opinions on BOV placement...

[ayjay]

ok, so in two weeks i am installing my redtop, and i am currently in the process of gathering parts and putting together my intercooler piping. one thing that i am still unsure of is the blow off valve placement...

one mechanic told me that the blow off valve should be placed 18" away from intake manifold, and another mechanic at a different shop says he prefers to install them on the hotpipe side since he wants the pressure to be relieved nearest the turbo and that's the way he was taught in australia. i am getting a TIAL bov, and no matter where it's installed it's gonna look pimp, but i was just wondering what difference it makes whether it's installed before the intercooler (hotpipe side) or after the intercooler (intake side)?

thanks in advance!

[kota2240]

place it where you like it. There have been millions of arguments for both sides and in the end its just based on taste. NO real adavantages or disadvantages

[biglipzit]

I cna tell you for sure than on my rb20 i had 2 hks super sequentials, one on the hot pipe and one on the cold pipe and the one on the hot pipe always released over 50% more air than the one on the cold pipe. When i removed the one on the hot pipe and only used one BOV on my new IC piping setup on the cold pipe it just released alot alot more air since the hot pipe bov was absent but i do believe from that occurence that closer to the turbo on the hot pipe is the best place to release the air since you minimize intercooler lag that way and it proves that the pressure builds up higher closer to the turbo than to the throttle body strangely enough.

[ayjay]

cooool! thanks guys, i guess it's going on the hotpipe then

[Luke]

Hotpipe here, works great

[gpeele]

i have a tial about eight inches from my throttle body, reponse is great and never experience compressor surge. im using a map sensor instead of a maf, so ive never had any problems with boging or backfiring also. biglipzit, how did you measure how much air the bovs were releasing under load? also the sudden rise in pressure is caused by the momentum of the air in your system slamming against the closed tb plate, this surge travels from the tb to the compressor wheel.

[biglipzit]

I held my hand against both whilst someone revved the car up and the difference was clearly noticeable that the one on the hotpipe released alot more air and produced a louder sound. I know that the pressure builds up when it hits the butterfly valve at the TB which is what i found strange but it seemed like pressure build up before the intercooler caused a high restriction to flow through the intercooler which caused higher pressure build up before the intercooler. I am not sure if my old intercooler was tooo restrictive because there was a great pressure drop through it. I use to run my car at 11psi daily driven and upgraded the intercooler to a spearco mkIII supra upgrade and even with larger IC piping for increase volume the pressure increased to 14psi daily without any boost controller modifications. I use to have a stock supra mkIII intercooler before the upgrade for it.