Advanced CIS Turbo Tuning Discussion Thread. Ultimate?

[911st]

Mission accepted!

However there is probably an easer way. It would probably be more in the form of an adjustable metering plate. Or trial and error of fitting an air dam down into the Metering assembly bowl. How about if we trimmed the metering plate some so a dam might even be made to slip over the top and down into the pot of the end where the metering plate so quickly opens up an dumps air off the end.

Though most are not varying much from each other as to the upper target builds these days with similar cams, IC's, turbos, and boost as limited by fuel quality so one sise might fit all. It would just come wht a little richness past HP peak to those that come up lower than expected. Much better than going to lean.

This also might open up up a strategy of using a vacuum enrichment WUR like the 3.0 turbos did instead of boost enrichment for better throttle response and less of that off idle lean spot that comes with a 3.3CIS motor.

[JFairman]

I think the biggest motor that ever got CIS was the Mercedes 450 SEL 6.9

Maybe there's something about that version thats different from the 4.5, 5.0, and 5.6 liter Mercedes V8's on CIS that was different.

[WinRice]

Just kidding around

There is no doubt in my mind that a CIS system could be re-designed and/or re-engineered to function well on a 500 fwhp-600 fwhp engine, even 800. But would it be worth the time, effort and money?

It would be fun, though!

[911st]

J,

There might be some ideas there. There fuel heads might have potential. Especially for an extreme build if one uses the two extra injector lines for extra fuel as additional injectors.

The modified throttle plate idea thats pictured several posts back supposedly came form a 6.9 MBZ or AMG I hear.

[mark houghton]

I thought I would move 911st's comments found on a different post over to this advanced CIS tuning thread. On the topic of boost vs. vacuum sensing WUR's:

How about donating your old WUR for study. Maybe someone could document how to convert to a vac-sensing WUR from the boost sensing. Lee Rice used to do this on his "Rice Fueler" WUR years ago.

The boost sensing WUR's reduce the resistance of the metering plate to movement upon acceleration. Doing this would increase pre-boost response if set up right.

Of course this is not a good fit with a set up on a car that is set up to dump to much fuel on boost. However, I believe a heavily modified 930 could be set up to still work with this by getting the control pressures right for the fuel head used.

This would not only reduce resistance at the metering plate but could reduce the lean surge off idle that is typical with CIS.

That seems to be Porsches intent with the 3.0T's. Emissions were probably part of the reason for the boost triggered unit on the 3.3T's.

If the earlier WUR's do indeed respond to vacuum, then wouldn't it have to be an all-or-nothing response...since vacuum doesn't progressively build like boost does, and rather is either there or not? I can understand the proposed benefit of getting an early onset of metering plate deflection by the WUR reducing control pressures in response to vacuum, which should happen as soon as your foot hits the gas pedal. But would that assure enough enrichment after boost starts to build?

[911st]

My understanding is both the Vac-Sensing 3.0 and the Boost-Sensing 3.3 Turbo WUR's are all or nothing. There is not really a progressive nature to either when triggered. (However I am sure someone could engineer a progressive system which would have benifit.)

With CIS the AFR's are not really liner. They are more of a curve.

We basically have a Cruse-AFR curve. And,

We have an Acceleration-AFR Curve.

Then there is a quick 'transition between the two fuel curves.

I do not believe that if you could plot the two curves they would have a consistent delta between them. The control pressure can determine the slope of each curve. The the metering cone determines the rate of change of the curve at different air flow rates.

The typical 3.3T boost-trigered enrichment CIS goes lean with first accel then stabilized pulls back to near 14.5/1 untill enrichment is effected depending on one's CO setting.

My thought is we should be able to set up with a vaccum-trigered WUR where we are at around 14.7 at idle and get an instant 13/1 AFR with acceleration just off ideal which is where a 911 motor makes its most normaly asperated torque.

If we continued to accelerate we could set up the fuel curve so it would continue to become richer until it is gets into the low 11's at Torque Peak (apx 5krpm)which is where we are most sensitive to detonation. After that it might start to lean some depending on how much fuel and air one can flow.

The other place we are concerned about our AFR will be on curse. If cruse is under 3000rpm we should be able to stay at above 14/1 with out much issue and at still meet our other goals.

Here is a crude drawing of what we might be working toward.

[mark houghton]

We need to be able to modify a WUR to do both...vacuum as well as boost enrichment. Use a boost enrichment delay solenoid in conjunction with vacuum enrichment modification (if possible) to get what you're trying to achieve. Or, the infamous "cone head" on the metering plate.
I have a perfectly good '87 WUR that I could play with in this regard, but really don't want to risk trashing it.

[e170drvr]

OK, kinda shootin from the hip here. If I am reading correctly we still have some travel left in the arm for the metering plate. I have a lot to learn about cis, but the issue as I understand it, is that our metering plate as a result of it's tilt has exceded it's critical angle of attack and stalls. Maybe this has already been considered, but what if we modified the plate so that it would pivot, and then use a small rod attached to the center of the plate that is inserted into a sleeve attached to the crossbar. This would allow movement throughout the entire operating range, with the plate remaining flat thus never stalling. Just a thought.

Eric

[911st]

Mark,

I do not think we can combine approaches. To do the Vac-loss enrichment with an extended HP car we would have to fix the over rich issue in some other manner than using the rpm delay clamp. This takes us back to curing the metering plate stalling issue or just tuning around it with the WUR.

When we did the first of what bacame the HF head we found it went way to rich everywhere but near the end of the rpm range. With my suggestion we tryed running it without any lowering of the CP on boost. It looked like a near perfect AFR's and it even extended our fueling some up top. But again, the metering plate would start to stall and we would not get all the increase we needed nor that was available. That is when I came up with using an rpm clamp to delay enrichment. With this, the vac sensing is not viable.

Just a side note, Volvo makes a "delay-pill" that goes into the vac line to the WUR that might be somthing to look at as an easyer way to delay on boost enrichment. I do not know anything other than it exists.

One could use an Andial fueler but delay it with the rpm switch combined with the vac sensing WUR. This would give one two stages of control pressure lowering. The first with vac-loss at the WUR and the second lowering of CP under boost and later in the rpm range.

I do not think any of these add one's are required if we can match the fuel head to the WUR settings, and fix the metering cone so we do not get stalling after about 300hp worth if air flow or so.

Years ago when we were doing this, some were finding good low end response improvement with the Rice Fueler that was vac sensing. It provided both vac-loss enriching off idle and combined this with a lower on boost CP for more fuel on boost. Back then there was not the HF head to exadurate the issue. However, it was hit or miss depending on how the motor was set up. For many the early lowering of CP let the turbo spool up faster. For some, it might go fat earlyer. Just depended on the set up.

Because of this and my experance with agressively lowering the CP with my own electronic WUR I know there is a performance gain to be had.


Eric,

You are on the right track. It would probably be easer to add volume to the top of the plate (see picture in post 108). Another thought is to reset the fuel head to flow say 15% more fuel (HF) and then maybe bend up the end of the metering plate. If one hit the sweet spot, the metering plate might advance 15% slower at first as more air is escaping around it to offset the added richness coming from the HF head but then the bent lip would stay further up in the cone so it would not stall as soon. If the factory did it it would just re-profile the cone and come up with a matching WUR that has the right control pressures.

[mark houghton]

Originally Posted by 911st

One could use an Andial fueler but delay it with the rpm switch combined with the vac sensing WUR. This would give one two stages of control pressure lowering. The first with vac-loss at the WUR and the second lowering of CP under boost and later in the rpm range. .

That was a suggestion I floated some time ago if you recall, but in combination with an rpm window switch and vaccum sensing relay, and a stock boost reactive WUR. Set the window switch to activate and deactivate at something like 1500/3500 rpms and tied in series with a vacuum switch. Operation of the Andial frequency valve would occur immediately once vacuum is seen AND the pre-set lower rpm limit is met, and would deactivate once 3500 (or whatever programmed) rpm was reached....just in time for the WUR to start enriching as boost builds (all dependent upon the turbo being used and how fast it spools). Net-net would be a controlled stepped enrichment through the entire power band.

It just so happens I still have my Andial enricher still installed but no longer using since my Leask WUR provides all the control I need. May just have to scab together the rest of the parts and test out the theory.

[911st]

Could just put an activation switch in place of the hobs switch but in the cab and push it any time you want to activate the Andial. You could hit it off idle for lowered control pressure if you want or on top of the BL at high rpm to see if there is any benifit to lowering the CP any more up top.

[964 T #304]

Or you could use a digital wur and lower the control press. @ any rmp you want

[911st]

That is the best way.

I has probramable control over control pressure on my C2T 7 years ago and it greatly helped off idle response. Probably the most noticable improvement along with increasing my AFR potental by abut 1 point in the upper RPM's.

Still, if I get to do a third CIS turbo I will do it without add ons and a vac-sensing WUR conversion.

[Erland Cox]

I did some research and found out that the metering plate hat was used in the Mercedes 190 2.5-16. This was a 4 cylinder high performance car that was a homologation special for DTM, the German touring car championship. The earlier model 2.3-16 which did not have the hat on the metering plate had shorter stroke, a little milder cams, more compression ratio and a thinner exhaust header. The bigger engine has 202 hp instead of 185 and that is comparable to the increase in capacity. Maybe Mercedes where running close to the limit of plate stall with 185hp already so they invented this trick to be able to continue to use the same injection? There was a special evolution model of this car with 30hp more and maybe it was only this one that had the plate mod? I will check on that. I will check if this car uses an 6 cylinder unit which it should. I also know someone who has an 450 SEL 6.9 and I will ask him if this mod was used on this older car. Below a link to some info:
http://en.wikipedia.org/wiki/Mercedes-Benz_W201
Erland.

[911st]

Welcome Erland.

I bought a 190E 2.3 in 1985 and lusted for the 16v.



"The roadgoing version of the engine was reconfigured with reduced inlet and exhaust port sizes, different camshaft profiles, no dry sump configuration and Bosch K-jetronic replacing the specialised Kugelfischer fuel injection."

Are you saying any of the models has a metering plate with the added profile or are you saying they might be a place to look.

AMG at one time developed a black box that used a frequency valve to effect Control Pressure for more fuel on some there cars. Andial borrowed this and it became the Andial Fueler.

I borrowed the plumbing part and made up my own controler so I could program my AFR's at all load and rpm points. Bassically an early version of the D-WUR.

It makes sense that a manufacture would tune the CIS system so the metering plate would stall at peak HP. Otherwise the motor would go rich after peak HP where efficiencies are falling off and no additional fuel is needed.

[Erland Cox]

They are very nice cars. My friend bought one in southern Germany and I drove it home to Sweden. I wouldn't mind having one myself. According to my source all the 2.5-16:s have them. He also says that the W124 300E-24 also has this mod. The 6.9 doesn't. He was going to check his manuals and also measure the plate diameter on the 2.5-16. It has a 4 cylinder fuel head but I guess that the metering plate is the 6 cylinder size. Does the Porsche have a V8 unit with a 110mm metering plate? I will try to take a look at the metering plate of a 300E-24 and see how big it is. My friend thinks he has one somewhere and probably Mercedes still sells them. They still stock Pankle titanium rods for the Evo versions of the 2.5-16. The first racing 2.3-16:s had K-jet, i believe up to 87 and electronic injection after that. They had around 270 hp with k-jet. I think Porsches metering plate is bigger than Mercedes though so this is only a link to where the special plates where used. I have a 911 SC and on that I used Splash Zone A-788 epoxy to reshape the inlet to the metering plate. No before and after dyno tests where done though. I am working on a Volvo 240 turbo with K-basic right now so I read through the thread to get some ideas. I need to double the stock output and I want to keep the K-jet. The plate hat and the probable added travel is something that I am going to try. Erland.

[cole930]

Welcome Erland,

I'm the guy who has the velocity cone. It came off an earlier MB V8 ie, 6.5 or
6.9 I find it very interesting they show back up in later models which brings us
full circle to our original quest. Why were they used and what advantage, if
any , were they. We all would be very interested in any information the might
be out there.

Cole

[911st]

Erland,

I saw a digram of a Volvo once that had something called a Delay Valve and it is plumbed in to the vac line going to the Control Pressure Regulator.

Do you know any thing about it?

I wonder if it might help some of here that want to delay there on boost enrichment with WUR's that go to fat at first because they have lowered CP's dialed. This could possibly be an option to using a MSD & solenoid valve as a boost clamp.

[911st]

Now that I look at the WUR I am wondering if it is a two stage setup. It has two source tubes plumbed into it with one hooked to the Delay Valve. Could be two different levels of boost or one boost and one loss of vac (acceleration).

[Erland Cox]

I haven't seen that on a Volvo myself but SAAB had two different systems with electrical control valves. The oldest one had a non adjustable WUR that was bypassed above 130 km/h or by a throttle switch at 2/3:s throttle by an external line and a solenoid. From 1980 there was an adjustable WUR with a control valve on the pressure line from the manifold.
On my Volvo I have done several tests to see what happens with the pressure and my WUR will not lower control pressure below 2,5 bars with boost. Full boost CP lowering was in at 0.5 bar but this must be adjustable by changing the bottom spring in the WUR. I will try to rise my CP above the 3.5 bars I have now to see if The WUR still lowers to 2,5 bar or if CP can only be lowered 1 bar by the boost diaphragm. It would be nice if there was a manual from Bosch for the old K-basic racing systems. I can scan and post the drawings from the SAAB workshop manual as soon as I have somebody here to help me with it. I am not a computer expert and that might just be the reason I like mechanical things like k-jet. My Mercedes friend brought a leak tester yesterday. It pressurizes the intake system with smoke from heated baby oil. It showed that my aluminum and plastic intercooler was leaking a lot. A leak check is very important before you start adjusting. Erland.