So I loaded up and got a new fun DD. Its a '93 Capri XR2. I'm lookin to put a Blowoff Valve on it and have a question. It currently uses a recirculated BPV. How can I change it so I can get the fun noise we love without the stalling issues that some cars are notorious for? Also the turbo is uber quite, anything I can do to make the suction sound loud other than a open element filter?
A recirculation valve is simply a blowoff valve with its output fed back into the inlet tract. Unplug the BOV output from the inlet tract and plug the hole in the inlet tract.
Intake i prolly designed more for noise control than power, ditch is for a simple or DYI CAI, going from recirc to VTA is fine but you may get back fires or a studder between shifts, some cars do some dont...
The BPV on my MS3 was almost completely muted by the stock intake. When I installed the Cobb short-ram intake to the car, the BPV became much louder.
on this car you cant hear only a very slight shrill. Would like it to be LOUD! The BPV on these sould like a cow moooooing when @ 0 vac/boost...lol
Check out this post on BPV vs. atmospheric BOV vs. hybrid BOV. It's for the MS3, but it may apply to your Capri since it came with a BPV stock:
http://www.mazda3forums.com/index.php?topic=80641.0
TL;DR version: BPV or hybrid BOV should be fine, tread carefully with a atmospheric BOV.
Does the XR2 have a VAM? as this was common on Ford Turbo cars from the 80s. How exactly does it measure airflow? Is the recirculation port before or after the air flow meter? Is this a manual or an automatic car? If it's a manual and the recirculation happens before the air meter, then yes just unplug the recirculation port, if it's upstream of the meter you could run instantaneously rich on shifts leading to bogging or worse since the computer may temporarily cut fuel sensing a rich condition thus leading to a lean condition soon afterward, and banging back and forth until it settles out. This is why you need to understand how your system works before going for an atmospheric blow-off. We have it setup on our XR4 for simplicity (track rat) but that's because we're running a MAP sensor off the intake so it doesn't matter what happens downstream of the sensor. Most factory turbo setups are notoriously dodgy when it comes to atmospheric blow off because they were designed to comply with emissions laws which does not allow for atmospheric blow off, and the sensors used are 'economical' like vane air meters. The problem with them is they've assumed a certain amount of air past that point in the intake, if you drastically alter it for any reason you've 'upset' the closed-loop functionality of the control system by introducing a huge leak. I wish you luck, but if it's not a simple change, it's really not worth the trouble...
The BOV should be recirculating back into the intake. the ECU assumes it is and will dump extra fuel in thinking more air will be there that there is.
Doesn't this have a Mazda B6T?
Recirculate that thing. You may be able to get a better noise going to an aftermarket recirc unit. Look into Forge or Turbosmart possibly?
Enjoy your quiet car. I believe this car has a Mass Air Flow (MAF) sensor. In which case it measures the amount of fuel to mix by measuring the amount of air that goes past the MAF. If you vent your BOV to atmosphere you'll throw all those careful calculations off.
The only way around this would be to change the computer to something that uses another system to measure the air to fuel ratio like a Megasquirt.
how about just making the turbo louder while spooling? any ideas? Yes it is a B6t :)
Maybe an open element air filter setup would give you some of that sound you want without screwing up the management and operation of the motor.
Yep, in stock trim a B6T would have a vane air flow meter. It's closer to the engine management used on a '90-'93 Miata or a Probe GT than what was on Ford's 2.3 Turbo though. Not sure I'd want to vent the BOV to atmosphere on a stock computer.
dansxr2 wrote: how about just making the turbo louder while spooling? any ideas? Yes it is a B6t :)
see if your turbo has a silencer ring on the inlet face if you really like annoying loud noises...
Being that it's a B6T, it may or may not tolerate a vented to atmosphere BOV.
My MX6 SHOULDN'T tolerate mine, but it does. No driveability issues at all.
Grab one that can be used either way. Try it without. If it bogs or stalls, then recirculate it. Some work, some don't.
cheapest bet would be to by an open element intake. It'll make your stock BOV more audible. Then to step it up go buy a ricer HKS "super sequential" BOV, which is recirculated by the way to get more of a swoosh noise...
much cheaper.
http://cgi.ebay.com/ebaymotors/CHROME-CAR-TRUCK-MUFFLER-TURBO-SOUND-WHISTLE-/380239376741?cmd=ViewItem&pt=Motors_Car_Truck_Parts_Accessories&hash=item5888087165
WHISTLE TIPS YO: WOOOOOOOOOOOOOOOOOOO WOOOOOOOOOOOOOOOOOOOOOOO
You's SUPOSED to be makin breakfast, it's like an alarm clock WOOOOOOOOOOOOOO
http://www.youtube.com/watch?v=btCAdhRB49w
Crazy kids!
I'd rather walk softly and carry a big stick.
Dan!!!! What did you do with the Corrado?
Turbo sound>>> get a cheep tinny intake and a creep knockoff turbo off CL
Keep ti a bypass and do not do a BOV to the atmosphere it can screw up the AF and make things get weird. BUT you could go to a MS using speed and MAP. Then a BOV should not affect anything.. .. . I think.. .. . . . (Apply usual disclaimers here)
pres589 wrote: Maybe an open element air filter setup would give you some of that sound you want without screwing up the management and operation of the motor.
That will help making the turbo nore noticable. I modded the airbox on my wifes 9-3 and she called me on her way to work asking if something was wrong with the car. 
could you rig up a kazoo to the BOV? Always wanted to do that... 
DukeOfUndersteer wrote: could you rig up a kazoo to the BOV? Always wanted to do that...
Stay tuned... 
In the next couple weeks i'm going to be going to Gander Mountain and getting all the "calls" i can afford and playing with them.
Here's a few that are gauranteed to have you rolling in laughter:
Trumpet: http://www.youtube.com/watch?v=96URb78itcg
Turkey AND Bird call at the SAME TIME: http://www.youtube.com/watch?v=WLSyIKk16gU&feature=related
In reply to 93celicaGT2:
HAHA!! That is so awesome and epic! I am doing it!
kb58 wrote: A recirculation valve is simply a blowoff valve with its output fed back into the inlet tract. Unplug the BOV output from the inlet tract and plug the hole in the inlet tract.
That's not completely true. A blowoff valve typically has a stiffer spring to keep it from opening under vacuum such as idle and cruise. This can make them quite difficult to tune correctly so they release at light boost levels.
And since they do have a tendency to open up under those conditions and act as an inlet, they need a filter. Those foolish ones with little airhorns on them hurt engines unless the springs are cranked up, and then they don't work as well.
Want more turbo noise? Ditch the factory airbox and inlet and install an open element filter. You'll get both more inhalation noise and more recirculating noise. We see this with our upgraded intakes for the Mazdaspeed Miata.
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