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proffighter's Avatar
 
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Of course, I don't want to harm Pelican...

Yes, I have two manuals; the one that you can download at the wellknown UK Homepage and the other (Original German) as Photocopie

I will check the German one tonight and see, if there are some differences

Off topic: Great people here
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Roland

930 Turbo '81 Too many modifications to list
Old 03-31-2010, 07:59 AM
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I am starting to wonder or be willing to accept that the euro 930's may not have any boost retard. This would put them at -29 on boost compared to our US 930's at about -16 to -18 on boost.

A stock euro motor at .8 bar boost and is 7/1 compression for an equivalent compression ratio of about 10.2.

I guess with really good fuel this might be possible as some single N/A race motors on race fuel can do this and more. I think the euro 3.2 is almost at that compression but it dose not have to deal with an elevated intake temp like a turbo. I think it ran about -23 to -25 at WOT.

For comparison I believe the 91-94 C2 turbos run about 21deg of advance on boost +/- 3 deg for intake temperature variations per info Thierry25 posted on the Ultimate 930 Distributor, advance, retard, timing, Turbo lag, MSD, mod, thread. thread. He also noted that FVD sells an adapter to relocate the crank sensor for 6 deg more advance at all points. That could put one at 29 deg on boost so maybe it is possible to run a much more aggressive on boost timing value than the US 930's have been set up for. I am not saying we can run -29 at 1 bar boost but -25 might be possible.

1 bar boost with 7/1 compression is equal to about a 11/1 CR which is close to what the 993's run at. At WOT they run about -16 but with twin plugs for what it is worth. I think I might pull timing back a bit more than to -26 deg that is running a single pot dist on USA fuel.

Buy the way, the C2 turbo pulls up to -40 deg timing on cruse for better fuel economy.

Thus, maybe the single pot dose not have any on boost retard and runs a lot more timing on boost than the two connection pot that has boost retard.

I guess live and learn.

Last edited by 911st; 03-31-2010 at 09:08 AM..
Old 03-31-2010, 09:06 AM
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I am still waiting for the distributor part number, but if this the distributor that I think it is, I have the following comments:
The distributor rotates counter-clockwise.
The pressure capsule mounts the same way as the US version.
Mounted in this way it is not possible to retard the timing with vacuum, only advance it. Vacuum in the capsule will pull the control rod in, which advances the timing.
The capsule under pressure can retard the timing in this configuration.
The vacuum retard curve in the manual is using the term vacuum in the systems sense, as in the vacuum retard system, and not the sense of a negative pressure. I think the chart therefore refers to boost retard at those pressures. The machanism can work in no other way. Porsche would not run a car at 29 BTDC without air temp control, like the C2 has.
This distributor runs on static + centrifugal advance, with boost retard of about 10 to knock it down to 16 BTDC under boost.
Old 03-31-2010, 10:11 AM
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SS,

That makes sense to me and what I have mostly thought. Retard with loss of vac.

Dose looking at how timing retards with Vacuum on the chart Roland posted effect what you are saying. It looks like it retards with increases in Vac, not advance. This makes sense for an SC but having a challenge with it for a turbo.

Still a mystery but my mind is open.
Old 03-31-2010, 11:05 AM
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I just checked my German manual:

29 BTDC at 4000 1/min with vac hose disconnected

Then 0 +/-2 at 1000 1/min with vac connected

Charts are the same as I already posted in English
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930 Turbo '81 Too many modifications to list
Old 03-31-2010, 02:58 PM
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Where is the connection on a 3.3 euro distributor pot? On the outside?

Last edited by 911st; 03-31-2010 at 03:15 PM..
Old 03-31-2010, 03:10 PM
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Ok Speedy, here is the best I can get without pulling it apart and I'm not doing that until the weekend. It's too nice out not to drive it.

It looks like the numbers are 0 237 301 00 and PGFUDB



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Old 03-31-2010, 04:27 PM
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Quote:
Originally Posted by Speedy Squirrel View Post
I am still waiting for the distributor part number, but if this the distributor that I think it is, I have the following comments:
The distributor rotates counter-clockwise.
The pressure capsule mounts the same way as the US version.
Mounted in this way it is not possible to retard the timing with vacuum, only advance it. Vacuum in the capsule will pull the control rod in, which advances the timing.
The capsule under pressure can retard the timing in this configuration.
The vacuum retard curve in the manual is using the term vacuum in the systems sense, as in the vacuum retard system, and not the sense of a negative pressure. I think the chart therefore refers to boost retard at those pressures. The machanism can work in no other way. Porsche would not run a car at 29 BTDC without air temp control, like the C2 has.
This distributor runs on static + centrifugal advance, with boost retard of about 10 to knock it down to 16 BTDC under boost.
Speedy,

check this out - - My mechanic changed out my vacuum pot a couple months back and because i have a '79, told me that my pot [single] wasn't available any more. so, put a two port pot on it and left the vacuum advance open to atmosphere. I connected the vacuum retard to the "E" port on your pictures...

because my dizzie turns couter clockwise, he mounted the pot "upside down" so that it would work under vacuum.

i've attached the pictures of the dizzie and the pot. you can read the number off of the dizzie. my question is: did he do right?



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Last edited by mooney265; 03-31-2010 at 07:22 PM..
Old 03-31-2010, 06:21 PM
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Edited!

The US dual connection "pressure box" (I guess that is what the factory calls it.) that only has Retard via Boost or Vacuum. The inside or connection closest to the dist is vacuum retard and the outside is Boost-Retard. The pressure box only pushes in toward the dist. So pushing in toward the dist seems to be retard.

Quote:
Originally Posted by JFairman View Post
Euro or single connection "pressure box"

From the construction of the pressure box it looks like in can only move away or pull at the dist based on it construction as the internal diaphragm is at the seam. I looks like it is on the other side of the dist thus it looks like it must be a Vacuum Retard pressure box.

Do I have this right or did I mess it up. Dose this look like the case to anyone else?

Quote:
Originally Posted by equality72521 View Post

Last edited by 911st; 03-31-2010 at 09:34 PM..
Old 03-31-2010, 09:27 PM
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OK, unless someone sees that I make a mistake on the above, I am leaning toward the euro only has Vac Retard and not boost retard.

FYI, the Calif timing spec is -31 deg advance I belive. How do we process that info?
Old 03-31-2010, 09:40 PM
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Quote:
Originally Posted by 911st View Post
...I am leaning toward the euro only has Vac Retard and not boost retard.
Bingo

Attention: JFairman's distributor turns clockwise, Turbo's from '78 on anticlockwise
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Old 03-31-2010, 11:48 PM
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Ok guys,
So a late model euro cvs turning dizzy only has vac retard? So on boost it is 29 deg btdc right? So my US 87 930 is 26 deg btdc also. It has a dual pot one for vac retard the other side for vac advance. The dizzy will not respond to boost pressure because the signal on both sided of the pot on boost cancel each other. If euro= 29btdc then US 26btdc makes sense to me. Early 930s run less advance on boost, but they also do not have an intercooler. Wish I could get my hands on the factory bulletins covering the late "87" dizzys.
Eric
Old 04-01-2010, 06:58 AM
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Anybody confused yet?
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'85 930 Factory Special Wishes Flachbau
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Old 04-01-2010, 07:07 AM
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Quote:
Originally Posted by WERK I View Post
Anybody confused yet?
Yes!
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Old 04-01-2010, 07:09 AM
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Roland,

So the pic of the single pressure box is from a 3.0 turbo? Anyone have a 3.3 single box distributor?

Eric,

Interesting point. Now on has ever said that. One small correction it has Vac-Retard (not advance).

Some of us believed the solenoid on the Vac Retard side blocks its signal. One owner put pressure to both sides and did find his distributor did retard.

Retarding on boost is a basic principle to get the most out of a Turbo motor so I lean toward thinking a properly functioning dual connection pot dose retard on boost.
Old 04-01-2010, 07:25 AM
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I see an Electromotive XDI in my future.....
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Mark 1979 930 Euro ***GONE AND DON'T MISS IT AT ALL***

"Worrying about depreciation on your car and keeping mileage down is like not ****ing your girlfriend so her next boyfriend finds her more appealing"
--clutch-monkey

Last edited by equality72521; 04-01-2010 at 07:58 AM..
Old 04-01-2010, 07:32 AM
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Mooney,

I am not an expert but I am a bit concerned about what your guy did with the dual pot on your single pot dist.

A vac-retard pot is going to pull to retard. A dual pot pushes to retard.

If you put a push pot in place of a pull pot, hooked up to the boost retard connection you will get 'boost advance'.

You can work with Boost Retard, Vac-Advance, and or Vac-Retard. Not boost advance. You could get Vac advance by hooking to the other side of the pot. If you do that you would want to time it with the tube hooked up at 4000rpm. Also you need a connection at the TB that dose not show Vac at idle and it basically blocked (ported Vacuum).

You can check this with a hand pump at idle. Advance increases idle speed.

Can I get a ya or a na on this from someone else.

Last edited by 911st; 04-01-2010 at 07:41 AM..
Old 04-01-2010, 07:38 AM
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Mark,

Do some more research before going to Electromotive. Its main advantage is going to twin plug. However, some are saying it's spark is not as hot as a CDI system. On boost that can be important. I do not know a lot about this.
Old 04-01-2010, 07:46 AM
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Quote:
Originally Posted by 911st View Post
Mooney,

I am not an expert but I am a bit concerned about what your guy did with the dual pot on your single pot dist.

A vac-retard pot is going to pull to retard. A dual pot pushes to retard.

If you put a push pot in place of a pull pot, hooked up to the boost retard connection you will get 'boost advance'.

You can work with Boost Retard, Vac-Advance, and or Vac-Retard. Not boost advance. You could get Vac advance by hooking to the other side of the pot. If you do that you would want to time it with the tube hooked up at 4000rpm. Also you need a connection at the TB that dose not show Vac at idle and it basically blocked (ported Vacuum).

You can check this with a hand pump at idle. Advance increases idle speed.

Can I get a ya or a na on this from someone else.
You are correct that the only way to tell what is happening with his exact unit the way it is hooked up to the throttle body is to temporarily disconnect the vacuum hose and install a hand vacuum pump and watch what happens to the idle timing as vacuum is applied. Document the maximum timing change at 10-12psi vacuum since this will be about the max your engine will pull.
Then apply a pressure of 14.5 psi to the same line and see what happens. This will simulate boost of 1bar.
This is the only way to know for sure what the pot contributes to timing change.
Then run the idle speed up to 4000rpm with the lines disconnected to see what portion the mach advance contributes..
Keep us posted on what you find out.
Irregardles of his results......what is consensus on a safe max timing advance at 1 bar boost? I am reading 18-20 degrees from the various posts on the forum past and present.
Am I right?
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Last edited by fredmeister; 04-01-2010 at 07:59 AM..
Old 04-01-2010, 07:55 AM
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Quote:
Originally Posted by 911st View Post
Mark,

Do some more research before going to Electromotive. Its main advantage is going to twin plug. However, some are saying it's spark is not as hot as a CDI system. On boost that can be important. I do not know a lot about this.
Here we go......... CDI vs. Inductive. Plenty of track cars running Inductive (single or twin) with no issues. Long duration spark (inductive) vs. short duration spark (CDI). The debate will go on forever.

Those with distributor style ignitions should have the distributors rebuilt and recurved to match your engine's needs. There are still a few tuners out there that have the Sun-Machines style distributor machines that can fine tune your distributor. These engines are getting long on the tooth with advance/retard actuators/platform getting gummed up, advance springs aging, etc. You may be leaving some performance on the table or worse, potential damage.
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Old 04-01-2010, 08:05 AM
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