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Easiest way to get more fuel

I read the Advanced CIS Turbo Tuning thread with great interest and I didn't want to hijack it.

I have 964 3.3 turbo with a HF turbo that I run at 0.9 bar (EBC).
I estimate my hp to about 380.
It's a track car so it's being driven hard.

When logging my AFR using a Zeitronix unit, I'm running between 13.1 - 13.4 at full boost. Last time I checked it was 12.5, so it seems to be getting worse for some reason.

My engine is out so I have easy access to the WUR, the downside is that I can't check my system and control pressure.

What would be the easiest way to get more fuel and what should I aim at?
I don't want to go EFI or DWUR, at least not yet.

My initial plan was to make my WUR adjustable possibly moving it for easy adjustment (the WUR is hard to access on a 964 turbo) and adding a gauge for control pressure, is this the way to go?

After some reading I saw posts about increasing the system pressure to get more top end fuel, would that be valid in my case?

Thanks for your help, cheers!


Old 03-11-2009, 05:22 AM
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13's are way too high on boost, should be 12 or high 11's street, mid 11's for track use.
The stock fuel system will support 375whp. Start with an adjustable WUR and go from there.
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Old 03-11-2009, 06:08 AM
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The "easiest" way to get more enrichment is to open up the WUR and tapping down the gold pem in the bottom section of the WUR. If the unit is out this only takes a few minutes.

As you have the 3.3T the system pressure drop as I recall is ~1.3 bar...what you might want to shoot for is the 3.6T pressure drop of 1.6 bar. I should mention that you should be very careful when tapping down the pem as you don't want to over shoot the pressure drop. You can get a lot of fuel if you do. So much you'll be way to rich at peak HP and off your afr guage at peak torque. This change adds more fuel across the rpm range after ~6-7 psi of boost and will give you the typical too much fuel in the lower rpm's and enough (ie....how ever much you want) at redline.

With that said if you chase this route it's advisable to have a CIS tester. Actually I would say if you don't have a CIS tester...don't do this tweak! And this will not address the rising AFR's typical of the modified CIS Turbo motor.

I see you mention your AFR's are changing. I've noticed the same thing (I have the LC1 mounted). Can't say what it is but would venture it has to do with outside temps and which brand of gas I've filled up with.
Old 03-11-2009, 06:56 AM
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Thanks guys!
Ok, so I need to open up the thing, thought it was the brass thing on the outside that needed tapping.

How much tapping are we talking about, like 1mm or 2?
I heard about the dangers of tapping too much and the hassel of getting it back up.

How/where/when do I measure this system drop of 1.6 bar?

Lots of fuel at low rpm concerns me, what is the cost for the rpm switch?

Last edited by staffanbe; 03-11-2009 at 07:40 AM..
Old 03-11-2009, 07:37 AM
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Hey staffan...it's the brass thing on the inside! As far as how much, that's a TBD and hence the need/requirment for measuring your pressure drop when doing this. The reason you don't want to go to far is the C2 Turbo's WUR is more complicated then the earlier versions and not as easy to tap the other direction if you over shoot. You'll see when you open it up. A 1 mm movement would be a good start. It might take you a few iterations to get to your target. Again...you want to go slow, no cutting corners.

Lots of rpm switch's out there...I'd try an ebay search. The newer msd electronic version (8969) looks like you can set the rpm digitally instead of using pills. And it's price is ~$150. You'll also need the valve to redirect the vacuum signal (which you can scavenge from the air pump egr system).

As far as the how to measure pressure drop...that's all detailed in the CIS tester literature. Essentially you intall a gauge inbetween the WUR and fuel head.
Old 03-11-2009, 10:25 AM
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Thanks Jeff, I can tell I need to some more reading.
Will search for a threads about adjusting a WUR and installing a rpm switch (including the vacum plumbing).

But I think I'm starting to grasp the basic idea, not giving the WUR any vacum signal until above a dialed in RPM.

I'm a bit confused about the system pressure drop, thought I was looking for manipulating the control pressure, but again I need to do some more reading about this.
Old 03-12-2009, 03:30 AM
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I have played about with the wur quite a bit internally i would go for maybe say 0.5 mm on first attempt,making sure you knock down evenly also with measuring the height it sticks up at first,, say at postions 12,oclock,3 oclock,6,9 etc.

From memory it only sticks out 1.5-2mm approx in height and before you start knocking it down its best to measure to confirm you have knocked down even all the way round the circumference.

Brass round stop is arrowed in right half shown
The diaphram steel insert in on the left hand picture,,this is what moves with manifold pressure and contacts the stop..

In my opinion you will need rpm switch to stop rich midrange if you adjust this.

P.M me if you need one,i have one for sale(msd)


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Old 03-12-2009, 04:00 AM
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Thanks stup
I'm interested in your rpm switch, will send you a pm
Old 03-13-2009, 02:13 AM
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I have the adjustable WUR from Brian Leask and with that one you tap in the large center thing on the bottom to lean out boost enrichment by raising boost control pressure but then you have the option of pulling it back out with a little tool he supplies with it to get the exact pressure you want using a 4mm allen wrench.
He also puts warm steady cruise control pressure and boost threshold adjustments on the bottom along with the cold start control pressure adjustment on the top.

All that said and having adjusted the thing alot and watching pressures with the correct CIS gauges, I use the opposite end of dial calipers for measuring depth and tapping it in .005" at a time makes a noticeable difference. I wouldn't move it more than .010" at a time and .040" is 1 mm and thats too much adjustment at a time unless you got lucky.

Also for every adjustment you do on the bottom of the WUR for warm steady cruise, boost enrichment, or boost enrichment threshold you will affect and change the cold start control pressure setting on the top so you'll have to go back and set that again.
Old 03-13-2009, 12:37 PM
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Quote:
Originally Posted by JFairman View Post
I have the adjustable WUR from Brian Leask and with that one you tap in the large center thing on the bottom to lean out boost enrichment by raising boost control pressure but then you have the option of pulling it back out with a little tool he supplies with it to get the exact pressure you want using a 4mm allen wrench.
He also puts warm steady cruise control pressure and boost threshold adjustments on the bottom along with the cold start control pressure adjustment on the top.

All that said and having adjusted the thing alot and watching pressures with the correct CIS gauges, I use the opposite end of dial calipers for measuring depth and tapping it in .005" at a time makes a noticeable difference. I wouldn't move it more than .010" at a time and .040" is 1 mm and thats too much adjustment at a time unless you got lucky.

Also for every adjustment you do on the bottom of the WUR for warm steady cruise, boost enrichment, or boost enrichment threshold you will affect and change the cold start control pressure setting on the top so you'll have to go back and set that again.
I'm expecting the tooth fairy to deliver my Leask WUR this afternoon. Your comments here help to paint a picutre of what I'm in for. Doesn't sound too awfully complicated. What, though, is the boost threshold exactly...and how does it relate to the boost enrichment? It must not be a delay as to when the enrichment begins (as the word threshold suggests?), otherwise the need for RPM controlled delay would not be necessary.
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Old 03-13-2009, 01:04 PM
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Easiest way to get more fuel is to set the idle CO fat.

On a C2T I always wanted to try grounding thermal 12 at the Lambda control unit under the drivers seat to enable the acceleration fuel circuit which triggers the factory frequency valve to 75%. Could be a good place to use one of those MSD rpm switches. This could be the cheapest fueler yet.

Old 03-13-2009, 03:04 PM
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"What, though, is the boost threshold exactly...and how does it relate to the boost enrichment? It must not be a delay as to when the enrichment begins (as the word threshold suggests?), otherwise the need for RPM controlled delay would not be necessary."

Thats what it is. He dreilled, tapped and put in 3- 3mm allen heads under the circumfrence of a large diameter spring inside so you can increase tension on it.

It is supposed to do what you say but it is so subtle I can't see any difference with the ultra way too rich IA modified fuel Head I have on mine right now.
I've tried the adjustments to the length of the threads of the little allen head grub screws and I see no difference on my innovate AFR gauge, but maybe with a stock fuel head ypou could see a difference.
Screwing them inwards is supposed to delay boost enrichment a little bit but you need the rpm switch if you need to delay it alot like when the IA head is installed.

You'll see it all in the very in depth instructions with pictures that Brian gives you with it.
Old 03-13-2009, 03:38 PM
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[QUOTE=JFairman;4542030]Thats what it is. He dreilled, tapped and put in 3- 3mm allen heads under the circumfrence of a large diameter spring inside so you can increase tension on it.QUOTE]

Thanks for the description. Since I'm not running with a modified fuel head such as you, the threshold delay/adjustment may be sufficient. I'll be dialing it in to run 1.0 bar and will most likely end up quite rich midrange, though. I guess we'll see where the AFR's settle in after the first run, and go from there. Each setup is unique, I'm sure. I have in my back pocket the MSD/solenoid for delaying things if need be...would be a simple matter to hook it up. Time will tell.
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Old 03-13-2009, 04:35 PM
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Quote:
Originally Posted by JFairman View Post
I have the adjustable WUR from Brian Leask and with that one you tap in the large center thing on the bottom to lean out boost enrichment by raising boost control pressure but then you have the option of pulling it back out with a little tool he supplies with it to get the exact pressure you want using a 4mm allen wrench.
He also puts warm steady cruise control pressure and boost threshold adjustments on the bottom along with the cold start control pressure adjustment on the top.

All that said and having adjusted the thing alot and watching pressures with the correct CIS gauges, I use the opposite end of dial calipers for measuring depth and tapping it in .005" at a time makes a noticeable difference. I wouldn't move it more than .010" at a time and .040" is 1 mm and thats too much adjustment at a time unless you got lucky.

Also for every adjustment you do on the bottom of the WUR for warm steady cruise, boost enrichment, or boost enrichment threshold you will affect and change the cold start control pressure setting on the top so you'll have to go back and set that again.
Thanks for the heads up on how much to adjust and how the BL WUR works.
Didn't know that the Brian Leask WUR have a number of adjustment possibilities.
Going to have a look at this thing, it's probably a bit to expensive for me at this point though, need to fix my gearbox.
Old 03-14-2009, 03:42 AM
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Quote:
Originally Posted by 911st View Post
Easiest way to get more fuel is to set the idle CO fat.

On a C2T I always wanted to try grounding thermal 12 at the Lambda control unit under the drivers seat to enable the acceleration fuel circuit which triggers the factory frequency valve to 75%. Could be a good place to use one of those MSD rpm switches. This could be the cheapest fueler yet.
Ooops, you are right, I haven't fiddled with the idle co for a while, this could explain the difference in AFR over time. This is obviously the first thing I should do, perhaps I can get some semi decent numbers.

Do you mean grounding pin 12 to increase fuel at top end?

I have been under the impression that when you floor it the frequency valve goes to 75% (Edit: this is wrong, see below) and stays there, but this is from my memory. I recall reading somewhere what this control unit does during acceleration and what triggers it, will look for it.

Edit:
When looking through posts on this forum I've seen comments suggesting I shouldn't be so concerned about the fueling at high revs since it's more likely it would knock around max tourqe due to the "kind" stock cams. I have been under the impression that I should aim for around 11 at top end mostly due to cooling, would be good to understand this.

Last edited by staffanbe; 03-15-2009 at 03:02 AM..
Old 03-14-2009, 04:12 AM
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Regarding manipulating the accelerating enrichment.
Looked through my documentation.
It goes into 50% duty cycle at full throttle (should have known this).

To my understanding higher duty cycle means more fuel. So grounding the 75% pin should give more fuel. I will do some more searching on forums, over the years this must have been tested.

I verified that the control pressure drop on my WUR is 1.3 bar, and 1.6 on the 3.6 turbo.
Old 03-15-2009, 03:38 AM
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I have never seen anyone else talk about using the "enrichment" function on the C2 Turbos is this way. I figured this out years ago when developing my 91. Unfortunately the PO converted my car to a Euro Head which very much disappointed me.

Tuners converting USA heads to Euro heads, fuel lines, and or injectors is evidence to me that many tuners have not really taken the time to understand how these cars work. This goes double for the C2 series of Turbos.

When I got done with my car it had AFR's in the 14's at idle and cruse, instantly went to 13/1 with acceleration and progressed to the low 12's on boost. No dips in to the 11's or 10's. My AFR was linear to red line and my head delivered one point more fuel at red line. I lost not boost between shifts, and had instant .5 bar boost with acceleration from cruse.

Old 03-15-2009, 08:57 AM
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Quote:
Originally Posted by 911st View Post
I have never seen anyone else talk about using the "enrichment" function on the C2 Turbos is this way. I figured this out years ago when developing my 91. Unfortunately the PO converted my car to a Euro Head which very much disappointed me.

Tuners converting USA heads to Euro heads, fuel lines, and or injectors is evidence to me that many tuners have not really taken the time to understand how these cars work. This goes double for the C2 series of Turbos.
I could just make a manual switch and see what happens AFR wise when I ground it. The rpm signal is under the seat as well so adding a electronic switch should be fairly easy.

Quote:
Originally Posted by 911st View Post
When I got done with my car it had AFR's in the 14's at idle and cruse, instantly went to 13/1 with acceleration and progressed to the low 12's on boost. No dips in to the 11's or 10's. My AFR was linear to red line and my head delivered one point more fuel at red line. I lost not boost between shifts, and had instant .5 bar boost with acceleration from cruse.
You turned me on
Old 03-15-2009, 09:26 AM
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You asked about the cheapest way to get more fuel.

I a very suspect that when The 92C2 Turbo was campaigned in IMSA (?) they may have triggered the enrichment system but I do not know this to be true.

However, I did not achieve those results it the manner we are talking about. I used a Andial Fueler frequency valve with a special controller to manage my control pressures at all load by RPM points.

The Ultimate WUR dose the same thing today and I would get one if I was doing a car today if they have it working will.

I also changed my Bosh compressor surge valve out for an after market unit I reversed and set up so it was open with no load so the turbo would spin faster in reserve. This reduced exhaust back pressure on the freeway and gave me instant boost when the BOV would slam shut with loss of intake manifold vacuum with acceleration.
Old 03-15-2009, 12:22 PM
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Might be good to put a volt ohm meter on #12 to verify it is a ground that triggers the enrichment function and not some other type of signal. Studying the factory C2T supplement is not clear. I can find out the conditions required to trigger that function if you need it.

Putting a Dwell meter on the factory lambda valve and triggering the enrichment function could also be an approach.
Old 03-15-2009, 12:29 PM
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