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Old 04-18-2012, 08:40 PM   #1
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Default recirculating diverter?

So I'm building my first turbo setup on a learn-as-i-go type of plan. I've learned a lot through the process and I'm only a few steps away from turning that key again. Right now my struggle is with the bov. I bought a turbo setup from an online contact that was "apparently" running in his miata. He left me with a lot of loose ends that i've managed to overcome with a few new parts and some welds but the blow off valve was a knock-off blitz atmospheric bov. I'm under the impression that in order to avoid running problems and engine codes I have to run a recirculating diverter valve. I'm looking at picking up a Forge diverter valve from Automotive warehouse in Niagara on the Lake but it's pricey so I'm wondering if anyone knows if this is the right road to take and perhaps what the best way to take it is. Any feedback would be helpful. I'm kind of a cave dweller so I've been pretty much on my own until now.
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Old 04-18-2012, 09:00 PM   #2
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You need details on your setup in your sig.

If you've done a full ECU and deleted the MAF (which you should do -- no reason to run bandaids in 2012), then you don't need to worry about VTA. It doesn't matter.

I did recirculating. These are simple devices, and even the cheap, Chinese knock-offs work fine. I bought my original valve from siliconeintakes.com. It was a bit louder than I wanted and whistled at part throttle, so I eventually replaced it with a Bosch unit. Note that functionally, the original worked just fine.
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Old 04-21-2012, 05:58 AM   #3
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I've also heard good things about the Bosch valve. Does anyone know the best source for them?
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Old 04-21-2012, 12:30 PM   #4
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I bought mine from:

http://www.thesaabsite.com/900new/NG900turbo.htm

Actually an AFT brand replacement for the Bosch valve. OEM application was mid-90s Saab 900. I got it on sale for $45, but it looks like that deal isn't there any more.

BEGI sells one. Search around -- might find a good deal somewhere.
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Old 04-21-2012, 03:04 PM   #5
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i spent money for the diverter frm BEGI...it just wasnt worth it.

Fitment issues and looks out of place and provides no power.
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Old 04-21-2012, 06:50 PM   #6
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Quote:
Originally Posted by misfit77 View Post
i spent money for the diverter frm BEGI...it just wasnt worth it.

Fitment issues and looks out of place and provides no power.
Well it's not supposed to provide any power. It just gives the boost somewhere to go when the throttle is closed, until the turbine can spin down or the gear change is complete, without making that obnoxious PSHHHT noise all the ricers love.



Quote:
If you've done a full ECU and deleted the MAF (which you should do -- no reason to run bandaids in 2012), then you don't need to worry about VTA. It doesn't matter.
The MAF is a minor flow restriction ... and some of us want the car to pass OBD2 inspections without having to spend a weekend replacing stuff.

I believe my unit is a Bosch. Works seamlessly, and doesn't make any noise at all other than the whooshing of the airflow itself. Not an issue so much with a turbo as opposed to my rotrex.
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Old 04-21-2012, 07:43 PM   #7
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Originally Posted by Mobius View Post
Well it's not supposed to provide any power. It just gives the boost somewhere to go when the throttle is closed, until the turbine can spin down or the gear change is complete, without making that obnoxious PSHHHT noise all the ricers love.

Wow...Really? No ****? After the miata install and owner of 2 turbo cars I did not know that.

My point was that it provides no power, why pay or even bother with it? Only necessary for higher boost.
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Old 04-22-2012, 12:48 AM   #8
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Because if you still have a MAF, you have to have it.

Edit: the OP doesn't have any info in his sig (repeat so OP notices - you do not have any info in your sig), so I don't know exactly what year his car is. But he mentions wanting to avoid throwing engine codes, leading me to believe he has an OBDII car and still has his MAF. I may be wrong. But my point is the information is incomplete, and you're telling him he doesn't need it why bother, when in fact he may have to have it. It absolutely is required at any boost level, if you are still using a MAF.

So Dave, make an intro thread, and put some useful info in your sig, fool!

Last edited by Mobius; 04-22-2012 at 01:07 AM.
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Old 04-22-2012, 12:59 AM   #9
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you don't have to have it, but it is a good idea to have it.
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Old 04-22-2012, 08:03 PM   #10
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I mispoke, meant AFM. Getting rid of the AFM is definitely worthwhile. Can't speak to OBD2 inspections. Not something that I need to deal with thank goodness.

Also, I think misfit's point is that at low boost, compressor surge isn't so bad, so don't bother with either a VTA or recirculating valve. That's assuming you resist the urge for moar boost!
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Old 04-23-2012, 03:17 AM   #11
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Sorry for going M.I.A. on this thread guys. Been stupidly busy with exams coming up and haven't had much time for the car or the computer. I'm a little technologically impaired but I believe I've fixed my sig now. Either way, I have a 1992 Sunburst Miata. 1.6L OBDII and yes, keeping my MAF and all parts to pass Ontario emissions. I've spoken with Ryan at Automotive Warehouse and he seems to know a lot about the valve, it's fitment options, and it's common application to VWs, AUDIs, and the like but was otherwise unsure about my build. He was kind enough to order two of them in black for his display whether I choose to buy it or not. They'll be in on Tuesday along with the fitting for my oil feed line that I broke , and if I make a decision by monday, the necessary tubing can be in then aswell. From what I'm reading, I feel like buying a recirclating valve is a corner easily cut, but I think it's probably the best way to go and I don't want to dance around price tags. As much as it hurts to let her sit while I make money. As for fighting the urge for mo boost? I may have to. From my research I have myself spooked that my stock open diff will go out with a bang if I'm running any higher than 3 or 4 pounds and even then I'm going to be avoiding heavy clutch dumps and hard pulls. At least until I can get my hands on an LSD from a newer miata.

All that being said, I still have a few hurdles to jump. I still have no idea how stiff to mave the recirculating valve, figure out my water cooling which I feel won't be too rough, and I still don't know what my fuel pressure regulator is or what it does or where it goes. I appreciate all the feedback guys.
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Old 04-23-2012, 06:31 PM   #12
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A 1992 1.6L would not have OBD2 or a MAF. It will be OBD1 and have an AFM.

Megasquirt should be your next mod.
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Old 04-24-2012, 01:37 PM   #13
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What he said.
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Old 04-24-2012, 01:43 PM   #14
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Quote:
Originally Posted by Thr33GenAccord View Post
Either way, I have a 1992 Sunburst Miata. 1.6L OBDII

no you dont.
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Old 04-24-2012, 01:52 PM   #15
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Heh. Turns out you're right about the OBDI and I shamefully am unaware of the difference between a MAF and a AMF. I though they were two ways of saying mass air flow sensor. So at the end of the day I still want to be able to pass Ontario emissions but given that I was wrong about that little grey box attached to my intake, should I still be concerned with engine codes and running issues? Or should I follow through with my original plan to recirculate? The parts are coming in today at 2:00. I'm in a pipe welding exam from 1:30 to 3:30 and then I was planning on picking up my parts and getting to work. I feel like, everything considered, recirculating is probably still my most stress free option. Now I just have to figure out the fuel pressure regulator and how that plays its role in all this. Thanks again for the continuing advice guys. I'll pop back on here when I'm in the shop before I get to work. If anyone has helpful info on the FPR, it would be greatly appreciated.
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