i love the sound of a bypass or bov but is it necessary to put one on a Lancer Evo 8 or is it a waste of money.i mean is the stock valve good enough or should i waste money on a new one? thanks.

 

the stock one may be okay when running stock boost conrol. If you plan on getting a MBC, then I would say get an aftermarket BOV. The stock one's are known to leak at high boost and sometimes even stock boost. I have the JDM MR DV and I highly recommend it.

 

where do i find the jdm mr valve from ? also if i do like a hks bov that vents straight to the atmosphere will i have problems or should i stick with a recirrulating valve? thanks for the help

 

theres also a bunch of good aftermarket BOV's

 

Install a BOV that doesn't leak until higher boost levels. If you don't, anything you do to increase boost will be fruitless. You even run the risk of damaging your turbo by stressing it trying to get higher boost.

Here is what happens, if you do mods that increase boost (intake, exhaust, modding stock boost controller, installing after market boost controller, installing larger turbo etc) before upgrading the BOV. Air is sucked into turbo, compressed, sent to the intercooler, then past the BOV, to the throttle body, into the intake manifold, and into the pistons. The BOV vents into the intake system BEFORE the turbo which is effectively like venting it outside in this case because it is allowed to expand back to atmospheric pressure.

Now as the turbo spins faster to increase the pressure in the intake pipes beyond the leak point of the stock BOV, pressurized air in the intake pipes leaks past the BOV. The pressure in the intake pipes thus can't reach the point where the boost controller will keep the turbo from spinning faster and limit boost. So the turbo spins even faster to flow more air to try and get pressure up to the point where the boost controller will start regulating the turbo's flow, but air is still leaking out of the BOV and in fact as pressure increases the BOV opens more and leaks even more. The end result to this cycle is that either:

a) The turbo will eventually spin fast enough to overcome the leak and get the boost pressure up. At this point the turbo is running way outside its efficiency curve and is doing little else than pushing very hot air and working hard to do it. Hot air knocks, detonates, and contains less air mass than the same pressure/volume of air at a cooler temp (remember your physics PV=nRT)

b) The turbo never really can flow enough air to overcome the leaking BOV, all the steps in a) occur, and your turbo dies an early death.

 

ok so what bov would you guys reccomend

 

http://www.machevo.com/jdmevomrcoby.html

 

is the jdm evo mr bypass valve a good choice for an evo with just a dynoflash, exhaust, downpipe, and intake?

 

Either aps or the hks ssqv will hold boost.

 

Yes, it's a very good choice for those mods if the flash includes boost control. If not, then it's a so-so choice, because it's not really needed. Either way, you'd know the answer to this with even a slight attempt at searching...

 

even without any sort of boost control, its a worthwhile upgrade. I noticed faster spool up and better power everywhere after my JDM MR diverter valve