Best kit for Coil-On-Plug (COP) conversion for 550

Either way... far superior to original

 

Carl, I think Martin (hwyman) was referring to the Bosch OEM coilpacks used in the original ignition system on the 550 (and 456's and 355's). I don't know if Ford used them, but nearly every German car did and probably the Swedish ones as well.

I've always used Denso pencil coils made for the Suzuki Hayabusa motorcycles in my COP kit up until this last setup we built for xlr8 where I used an aftermarket version of the Hayabusa coils as my original source from 10 years ago for the Denso's disappeared and the alternate sources are outrageously expensive.

Jim (xlr8) looks like a really clean installation! Lots more room in the engine bay now that the coilpacks are gone. I look forward to your continued testing - did you notice any change in performance or the exhaust "sound"? Others have reported increased power but I think that was down to a badly misfiring engine or incomplete combustion with the old setup. For my own car, the only change I noticed was a more authoritative exhaust note.

 

If you're interested, here's the part number for the denso plugs on the 550 GTS Image Unavailable, Please Login

if Fchat downsizes too much it's:

129700-3881 JO 388

 

I was up early this morning, before any real traffic so I could push things a bit. Conveniently it was also about shift change for the local policia. Calmly drove the southbound lane about 15 miles to check for police in the northbound lane. Finding none, I turned around and pushed it a bit. Okay, I ran it up to redline in a few gears a few times, pulled very strong all the way, no hesitation or mis-fires. I found I can exceed the highest local speed limit in 2nd gear. I then found one of our "fun" back roads that I like to take with my Z3 coupe. Little traffic, lots of curves. I had a lot of fun and I am impressed at the width of the power band this engine has. I love driving this road in the Z3, the road was made for that car... It is even more fun in the 550. I can say the engine has never run better/stronger since I got the car. I don't know how much of this improvement is due to the engine work that was done to the car, primarily new belts and everything associated with doing a belt job, or if it was due to the COP setup. I suspect it might have been a bit of both, but I have no way of knowing as I put less than 10 miles on the car after the engine work before I dropped in the COP kit. There were strong indications the previous belt job was a "mark and pray" job rather than done properly with a degree wheel. I am very happy with the way the engine is running now. Tropical storm due in tomorrow and when that pulls out, I am heading out of town for just over a week so it will be a while before any more updates.

 

Jim, great to hear the car is running so much better and I'm guessing it's a cumulative effect of all the work you've done rather than any one thing. Others have reported a power increase with the COP system but I suspect they had latent issues in the OEM system. About how many running hours do you think you have on the system now?

 

Hi John,

I'm a relatively new to posting on the forum after having finally acquired my very own 550. My inspiration though - to a large extent - was reading your constant flow of knowledge. You seem to be having such a good time with it, I couldn't resist but join in. The 'Major' major thread in particular, following along with your build, sealed the deal for me.
So I'd like to thank you for always so openly sharing your findings and wisdom. Your willingness to share this says a lot about you.

Anyway, so today, based on the data you published some 12+ years ago, I built my own COP harness. I'm still waiting for some bits like the sealing ring for the top of the bore, and some additional coils, to actually be able to give it a test start.
What surprised me about the coil data you had posted is that the coils actually output more energy when wired in series, even though they each only see 6V. I presume this comes at the cost of dwell time, which was way higher in series.
The one part of the conversion that kind of annoyed me was the 20mm gap between the plugs and the 4420 coil. I had considered using standoffs as you have, but dug in on finding another solution. I ended up finding something which may be of interest to you too.
After scouring around online I found dimensions of the 129700-5020 coil, which are 15mm longer than the -4420 units. They are harder to find, but these ended up being a drop-in solution for the factory spark plugs as-is (with terminal nuts removed of course). They sit slightly more recessed in the plug bore than I'd like, but there's still plenty of clearance for the connector. I'll post pictures once I have the spacer boots.
I probably lack the intellect and equipment to properly characterize these coils as you did, but it seems to me all the 129700 series coils you tested would have worked fine in this application - do you agree?
If you ever need support with wiring/ee/controls engineering in your projects please reach out.

Cheers,

Roger

That's a 5020 on the left, (aftermarket) 4420 on the right
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Excited to see this play out in time for my 456m’s major.

 

Welcome Roger & thanks so much for the kind words! And yes I had a LOT of fun with my 550 and TBH, I think I had more fun working on it and improving it than actually driving it, but I'm a curious EE and by that nature just have to dig into things and try to make them "right" and better. You being a EE also will appreciate what I mean, LOL.

Do be careful using the longer coils because the SS standoffs I use serve a double purpose. Not only do they achieve the proper length for the coil/plug assembly, but they ensure a more robust mechanical connection between the coil & plug. Once the female ferrule/cap is removed from the plugs and the male threads are exposed, I found them to be very soft and the coil had a very weak mechanical connection to them. Since this is the only point where the coil is actually held down, it needs to be more robust.

The series connection of the coils has its advantages & disadvantages. As you pointed out the dwell time is increased by the series connection, however these coils have extremely short dwell requirements because they were designed for the Hayabusa motorcycle and will deliver full spark at well over 10,000 RPM. Parallel connection of the coils just does not work, as some other DIY'ers have discovered because the ECU's igniter chips' current limiting will kick in to protect the circuit. The only improvement to this situation could be a type of breakout box that provides a 2 for 1 output from the ECU. I actually tried this in my workshop and did see a marginal improvement in spark energy, but at that point the system was getting a bit too messy. The HKS TwinPower box also provided an improvement and I pleaded with them to continue producing the original version but they decided not to. I even had a personal relationship with Mr. Hasegawa (the "H" in HKS) but he/they elected to discontinue the product.

Best wishes on your system, as well as other mods that you come up with, & do report back on how you like it!

Edit: @Auraraptor, we're so close to having all the parts now Omar. Please hang in there with us!

 

Very exciting and no rush on this end. Just wrapping up my 575 major and the 456 wont be until next year likely at the earliest...

 

Hi Guys,
Do you know if any kits were made to suit a 1993 348 or can be made up from known compatible parts. I was thinking of converting it over to remove the HT lead system??
Regards
Paul

 

Hello Paul, I'm sure a 348 or 355 kit could be done fairly easily but only if I had one of those fine cars "at hand" to get measurements, etc. However, IIRC (If I Remember Correctly) there was a 355 owner who did his own COP conversion and it worked very well. Try searching either in the Technical subforum or the 348/355 subforum for details of his project.

 

Hopefully you some of these kits still as I'd like to purchase one for a 550 if you do. They are a very clean install as we have two other cars running them in the area right now

 

GM Joseph,

Thanks for the kind remarks; I received your email this morning and will reply to that.

John

 

@Cribbj can you give an update? Are these ready and available for 550's now? I see on the other thread you are still working out some details for the 456 with Nick.. thx and no rush here, I just don't want to miss out..

 

It was a long time coming but my 550 has John's COP set up at last. I had been pestering him with this since purchasing my 550 two years ago at a time when he was sadly busy with annoying domestic issues but it was well worth the wait. Now to be honest there is not a night and day difference with how the engine runs with the stock ignition but the small gains in idle stability and overall smoothness are the cherry on the cake when the main gain is to get rid of the spark plug wires and now NLA stock coil packs.

Thank you very much @Cribbj for this mod that should be worthwhile to any long term owner.

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Looks so sexy!

 

Thanks Thomas, I'm glad we got you squared away at last!

Greg we're cranking them out as fast as we can. The critical path as you might imagine are the harnesses which are hand built for each order and we've had supply chain issues with the OEM Bosch connectors, but have recently found an alternate aftermarket source. We currently have a waiting list of 10 owners and we're trying to improve the deliveries. Would you like to be added to the list?

 

John, could you kindly add me to the 550 delivery list please.

many thanks
Mark

 

Will do Mark & thanks for your interest.

 

I too installed my MSW COP kit earlier this month. The first for the 456GT cars. I can confirm, they work quite well even with the slight differences between the early cars and 550/456M cars.

The depths of John's research over the years to continue perfecting this is fantastic. Its nice this is a reversible upgrade to modernize our cars for the next 25-30 years! Happy to be part if this community

After install, I found the car seems to pull very linear through the whole RPM curve right up to and including the Rev limiter.
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Thanks Nick, I was really excited to bring this project to fruition and you were the perfect 1st 456GT customer. You've helped make this product even better.

Note to all: we are now confident the MSW COP system will work fine on the 456GT, 456M, and the 550.

You need not worry when, not if, you have issues with the OEM ignition system, there IS a proven path to the future!

 

Great to hear John! I wasn't sure where you were in the development process, glad to hear you are building them despite some hiccups.. I am in no rush but certainly expect to get one at some point.. I currently have more pressing things to sort out on the car but am hoping to get it back on the road this year after some down time.

Greg

 

I’m looking forward to my spot on the list and installing come Summer / early Fall when I do my major!

 

And if anyone is wondering... the weight difference between stock and MSW.

Weights for each side. Assumption that sparkplugs weigh the same.

Wireset 2lb 2oz
Coilpack 3lb 6oz
Hardware (screws) 1.4 oz

Total stock 5lb 8.4oz

COP x6 1lb 11.4oz
Sparplug extenders x6 0.60oz
Harness 6oz

Total COP 2lb 2oz

Roughly 3lbs 6oz lighter per bank or over 7lbs (over3kg) for the whole system.

 

A detail that suggests to me that more fuel may be burnt during the combustion process is that I seem to get less pops and crackles in the exhaust when prodding the throttle to rev match, when changing the gears down.

That probably makes sense if we consider that each spark plug can now use the full power of a single coil at the end of the compression stroke rather than share it with the other spark plug being ignited at the end of the exhaust stroke, as each of the 3 coils in the stock coil pack ignites two spark plugs at the same time.

I am no ignition expert by any mean though and probably assuming too much?