F355 coil-on-plug conversion

Do your 5 " coils snap onto the plug tops (either with, or without the screw-on plug nose) and fit snugly in the plug holes? If so, would it be unthinkable to just leave the plug covers off? If worried about water ingress perhaps an O-ring or grommet could be sourced to fit snugly between the coil body and the plug bore.

 

Today was the day for fire up and testing, but a stepped-on coil connector with a steel-toe boot derailed those plans. lol

The wiring harness has been the most time-consuming part of the project. Lots of wash, rinse, repeat, and repeat again. I wanted the wiring to look as factory as possible.

The main harness, supplied with the MSD, was shortened on driver side (5-8), while the passenger side (1-4) was lengthened. MSD manual suggests that wire gauge increase from 18ga. to 16ga, for output and input wires, and from 14ga. to 12ga. for power and ground. I opted for GXL wire which is a thin wall, single-conductor automotive primary wire. It also features cross-linked polyethylene (XLPE) insulation and has a voltage rating of 50V. Once the proper lengths were obtained, I used a premium heat shrink and attached the appropriate connectors. The secondary harness was the most tricky. Fortunately, I always erred on the wires being too long vs too short. They exit the front of the cam cover using the original rubber grommet, route thru the 4 gang spark plug clip, and terminate adjacent to the junior timer connector from the ECU.

Key to securing the terminals pins was buying the proper crimper. I bought the iWiss 1424-B shown here:

Image Unavailable, Please Login

Will need to exercise some patience and wait for new connector.

 

Finito

Thanks to Ian/Qavion for providing this wiring diagram. Made everything a snap. He integrated the colors from MSD and Ferrari.

Image Unavailable, Please Login

The earlier hand drawn diagram has channels 1 and 2 reversed. (DO NOT USE) This is the 6th version that Ian provided, and it is correct.

Most noticeable difference is the deeper tone of the exhaust? Baffled by this one? Why a change of tone?

Weather is going to delay a proper shakedown, but starts, idles, and revs nicely.

MSD states a wider spark plug gap is needed. Original spec is 0.023-0.027. Now set to 0.040. How will I know the proper gap?

Final decision yet to be made on whether to make spacers for the spark covers or use stand offs to provide cooling.

 

I have seen CoP coils that have a mounting hole, or holes, on their "heads" to secure the coil and some that do not have mounting holes at all. Does this relate to the actual connection to the spark plug? i.e. if the coil nose snaps onto the plug, like traditional plug wires, no bolting is necessary whereas if the actual electrical connection is simply accomplished with a "spring" compressing against the top of the plug with no real mechanical connection, mounting bolts are required. Anyone?

 

Jeff, the praise is ALL on your side of the table. This mod would probably not exist without your pioneering spirit and willingness to jump in the pool. Thanks!

 

For this application, the coil is secured to the threaded portion of the plug, and feels quite snug. Other cars may require a mounting bolt/screw.
Looks nice with covers off, but like Jeff, I want to retain an original look with the Ferrari lettering on the covers.

 

As anyone commented on this diagram where, to the best of my knowledge, it shows firing the incorrect cylinder pairs. The pairs should be 1&4, 2&3, 5&8, 6&7. No?⁹

 

This is 100% correct. This diagram from post 353 is all you need to correctly wire coils:

 

Thank you, I agree with that diagram.
I am currently taking an intermediate step and going with "Near Plug Coils " with 8 Corvette IGN 1A "Super " coils. I don't have a production 355 but a custom vehicle with a 355 drive train and aftermarket ECU. I hope to progress to COP at some point when I'm smarter.

 

Just an update - as much as I want to go the whole 9 yards and convert to CoP I decided to work with what I have (8ea IGN-1A coils used on GM LS motors. These 8 coils were mounted across the back of the engine (355) and include "ignitors" . Regular 7mm plug wires ran forward to each cylinder as seen in previous photos. I decided, since my components work, that I would use what I have but relocate the coils to a "Near Plug Coil" arrangement (See photo). I am not done yet, and only working one bank at a time, but will probably terminate new 8.5mm cables in a manner where I still keep the Ferrari cover plate (although it will have 4 holes through it

 

Don't know what happened to my post but I continue. The plate will have a plug wire hole over each plug. The actual wire length will be cut to approximately 6 inches and the coil signal wires will also be shortened significantly all of which I hope will provide a stronger spar

 

Image Unavailable, Please Login

 

Image Unavailable, Please Login

I functionally finished my "Coil near Plug" conversion (one bank anyway) and fired it up. Everything seems OK but I've got to tidy up some loose ends before I take it for a drive.

 

Hold the phone.... is that a custom fuel rail? Where did you get the fitting circled here that inserts into the rail where the regulator would normally go allowing AN line to be fitted?

Amazing build by the way!!! LOVE IT!
Image Unavailable, Please Login

 

I always assumed that the fuel rail was stock as there wouldn't have been any reason that I can think of to change it. The car was started in the UK about 10 years ago so I don't know much about it's origins except that the engine management system needed to be changed because of airbox interference issues. PROEFI out of Arizona was chosen. I will try to include a photo of the fitting on the other cylinder bank. This device is at at the fuel return and I assume is a pressure regulator. If you have more information on it and how it works I would be glad to hear about it. You can see that the back side seems to have a vacuum type connection. Hope the photo comes through . Image Unavailable, Please Login Image Unavailable, Please Login

 

The pressure regulator mounting looks fairly standard

Here's a different angle:

https://www.ferrarichat.com/forum/posts/148491953/

That part is standard. All normal. The vacuum lines go to the throttle bodies.

Image Unavailable, Please Login

 

Sorry i got ahead of myself as it was hard to tell in the original picture. That is the standard regulator.. just it has AN fittings adapted to it for more readily available hose. From a distance it looked like a custom fitting to replace the regulator.

This is still a great alternative to replace oem hoses and a way to ensure compatibility with modern fuels while not costing a fortune. However it doesn't solve the unobtanium FPR issue.

 

Did you see the adjustable version available from spaturbousa.com?

Image Unavailable, Please Login

They just told me today that they still sell them, but they are currently out of stock.

https://spaturbousa.com/products/ferrari-355-456-550-512-in-rail-adjustable-fuel-pressure-regulator-e85-safe?_pos=1&_sid=90fc87b9f&_ss=r

 

Yeah.. just that they are out of stock and the way things are these days that could mean anything regarding getting more. Could be tomorrow could be a year.

The one thing with that approach is you'll need some creativity to set their pressure setting. I dont think there is a place for a guage.

 

Getting back to the CoP theme, I just went for a drive and carried it to 6k with no issues. This justifies doing the other bank.

 

I am done with both sides now and have driven the car with all working well. I have taken the opportunity, while the back is off, to make several more changes. I added fresh air ducting and moved the coolant surge tank forward to where the coils used to be. Image Unavailable, Please Login

 

It seems to me that wasted spark (firing two cylinders at the same time) would not be necessary if you have a cam position sensor since the cam rotates at 1/2 the speed of the crank and can determine which of the two cylinders is on compression. While the crank sensor tells it when to fire the cam position sensor can tell the ecu which cylinder to fire.
The benefits of not firing a wasted spark would be greater coil recharge interval, spark plug life and ?

 

I like the idea, but I am not sure you would see any noticeable benefit.

 

I agree, it's just how I was raised that makes me want things the best they can be even if it makes little difference I feel good about it.
On a similar note, I won't run my Ferrari up near max rpm. That hurts me, I can up-shift.
At "only" 6000 rpm the valves are actuated 50 times a second! I can't even visualize that or how the intake charge has a chance to move.