DAW Posted August 3, 2005 Share Posted August 3, 2005 I have a twin-turbo (non-sequential) V6 (Maserati) that did not come with factory compressor by-pass valve (bov). I was going to install a bov in each intercooler outlet pipe before they join into the Y-pipe just before the throttle plate. I planned on using 1st gen DSM bovs and elbow pipes. I'm now thinking that it makes little sense to mount 2 bovs because if even one bov is in either of the intercooloer outlet pipes, it should equalize pressure relief almost instantly between both turbos/cyl banks and the single throttle plate. I'm leaning towards installing just one bov, in the intercooler outlet plumbing that's most accessable. This is a street driven car that might rarely see an autocross. I appreciate your thoughts on this and although not a Z-car it might be useful to others with non-sequential twin turbo engines. DAW Quote Link to comment Share on other sites More sharing options...
Clifton Posted August 3, 2005 Share Posted August 3, 2005 Z32tt's use 2. I use none. For as small as stock turbos are one should easily be able to handle enough volume to keep it from surging if it even does on a shift. Quote Link to comment Share on other sites More sharing options...
DAW Posted August 8, 2005 Author Share Posted August 8, 2005 Thanks Clifton, I appreciate the input. I'm now certain I'm not going with two bov's now...but I don't think I'll be able to resist installing the one on the side without A/C plumbing. It's probably overkill but I don't see a down side. I already have the valve, it can only help efficiency, and if I dump it to the atmosphere instead of recirculating it the engine mgmt should be slightly biased toward enrichment when the throttle is reapplied due to some metered air being lost, but calibrated-for re fuel ratio. Anyway, this car is FUN! Those crazy Italians dedicated a hairpin-turn length of pre-muffler exhaust pipe just to balance the exhaust note with the other pipe and it sounds great. A little bov note interspersed when the exhaust note falls will just be more nice music; for the sake of the art of the motore. DAW Quote Link to comment Share on other sites More sharing options...
Doug71zt Posted August 17, 2005 Share Posted August 17, 2005 A twin-turbo big-block Mopar I'm working on will use one (big) greddy BOV. It's almost on the road, we'll see how it works. Doug Quote Link to comment Share on other sites More sharing options...
DAW Posted September 23, 2005 Author Share Posted September 23, 2005 I appreciate the input and now that I've pondered it, I've even reconsidered using the 1st gen DSM bov in the left post-intercooler tubing (that's most accessible). There's an auxilliary air source tube about 7/8" dia. which runs from the junction of the two post-intercooler pipes (one from each turbo) right before the throttle valve, to an electric solenoid valve which allows auxilliary air into the plenum under cold-start conditions (normally closed when at operating temp). I'm just going to plumb in a Porsche/Saab type Bosch compressor by-pass valve (about 1" inlet/outlet) with a tee fitting into the line I've described. I think this will provide a suitably-sized relief for the turbo(s) sizes and provide a balanced relief for both turbos. I know that it's not a huge amount of surge I'm dealing with but I see no rationale to not eliminate it when it can be done so easily. If it works well I'll pass it along as it may be an easy route to plumb a bov without going to a lot of hardware and hassles for lower p.s.i. street-purpose cars. DAW Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted September 23, 2005 Share Posted September 23, 2005 One should be fine. The 1st gen Eclipse/Talon BOV works great and can be had cheap. I know a guy here in SoCal (U.S.) selling one for $40 if I remember right (+ shipping of course). It was in great shape and was still attached to the section of pipe that has the flange you need for welding to your pipe. I have that same BOV, and have it installed immediately after my intercooler. I know it's not one of the two most often recommended spots to put it (most people recommend right before the throttle body, or right after the turbo), but seems to work fine there for me, and was definately the easiest place to put it in my case. I have mine set up as a recirculation valve, not just dumping to atmosphere. I have no problems with compressor surge. Quote Link to comment Share on other sites More sharing options...
DAW Posted September 23, 2005 Author Share Posted September 23, 2005 You missed the detail...totally. Quote Link to comment Share on other sites More sharing options...
DAW Posted September 23, 2005 Author Share Posted September 23, 2005 I'm not trying to or risking being rude, your comment had been covered in my initial post and I'd abandoned that evolution long-since within the thread itself... There's a space issue, a system capacity issue (turbos are twin, one per bank of V-6 18-valve heads...I'm abandoning this thread becvause I just remembered there's a Z-Hybrider stationed in Naples, Italy looking out for Euro Zcar parts for me...I've got to get in touch and have him look for the dohc 24-valve heads for me which I believe just bolt-on to the block Aluminum block). Hey, you also just gave me a great idea! For some reason this just popped into my head... we inline 6 cyl'ers should look to esoteric or little-appreciated V-12 aluminum heads in interesting configurations (Jag, BMW, Bentley, Lamborgini, Ferrarri, etc). Quote Link to comment Share on other sites More sharing options...
jonus079 Posted October 17, 2005 Share Posted October 17, 2005 Z32tt's use 2. I use none. For as small as stock turbos are one should easily be able to handle enough volume to keep it from surging if it even does on a shift. you dont mean all stock turbo cars do you? just Z32tt... Quote Link to comment Share on other sites More sharing options...
Clifton Posted October 17, 2005 Share Posted October 17, 2005 you dont mean all stock turbo cars do you? just Z32tt... Right, Z32's use 2. I did end up adding a BOV ( Greddy type R) on the 7M car. I had quite a bit of thrust bearing wear. They are 5 times as much as standard shaft thrust bearings. Quote Link to comment Share on other sites More sharing options...
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