CBV - compressor bypass valve

[han74j]

anyone know who makes CBVs?? everyone makes BOVs but i haven't seen any CBVs..... please give me some info please thanks

[ItsStockOfficer]

A rose by any other name would smell just as sweet.

[evod]

han,
a compressor bypass valve is just a more technical name for a reciculated blow off valve. compresser = turbo, bypass = ...well...bypass...and...valve...yea. basically it "bypasses" the air that has been forced out of the turbo from going into the manifold, and by bypassing, it returns it to the intake path right before the turbo. have fun an' boost safe yo =)

[han74j]

hey dave then how can u tell which bov is "cbv"??? which is lets the air out? do u know any bovs thats a "cbv"?

[ItsStockOfficer]

EVERY CBV is a BOV and EVERY BOV is a CBV.

[evod]

hehe...itsstockofficer is right. just about every valve u see on the market is more or less a compressor bypass valve. its just the VTA are bypassing the normal flow and letting it into the atmosphere...where recirc are bypassing the normal flow and putting it back into the intake tract pre-turbo.

[han74j]

dave u talking about the hks SSQV?

[evod]

han, i'm talking about bov's in general. the SSQV, for example, as it comes from HKS is non recirculating/VTA. however, if you get their recirculation kit(just a fitting and a piece of hose) then u can make it into a recirculating. both however, are bypass valves...and they simply bypass the flow of the air post turbo out of the system before it reaches the t/b or manifold.....one releases it into the atmosphere, the other back into the intake system pre-turbo.

[han74j]

icic so pretty much every bov is the same shit!!! if i want to make it into a CBV/bov then i need to get the recirculation kit?

[evod]

han, yup...most bov's are the same design. a piston/valve that closes a pathway between the intercooler tubing pre-trottle body and the pre-turbo inlet tube. most designs have the valve oriented so that the boost from the intercooler tube will "push" the valve open...the SSQV (listed as a "pull type") is different in that the boost from the intercooler tubing actually pushes the valve closed even more...that's why one can claim that there is 0 leak with that bov. the larger diaphram design of the hks unit allows for the pull type valve to open just as if it were a push type, and the twin valve design really helps it in the response area =) don't worry guys...i'm not trying to sell nething here...i just really really like that one =D

[han74j]

the ssqv is a twin valve design?

[evod]

yup! a smaller valve for quick response, and a larger outer valve to allow it to flow like a larger one..

[han74j]

nice thx

[ItsStockOfficer]

HKS is complete crap. Cool looking though

[EVO Neil]

Forge makes a recirculating BOV or CBV, whichever name you prefer. Here are two links for it:

http://www.forgemotorsport.com/mitsubishi.asp?cat=mitsu&product=FMDVEV015

http://vividracing.securesites.net/catalog/product_info.php?manufacturers_id=40&products_id=718&osCsid=1c4627c27c74a8e6acf7c0667f33597e

[evod]

itsstockofficer, i'd like to know why you think so about the HKS one? i've had experience with them on quite a few cars, and know a lot of people that have them as well. i have heard of cases where people don't get positive results from it, but i'd like to know your experience or opinion and why so? thanks =)

[ItsStockOfficer]

itsstockofficer, i'd like to know why you think so about the HKS one? i've had experience with them on quite a few cars, and know a lot of people that have them as well. i have heard of cases where people don't get positive results from it, but i'd like to know your experience or opinion and why so? thanks =)The surge alot. And they sound like surgining wwhen there opening, so you can tell when there surging. And they open and close instead of staying open. They don't leak but they open like crap and there is no way to tell. My 60-1 was destroyed after 4 months with one.

[evod]

itsstockofficer, as far as i can remember, the "surging" is, like u said the valve opening and closing repeatedly. this is because the design of the valve causes it to start closing as soon as the pressure diffrential between pre and post throttle body(pre is where the i/c piping is, post is where the vacuum line for the bov is routed to) drop below a certain level. so its not actually surge(assuming that the valve is adjusted correctly) you're hearing, the the valve opening and closing repeatedly many many times in a short interval. the way the ssqv is designed causes it to be highly sensative and responsive...sometimes too much so. but if the valve were adjusted a little looser, it'll tend to stay open longer.

i had had them on an alltrac, a mk4, ej20, sw20 before, and none of mine had ever had surging problems, all releasing the air in one full burst.....except why my brother's supra started putting ...uh...i'll say an excessive amount of power out. surging only came then because the bov would no longer release the air enough to stop the turbine from surging. but regarding ur experience with ur 60-1...i'd b interested in knowing more as to the setup you were running, etc. thanks again for the response =) ...oh yea...and sorry for pulling the thread kinda off topic now...hehe

[ItsStockOfficer]

Typical setup. Stage 3 turbine, 60-1 compressor, 272 cams, safc, 720's.

The valve opening and closing CAUSES surge. It should stay open until it can no longer blow off, If it opens and closes and continues to blow off(which it does), then during that period it was closed there was higher then atmospheric pressure in the UICP obviously. Thats bad.