really obvious if you know what a BOV looks like.

 

Thanks Gitmoe. I've looked around a little and nothing looks aftermarket, so I guess it's the plate your referencing.

Thanks for the help!

 

Do you think you have a blow off valve because you can hear it? Or do you see it. A stock MCS will make a sound like a blow off valve, but it actually is a diverter valve blowing it back into the intake.

 

Spice, I'm thinking that I have a BOV due to the sound. My old Eclipse has a recirculating BOV, and it made a little sound, but this is a very loud and distinctive "KISSSHHHHHH" sound.

And my mother in laws stock MCS doesn't make the same sound. Is there a difference in sounds between the standard and auto models?

 

My JCW is much louder than my Mcs was. I do not have any modifications to the engine and I can clearly hear it. On my Mcs I had a cold air intake. That made the sould very loud. When it was stock i could hear it, but it was very quite. Do you have a cold air intake, or after market air filter? This will make it sould like it is aftermarket. The diverted valve is muffled by the factory air box.

 

If the diverter valve looks stock, check under your airbox, there might be a Turbosmart bov hiding back there. Another good way to know is whether the blow-off sound is constant or if it changes under different throttle. You'll know if you have an aftermarket under there if it's a lot louder when you're wide open throttle.

 

It's louder at higher RPMs. Longer as well.

It sounds like an atmospheric BOV to me and several others who are more learned / experienced with turbo setups.

I'll try to get a video of it posted up sometime.