Ultimate 930 Distributor, advance, retard, timing, Turbo lag, MSD, mod, thread.

[LOWFAT]

I am following this with interest. I have a electromotive xdi and twin plugged engine but my timing is at factory settings because I have no idea on witch way to go for timing issues to get more performance. This system uses a map sensor to retard timing under boost. It is set at -26 total . I also have all the usual upgrades k27,adj wur,fuel head, enrichment rpm switch,etc, The car just not perform the way I would think that it would and have always suspected that playing with the timing would help performance. The problem around here is who can help ? most of the shops in my area only know about the stock set up and the ones with a dyno I wouldnt trust with a pedel car. So if you guys think that my set up will be comparable with the stock set up in timing adjustments Im gonna give your settings a try . Timing just reads like german to me so I am gonna try to learn from your experiments. Thanks....Ben

[mark houghton]

[QUOTE=911st;4915859]MSD!

Mark, Chris or anyone that has done an MSD conversion, can you confirm what needs to be done?

Tach drive?

Rotor, eliminate resistor?

Rev-limiter, do we need a "pill" at the MSD box to reestablish the rev limit?QUOTE]


The "Old Man" on the block spelled it out pretty well. If you already have an MSD6AL ignition, then it's a simple matter of adding the Boost Timing Master 8762. If you don't have the 6AL, MSD also makes a complete unit which combines the 6AL features with the boost timing master in one nice package.

The two work in conjuction with each other and I think I only had to connect ground, power, disconnect one wire from the 6AL and connect it to the 8762 and off we go (oh...don't forget to attach the vacuum line to where your normal boost signal is taken). Very simple installation. You then dial in how many degrees of timing you want to retard for each psi of boost...which you also dial in. The key is to drop all the extra timing by the time you're seeing any significant boost. Still running with the 6000 rev limiter chip in my MSD6AL.

Once installed and you've set your static advance to where you think you want it, you then take your handy-dandy Mity Vac or suitable source of compressed air to check that the timing retards as you add boost pressure. Do this at idle to see that it all goes away, and do this at 4000 rpm to see that you still end up with 26 BTDC (or whatever your engine specs calls for).

[911st]

Cole,

Thx! Very resourceful.

Yes, Jerry Woods is a great thought. Years ago Brent 930 sent his dist to them. I recall them wanting the throttle body to so they probably changed the vac to a full on connection instead of a modified ported one. I believe they abandon the Vac-Retard side which I assume makes is more like a Euro Dist. The also recurved it which I assumee was for faster advance. Someone should get with them and find out what there program truly is if they will disclose what they do.

I have to ask, are you sure about there only being 4 deg of on boost timing retard and they you end up at -24 on boost? From what I have learned a 930 has about 9 deg of retard and should be at about -16 at full boost. I know that is for a US dist but I would not expect much difference except for the total advance. I have to say, until I looked into it, I thought that they were at -25 on boost to. I believe my 3.2 Carrera is only about -25 at WOT, it is a higher compression, and dose not see any boost.

From 911Chips.com web site:



Note full advance by 2500rpm.

The best.

[cole930]

Hey Mr. Mark great to hear from you, glad you've stepped in here.

What are you using for initial advance at idle, when are you starting retard, how much timing do you take out per psi, what do you have at redline, and has initial advance enhanced your low end performance.

I thought I might post a couple pics of "The Old Sled" as I'm in the process of cleaning up the wiring for the MSD, LM1, MAP & Pressure sensors, AFR Display,
EBC, and related switches.











Cole

[911st]

I love pictures!

[mark houghton]

Originally Posted by cole930

Hey Mr. Mark great to hear from you, glad you've stepped in here.

What are you using for initial advance at idle, when are you starting retard, how much timing do you take out per psi, what do you have at redline, and has initial advance enhanced you low end performance.

Cole

Hey Cole,

You know, sometimes I feel like I'm playing with a very expensive fire, but I'm the kind of old guy that learns by doing. Take the best information I can get my hands on, use my own at times twisted logic, and go for it.

At idle I'm at 8 BTDC...as much as I could get twisting the distributor to it's stops. I'm gonna have to look at the dials again, but I think I set it to begin retarding at 1 psi boost and adding 1.5 degrees of retard for each 1 psi. So basically by 5 psi (about .34 bar) all those 8 degrees of advance have been taken out. Some may say that I should have all the advance gone by .2 bar, so maybe I'm living on the edge here. Would love to hear any comments in that regard.

At redline, I simply don't know (I rarely touch 6000). But at 4000 and no boost - tuning in the shop - timing is at about 34 BTDC (the 8 degrees I added at static plus the normal 26 from mechanical distributor advance). When on boost, 8 degrees of that comes off due to the MSD thingy, and probably another 8 degrees comes off due to the vacuum distributor boost retard, leaving about 18 degrees advance at full boost.

My goal was to add static timing and take it all back off at boost, resulting in the same advance @4000 rpms as the book calls for. I would like to try more static (as in up to 12 degrees) but the damn dizzy won't let me...yet!

Performance improvements? I wouldn't say it knocks your socks off, but I will say it gives more grunt and quicker revs from 2000 to 4000 rpms...which is where I wanted it. As a result boost seems to build just a little quicker, which is good for my 7006 turbo.

Mark

[356-930]

Originally Posted by 911st

MSD!

Mark, Chris or anyone that has done an MSD conversion, can you confirm what needs to be done?

Tach drive?

Rotor, eliminate resistor?

Rev-limiter, do we need a "pill" at the MSD box to reestablish the rev limit?


MSD in concept is a great fit with a 930's lower compression ratio pre-boost than almost any other turbo cars and with it's CIS that tends to have a lean surge off idle. These two factors make for potentally a difficult mix to fire. Outside of twin-plugging it seems a very good way to address this. Even if it is not used for any other purpose.

There are three different MSD “systems” that can be employed to improve the 930 engine’s performance:

a. P/N 6462, aka MSD-6BTM, has an integral boost retard controller, providing for a boost controlled retard rate from 1 to 3 deg/psi, maximum 15 deg. Retard onset pressure is fixed (starting at 0 to 1-PSI?).

b. P/N 6420 with P/N 9762, aka MSD 6AL with Boost Control Module. Improves on a. by giving control of boost retard onset pressure from 0 to 5psi.

c. P/N 6420 with P/N 8977, aka MSD 6AL with Multi Function Ignition Controller with Boost Control. Improves on a. and b. by providing control of ignition timing by rpm and boost retard onset and rate (up to 25 degrees retard). Boost retard is "additive" to any timing map. In other words, lets one build a detail/custom timing map.
This digitally controllable system can be used to eliminate the distributor’s vacuum/boost advance/retard and mechanical advance.
Not an engine management system (EMS) but rather a total ignition timing management system (TITMS).
The system uses PC based Pro-Data+ software (free) or for the non-computer racers, there is a hand-held Programmer Monitor ($229).

Factory costs:
a. $415
b. $513
c. $729

Re Rotor - These systems generate/put out a major amount of energy. If the stock ignition rotor has a resistor (buried in the black epoxy bed, center top of rotor), it should be dug out, a 12AWG solid copper wire soldered in its place and re-epoxied. (There are those who have never eliminated the resistor and had no problem and there are those whose ignition failed on the road, on the track when the resistor became toast. Resistor roulette doesn’t seem a smart game to play.)

Re Tach Drive: MSD has a 12 volt square wave signal with a 20% duty cycle. If the stock 930 tachometer cannot accept this signal, add/use MSD P/N tach adaptor ($65).

Re Rev Limiter: MSD-6AL series uses a rev limiter "module," a small 2-pin device that plugs into the bottom of the ignition, set for a specific RPM. Available in 100-rpm increments i.e. 6500, 6700, 6800 etc. NOTE: If the module is removed, falls out, No rev limit. Mounting the MSD-6AL upside down makes sense.
Unknown how Multi Function Controller (P/N 8799) handles rev limit, most probably via software.

Of the three systems, I vote "c." for a CIS-930.

[911st]

Excellent Chris!

And big, big thanks for helping me learn to try to learn about a 930's ignition.

The best.

[beepbeep]

Great thread. I would just like to point out few things:

Originally Posted by 911st

They shaved most the cooling fins off the cylinders to get the motor to run hotter

No, they did it to try to equalize temperatures above and below the cylinder. It's only the top part of the cylinder that doesn't have fins and you might find that even 917/30 had shaven fins on the top of the cylinder.

Originally Posted by 911st

they put small intake ports and funny tops on the pistons to get a better air/fuel mixing and who knows what else.

Small ports are to boost air velocity and thus better cylinder filling at low revs. There are no "funny tops" on 930 pistons, they are completely flat. SC had crowned pistons.

Originally Posted by 911st

They also seem to have made compromises with the ignition by adding a Vacuum-Retard function whose prime function is reported to increase heat in the motor for emissions. This appears to be at the expense of low rpm throttle response.

This is only done on US (and Japan?) cars. ROW didn't have this.

[911st]

Goran,

Good catch. You are correct, I was thinking of the SC pistons.

On the turbo they needed a flat piston for low compression so a piston that would create swirl in support of better mixing was not an option.

As we know, CIS sprays fuel for two compete turns of the crank (720 deg's) for each one time the intake valve is opened (apx 220 deg). That fuel just sits near the top of the intake valve waiting for air to come by and mix with it. Increasing volocity at the intake port help this and better lifts any wet fuel sitting on the sides of the intake port.

It takes more than an increase in volocity at the intake port to benifit low rpm power. It needs to be combined with just the right intake runner length and volunm to create the pressure waves needed to push more air into the cylinders at the targeted rpm.

Thus, my personal belife is this velocity has little to do with filling the cylinder for stronger low rpm operation and was a trade off to support a weakness that comes with CIS to better meet emissions. I know this is not what most have concluded.

I also wonder if we were not running 2.0 911T sized intake ports, if we might actually increase low rpm filling but as a lower volicity. In any case larger ports should reduce restriction during "spool" time (boost onset to full boost).

Interesting about the shaved cylinders. Bruce Anderson says the same thing in his book about the cylinders being shaved. Could there also be other reasoning?

It is interesting that with the later 3.3 & 3.6 C2 Turbo's did not do that, nor the 993TT. Nor was any of the upgrade P&C kits like the 3.4, RUF short skirt 3.4, or 3.5 kits. I guess as this happened at about the same time Porsche went to a 5 blade fan on the 1977 911's in and effort gain more heat for the thermal reactor exhaust (not increase HP with less drag), it seems easy to think it might possibly be emissions concerns were at least part of the reasion.

The 3.0 turbos has both full fins and larger intake ports.

I am not saying I am right, just what I belive.

Thanks for the input.

[JFairman]

I have a set of 1976 3.0 turbo heads for a 95mm bore sitting in a box waiting to have the edge of the combustion chamber beveled one full mm into the squish band all the way round so I can use them on a 3.3 with 97mm bore.

I'm mentioning that because I've measured with calipers and the intake ports are 32mm just like a later 3.3 head.
It's the exhaust ports that are 2mm wider in diameter and that seems to be in the middle part of the exhaust port area a little after the valve guide and before the before the exhaust port flange. The port diameter right at the flange is the same as a 3.3 so the exhaust headers match up the same.
The port sizes for different years of all the air cooled 911's are in the specs in the back of Waynes book.

I've heard the reason for the half finned 930 cylinders was to try and keep the clamping force of the 4 headstuds closer to equal. The exhaust valve side of the head runs alot hotter than the intake side and do to heat transfer the cylinder and the headstuds do too. This causes the headstuds on the bottom or exhaust side to expand more and the clamping force weakens on the bottom side leading to the bottom side of the cylinder heads lifting under high boost.
So, Porsche removed the cooling fins on the top side or intake side of the cylinders to try and equalize the heat in the cylinder and maintain closer to equal expansion rates of the cylinders and headstuds for better sealing and less chance of warping or leaking.

and, I don't know for sure if that is correct or not.

[911st]

Thanks jFairman.

We have learned a lot about head studs sense then and the concept is interesting. I think on at least one of the 911's Porsche put different studs (delivar?) on the bottom and steel on the top which supports the thought.

Could be a combination of reasons. Me, if I were to build a 930 motor I would want full fins.

I wonder if the heat from the thermal reactors was the source of the extra heat that the bottom of the motor had to deal with. If so, they could have sacrificed cooling on the top of the cylinders to get them hoter. Cured a different problem than we were thinking of.

Still an emissions issue but not done because they wanted the motor to run hotter, it was just that the exhaust ran to hot.

Makes at least a little sense. Just a guess.

Fun!

[John at J&S]

The SafeGuard is a great alternative to the MSD boost retard system.

It has an option for a second coil driver, so one system can drive two coils.

The ignition is inductive, with constant energy dwell control, similar to Bosch Motronic ignition.

The unit can trigger the Bosch CDI unit if you prefer to retain it. No other system does this, as the Bosch CDI requires an ac trigger signal.

There are two adjustable rev limits (staging and top end), which can be set with just the key on and a voltmeter. Measure the test point and turn the adjustment knob to get the desired rev limit. For example, 6.25v equals 6250 RPM.

There are four retard modes, including cranking retard, nitrous retard, boost retard, and individual cylinder knock retard. The boost retard includes a start knob, allowing you to enable boost retard as late as 10 psi. Test points allow you to pre-set the Start and Rate knobs.

Individual cylinder knock retard protects the engine while allowing the highest efficiency. The final frame of the video I linked to above shows cylinder #5 is retarded eight degrees. No other cylinders are retarded.

Cylinder #5 is known to run hot on those engines. One tuner that I know uses a heat range three numbers colder than used in the other cylinders.

Remember, when you set timing for "no knock" you are setting it for the worst cylinder, the one that pings the easiest, robbing power from the other cylinders.

[cole930]

John,

Appreciate your participation but I'm not hearing much from you about timing curves. I feel like your selling me something. If that's the case please give me a web site and then give me your input on the timing curves for 930's.


Thanks !!!
Cole

[911st]

We do need to know some bench marks.

What dose a turbo motor with 7/1 compression running .8 or 1 bar should expect to be:

At idle,
On boost,
On the freeway

John makes a good point about variations in heat between cylinders.

We also have various with air flow and fuel delivery with each cylinder.

There is also increased sensitivity at different RPM depending on the cam, and actual AFR we all know varies a lot on a modified CIS 930 accross the RPM range.

Add to that the fact that these cars have little to no compensating features and that is a lot of exposure.

So when someone says they make more power at 12.2/1 AFR or at -27 deg advance they are running closer to the line. If in good balanced tune they may be ok. If not...

[zcoker]

Don't the euro cars run 29 degrees full advance? Only heard of vacuum retard at idle on those motors, single pot dizzy, no boost retard. What's up with that?

[John at J&S]

Good catch, yes I would like to see more of these used on this platform.

This unit is designed to work with an existing timing curve, whether it's generated by a mechanical distributor, or a fully mapped curve generated by an ECU. As is the MSD-6.

Engines with a fully mapped curve can also benefit, as shown in this series of dyno runs taken from a 2.0L Eclipse engine used in a Formula III car. It's naturally aspirated, but the compression ratio is 14.0:1.

The timing curve was mapped on the dyno with a MoTeC using headphones with a knock amplifier. Timing was set to provide a two degree safety margin from knock as indicated by the headphones. The SafeGuard was then installed, and the timing was progressively bumped in two degree increments. No other changes were made, except for the last run, where spec fuel was used.

The engine was run for the '04 season with the SafeGuard with no damage from detonation.

The data is from Ian Whiteside, a calibration engineer at Mercedes/Ilmor in the UK. To be clear, it's from his personal F3 car, and the runs were not done at his place of work.

[911st]

Originally Posted by zcoker

Don't the euro cars run 29 degrees full advance? Only heard of vacuum retard at idle on those motors, single pot dizzy, no boost retard. What's up with that?

Very interesting question!

I have been wondering about that and we need to verfy if that is the case.

However, that would not add up from what I understand so far. From my reading Vac-Advance is to premote fuel economy when not under load and Vac-Ret is to permote heat for emmissions.

Thus, I can see why we have Vac-Ret added to a smog 930.

However, with a turbo we have to have "boost-retard" for safe running under boost.

As the Euro and 3.0T's only have one conection to the can on the dist we can not have both vac-ret & boost-ret.

Thus, somthing is not adding up unless there is two different euro cans. One with two conections and one with a single conection.

Further, the euro has a broder timming range by 2 deg (see below). Is that extra range in the mechincal advance or in the Vac-Retard (if it has such)? I do not know.

I would guess a euro turbo that have a can with one vac/boost line conection would just have boost-retard.

As such, timming at idle (conected) sould start at somthing like -11. It would have mechanical advance to take it up to -29. Under boost timing would be pulled back to about -19 (to run w the better euro fuel).

Dose anyone have the timing igntion specs for a 75-77 3.0 turbo? Or, is there an early euro timming spec?

From another post, the specs for US and Euro:

--------------------------------------------------------------------------------------
USA 1 +/- 2degs at idle (950rpm +/-) Vacuum Hose CONNECTED

Euro 2 +/- 2degs at idle (950rpm +/-) Vacuum Hose CONNECTED

And to adjust timing:

USA 26 +/- 1deg BTDC at 4000rpm Vacuum Hose DISCONNECTED

EURO 29 +/- 1deg BTDC at 4000rpm Vacuum Hose DISCONNECTED
--------------------------------------------------------------------------------------

[RarlyL8]

The early single pot Euro distributors do not have boost retard. I have stated this in many threads and it seems to be a cause for confusion. The single pot is vacuum advance. Once you get on boost you no longer produce vacuum so advance stops. I set them at 26* and lock it down.

[drmatera]

at first glance 26* of advance sounds very aggresive for an engine running 12-14psi of boost and designed to run on 93 octane. But since this engine has only 7:1 compression I can see how it would tolerate that much advance. Now the car comes over to the states with all it's power robbing emissions crap, and Porsche knowing damn well some moron is going to pump in some cheap 87 octane fuel and beat the heck out of the car in Arizona in August, it's easy to see why they would add the second vacuum/pressure reference to the dizzy which pulls some timing under boost. My mechanic told me to yank the vacuum hoses off and lock the dizzy at 25* the day i bought the car because he knew i would only run good fuel.