Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Technical BBS > 1- Porsche Technical Forums > 911 / 930 Turbo & Super Charging Forum

Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Manassas, VA
 
lucittm's Avatar
 
Join Date: Apr 2007
Posts: 1,211
Garage
I was thinking...

There is some debate (naturally) about twin-plugging heads on turbos. Yes, they are mostly flat topped, lower compression piston applications, but with some boost, it seems that attacking the air-fuel mixture from both sides would speed up the flame front. And the best side of the argument is that it probably couldn't hurt.

Anyway, I was wondering how to 12-plug the 965? Has anyone done this?

The spark is triggered from the crank (ok, the flywheel), and the EZ69 digital ignition module does the spark timing and dwell based on engine speed, manifold pressure, temperature, and engine load. Could this signal be split and sent to a second coil (ignition transformer) and Carrera-type dual distributor (for spark distribution only)? Would it fit in the cramped engine bay? Would a single distributor with 12 wires be a better solution?

I am not sure, but I don't think it takes much to trigger the coil. By wiring two coils in parallel, it may be possible to fire two plugs at once.

Taking this idea one step further, another EZ69 could be used with a separate flywheel trigger. But that would require more wiring and design issues.

Thanks,
Mark
__________________
1991 964 Polar Silver Metallic Turbo Coupe
Old 09-02-2008, 02:08 PM
  Pelican Parts Technical Article Directory    Reply With Quote #1 (permalink)
Registered User
 
onboost's Avatar
 
Join Date: Mar 2006
Location: Metro DC
Posts: 5,280
Mark,

Based on your location you need to take a trip down to Tyson's corner and see Charlie Murphy at Intersport, or head over to see Ivan Arzola at IMA in Chantilly/South Riding.

Either can thoroughly/locally answer your question and you'll get to see lots of eye candy!

Paul
__________________
RGruppe #180
So many cars..so little time!!
Old 09-02-2008, 02:15 PM
  Pelican Parts Technical Article Directory    Reply With Quote #2 (permalink)
Manassas, VA
 
lucittm's Avatar
 
Join Date: Apr 2007
Posts: 1,211
Garage
I've been to Intersport, but they only seemed interested in the newer cars there.

Thanks for the tip about IMA, I live down the road from them on I-15 and I surely need to stop by and see them.

Thanks,
Mark
__________________
1991 964 Polar Silver Metallic Turbo Coupe
Old 09-02-2008, 02:48 PM
  Pelican Parts Technical Article Directory    Reply With Quote #3 (permalink)
Registered User
 
930turbo's Avatar
 
Join Date: Jul 2006
Location: Valrico Florida
Posts: 199
I've twin plugged vintage motorcycles. The trick is a dual lead coil. There are plenty of after-market companies that can supply these. Most current 4-cylinder bikes utilize two twin-lead coils to get the job done (two cylinders fire at one - with one waste spark). I used this method initially on my twin-plugged 914 as well, it worked great.
__________________
'77 930 turbo Garretson I/C 1 BAR spring, (2) '82 Triumph Bonneville Royal Wedding Edition
Past rides: '74 914 1.9 liter twin plugged track car, '83 928S, '87 924S, '75 911S w '78 ROW 3.0, '72 911T, '70 911T and various other insignificant domestic examples. Happiness is a grey tailpipe! Turbo lag......it's worth the wait!
Old 09-02-2008, 06:54 PM
  Pelican Parts Technical Article Directory    Reply With Quote #4 (permalink)
Manassas, VA
 
lucittm's Avatar
 
Join Date: Apr 2007
Posts: 1,211
Garage
Come to think of it, my 1975 Honda 750 had two coils for four cylinders...
__________________
1991 964 Polar Silver Metallic Turbo Coupe
Old 09-02-2008, 08:18 PM
  Pelican Parts Technical Article Directory    Reply With Quote #5 (permalink)
Registered User
 
rsrmike's Avatar
 
Join Date: Jan 2008
Location: Birmingham, AL
Posts: 538
First of all, unless your going to get fairly radical and spend serious money tuning to maximize the benefits of twin plug, it may not be worth it in your case. Considering the difficulty involved.

That being said, here is one way you could do it:

Obtain and mount a second ignition control module and coil.

You should be able to split the signal from the crank sensor with a fabricated "Y" harness.

You would need to find a way to mount a separate air temp sensor as I don't think you can "split" that signal. It needs to read the same air temp as the other so the timing won't alter from different temp sensor inputs.

You can then mount another coil and obtain a twinplug distributor but that will open another can of worms.

There may be some difficulting fitting all that as you know. It can be done but would require extensive, expensive fabrication IMO.

You can also split the MAP sensor hose w/ a T for each control unit.

I've never done this but I don't see why it wouldn't work.

A better aproach would be to split the signal from a single contol unit and fire two coils but I don't know how to do that. I think the 965 may be a newer mercedes sourced CD ignition?

Andial makes a splitter that works well for a 964 dizzy in a 3.2 motronic setup.
I have used one of these and they work, I don't think it works with your ignition though.

And finally, you could use an Electromotive XDI2 twin plug setup. You would need to remove your crank pulley and send it to Richard Clewett. He can machine the 60-2 teeth into your pulley that will align with his sensor mount.

But then you are switching to a wasted spark setup that is not a good as your CD ignition in many peoples opinions.

You would also need to leave your existing crank trigger and ignition control unit in place to operate some of the CIS control units, mainly the fuel pump relay trigger, overboost protection, etc. All that relies on the factory rpm signal and they are not the same from electromotive to 965.

In the end, I say spend your money on bolt ons for the engine and CIS tuning. If you run out of stuff to do in that department then you've likely spent enough money to where a nice MOTEC setup w/ coil on plug would look cheap.

Just my opinion, but FWIW, I have a 965 ignition module I would love to sell but I think you would be wasting your time.

Good luck w/ the brainstorming-no harm in thinking...
__________________
Professional Overcomplicator

Last edited by rsrmike; 09-02-2008 at 08:43 PM..
Old 09-02-2008, 08:34 PM
  Pelican Parts Technical Article Directory    Reply With Quote #6 (permalink)
 
Now Available for Ordering:   101 Projects For Your BMW 3 Series 1982-2000  [more info]
Registered User
 
rsrmike's Avatar
 
Join Date: Jan 2008
Location: Birmingham, AL
Posts: 538
BTW I've twinplugged a 3.6T 965 w/ electromotive. It's quite the PITA and was not worth it in my opinion, but I was not in charge back then...

If you go to full EFI you can mount either a 964 dual mass or clubsport flywheel and use your existing crank sensor and bracket to trigger most EFI setups w 60-2 trigger pattern

The sensor will be at the leading edge of the 15th tooth past the gap at TDC #1&4
Electromotive Ignitions and EFI units set up on the 11th tooth in this case, but TEC has provisions in the software to change this.
__________________
Professional Overcomplicator
Old 09-02-2008, 08:42 PM
  Pelican Parts Technical Article Directory    Reply With Quote #7 (permalink)
Manassas, VA
 
lucittm's Avatar
 
Join Date: Apr 2007
Posts: 1,211
Garage
Electromotive is redundant in my mind since I already have the crankshaft trigger and digital ignition unit. It is a great upgrade for a points/condenser system.

There is no way I will go back to the dual mass flywheel.

1. A second EZ69:

I don't know what the output of the EZ69 crank sensor is. If I divide it by using a "Y" harness it will cut the signal in half. That may still be enough to fire the electronics in two of EZ69 modules, or not.

A second air temp sensor is easy since it does not have to be in exactly the same place as the crank sensor does. I would have to try and match them for output at ambient temperature though.

Also, I don't have a MAP sensor but the manifold pressure into the EZ69 is easily split with a "T" connector.

2. Split the output of the existing EZ69:

Two coils would be pretty easy (does anyone want to donate a 965 coil?).
the only connections would be another 12V power, the trigger from the EZ69, and of course, the high tension lead to another distributor cap. I could even wire in a switch so that I could go from 6 to 12 plugs for comparison.

I can talk to Andial and see if their signal splitter would work. I think it splits and amplifies the signal for a zero insertion loss.

3. "930turbo" approach:

Use a motorcycle type coil with two high tension leads to feed two distributors. I think this idea has merit. If I could find a coil with enough juice to replicate the spark of the Porsche coil, it would place the dual coil wiring inside the coil.

4. Marelli-type V-12 distributor:

Can this be modified to fire two plugs at a time? I have seen these conversions and I don't know if they use one coil or two.

More thinking required...

Thanks,
Mark
__________________
1991 964 Polar Silver Metallic Turbo Coupe
Old 09-03-2008, 06:31 AM
  Pelican Parts Technical Article Directory    Reply With Quote #8 (permalink)
Registered User
 
rsrmike's Avatar
 
Join Date: Jan 2008
Location: Birmingham, AL
Posts: 538
I don't blame you on the flywheel.

The crank sensor puts out a minimum 3V generated by the sensor itself.

There is virtually no current draw on the signal as it is only being "read" by the ecu.
splitting it should work fine. For that matter, closing the gap slightly between the sensor & flywheel would raise the voltage slightly, but it shouldn't matter

The electromotive signal works the same way and people used to split them all the time to run twinplug, before their newer systems came out.

I was referring to the airtemp sensor that bolts into the intercooler.

In order to use two, you would need to find a sensor that had identical thermistor values but possibly had pipe threads or some way to mount it in the intercooler other than bolting in. There is no where to put another factory air temp sensor in the same place. You don't want to read ambient air. You want to read the air going into the throttle body so when the intercooler gets hot the timing functions accordingly.

I was referring to the MAP sensor built into the ECU, yes, the vacuum T would be the simplest part of this whole process.

The Andial unit won't work, I'm sorry I brought it up. I realized it simply converts the signal from a 3.2 motronic coil driver in the DME down to where it can trigger two bosch transistor control units. You can't fire 965 coils w/ Bosch transistor control units.

Using a single dual pole coil from a wasted spark system would not provide suffucient power to drive two plugs at once in the same cylinder.

The way wasted spark works is complicated but essentially, that setup is used to fire a single plug in two different cylinders. Both at TDC but only one under compression. Somehow, the majority of the spark energy goes to the cylinder with compression and a mixture to fire the plug, the other cylinder is on the exhaust stroke and under less pressure so it doesn't pull a very strong spark. Wasted spark is notorious for being weaker than Capacitive discharge and you would be cutting that weakness in half again.

I don't see why you couldn't run a gutted JB racing twin plug dizzy and mount another EZ69 unit and coil. Then just split the crank signal and "t" the vacuum line. And figure out the air temp sensor issue.

Then of course there is the whole process of maching the heads and valve covers and making up a set of wires with copper core and factory resistor plug connectors on one end and hopefully 1K ohm connectors on whatever dizzy cap you end up using...

Good luck, sounds like a interesting but fun challenge!

http://www.jbracing.com/eng_porsche.php#ignition
__________________
Professional Overcomplicator

Last edited by rsrmike; 09-03-2008 at 07:46 AM..
Old 09-03-2008, 07:34 AM
  Pelican Parts Technical Article Directory    Reply With Quote #9 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 10:44 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2017 Pelican Parts LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.