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Fuel control via WUR + rpm boost switch
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 2309
Location: Somerset, UK

PostPosted: Sat Jul 02, 2016 7:39 am    Post subject: Fuel control via WUR + rpm boost switch Reply with quote

Looking for some advice in tuning the fuel delivery. Running way too rich at WOT with AFR's in the high 9's and low 10's. Cruise and idle is in the 14's, usually bang on 14.7. Mid throttle and mid boost of 0.6-0.7 bar sees mid 12 AFR. So looking to lean off WOT without affecting the other results. Suggestions please as Google searching this forum has come up blank so far. Thanks
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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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Last edited by Carrera RSR on Mon Jul 18, 2016 5:52 pm; edited 1 time in total
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Rasta Monsta  



Joined: 12 Jul 2006
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PostPosted: Sat Jul 02, 2016 9:31 am    Post subject: Reply with quote

Adjustable WUR?
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morghen  



Joined: 21 Jan 2005
Posts: 8868
Location: Romania

PostPosted: Sat Jul 02, 2016 3:52 pm    Post subject: Reply with quote

I have the same issue. WUR's natural responce is that it enriches too much on higher boost. All that fuel will actually cause detonation. This is the limit of the CIS. If UTCIS would have worked as intended we would all have very good control over the mixture..but it just does not.
In a month or so I will test out a modified S1 WUR with adjustability added. The way i see it, that screw will limit the amount of fuel the WUR will provide.
If it does that, i might just keep CIS for a longer period of time.
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Carrera RSR  



Joined: 08 Jan 2010
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Location: Somerset, UK

PostPosted: Sat Jul 02, 2016 5:31 pm    Post subject: Reply with quote

Rasta Monsta wrote:
Adjustable WUR?


And.....
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Carrera RSR  



Joined: 08 Jan 2010
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Location: Somerset, UK

PostPosted: Sat Jul 02, 2016 5:41 pm    Post subject: Reply with quote

morghen wrote:
I have the same issue. WUR's natural responce is that it enriches too much on higher boost. All that fuel will actually cause detonation. This is the limit of the CIS. If UTCIS would have worked as intended we would all have very good control over the mixture..but it just does not.
In a month or so I will test out a modified S1 WUR with adjustability added. The way i see it, that screw will limit the amount of fuel the WUR will provide.
If it does that, i might just keep CIS for a longer period of time.


Whilst a rich mixture is said to cool combustion and avoid det, it can also increase the risk as well. Too much fuel can also increase EGT's. So I'd like to get AFR close to 12 on WOT. I have a Bosch manual. It explains all the CIS parts but not how to control fuel. FSM's and forum threads discuss fuel pressures to factory settings. I cannot find any discussions on pros / cons for turbos in getting fuel control on modified turbos across the throttle and boost range . So I'd like some further learning before I go down this road.
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Cedric  



Joined: 27 Aug 2004
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PostPosted: Sat Jul 02, 2016 7:00 pm    Post subject: Reply with quote

Bleed valve on the boost line to the wur

http://forums.pelicanparts.com/porsche-911-technical-forum/218814-made-adjustable-wur-step-step-got-pics.html

I suppose an adjustable wur like In the link above just offsets the curve.
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Carrera RSR  



Joined: 08 Jan 2010
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PostPosted: Sat Jul 02, 2016 8:37 pm    Post subject: Reply with quote

Thanks Cedric. This is the reason for my post. Adjusting control pressures via the WUR appears to move the curve up an down the Rev/boost range. Leaner at the top means very lean at the bottom end. So just sounding out the theory and experiences here
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morghen  



Joined: 21 Jan 2005
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PostPosted: Sat Jul 02, 2016 9:50 pm    Post subject: Reply with quote

This looks different.


http://www.928motorsports.com/parts/cisreg.php

I'm wondering if there is a way to limit the travel it does to upp the control pressure.
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morghen  



Joined: 21 Jan 2005
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PostPosted: Sat Jul 02, 2016 10:10 pm    Post subject: Reply with quote

Anyway, now thinking about another way to control this.
The thing you have to do is lift up the bimetal so more fuel goes to the tank instead of staying there to make the air plate lift higher.

So...boost pushes the bimetal down...(if no boost is applied no enrichment).
How about an inline boost controller to limit the boost that the WUR gets?

Say you're runin 1bar at the manifold and 1bar at the WUR means 10AFR.
Well lets try to reduce 1bar at the WUR to 0.8bar.
So we need a pressure restrictor inline between the manifold and the WUR.


EDIT -Here is what i'm thinking:
idea by m0rghen, on Flickr
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Last edited by morghen on Sat Jul 02, 2016 11:13 pm; edited 1 time in total
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Carrera RSR  



Joined: 08 Jan 2010
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PostPosted: Sat Jul 02, 2016 10:55 pm    Post subject: Reply with quote

morghen wrote:
This looks different.


http://www.928motorsports.com/parts/cisreg.php

I'm wondering if there is a way to limit the travel it does to upp the control pressure.


Makes a WUR which isn't boost controlled to one that is. We have this in our WUR's already and leaning out too far. Would work in conjunction with the AFR guage

Every thread I am reading is trying to richen the mixture at 1.0bar plus, not lean it off. I've run my car upto 1.3bar and still get 9.8-10 AFR. I also get det easier without octane boosting.

Quite like the idea of bleeding off boost to the WUR to limit the boost enrichment. I only sold a turbosmart boost controller last year damn it. Could rig up another boost gauge to ensure I avoid cutting off boost completely.

Some days I wish I did go EFi.
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morghen  



Joined: 21 Jan 2005
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PostPosted: Sat Jul 02, 2016 11:27 pm    Post subject: Reply with quote

Or a simpler one i think: a small flow restrictor that bleeds out the boost before the wur.
Ofcourse bleeding boost = enriching but since the WUR responce isnt linear this should still be effective.

idea2 by m0rghen, on Flickr
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morghen  



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PostPosted: Sun Jul 03, 2016 5:51 am    Post subject: Reply with quote

more refining

idea3 by m0rghen, on Flickr
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Carrera RSR  



Joined: 08 Jan 2010
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PostPosted: Sun Jul 03, 2016 7:32 am    Post subject: Reply with quote

Is the solution throwing Brian Leask $600 for a modified adjustable WUR and rpm enrichment device?

If so I'll be looking for a stateside buddy to sell me and post a WUR direct to mr Leask on my behalf in the near future.
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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
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PostPosted: Sun Jul 03, 2016 3:16 pm    Post subject: Reply with quote

you might contact Mittelmotor, I asume they run above 0.9 bar with their GTS replica.

Or convert to KE jetronic:


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Carrera RSR  



Joined: 08 Jan 2010
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PostPosted: Sun Jul 03, 2016 6:15 pm    Post subject: Reply with quote

I have already contacted Mittemotor for their suggestions. Awaiting a response.

I'd bypass the KE and go full EFi if I wanted the to go through the pain of converting to anything. The romantic in me wants to keep CIS and the original look. The head wants more control, cleaner burn and more reliable hp.
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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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