My question is simple, and I would appreciate if some knowledgeable minds could throw in their input, or link me to a post that I may have missed in my search.

I am aware of the downsides (running rich) of having a blow-off valve installed. Can this negative effect on my performance be corrected when the car is properly tuned?

Thank you.

 

A properly tuned car will make the effects less noticeable since the power is increased over the entire usable rpm range but if the blowoff valve vents too much already metered air to the atmosphere, I don't think tuning will be able to compensate. The valve vents the air when you lift off the throttle (like between shifts) when there is positive manifold pressure and tuning is usually done at full-throttle. I'm not sure a momentary rich condition can be fully countered by tuning unless a different method of metering intake air were swapped in place of the mass air flow sensor.

Obviously the worst offender would be a BOV that vents 100% atmospheric and some members report varying degrees of problems with the overrich condition but it won't be as transparent in operation as a factory-type recirculating bypass valve.

Maybe one of our knowledgable tuners will see this and offer another point of view.

--
0==WW==0
"…axles of evil…" - george w. bush

 

Thank you for your input, WW.

Reading your reply places things into a better perspective. I just talked to a friend of mine who said a momentary rich condition (like that between shifts) shouldn't affect things too badly.

Would an HKS SQV be bad a bad blow-off valve to look into? I'm not too sure if it recirculates. I haven't had time to fully research it.

 

the hks dumps to the atmosphere. if you really want the sound get something that recirculates and dumps (ex. GFB). I'd reccomend going with an intake (ex. SPT) instead because then you will be able to hear the oem bpv and not lose power. (

 

spend the money on the intake instead of the bov. ive heard of people having numerous problems with open-air bovs, especialy between shifts. but i havent had any problems with my HKS.

 

The ONLY tuning that will 100% correct atmosphere discharging BOVs is to go with a standalone ECU that is able to use MAP instead of MAF for fueling OR use the UTECs Speed Density setup OR you can go Blow-thru MAF w/ any EM.

 

get the HKS and by the recirculating kit for it. ITs about twenty dollars and will make the HKS SSQV recirculating.

 

I second this motion. I have had both situations, BOV and CAI. I put a 100% bov on my sti before i did any mods and it was a complete waste of time and money. It just seemed like the car was hiccuping and just didnt like the bov.

So i removed it. I then progressed and got a CAI. Typhoon short ram to be exact. Much better advantage for the cars performance and with a tune the CAI will increase performance much more than a bov could ever do, on stock that is.

So after i got tuned and i started driving it more the CAI produces the same sound a BOV does just without the disadvantages.

Like PJ21086 said you can hear the stock bov through the cai. I get the whoooooosh in between shifts. Much better option. And you get more of the jet sound on acceleration. Just my 2 cents.......

 

really where do they sell this kit??

 

http://www.hksusa.com/products/?id=3262
http://www.hksusa.com/products/?id=799
it says it comes with a recirculation insert. the 2nd link isnt for the subie, but you could probably use your OEM tubing an fit it onto the insert. just to show you they make a kit.

 

Thank you very much for sharing your trials and errors!

This will aid me in making the better decision of choosing a CAI over a BOV. I'm not too worried about the sound between the shifts. I was more worried about the compressor surge that I read about if no BOV is present. I'll look into CAIs.

Thanks for your comments everyone.

 

No prob man. Thats what we are all here for. The only time you have to worry about compressor surge is if you have a bigger turbo than stock. With stock you wont have to worry about pressure surge. Hope that helps. And if its the sound you are not worried about go with the CAI due to the fact that its better for a stock engine and turbo.

Laterz!

 

I've been reading around more.

After seeing what problems the CAI seem to cause (with the exception of a few people) I am going to go with the Snorkus removal, plug the fender hole and drop in a Green Filter.

Either that or a Cobb Short Ram intake. The Snorkelrectomy seems like more fun though.

I won't be needing a BOV until later when my boost surpasses the stock BPV's capability. The STi takes in enough air as is, I'll focus more on exhausting air.



I heart the search feature.

 

Sweet thats what i-club is all about. Let me know how it goes. Good luck!

 

Thanks mate!