I have heard all types of answer to this questions I jsut want ot know other thoughts....
Is there apoint to a BOV "blow off vavle" other than the nosie they make? Im new to the turbo world so I really dont know...

I like the great phhsssttt sound they make but I hear there bad for the evo...I also here they do nothing for the performance, which is fine because really I just like the sound. What are all the thoughts on the subject??

Thanks
-B

 

Yes a BOV is only good for sound. You are better off with a DV (recircing BOV) like the Forge Motorsports DV. Because the Evo is a MAF system the air is metered and you don't want to release it to atmosphere. If you plan on getting an intake (cone filter) you will hear it anyway. The only potential power gain is that the stock valve can leak boost.

Regardless of the people who will answer and say thier BOV works fine, it is just better not to do it. It can cause idle problems, etc. It may work for them but it may not work for you.

I strongly rrecommend the Forge valve and recommend against the HKS valve. The spring in the HKS is too strong and it doesn't work as well on the Evo. This is backed up by testing of various valve. See the thread on the SCC article on BOVs.

 

At 21psi the stock valve does leak a bit of boost at high RPM's.. There are several factors for boost taper at high pressures, for example exhaust system backpressure, or intake efficiency, but with those things resolved, you will find that the way the stock DV is configured, it opens very easily and leaks a bit.. I definitely recommend a Recirc BOV, either a forge motorsport or the Greddy (There is post elsewhere on the site with someone who spent the time calibrating it and has a few recommendations) with the 2G flanges and recirc adapter.. There is no point in using a VTA BOV (Vent to atmosphere) Ultimately it results in drivability issues, and a misconfigured BOV can cause surging.. If your not turning up your boost, and not using a boost controller to try to maintain higher boost through redline, the stock part is fine..

 

I just installed my Forge Recirculating BOV over the weekend. Noise wise, I don't hear any difference between mine and the stock one. Some say you can hear it more, I personally can't yet (till I get a cone filter). I love it, it holds boost MUCH farther the the stock one, my butt dyno confirmed that this weekend. It doesn't fall off boost at around 5600 rpm like the stock one did. It feels strong all the way to red line. I love the psshhtt sound of VTA but I would much rather have a recirculating one for engine performance purposes. Besides....with an intake kit, you will hear it. I recomend the forge piece (polished look, not stealth black) it really stands out and I loved the plug and play design.

 

if its sound your after, prolly an open element intake would make a bit more noise even with a re-circ

 

thank you all for the tips. I know nothing about turbos and turbo motors.. A N/A I can build blind folded.. but turbos...... Its a new world
So thanks for all the tips guys, and girls....

on
-B

 

Just a side note: Mitsu's dont use a true BOV they use a CBV (comperessor bypass valve). Or is this the same as the DV you are talking about, just another name for it? not familiar with that term.