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Fuel control via WUR + rpm boost switch
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Dutch924-racer  



Joined: 23 Jul 2007
Posts: 1059
Location: The Netherlands

PostPosted: Wed Jul 06, 2016 4:27 pm    Post subject: Reply with quote

good find, let us know if it works
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937 trackday car
Series 2 engine
951S turbo and intercooler
937 DITC
Fast road camshaft
Forge recirculation valve + boost controller
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morghen  



Joined: 21 Jan 2005
Posts: 8166
Location: Romania

PostPosted: Wed Jul 06, 2016 5:57 pm    Post subject: Reply with quote

Will wedge this in the vaccum line that goes to the WUR and give it a try while monitoring AFR values.

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Ruby-sh 924
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1973
Location: Somerset, UK

PostPosted: Wed Jul 06, 2016 6:01 pm    Post subject: Reply with quote

If it doesn't there may be trouble ahead if too lean Calculations may be a bit trial and error to get the restriction correct. But at least it is cheap and easy install

At least with a MSD digital rpm switch you can incrementally raise the rpm limit to hold back enrichment and know it will trigger the WUR before the fuel is need at the top end when monitoring an AFR gauge. I prefer the digital switch which is adjustable per 100rpm increments v's using the set pills with the analogue version.

I am also checking to see if my Zeitronix datalogger can trigger the Pierburg boost switch at a set rpm. I seem to recall there was a powered output which can be triggered at different parameters
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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morghen  



Joined: 21 Jan 2005
Posts: 8166
Location: Romania

PostPosted: Wed Jul 06, 2016 8:03 pm    Post subject: Reply with quote

Too many things to fail in my opinion. I'd rather go EFI than invest a few hundred in a partially effective solution that could kill the engine if one of its several components fails.

I'll install that restrictor and creep up the boost with my eyes on the AFR gauge.
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Ruby-sh 924
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1973
Location: Somerset, UK

PostPosted: Thu Jul 07, 2016 6:37 am    Post subject: Reply with quote

My Zeitronix data logger can trigger an rpm signal to a relay and then onto the Pierburg boost pressure switch. All parts on their way at a fraction of the cost of the Leask kit. Will sort out the delayed boost signal to WUR first, monitor and then decide whether my current WUR need further pressure adjustment or to get a 4 way adjustable version later. Here's hoping to a few more horses being liberated in the mid range.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Dutch924-racer  



Joined: 23 Jul 2007
Posts: 1059
Location: The Netherlands

PostPosted: Thu Jul 07, 2016 4:58 pm    Post subject: Reply with quote

Nice job Steve, keep us posted!
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937 trackday car
Series 2 engine
951S turbo and intercooler
937 DITC
Fast road camshaft
Forge recirculation valve + boost controller
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morghen  



Joined: 21 Jan 2005
Posts: 8166
Location: Romania

PostPosted: Thu Jul 07, 2016 5:05 pm    Post subject: Reply with quote

I dont really get it how is a switch going to control an analogic function.
You're reading the RPM, say its revving up and reached 4000RPM, now the trigger sends the command to the relay that switches ON the boost switch which shuts the door to the WUR...so now you're running without boost enrichment because the boost switch is not an actuator but a on/off thing.

I dont see this as a solution unless the whole system is running(without boost enrichment) as rich as the engine needs to at full boost and you're just canceling the enrichment in the mid range.
This would make the low end rich and probably the top end rich but the mid just where you want it.
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Ruby-sh 924
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1973
Location: Somerset, UK

PostPosted: Sun Jul 10, 2016 11:09 pm    Post subject: Reply with quote

Having issues with the rpm signal from -ve coil or back of tachometer to the Zeitronix. It is wildly over reading and bouncing from 27,000 to 99,999 rpm. In theory the Zeitronix should work with all ignitions with no extra parts or control boxes. Software is set to 4 cylinders. Any ideas of issue or a fix?
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1973
Location: Somerset, UK

PostPosted: Mon Jul 11, 2016 11:17 pm    Post subject: Reply with quote

morghen wrote:
I dont really get it how is a switch going to control an analogic function.
You're reading the RPM, say its revving up and reached 4000RPM, now the trigger sends the command to the relay that switches ON the boost switch which shuts the door to the WUR...so now you're running without boost enrichment because the boost switch is not an actuator but a on/off thing.

I dont see this as a solution unless the whole system is running(without boost enrichment) as rich as the engine needs to at full boost and you're just canceling the enrichment in the mid range.
This would make the low end rich and probably the top end rich but the mid just where you want it.


Boost switch is closed at all rpm by default. When the Zeitronix hits a given rpm, say 4000rpm, it triggers a warning unit the ZAVT, which in turn triggers a relay to open the boost switch, therefore returning the full boost fuel enrichment to the engine avoiding the power sapping over rich mid range but giving full fuel at high rpm. The only trial and error is what rpm to turn enrichment back on. I would guess given some responses on the 930 forums circa 4200 to 4800.

If I can get the rpm issue figured out I can start testing with the Zeitronix datalogging. I'll start at 4000rpm and work up so to avoid going lean early!
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1973
Location: Somerset, UK

PostPosted: Mon Jul 11, 2016 11:20 pm    Post subject: Reply with quote

Carrera RSR wrote:
Having issues with the rpm signal from -ve coil or back of tachometer to the Zeitronix. It is wildly over reading and bouncing from 27,000 to 99,999 rpm. In theory the Zeitronix should work with all ignitions with no extra parts or control boxes. Software is set to 4 cylinders. Any ideas of issue or a fix?


Lots of threads across the tinterweb with a similar problem but no one has posted a fix. Looks to be HT noise interfering with the signal. A resistor is needed but not sure on spec or success. Given I need an accurate rpm signal to trigger the boost enrichment, it needs to be a robust solution to avoid going lean or mis triggering the fuel incosistently
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Dutch924-racer  



Joined: 23 Jul 2007
Posts: 1059
Location: The Netherlands

PostPosted: Tue Jul 12, 2016 2:03 am    Post subject: Reply with quote

Have you contacted Zeitronix yet ?
_________________
937 trackday car
Series 2 engine
951S turbo and intercooler
937 DITC
Fast road camshaft
Forge recirculation valve + boost controller
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morghen  



Joined: 21 Jan 2005
Posts: 8166
Location: Romania

PostPosted: Tue Jul 12, 2016 3:10 am    Post subject: Reply with quote

At this point, if i were you i'd drop the idea of controling a complex system with that thing. In my eyes its just too complex and risky.
I'd rather take my chance with a pressure restrictor.
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Ruby-sh 924
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1973
Location: Somerset, UK

PostPosted: Tue Jul 12, 2016 4:32 am    Post subject: Reply with quote

Dutch924-racer wrote:
Have you contacted Zeitronix yet ?


One email returned from them today asking how I have earthed the ZT2. Awaiting for more responses
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1973
Location: Somerset, UK

PostPosted: Tue Jul 12, 2016 4:37 am    Post subject: Reply with quote

morghen wrote:
At this point, if i were you i'd drop the idea of controling a complex system with that thing. In my eyes its just too complex and risky.
I'd rather take my chance with a pressure restrictor.


The Pierburg switch is the same as the Brian Leask solution used by many 930 owners. This same switch is used all modern turbo cars including Porsche. The control of it is no different with my Zeitronix as the Leask supplied MSD rpm switches. The Zeitronix has been proven to control NOS, meth injection, boost controllers/switches in the same way. So I don't see it being complex. More complex than a pressure restrictor, yes.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
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morghen  



Joined: 21 Jan 2005
Posts: 8166
Location: Romania

PostPosted: Tue Jul 12, 2016 4:43 am    Post subject: Reply with quote

ok, i'm quite interesting on what you can do with this setup.
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