T,

Great info. This just keeps getting better.

I appricate the shop stated values for 3000 rpm w no load of 40 deg +/- 3 deg which gives us -37 to -43 which is very much with in the timing base values I have seen on tuner turbos. However, they also pull these back very quickly with any increase in load. Running -40 or so on cruse should make for much better fuel economy than running -26 like on a US 930.

These can not be achived on a stock 930 unless we can get a lot more retard functon by modifing the vac/boost pot's limiting stop and the diphragm dose not hit an internal stop.

-21 deg at full boost w +/- 3 deg depending on temp input is -18 to -24. The -18 is about equal to the timing value of a euro 930 (-29 deg w -9 to -10 deg of boost retard).

This might seem to support the thought that Porsche is consertive w the 930 as there is no timing adjustment or compensation for varitions in conditions.

My 91T "Service Information Technik" p2-26 notes "( idle firing angle of 0 deg +/- 3 w 0 deg throtle swith closed.)" This, it looks like idle is subject to the same varation or there is a conflict in the factory info.

If this is the case and you use idle timing of 0 as your referance for the scope mesurement, this might effect your net readings +/- 3 deg.

Thus I belive the idle also adjusts up to 6 deg depending on temp sensor input.

At a minimum we can see there is a lot of room for improvement and that Porsche did get more agressive w the C2T when it updated the ignition system. As Porsche did not seem to enable the octain jumper for the US cars, the igntion settings are probably concervitive side for the euro fuel if it is of higher octain.

This helps support FTD's mod.

Also we should note the C2T has what I belive to be one of the more effecent intercoolers. IC effecenty has a lot to do with how much boost and or timing advance can be run.

If the factory alows for up to -24 deg of timing at .75 bar on a cool day we are leaving a good 8 deg of advance or more on the table at times when set to stock US timing (-16 v -24).

Setting a US 930 to euro spec might be a possable concideration. That would put us at -29 on cruse and about -19 or -20 on boost. If running 1 bar on a hot day it might be be to much for a 930.

Cool info!!!

K

I was thinking about the advancements that the 965 has over the 930 that allow it to safely run so much more advance:
* better intercooler
* Ignition that receives the following input of parameters
- accurate engine speed and crank reference
- Intake air temperature
- Engine temperature
- Engine load

With all these parameters it's possible to safely run much more advance than a 930 that can only sense engine load.
As for the FVD bracket I'd love to try it but it would be a big risk.

AFR and fuel quality also being a factor.

If one is fat near TQ peak I suspect the motor will be less suseptable to detonation.

Today I took my distributor out and lengthened the timing adjustment slot with a carbide burr in a die grinder so I can turn it a little farther clockwise, advancing static timing some more.
Then I found the bottom of the opposite edge of the adjustment flange and slot would hit the engine tin keeping it from turning clockwise any farther so I sanded some aluminum off the bottom of that edge.

I could have just reindexed the distributor gear one tooth more advanced but then the distributor would be more counter clockwise when installed and the vacuum pot would have been sticking out away from the motor farther than I like. This way it's tucked in closer to the chain case cover.

Put it all back and the thing definately gained a little more pep at low speeds, again.
It was such a lazy slug getting away from stop lights back when the idle and low speed timing was stock.
964 cams, stock 7:1 compression, stock timing, and a K27 7006 turbo made for a lazy motor during city driving so advancing timing at low rpms before boost really woke my car up.. alot.

I'm guessing it's idleing around 12-15 degrees before top dead center with both vacuum lines on the '87 USA distributor at the moment.
Then it started raining just as the motor was warmed up so I couldn't do more test driving.

I have MSD ignition and the MSD 8762 boost timing master with the boost retard slope control in the car to retard the timing under boost.

I have an email into Split Second Timing to see if they can make us a box so we can map the timing on a 930.

I am asking that we be able lock out or mechanical advance and disconnect the Retard Pot and set timing at about -20.

Then be able to advance and retard timing from there based on load and rpm.

And that we have a correction factor to add or subtract timing based on intake air temp (new sensor set in the intake manifold or intercooler exit tank).

They also have an ability to feed real time data through the box on MAP, RPM, temp and other functions on a 0-5v or 0-12v scale is wanted.

This could allow running closer to and ideal at all points including bend the timing curve around TQ peak where timing is sensitive.

JFairman,

Good to hear more evendence these cars respond to timing pre boost.

I want to put out a heads up on the MSD programmable systems. They still have a lot of potential but from the limited reading I have done there programing capacity may be limited. Further there range of adjustment may be limited to about 25 total degrees.

The seem to only have retard function for boost and from the base timing. They do not have vac advance. Thus, if we want to start at -10 off idle our total advance on cruse could be up to -35.

You program it like setting the mechanical advance. Then you program in the boost retard amounts. One advantage is you can easily manipulate the base advance curve and bend it around more sensitive areas like near TQ peak and advance it more early where the motor seems to be able to take more timing.

It is relatively simple to set up as it is not programmable by load and rpm.

I see the limit being you probably can not set cruse timing at say -43 and pull it back quickly with loss of manifold vac.

Further, it looks like we start by locking out the mechanical advance and killing the pot and setting timing to our max advance. Then we retard from there. This may put or rotor at a less than ideal angle at some points. For example if base timing is set at -35 and we retard to -10 the rotor probably will not be well lined up.

I would still put this on a race car. It just may not achieve the best MPG on cruse that is possible and be programable to a fine degree like a modern EFI system.

Disable vacuum retard and boost retard, lock out the mechanical advance mechanism, twist the distributor to set your initial timing way high (like 35 degrees advanced at idle), program 25 degrees retard at 900 rpm to end up with say 10 degrees idle advance, then plot similar retards at varying rpms up the scale from there. The rotor will line up fine being that it's a very wide arc. Simple, it would seem.

Thanks for the info Mark.


Thinking out loud.

I was thinking the rotor angle followed the timing. However we can manage the rotors angle by where and how we lock down the mechanical advance.

If the rotor turns in about a 3" diameter circle then a 25 deg range is about .65".

Then the rotor orientation should be able to be managed by locking the mechanical advance in the right place.

I would think we would want the rotor centered to the poles at about -22 which is the half way point between -10 and -35. I am guessing we are looking at about -20 under max load so that should be good.

Then at idle and cruse the rotor would only be off perfect center about a third of an inch (.33").

It would be interesting to measure the width of the tip of the rotor and the width of a distributor pole to see what our coverage is.

My guess now is it could be fine if the orientation of the rotor is managed properly.

If not, there is a chance it could be severely out of phase.

Consider this: Even if we got out of phase with all the initial advance, wouldn't the impact be felt more at the bottom end/lower rpms, but as the rpms rose the phase would come back in line? I'm thinking it's probably less of an issue than we might think.
Granted, this is new territory. Won't be too much longer and we'll have some real-life experience to draw from. Stay tuned.

I do not know if we would even feel it.

Best to be out low down when the effective is low where less damage might result.

Might just eat up rotors and caps but have not clue.

Anyone have a Dist cap and rotor and can measure them?

If keeping the rotor aligned properly was not important, Porsche would not have installed advance mechanisms in all there EFI cars including the C2 Turbo even though there it no trigger in the dist.

Still, I do not know how important this might be. Just makes sense to manage it the best we can.

The other way to go is install flying magnets some way for crank position and use an MSD Hall Effects sensor as a trigger and leave the dist advance mechanism in place for alignment.

I wonder if the Porsche trigger can be mounted to the dist shaft so it dose not move but the advance function stays in place.

so far with my modern EFI i've run as much as -30* at idle and ramped up to -38* from 1100rpm on up with good results. Ofcoarse timing drops as boost comes in but the car really is noticably more responsive off boost.

Now there is a hint. I think the Gimpy Big Dog bit the bullet here.
Way to go Bro!!!!!!

The new 6AL-2 does have a built in dwell circuit so dwell angle should not be
an issue. Also 930's don't like at lot of max timing and therefore I can't see a
max retard of 25* being a problem.

But then again if we get all these issues resolved we'll end up playing
computer Tic Tac Toe here. But wait !!! we still have Mr. Gimpy's 964 BOV
short neck cooler conversion pictorial thread to look forward to.



Cole

For reference, the C2 Turbo has about 43 to 46 deg of timing range.
(Idle from -3 to +3, cruse from -37 to -43.)

Not a big deal. Just have to give up a little economy on cruse and smog at idle.

As long as we can control and bend the NA WOT curve and set the boost retard by rpm and load, there is much opportunity for performance improvement.

The key will be to get the AFRs set and set it up the timing properly on a dyno.

Keith,

It's funny when I start thinking about it but I must admit, I'm a stubborn old bastard, and I just can't let go of the idea of making a 375 - 400 hp street 930 with CIS that works.

I'm mean good afr's, easy starting, smooth running, detonation free, daily driver, 1bar beast. I'm not talking about a 40K built block, fancy pistons, ported and polished heads. twin plug, high compression, tunned intake and exhaust, efi'd, crankfired motor. I'm talking stock 3.3 turbo with bolt ons. That's old school and that's cool.

Now don't get me wrong because if I win the lottery tomorrow there will be a Dauer Street 962 in my garage within 30 days and I'd even buy you another turbo just so you could try out all your hair brained ideas. And we would crown you the official Turbo Thread Director of R & D.

For many years now it's been nearly impossible, except for professional tuners,
to accomplish that and have it stay together. We have always been fighting fuel and detonation and now we're at the moment of truth. We got the fuel head mods, the DWUR, and now an affordable programmable ignition. I think this will determine, finally , whether it can be done or not.


Cole

There is somthing about a 930 that attracts owners they alwas want more out of it.

The other goal has alwas been to reduce what many think of as Turbo lag.

For the years I have watched and played w CIS Turbos and ignition alwas seemed to be left out of the equation. The except being thouse that went w twin pluging. Even then most did not seem to work toward optimizing timing.

All the chip tuners do this for the EFI cars but we seemed to stick w the the mechanical aspects of stuffing more air and fuel in the motor.

For me it has been fun to try to learn more about the spark side of things after figuring out the CIS prety well.

Air flow, fuel, spark. 930's are a car of limits and how close to the limit we wants to play.

With its old tec that can not adjust for changes in conditions, staying close to stock on the spark side and under 400fwhp on the fuel side keeps our investiment safer.

Adding adjustment to spark is one part of optimization.

Adding compensation functions like intake manifold temp is the other. The ideal would be knock sensing like the C2 has.

On the fuel side we do not have much compensation. We can have plenty of fuel on a hot day only to go lean on a cool morning when the air is dense. Adding a Wide Band and or EGT alow us to watch things but things can happen fast with a turbo.

The C2 Turbo has some added compensation. There WUR has a compensation feature added to them that help some and the new electronic igntion adjusts for differances in intake air temps to a degree.

I suspect there is not really much limitation as to how much fuel we can get through CIS. We can probably still get more out of the fuel heads by running higher pressure fuel pumps and jacking system pressure further and or going to an 8 injector fuel head kind of like Porsch did for the 924GT CIS race cars. 600-700 or more should be doable for one that is modivated to do so.

Air flow is a different story. CIS's method of sensing air flow is restrictive by its nature. Most race cars have nothing that mesures air flow. Not even AFM or MAF. Porsche new this in there turbo racing days. I belive that with there change from there CIS race system to MFI I think they many have picked up another 100hp.

I very much agree that a well tuned 400fwhp 930 is plenty of car and can even be faster where it counts than a 400rwhp car in the hands of the right driver.

I love these cars. ;)

Locked Dist & rotor alignment for a locked system.

My idea of setting the rotor at -20 and locking the timing at -35 to accommodate a timing range of -10 to -35 w the programmable MSD probably can not be done as I was hoping.

I believe the rotor's orientation is fixed to the timing wheel. We would have to find a way to change this to get the rotor alignment we need.

I have not had a dist apart in decades and forgot this.

Dose anyone know if there is an easy way to change the phasing of the rotor and the timing wheel by about .33"?

You want detonation free but you don't want a knock controller. Doesn't make sense.

The 935 Blackbird has it, but it's not THAT expensive, as many Corvairs and VW's have it as well.

Andial used to use knock headphones to tune with. Better than nothing, but why not use a system that responds to inaudible knock and corrects in one engine cycle, on only the knocking cylinders?

You probably want to tune for "no knock". Are you going to use a knock indicator? Not to mention, the knock threshold changes with the weather, etc., so are you going to drive around with headphones on after you fill up at a strange station?

You can spend $1500 on "The Knock Box" (headphones).
Wolf Engine Management - Engine Knock Detection and Knock Sensor Kits

Or $750 on the Gizzmo Kmon:
Gizzmo KMon Knock Monitor & Analysis

Or $400 to $800 for the Phormula:
Phormula - Engine Knock, Detonation and Pre-Ignition Detection and Monitoring Systems

Or $889 for a knock meter:
Livorsi Marine - Gauges: Monster Racing Series

Another knock meter for $731:
Knock Meter | Performance Meters | Demon Tweeks Motorsport, Motorcycle, Car Modifying, Parts and Accessories,Sparco, Arai

All detectors. For less money you can have a closed loop individual cylinder controller. Plus, it has boost retard. If you see too much knock activity, you can dial in some boost retard.

I know you guys see me as just a peddler, but I initially designed this for my own use. I turbocharged my Fiat 131 in 1980, and it "had issues". At the time, I was a technician at Hughes Aircraft in SoCal. I set up a home lab, and in my spare time started work on a boost retard ignition. I put it into production in '81 and had AK Miller and Kas Kastner sell them. This was before MSD had a boost retard unit.

In '83 Carter Carburetor came out with the Engine Knock Eliminator (EKE), so I started work on knock sensing. The EKE worked ok on quiet engines, but my Fiat was too noisy for it. Shirley and I would instrument the car in the evening, and drive around making knock tapes, which I would play into my design on the bench.

At the time, I worked in a signal processing group, so I had access to some bright young engineers, and they were happy to discuss my findings and offer solutions.

By '85 I had a system that worked better than the Carter unit. The detector was based on a signal processing chip being used in the lab. The scheme also used a knock window, something the Carter unit lacked. I used a PLL to set up and control the window.

In '87, I read the Road & Track review of the Porsche 944 Turbo, which had individual cylinder knock control. At the time, it sounded fantastic. Looking back it was pretty crude, retarding three degrees, then three more.

I became obsessed with making my own version, but I didn't do uP's, so I bought a surplus AIM 65 and learned assembly language.

I designed an algorithm to replace my hardware processor, and tested it on the AIM. It worked.

I was laid off in early '89, so I decided to try to make a business out of knock control. I had an analog version that worked, and Dinan Engineering was buying them for their BMW turbo kits.

It took almost two years to make my processor based version work as well as the analog one. It was introduced in '91.

It featured individual cylinder knock retard, constant energy dwell control ignition, and a rev limiter that cycled the miss-firing cylinders.

Riches and glory did not follow. It's been a long struggle, and there still are no other standalone knock controllers (EKE is gone). The only other way to get individual cylinder knock retard is OEM or get a high end system like MoTeC or Autronic, and they didn't have it until this year.

John, is there a way to integrate your knock control into a 930 or 965?

Thumbs up for John for the effort he's done.

Tinkering with a car with me7 ecu is so forgiving. You just log and see how much retard you got. Up to 20 degrees wrong is OK.