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Porsche Crest 930 EFI Spark Plugs

I am looking for input on spark plug choice for my 930 EFI conversion. I know that the W3DPO plugs are "cold" and the factory did this for a reason. But, are they necessary for electronic fuel injection?

I will be running a 3.2 Motronic ECU with twin plugs being fired from a JB Racing distributor. The fuel pressure regulator is a Protomotive rising rate unit. My injectors are Bosch 944T (as designed by Todd Knighton of Protomotive).

I am looking for an educated, first hand opinion here. Please, no shoot from the hip suggestions.

Thank you,
Rich
Old 03-02-2010, 11:25 AM
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My car had W3DPO plugs in it when I bought it and they worked fine. I had no problems of any kind with them and may use them again someday.

I wanted to try new plugs so I put in Bosch W4CS which are around half the price of the DPO's.
They also work fine so I think they are both good choices.
Old 03-02-2010, 12:49 PM
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Rich,

Why would it matter the plugs you use, whether EFI or stock CIS? Both systems are injecting controlled rates of fuel. EFI just gives you more accurate control under a broad range of conditons. If you've had good experiences with plugs prior to your EFI conversion, then stay with them...no logical reason to change in my mind.

I used to use the W4CS...they were fine but maybe a touch cold for my liking. I have since switched to NGK race plugs R5671A7 (thought they were a little hot) and now am trying R5671A8 heat range. I like them just fine.
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Old 03-02-2010, 01:43 PM
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Mark,

My reason for asking this question is based on the diffrence between the amount of fuel and the relationship to spark plug heat levels. I noticed that all of the Motronic based turbo charged Porsches (993 for example) use a diffrent heat range than the CIS turbo cars. I thought there might be a relationship between the two systems (CIS and EFI) and heat range levels.
Old 03-02-2010, 02:56 PM
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What I understand is not whether its CIS or EFI it is the type of ignition you have on the plugs CDI vs EDIS vs Electromotive vs MSD multispark. So could someone enlighten me on that aspect I have EDIS which I would like to know the right plug for that? Sorry if this is a hijack I don't think it is.
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Old 03-02-2010, 04:53 PM
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IMO, if you are looking to really tune your motor, you are going to have to experiment a bit. I tried about 4 different plugs until I ended up with NGK BKR9EIX. The environment these plugs have to perform in is incredible and when you add boost and timing, you can run into real problems fast. Too hot of a plug and you risk detonation - too cold and you loose power. If you have CDI, you will benefit by using a rare earth metal like Iridium - very hot spark (not plug, the spark). These are large (and old) combustion chambers with two big valves, high pressure and high turbulence that need a hot powerful spark for peak performance.

Also, you'll need to experiment with gaps. I set mine to .032, starting at .025.

Good luck.
Old 03-02-2010, 07:55 PM
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What are some plugs being used with EDIS?
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76 Blazer also restored by me
Old 03-03-2010, 03:44 AM
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Don E,

I took a look at the NGK web site (excellent!!) and reviewed the specifications on your plugs. It is very interesting the the NGK heat range numbering systems rates a "9" as cold. This would correspond with the Bosch numbering system that is just the opposite, with "3" being a cold plug.

Your choice seems to reaffirm the factory rating.

Thank you for the incite.
Old 03-03-2010, 09:56 AM
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Quote:
Originally Posted by gsmith660 View Post
What are some plugs being used with EDIS?
EDIS can support upwards of 0.06" gap in NA applications. I would be curious to see what gaps can be achieved under various levels of boost.
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Old 03-03-2010, 10:42 AM
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Quote:
Originally Posted by DonE View Post
IMO, if you are looking to really tune your motor, you are going to have to experiment a bit. I tried about 4 different plugs until I ended up with NGK BKR9EIX. The environment these plugs have to perform in is incredible and when you add boost and timing, you can run into real problems fast. Too hot of a plug and you risk detonation - too cold and you loose power. If you have CDI, you will benefit by using a rare earth metal like Iridium - very hot spark (not plug, the spark). These are large (and old) combustion chambers with two big valves, high pressure and high turbulence that need a hot powerful spark for peak performance.

Also, you'll need to experiment with gaps. I set mine to .032, starting at .025.

Good luck.
Don, you are twin plugged plus you obviously did a lot of test and observation.
Did you notice any patterns top plug to bottom plug or cylinder to cylinder?
Could you or did you disable to bottom row?
Old 03-03-2010, 01:39 PM
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Quote:
Originally Posted by DonE View Post
IMO, if you are looking to really tune your motor, you are going to have to experiment a bit. I tried about 4 different plugs until I ended up with NGK BKR9EIX. The environment these plugs have to perform in is incredible and when you add boost and timing, you can run into real problems fast. Too hot of a plug and you risk detonation - too cold and you loose power. If you have CDI, you will benefit by using a rare earth metal like Iridium - very hot spark (not plug, the spark). These are large (and old) combustion chambers with two big valves, high pressure and high turbulence that need a hot powerful spark for peak performance.

Also, you'll need to experiment with gaps. I set mine to .032, starting at .025.

Good luck.
Since what I have read says EDIS is wasted spark and somewhat weak would I need a hotter spark such as what you say for CDI?
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" Porsche there is no substitute" I always liked that saying. Air cooled is the only way to go!
76 911 C.R.A.P. Gruppe #2 BIG time TURBO C.R.A.P. Bitz EFI/EDIS Now MegaSquirt 3
76 Blazer also restored by me
Old 03-03-2010, 04:51 PM
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Wo ist die Rennstrecke?
 
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Quote:
Originally Posted by copbait73 View Post
Don, you are twin plugged plus you obviously did a lot of test and observation.
Did you notice any patterns top plug to bottom plug or cylinder to cylinder?
Could you or did you disable to bottom row?
I didn't notice any difference cylinder to cylinder or top to bottom. Yes, I can disable top or bottom, but I didn't.

When I changed from wasted spark to CDI, I immediately noticed a smoother idle and better throttle response - it was amazing to me because the change was so noticable.

When I got down to tuning, I left the fuel alone and started playing with the gaps first (major pain in the ass with 12 plugs). When the gaps were too much, the engine would stumble and miss, especially at higher rpm. That's when I found the best gap was .032.

Then I tuned the timing - I didn't need as much mid to top, but low end was improved big time (I think it's equal to any 3.2L NA car now). By backing off the timing (a couple degrees), adding some more fuel (because it's now being burned completely), I could take the boost up to 1 bar safely (I have 8.0:1 CR).

Once this was dialed in, I started tweaking the fuel tables throughout to achieve a nice tan color on the plugs, proving I had the right AFR for the majority of my driving. In fact, I use the AFR meter to confirm what my plugs are telling me, not visa versa. To be clear, over 120 kpa or .2 bar, I start adding fuel fast and start moving timing back to 18 degrees at 6500 rpm at 1 bar.

Another indication my CDI and plug combination was working well, was when I floored it and there was no more puffs of black smoke (like when I had wasted spark using the same fuel table values). I found I could add more fuel which gave me more power.

Sorry to be so long winded on this, but I think the ignition system is sometimes overlooked in favor of turbos or headers. All components have to work together, but not much beats getting the fire lit quickly and completely while jamming as much fuel and air into the cylinders.

By the way, Neil Harvey at Performance Developments recommended the NGK plugs after I spent a couple hundred bucks experimenting on my own. He sold me the M&W CDI. Listen to the experts.
Old 03-03-2010, 07:27 PM
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Quote:
Originally Posted by DonE View Post
I didn't notice any difference cylinder to cylinder or top to bottom. Yes, I can disable top or bottom, but I didn't.

When I changed from wasted spark to CDI, I immediately noticed a smoother idle and better throttle response - it was amazing to me because the change was so noticable.

When I got down to tuning, I left the fuel alone and started playing with the gaps first (major pain in the ass with 12 plugs). When the gaps were too much, the engine would stumble and miss, especially at higher rpm. That's when I found the best gap was .032.

Then I tuned the timing - I didn't need as much mid to top, but low end was improved big time (I think it's equal to any 3.2L NA car now). By backing off the timing (a couple degrees), adding some more fuel (because it's now being burned completely), I could take the boost up to 1 bar safely (I have 8.0:1 CR).

Once this was dialed in, I started tweaking the fuel tables throughout to achieve a nice tan color on the plugs, proving I had the right AFR for the majority of my driving. In fact, I use the AFR meter to confirm what my plugs are telling me, not visa versa. To be clear, over 120 kpa or .2 bar, I start adding fuel fast and start moving timing back to 18 degrees at 6500 rpm at 1 bar.

Another indication my CDI and plug combination was working well, was when I floored it and there was no more puffs of black smoke (like when I had wasted spark using the same fuel table values). I found I could add more fuel which gave me more power.

Sorry to be so long winded on this, but I think the ignition system is sometimes overlooked in favor of turbos or headers. All components have to work together, but not much beats getting the fire lit quickly and completely while jamming as much fuel and air into the cylinders.

By the way, Neil Harvey at Performance Developments recommended the NGK plugs after I spent a couple hundred bucks experimenting on my own. He sold me the M&W CDI. Listen to the experts.
Don, lots of good info there. Thanks for sharing. Although I don't have EFI and have no experience with wasted spark ignitions, I don't use CDI and instead use MSD's ignition and gap my plugs at a tight .040. It doesn't miss a lick all the way to the top with NGK R5671A8 plugs and I'm running about 16 degrees timing advance at 1.0 bar boost....advanced 12* at idle for low/mid grunt and shaved off as boost builds. Not near as sophisticated as EFI I admit, but the net results are good. Outside of recurving the distributor and going with a digital WUR, it's about as good as we can get with add-ons.

Oops...sorry, off the plug topic! Dual plugs and EFI; well, that's a pipe dream for me. Did I say I like the NGK's?
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Old 03-03-2010, 07:55 PM
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Quote:
Originally Posted by DonE View Post
I didn't notice any difference cylinder to cylinder or top to bottom. Yes, I can disable top or bottom, but I didn't.

When I changed from wasted spark to CDI, I immediately noticed a smoother idle and better throttle response - it was amazing to me because the change was so noticable.

When I got down to tuning, I left the fuel alone and started playing with the gaps first (major pain in the ass with 12 plugs). When the gaps were too much, the engine would stumble and miss, especially at higher rpm. That's when I found the best gap was .032.

Then I tuned the timing - I didn't need as much mid to top, but low end was improved big time (I think it's equal to any 3.2L NA car now). By backing off the timing (a couple degrees), adding some more fuel (because it's now being burned completely), I could take the boost up to 1 bar safely (I have 8.0:1 CR).

Once this was dialed in, I started tweaking the fuel tables throughout to achieve a nice tan color on the plugs, proving I had the right AFR for the majority of my driving. In fact, I use the AFR meter to confirm what my plugs are telling me, not visa versa. To be clear, over 120 kpa or .2 bar, I start adding fuel fast and start moving timing back to 18 degrees at 6500 rpm at 1 bar.

Another indication my CDI and plug combination was working well, was when I floored it and there was no more puffs of black smoke (like when I had wasted spark using the same fuel table values). I found I could add more fuel which gave me more power.

Sorry to be so long winded on this, but I think the ignition system is sometimes overlooked in favor of turbos or headers. All components have to work together, but not much beats getting the fire lit quickly and completely while jamming as much fuel and air into the cylinders.

By the way, Neil Harvey at Performance Developments recommended the NGK plugs after I spent a couple hundred bucks experimenting on my own. He sold me the M&W CDI. Listen to the experts.
Go ahead and be long winded. This is all great stuff, invaluable information.
Thanks
Old 03-03-2010, 08:01 PM
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Quote:
Originally Posted by mark houghton View Post
Don, lots of good info there. Thanks for sharing. Although I don't have EFI and have no experience with wasted spark ignitions, I don't use CDI and instead use MSD's ignition and gap my plugs at a tight .040. It doesn't miss a lick all the way to the top with NGK R5671A8 plugs and I'm running about 16 degrees timing advance at 1.0 bar boost....advanced 12* at idle for low/mid grunt and shaved off as boost builds. Not near as sophisticated as EFI I admit, but the net results are good. Outside of recurving the distributor and going with a digital WUR, it's about as good as we can get with add-ons.

Oops...sorry, off the plug topic! Dual plugs and EFI; well, that's a pipe dream for me. Did I say I like the NGK's?
Depending on the model, I would bet your MSD is CDI. When you mention a gap of .040, it must be.

A well tuned CIS motor rocks....
Old 03-03-2010, 08:30 PM
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[QUOTE=DonE;5216721]Depending on the model, I would bet your MSD is CDI. When you mention a gap of .040, it must be.QUOTE]

I was referring to not using the stock CID ignition "box". MSD6AL is what I've always used, and I guess I've presumed that it uses something other than a capacitive discharge method of firing. All I know for sure is that it has enough oomph to sustain a spark across a larger gap. The folks at MSD - if I recall - even recommend a larger gap than I'm running (well, for NA cars anyway...they don't specifically address forced induction).
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Old 03-04-2010, 08:25 AM
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Sorry for breaking up the thread...

Mark,- going to 8-colder/ range from 7, did you feel more top end..Your thoughts..
I went to W24-densos' .32gap... Immed., noticed more performance/boost-top end.
Thnxs
Walt

Last edited by wjfk32; 03-04-2010 at 09:52 AM..
Old 03-04-2010, 09:47 AM
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Sorry for breaking up the thread...

Mark,- going to 8-colder/ range from 7, did you feel more top end..Your thoughts..
I went to W24-densos' .32gap... Immed., noticed more performance/boost-top end.
Thnxs
Walt
No huge noticeable change, other than what you would expect puting in brand new plugs. My old 7's had maybe 2000 miles on them and didn't look too far off on the heat range (what I really need is about a 7 1/2 heat rating), but opted to go on the colder side since I'm also running significantly more ignition timing.
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Old 03-04-2010, 10:53 AM
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