Hello !

This is a very interesting discussion ( good idea from Keith;)) with interesting inputs from many ! ;)

This thread seems more focused on 930T. However, as everyone know, the 964 3.3 engine is something very similar to the 930 engine (in it last version).

The timing values which are discussed here are very closed to those which are written into the Porsche control procedure for the 964 3.3 engine.

1000 rpm (iddle) : 0° +/-3°
3000 rpm ( EZ69 ignition hose disconnected) : 40° +/-3°
3000 rpm ( EZ69 ignition hose connected to a device which create 1.75 bar) : 21° +/-3°

So, in other words, with the stock car( 964 3.3) , under 0.75 bar of boost the timing is set at 21° . So far, I haven't see any measurement anywhere which could relate what happens exactly at higher RPM with the stock EZ69 ignition. ( I will make these measurements very soon... (I strongly believe that the EZ69 has not a correct behaviour while we increase the boost pressure...)

From everyone inputs, I read some strong beliefs but finally it seems that we are all in the dark at present time concerning the ideal timing values ( at low rpm or on boost).

There is one thing which maybe lead me to think in different way. As said before, the stock timing value on 964 3.3 is 21° (+/-3°) under 0.75 bar of boost. Now, in France, we have a reputed tuner who is using systematically the special ignition plate from FVD in their 964 3.3 tuning setup.


FVD Boutique Online


When installed, this plate advance the ignition (6°) along all the RPM range. So, under 0.75 bar of boost, the timing value is increased to 27° .... !!! In the mean time, they change the camshaft ( they are using 964 C2 cams) , they increase the intake ports size and they adjust the boost to 0.98 bar. (They claim to get about 430 HP with this setup….and it seems true )

This tuning package from this tuner is quite famous in France. They have modified many 964 3.3 like that and it seems there is absolutely no reliability problem...even at track ! So while some suggest to reduce timing under higher boost, I am just curious to understand why FVD and this tuner are increasing timing ? Any opinion here ? :)

Hi Thierry!

So now there are two of us who are curious! Those of us who are currently exploring this timing thing have intentionally stayed away from added timing while on full boost, assuming that the Porsche engineers set the stock timing the way they did for a reason. Generally, I think the timing advance on full boost is normally somewhere around 19-21 BTDC (calculated as starting at 0*TDC at idle, then gaining 10 degrees of advance when the idle retard goes away, and gaining another 18 degrees of mechanical advance, then losing 8* with the boost retard can on the distributor. Those numbers are all from memory from a zillion posts on the topic). So adding another 6 to 8 degrees advance on full boost seems a large departure from Porsche's intended setup. With racing gas, maybe that's ok...or with racing engines that get rebuilt frequently, maybe that's an acceptable thing as well....or, that timing may be friendly with the proper cams/cam timing. I'll tell you one thing, though: I'm not going there until the knowledge catches up with me.

Oh....how's your fueler working?

Thierry.

Great Data points and good to hear from you.

I have heard of ruining 40 deg and more on cruse with light load. This would improve MPG but not help our performance much.

Any idea how thouse timing values might be changed depending on which or if any Octane Codes Plug is in place or not? This should allow some manipulation of the timing values if someone can figure it out.

In Europe you have better fuel than us. California has to do with 91 octane and about 10% alcohol added. Some states get 93. Also, we often see ambient temperature of over 100 deg. Thus, the FDV mod's might work there but would probably be over the edge for us.

The 69 EZ has inputs for Charge-Air-Temp and Engine-temp. This should allow the C2T to run more advance in some conditions and pull back to safe levels with heat which is the enemy of tuning.

Also, the C2 Turbo has a WUR that compensates for changes in altitude & barometric pressure. It also has a Control Unit Acceleration Enrichment brain. These should provide for more stable AFR's with environmental changes.

Thus, the C2T can run closer to the edge safely than a 930.

930's need to have some safety built in. Yes, we can run more advance to get closer to an ideal but may then be over the edge if we get stuck in trafic on a 100 deg day.

FVD is a great tuner. However, I would be suspect if they are quoting 430hp with the stock Turbo. The stock turbo starts to top out around 380-390hp with CIS.

Except for the timing I had all there mods and more (biger core intercooler, euro fuel head, lines, injectors, Electronic - WUR like yours...) The best I could get on a Mustang dyno was about 330rwhp or about 380-390fwhp.

We probably need to do some dyno work under normal and hot conditions to see where our ideals are timing under boost. Of course this will vary depending on the build of the motor (cams, CR, IC efficiency, Turbo efficiency at peak TQ...) Every build is going to be different.

Not an expert, just my guess. ;)

PS, the CIS fuel system is also limitation on total advance. We are only as good as the one place on the HP curve where we are over the edge!

We could dial in a 930 on a dyno using normal procedures where timing is advanced a little at a time and then pulled back to where HP is not being improved which would typically give us the most powerful and safe tune to run. However, if one cylinder is a little lean, we have a problem.

If pushing timing, make sure the injectors are flowing evenly, AFR at TQ peak is a little fat, and AFR to red line stays lower than 12/1.

930's need margin on AFR's and timing to live a long happy life.

I think the first thing I would do is eliminate the timing retard at idle. While it is true that it reduces NOx, on the '86 to '88 930's the main thing it is there for is to raise the exhaust temp. These cars had 3-way cats on them. With the O2 sensor and frequency valve holding the mixture at stoich, the cat is probably over 80% efficient at reducing NOx, if it is hot enough. Get rid of that retard to keep things cooler under the tail in traffic. 0 to 10 BTDC makes for a cooler cylinder head at idle.

Now, when you get into it, the first few seconds are fine, but after that the intercooler is getting hotter, and the inlet man temp starts to go up. Here comes trouble. That ragged edge timing you developed on those five second power runs goes over the edge.

That is the real reason why the stock timing is so conservative. No intake manifold temp feedback on the 930's (until after 1991).

That is the problem with the MSD units also. They are really for drag racing, where you won't be in it long enough to get too hot. Pressure feedback doesn't really cut it for us. If you're racing a hot 'vette on M14 you ARE going to get higher inlet man temps. There isn't a whale with a big enough tail to cram all the air you need through your intercooler.

You NEED intake air temperature feedback to run serious timing. Cyl had temps are also good, better than knock sensors IMO for staying out of trouble.

Everybody thinks EFI is about squirting in the fuel, but half the bang comes from much better timing control.

Speedy Squirl,

I also thougth as you are perposing that leaving the idle Vac-Retard disconnected might make for some off idle improvement. However, I suspect that if that is done the Boost-Retard will fully retard with about only about 5 lbs of boost.

I am suspecting that we need boost to enter both sides of the pot to slow down retard under boost so it comes in at a slower rate. May not make a big difference. However, it should keep the spool time a little shorter.

Keeping the timing near TDC to -3 deg at idle might allow for easer start. Then as soon as we blip the throttle the timing advances about 10 addational deg.

Per the shop I use I understand we can modify the stop between the pot and the dist to alow for greater retard. If we can get another 5 deg we might make for a solid improvement. This could alow us to get to about 15-18 deg of advance quickly off idle. It would also alow is to run about 30-33 deg on cruse instead of about -26. What is cool about this is the on boost timing would remain stock.

Also, I replied to your post on getting a new Pot and was hoping you might check out my suspensions as to how it should operate.

Thanks if you can help.

:)

Hi Mark !

Your input let me feel your great ( and respectable) amount of wisdom. It makes sense if we consider what Porsche did in their original setup. Like you, I would like to get the full understanding of the original engineer choice prior to make any strong modification in this way.

As to my fueller/boost controler setup, it works very well and I am still very happy with it ! I already drove about 8000 km since and I have nothing wrong on the car. ( ;) except for the clutch disk for which I've got recently a sign of weakness while I made a test @ 1.4 bar of boost @ 4500 RPM) And you, will you in this way or any other way you would like to experiment ?

Hello Keith

Interesting comments and idea from you ;)

Actually, the on C2T, the octane code jumper allow to reduce 3° only. But we don't know if this reduction is operated allong all the RPM range and under all MAP information. I bet it is the case but I never experienced and measured it until now.

That's true that your fuel may be lightly different. Your temp is maybe also different. ( We also have about 100°F during summer here ) . You are right, that's also completely true that I spoke about 965 3.3 C2T which include some electronic which could allow to play closer to the edge compare to a 930. In all of case, we must consider a margin. But what margin ? That's finally the question.

As to the setup I spoke, they use the stock turbo (K27-7200) to achieve the 430 CV! ( not kidding you) As mentionned, they use 964 C2 cams, lightly enlarged intake port, 1 boost of pressure and this FVD ignition sensor plate ....and that's it !!! I am pretty sure the ignition plate is one of the key of this result. Actually, with higher timing at high RPM, they can get better efficiency and more torque. So they don't need to fill more air ....with the same amount of air, they just get more torque...so more HP.

I didn't get opportunity to measure the timing during my last dyno session.
However, from my several experience on my C2T, there is some points I am sure on my car:

- when I increase the boost pressure above 1.1 bar and above 5000 rpm, I get less power !!!!!
- If I run AFR near 11.7 above 5000 RPM , I lose power and I increase EGT...
- If I run AFR near 12.5 or more above 5000 RPM, I win power and I drop EGT...and there is absolutely no ping or detonation

These 3 points (and others) let me think that the stock timing and the behavior of the EZ69 is very conservative. Just a though ...

T,

I remember a read of a tuner in Germany that modified a 3.6T with a system that not only manipulated Control-Pressure electronically but also the wast gate and blow off valve (where I got some of my ideas). Further they optimized timing with there piggy back DME that also had the ability to run its wide-band O2 correction in closed loop where they wanted. (I think Gemballa (SP) offered a similar system for about $4k and the UniChip could be adapted to work this way.)

On the dyno, there tests with the K27-7200 could not push past 390fwhp. When they added a larger turbo and when they got done tuning they pulled 425FWHP.

The most I could get from my 3.3 C2 Turbo with a larger re cored inter-cooler (as part of Andial/Porsche's $10k S2 race kit), full Euro fuel system including injectors lines & head, full programmable electronic manipulation of control pressure (as you have), SC cams, big ports, headers, cup flywheel and a K27-7200 was about 335rwhp/390fwhp on a dyno of the type where you remove the wheels, bolt the hubs up, and you can sustain a load at any rpm point. However, I do not remember if this was before or after I cut open my B&B muffler and found it was restricted down to what was equal to only about a 2.5" tube and then changed to a straight through 3" Borla muffler and gained an instant 30hp.

Having said that, I believe one of our better tuner's here has a combination that included shorter gears, modified pivot point on the Metering Arm to extend fueling, bumped the compression to 8/1 on a 3.5 build, SC cams, twin plug MSD, .7 bar boost, and muffler and he noted 425fwhp from a K27-7200.

Thus, it may be possible to make 425hp with cams, ports, and a timing change on a K27-7200 turbo, but I am not sure I am buying it.

MSD 6AL-2 Programmable, 6530 w Launch, Burn Out, & retard triggers.

MSD by it's self has advantages for a turbo. It has a stronger spark to ensure combustion on boost where effective compression rates are very high and ignition can be difficult.

It also has the multiple spark function below 3k rpm to help combustion where effective AFR's are often lean with CIS combined with very low compression rates that make combustion sometime very difficult also.

Even without MSD a programmable system of any type would allow more accurate timing over at all points along a motors operating range. The 6AL-2system is programable every 100rpm against mandfold vaccum/boost. With this we can run 40deg on cruse for better economy and pull it back for boost. If we can handle only -18 deg at TQ peak at .8 bar and -16 at 1 bar, but at peak HP we could handle say -21 at .8 bar or -19, we can have it instead of being caped at our 1 bar peak TQ numbers of -16.

The stock system with its weights, springs, & retard-pot is can only be liner as to timing advance curves. Thus if there is one point where the motor is most sensitive to detonation or one point a point where peak power is made the points might set our out timing limits for a mechanical advance curve leaving other areas along the RPM range at less than ideal levels.

The MSD 6AL-2 also has Launch, Burn-Out, and Retard functions that can be triggered at the unit.

Could be cool to push a switch and have RPM's limited to a given point for max launch in that stop light battel or 1/4 mile run. Or held to a max RPM for a burn out or as a safe lower rpm limit when someone else is driving the car.

Not sure but the "retard" function might help with safer start up if we are running aggressive advance at idle. Or possibly as a safety when poor gas quality is suspected or operating conditions are such (hot thin air). Maybe we could put a temp switch in the intake before the throtle body to triger this above a given temp for protection. Could add a switch on the dash wired in parrel to be enabled at will.

One function that I wish it had was some level of temperture compensation that could pull back timing with changes in air temp's.

Still, a cool way to go.

Rather than move the pickup 6.5 degrees with the FVD plate, could we not spin the distributor 6.5 degrees and drill a new hole for the retaining stud? Or, mill a slot so that we could actually adjust our spark timing?

If anyone has a spare 3.3L turbo distributor body I would volunteer to try either concept on my '91 Turbo.

Just a thought.

Mark

No. The distributor only has weights in it to keep the rotor lined up.

Timing is determined by the sensor on the crank and the program burned into the 69EZ ignition.

Moving the sensor tricks the motor. One could also use a piggy back system such as the Unichip system for much more control over timing.

Probably not important but but 6.5 deg at the crank is only 3.25 deg at the dist.

Yes, I was talking about turning the distributor until 6.5 degrees of crankshaft advance occurs. I'm not sure how else to measure the advance other than from the crankshaft pulley.

I understand the distributor in my car only advances the rotor to "keep up" at higher rpm. But please explain why turning the distributor CW 3.25 degrees would not provide spark advance. My theory was that instead of "tricking" the engine with the FVD bracket, the EZ69 would deliver the correctly timed spark but the rotated distributor would deliver the spark early.

Am I confused?

Thanks,
Mark

Because the ignition trigger is not in the distributor on a 964 so turning the distributor will just make the spark jump farther from the end of the rotor to the electrodes inside the distributor cap and increase the chance of crossfireing.

The ignition trigger is magnets embedded in the flywheel like 'crankfire' on a 964 and all the newer motronic cars so timing changes have to be done electronically or use an adaptor bracket to move or reindex the magnetic pickup sensor next to the flywheel.

Got it, thanks. In these cars it is literally, a distributor of the spark.

Mark

FWIW - i just finished up my megasquirt2/EDIS6 conversion. I found the best timing for stability and smoothnes was 20* advance. 15* was so so and it just about hated 10*, so i don't know how the hell these things even run with 0 advace at idle

drmatera,

Is there any issue with starting the motor at -20 at idle?

How much advance are you running on boost at say .8 or 1 bar?

Was that just the setting in the software, or actually measured with a timing light?

Has the TDC on the pulley been verified that it's actually 'TDC'?

Seems awfully high for idle timing.

That is a boat-load of timing IMHO, especially if the vacuum retard is all in as it should be at idle. If so, that 20 degrees will become something like 28 as soon as you step on the gas, and close to 46 at 4000 rpm no-load. Take about 8 degrees off for boost retard and you end up with around 38 on boost...just a touch more than the "debatable" safe 20+ of a stock setup.

Now, if that 20 degrees at idle is without the vacuum retard line attached, then theoretically you would end up with 8 degrees less timing advance across the board; i.e., 30 degrees on full boost.

I know of folks that have tried to run as much as 14 degrees initial advance and found that the car misses pretty bad. I'm suprised you can get it to run smoothly at 20 degrees.

I must be missing something here in drmatera's description.

yes, you are missing the fact that I have EDIS 6 coil pack with crank trigger and I plot my own timing curve. :)

I run a total of 16* at WOT full boost. Check out my EFI thread as i put a screen shot of my timing table on there.