Advanced CIS Turbo Tuning Discussion Thread. Ultimate?

[cole930]

Anyone here presently running CIS and logging afr, rpm, map (boost and vacuum), and cp. What is the max control pressures you've seen.

I am in the process of putting my hardware together to log afr, rpm, map and cp. I am using the LM1,
LMA2, Bosch wideband O2, 3 Bar GM Map (boost / Vacuum), 0-100 psi pressure sensor, RPM converter, and a LED display that displays vacuum in negative numbers and transitions to positve numbers for boost. I'm installing the LM1 permantly and will use LogWorks to map the data through my laptop. I,m interested in logging timing advance and retard also. Has anyone logged timing with the LM1?
Cole

[RarlyL8]

Cole are you talking system pressure? If so that can be shimmed to about 110psi, maybe more.

[911st]

Brian, I am rusty but I am not sure that bumping system pressure dose anything. It is the differential pressure that effects fuel deliver quantity. The CIS fuel head is a very elegant fuel pressure regulator. It self compensates for variances in any thing in the fuel system that may effect fuel flow at the injectors like a Fuel Pump thats pressure might vary depending on age or how cold it is our. Thus, bump system pressure and I believe the head self compensates and still delivers the expected fuel quantity. Change the tension of the internal springs around the internal orifices to effect the differential upper lower head pressures and you change the delivery quantity. Again, I am rusty on the fine details.

I believe they are talking about Control Pressure as set by the WUR that determines the movement of the metering plate/arm/pin.

Cole, high CP is off boost, low CP is on boost. Do you want to know how high CP goes, how low it goes, or both. These are both easyly tested at rest. You might be talking about the Digital WUR ranges. Sorry if this is not helpfull.

It would not be difficult to add a pressure sensor on the fuel head for an output to track CP of one wanted to. I put a VDO pressure gage on my head that stayed there full time.

[stup]

I did bump the pressure up in the thread below and it defo gave me more fuel up top!!...see link....second batch of pictures

Digital WUR

[911st]

stup.

I went back and looked at your snaps. Great info but did not know how to conclude that you may have more fuel after the adjustment.

It looked like you did some tunning after you shimmed the system pressure which would make the two sets of screens uncompilable I would think. Plus, the cross section's where at different RPM points.

Again, I am just not understanding the comparison.

If you have a before and after with the only change being the shim I would love to see.

Or, tell me what you see that lets you conclude it effected your AFR's. Did you find that at near redline with the same on boost control pressures you saw .5 lower AFR or somthing like that after the change?

I think, rasine the system pressure raises both upper and lower head pressures in a way they cancels out said change and thus deliver the same fuel quantity. But that is just an opinion and I could be wrong. It has been about 6 years sense I looked at that. I just remember when I did, I concluded it was not viable.

[911st]

System Pressure I think is the hurdle pressure the fuel pumps have to achiave for the fuel head to be sure it has enough fuel to operate correctly.

Increase this to much and the fuel pumps might not have the ability to support it.

If the fuel pumps can not deliver at a pressure above the system pressure setting, no fuel will blead off out of the valve you have shimed and then go back to the fuel tank.

I could be wrong.

[fredmeister]

Originally Posted by 911st

System Pressure I think is the hurdle pressure the fuel pumps have to achiave for the fuel head to be sure it has enough fuel to operate correctly.

Increase this to much and the fuel pumps might not have the ability to support it.

If the fuel pumps can not deliver at a pressure above the system pressure setting, no fuel will blead off out of the valve you have shimed and then go back to the fuel tank.

I could be wrong.

You are right about the differential presssure being controlled within 0.1psi or so by the internal springs in the fuel head and remaining relatively independent of this system pressure value. Theory is that you are controlling flow WITH ONLY ONE VARIABLE THAT BEING ONLY by opening more area in the slits for the fuel to flow thu, eliminating flow changes due to any pressure differential that would arise without the internal springs. The CP does control the amount of travel on the plunger and thus fuel delivery. It is independently controlled of system pressure by the WUR. However, with higher system pressure I think the fuel injectors operate at higher overall pressure and thus flow more fuel. I am not sure but from what I have seen of exploded views of the Fuel head, this is how it seems to work.

[fredmeister]

Originally Posted by cole930

Anyone here presently running CIS and logging afr, rpm, map (boost and vacuum), and cp. What is the max control pressures you've seen.

I am in the process of putting my hardware together to log afr, rpm, map and cp. I am using the LM1,
LMA2, Bosch wideband O2, 3 Bar GM Map (boost / Vacuum), 0-100 psi pressure sensor, RPM converter, and a LED display that displays vacuum in negative numbers and transitions to positve numbers for boost. I'm installing the LM1 permantly and will use LogWorks to map the data through my laptop. I,m interested in logging timing advance and retard also. Has anyone logged timing with the LM1?
Cole

I like what your doing. Very logical approach in a very organized test procedure. I am definitey interested in purchasingone of these spun plates, I just wonder how the profile of the plate will be developed? Someone mentioned a direct copy of the original which is a good starting point, but I wonder if a wedge or other profile is better?
Dyno testing or something that measures A/F control is a must.

[JFairman]

With nothing else changed, adding shims to raise system pressure makes things run richer and removing shims to lower it leans things out across all rpms.

You can compensate the midrange and idle with the adjustable WUR, but lowering the system pressure will lean out the top end and the analog adjustable WUR can't compensate for that.

I know- I've tried it, and thats my experience.

I have Brian Leask's adjustable WUR, and the modified IA fuel head I have wants to run at 97psi system pressure. Any less and it will go leaner than 12.5:1 at 6000+ rpm.
Unfortunately whern at 97psi system pressure it goes to 10:1 or richer in the mid range even with the boost line disconnected.

CIS... it just plain sucks for anything other than a totally stock car or lightly modified car... Even then it's a compromise and never should have gone into production in my opinion since they already had L-Jetronic that was light years superior.
And the even earlier D-jetronic could be made into a very high performance system easily because it used no airflow meter to choke the motor of air.

whatever... it all came down to the american market and the EPA emissions mandates that ruined everything performance oriented.

[cole930]

Brian,

Cole are you talking system pressure? If so that can be shimmed to about 110psi, maybe more.

I want to monitor real time control pressure at the WUR and I will have a stand
alone system pressure gauge (like the one unwired offers for control pressure) in the engine compartment

Keith,

Cole, high CP is off boost, low CP is on boost. Do you want to know how high CP goes, how low it goes, or both. These are both easyly tested at rest. You might be talking about the Digital WUR ranges. Sorry if this is not helpfull.

I wanted to know max. cp's so I can select a gauge that allows me to scale it for the best resolution.

Fred,

I like what your doing. Very logical approach in a very organized test procedure. I am definitey interested in purchasingone of these spun plates, I just wonder how the profile of the plate will be developed? Someone mentioned a direct copy of the original which is a good starting point, but I wonder if a wedge or other profile is better?
Dyno testing or something that measures A/F control is a must.

The velocity plate I have is the original and has the profile that was originally used
and that's the plate we will have tested. The profile of the plate was developed by Bosch and Mercedes on Mercedes CSI's. If it does pan out I will make sure it's available to anyone that is interested. I will make sure nobody gets ripped off on price.

I want to be able to tune my 930 as well as possible by myself. It's my passion and I enjoy doing my own work. I do not have a lot of money so I try to make sure I'm not going off on some tangent that is just another fad or sham and has no practical benefit.

I have picked specific objectives for the car. Maximize the cars potential with
affordable bolt on parts. And secondly; do it in a manner that does not destroy the engine.

I had to do a top end so I did install sc cams, while doing the heads we did some light smoothing. I added headers and a different turbo, larger IC, MSD, short gears, fuel head air mod, 964 bov, and I have a DWUR comming.

I investigated what will break the engine. Too much boost, overreving, detonation. The first two are easy a boost controller maxed at 1 bar with the engine updates to support 1 bar and a 6500 rpm chip in the MSD. The last and most important detonation. Poor fuel, lean afr's, temprature, big boost, timing, and
no control over those variables will kill you. Enter the LM1.

If you can real time map AFR's, Map, Temp, CP, RPM, and Timing you can control detenation and optomize power. AND REALLY HAVE A LOT OF FUN DOING IT !!!!!!

Cole

[911st]

Found a reference on line also that seems to support that bumping System Pressure effects fuel at all points as you have found.

If we can fix the issue with the metering plate stalling out by doing the Rensport Systems metering arm pin relocation and or by adding windage to the top of the meteringg plate, it will not begin to stall untill the metering pin reaches fuell travel.

This will flatten the AFR curve which is important to make the stock head support more hp and to tame heads that have been adjusted for increased fuel. I like the ease of the substitute MP but suspect the RS/pivot has merit because it not only helps the pin reach full travel but also improves the rate the pin slows with changes in the metering arm angles relative to the pin (ie, flatter AFR curve).

Once this happens, one could readjust the WUR so modified heads can work properly. If a head delivers 15% more fuel every where we need to increase CP so the meteringg plate advances 15% less with ingresses in air flow. Same thing with CP on boost.

With out a method to keep the AFR's flatter this dose not work because the fuel flow would normal stall out and some of the increased fuel deliver capacity will not be achieved. I know because we tryed this with the first head that we had rebuilt for increased fuel flow that later became the IA head. We came up with the RPM boost clamp as a work around.

I believe it is possible to get one point better AFR out of the stock head because I have done so by dramatically reducing CP on boost using my own fueler based on the Andial fueler. With a flater AFR curve we can also the modified heads to work to near factory levels with out using electronics or a RPM boost clamp to delay enrichment.

Think about what the factory would do to support 450rwhp. They would probably change the cone around the metering plate to change the rate of advancment and ensure full range, change the WUR settings, and set up the head fo flow more fuel. ( Porsche changed the fuel pressure reg to a higher setting when they went from the Carrera 3.2 to 3.6 and reprogramed the CPR. Same thing.)

[911st]

Cole,

The Andial fueler is belived to have come from AMG.

Back then I do not think they were yet absorbed by Mercedes but almost the same thing as the MP.

[RarlyL8]

Cole, you mean a gage like this :

[RarlyL8]

911ST, what is your name, it escapes me.
The system pressure needs to be raised to 95-100psi for applications at or above 400whp in order to assure correct AFR at top end. This adjustment is also part of what allows the possibility of accurate full range AFRs without the use of the RPM switch. The flow rate over the entire range of function is increased to a level that will facilitate adjustability outside of normal parameters.

[cole930]

Brian,

Exactly !!!!!! some how I knew you would have one.

Cole

[911st]

Originally Posted by RarlyL8

The system pressure needs to be raised to 95-100psi for applications at or above 400whp in order to assure correct AFR at top end. This adjustment is also part of what allows the possibility of accurate full range AFRs without the use of the RPM switch. The flow rate over the entire range of function is increased to a level that will facilitate adjustably outside of normal parameters.

Agreed and accepted as to flowing more fuel.

An inexpensive HF head mod is seems.

Seems to add more fuel everywhere from what I am learning. Thus, should require recalibration of the WUR to work properly or AFR's between idle and redline WOT will be exaggerated.

If you get 10% more fuel every where you can readjust idle CO but need to slow the advancement of the metering plate about 10% for correction. Or do things like the RPM bost clamp I guess.

However, why not just access the fuel the stock head makes with an Andial fueler or using the reprofiled fuel plate first to retain more civil fuel delivery.

Of course, the Digital WUR can tame all bad behaver inherent in jacking the fuel deliver of the fuel head.

So many options. That is a good thing.

Keith

[911st]

How may ways can we deliver more fuel on a CIS system, let us count the ways:

Readjust the fuel head (IA or shim the head system pressure).

Increase flow of stock fuel head by adding windage to the top of the metering plate.

Increase flow of stock head by reprofiling and extending the cone that the metering plate rides in.

Increase flow of stock head by relocating the metering arm pivot (Steve W. Renn Sport mod).

Lower on boost control pressure using the Andial fueler or Digital WUR.

Lower on boost control pressure by using a 3.6 WUR or readjusting the stock WUR.



Us a fuel head from a V8 and plumb on or two of the extra injectors in as an additional injector (s).

Add an additional EFI fuel injector. (Not recommended unless driven at 100% duty cycle or uneven fuel distribution per cylinder.

[RarlyL8]

Keith, the core of the issue is to allow the complete system to utilize 100% of it's capacity.
Full travel of the fuel head piston and full adjustment of flow are what it boils down to. We concentrated on flow on the 400whp engine by adding a modded (out of spec) fuel head along with shimming. Result was 12.0-12.2 AFR at peak HP with good idle and fuel mileage above 20mpg on freeway.

[stup]

keith...as we have now all confirmed,on one of my first runs i could not go near max rpms because i had a shortage of fuel,i shimmed head by 0.5 mm and then i had more than enough fuel up top.

[911st]

Understood. But what did it do to the rest of the AFR curve?

If you got a full point at 6000rpm, you might have gotten another half point in the mid range.