MAP = Speed-Density

BPV function is simple: when there is a large pressure-drop across the throttle, the engine is eating much less air than the turbo wants to feed it, so the surplus air must go somewhere.

For small changes in throttle, it can just temporarily build up as pressure in the pre-throttle pipe until the turbo slows down. For large changes, it has to be vented somewhere to prevent compressor surge.

Simple, eh?

 

I have a stock evo 8 with the MAF system running18 psi and then tappering off by redline.. If I plan on running 22psi..and getting a mail in flash.. Would it be possible to run VTA valve after the mail in flash? Amd if so.. What "bypass valve" should I use?

 

Good write up! So often there is mis information floating around here so its nice to get a good truthful write up that can educate everyone.

 

NO

 

Mike, I will be running a 50 trim turbo kit on the stock ECU / MAF(?) with a piggy-back (UTEC). I am looking for a BOV that can hold high levels of boost (30 psi). I also don't want any stalling, fluttering, or driveablility issues. What BOV would you recommend for my application?

 

i wonder what mike from FORGE wil say?

 

y?

 

https://www.evolutionm.net/forums/search.php



VTA valve & "bypass valve" 2 dif things. read my friend till your eyes bleed.

 

I put an HKS SSQ BOV on a few days ago and ran it for a day and noticed my car was running rich. I took it off the next day and put my stock DV back on and I'm noticing a flutter from the stocker. I never heard anything before I put the HKS on and now my mileage is not as good anymore and I am still feeling jerkiness. I have reset the ECU, I don't know what else to do. This thread has definitely helped me to realize the advantages/disadvantages to using certain valves.

 

so i need a re circulating valve whether or not i have it tuned ..becuase i have a MAF?

 

yepper

 

I'm so confused. I thought you could get a VTA as long as you had your ecu tuned to a VTA valve.. And I have seen other evos with VTA valves and runnin just fine becuase they got it tuned

 

whether this is relevant or not, hopefully it adds something, generally if it's VTA, you obviously adjust the spring tension so that the BOV does not open from idle rpm pulses and yet opens sufficiently when coming off the throttle at all on-boost rpm points. Some people alter spring tensions to adjust the sound of the valve independently of the nozzle/outlet. This is because at a tighter spring tension you'll get a shorter, sharper sound, whereas with a looser spring tension you will encourage actual turbo 'flutter' sound through the air intake as well as cause a lower frequency and often sporadic/staged exit of air through the BOV.

Any BOV without a spring tension adjustment should not really be moved from car to car as compromises will be the sound will change when you move it (at best) or the car will stall badly as you pull up to idle


Trav

 

is it posible to "crush" the mr bov to get it to hold more boost? i remember on my 1g talon i crushed the stocker and it held alot more boost.

 

yes it is but you likely wouldn't need to and wouldn't want to for applications beyond the mr valve's capabilities you'd want to do something like a dejon tools leak stop kit mod.

why does anyone think that a leak at idle is good or is normal?