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Lightspeed Plasma III (dual system) IO-540

Tweetr

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Does anyone have pictures of the coil installation for the Plasma III on an IO-540? I'm installing a dual Plasma III in the RV-10 project. I can make up my own coil installations, of course, but I'd rather not reinvent the wheel.

As the coils are considerably larger than those on the Plasma II on my RV-4, installation will have to be a little different. A couple of different methods come to mind.

1. I've seen references to mounting all six coils on the back baffle near the center of the engine: 3 on the front side of the back baffle and 3 on the back side. The front side would power the top plugs and the back side would power the bottom plugs. Advantages: neat installation, relatively cool location. Disadvantages: the weight of the coils would require stiffening that back baffle; lower plug wires would have to be pretty long.

2. Mount the three top plug coils on brackets on the top engine case bolts; mount three bottom plug coils on cushion clamps along the lower engine mount cross tube. Advantage: about the shortest spark plug wires possible. Disadvantage: lower coils are in the hotter engine cooling airflow.

How did you guys solve the competing priorities?
 
Hi Tom,

I bought my RV-10 about 8 months ago and it has a dual Lightspeed Plasma III. I don't know too much about it but I have attached a couple of photos of the system if it will help. The previous owner installed the system and is extremely knowledgeable about it so if you are interested in connecting with him, please PM me and I can reach out to him to see if he would be willing to chat with you.

Cheers.
 

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Does anyone have pictures of the coil installation for the Plasma III on an IO-540? I'm installing a dual Plasma III in the RV-10 project. I can make up my own coil installations, of course, but I'd rather not reinvent the wheel.

As the coils are considerably larger than those on the Plasma II on my RV-4, installation will have to be a little different. A couple of different methods come to mind.

1. I've seen references to mounting all six coils on the back baffle near the center of the engine: 3 on the front side of the back baffle and 3 on the back side. The front side would power the top plugs and the back side would power the bottom plugs. Advantages: neat installation, relatively cool location. Disadvantages: the weight of the coils would require stiffening that back baffle; lower plug wires would have to be pretty long.

2. Mount the three top plug coils on brackets on the top engine case bolts; mount three bottom plug coils on cushion clamps along the lower engine mount cross tube. Advantage: about the shortest spark plug wires possible. Disadvantage: lower coils are in the hotter engine cooling airflow.

How did you guys solve the competing priorities?

Here are a few pictures of my crankcase mounts. I think LSE sells ready made brackets to do this now. You may need to do something a little different, depending on the routing of the fuel lines, etc.
 

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Thanks for the pictures! Those are both beautiful installations. Unfortunately those are the old-style ignition coils. The new coils are larger and have different mounting lugs. I'm leaning toward installing them on brackets on the top of the case for the top plugs. The question will be whether I can fit three of those large coils up there without interfering with the engine hoist lugs and the fuel distribution spider!
 
Plasma III

Here’s a picture of my install.
 

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Hi Tom,

I bought my RV-10 about 8 months ago and it has a dual Lightspeed Plasma III. I don't know too much about it but I have attached a couple of photos of the system if it will help. The previous owner installed the system and is extremely knowledgeable about it so if you are interested in connecting with him, please PM me and I can reach out to him to see if he would be willing to chat with you.

Cheers.

I have an almost identical setup. Flawless operation so far. About 250 hours. Starts like a car and I have a very smooth running engine at very lean of peak opps. At 11K alt, less than 9 gph fuel flow 162 kias true. 3500 alt ROP 25/25 182 kias true
 
I have an almost identical setup. Flawless operation so far. About 250 hours. Starts like a car and I have a very smooth running engine at very lean of peak opps. At 11K alt, less than 9 gph fuel flow 162 kias true. 3500 alt ROP 25/25 182 kias true

Beautiful numbers! That's a very quick RV-10.
Build 'em light! One of the significant advantages of a dual Plasma III system is shedding the significant weight (and known failure point) of two enormous magnetos.
 
I've been busy out in the shop fabricating. Here is my solution for the bottom six plugs. My design contstraints were:
(1) Central location to allow easy swapping of the wires to assign which coil fires which cylinders.
(2) High location out of the hot cooling airflow in the cowl.
(3) Outside the baffling to minimize wire penetrations into the baffling.

As you can see from the pictures, the newer ignition coils are substantially larger than on the older Plasma III system, and with different mounting lugs.

This is what I came up with: a triple coil mount to be attached to the upper engine mount crossbar with cushion clamps. The base plate is .063" 2024-T3 with cutouts for access to the sparkplug leads and coaxial cable inputs. The mounting brackets are riveted 1/8" 6061-T6 angle and bar stock. The coils mount to two long 1/4" bolts through the fore and aft mounting lugs with spacers cut from rigid aluminum tube to space the coils for easy access to the spark plug leads and to allow free cooling airflow around the coils.
And the assembly is painted Lycoming gray to match the engine case (although fire engine red would work too!)
 

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Here it is in assembly on the engine mount. Attaching the mount brackets to the engine mount tube with cushion clamps provides some shock isolation and allows free flow of cooling air around the coils.
The second picture shows nominal spark plug lead and cable routing. It looks like I will need to order longer leads for the bottom plugs to allow neater routing of the wires.
 

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More fabrication. Here are the parts I made to mount the coils for the top plugs. I decided to fabricate a flanged 0.040 stiffener plate for the back baffle to provide a place to install nutplates. I became concerned that riveting brackets to the back baffle would stiffen it to the point that I wouldn't be able to remove and install the back baffles. I decided to install the mount brackets with #8 screws and nutplates. Now the whole assembly can be readily disassembled if it becomes necessary to remove the back baffles. Because the back baffle has a lap joint in the middle, it was also necessary to install an .032 shim on the left half of the stiffener plate.
 

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Here are the coil mount parts installed on the back baffle, attached to the flanged doubler as shown above with #8 screws into nutplates. I decided ultimately on a bracket and strut installation. Design constraints:

1) Inside the baffles to minimize baffle penetrations.
2) Central location to allow swapping wires to assign which coil fires which cylinders.
3) Coils obviously have to fit under the top cowl, which drives the coils aft where the cowl has more height available.
4) Leave the engine hoist lugs usable without extensive disassembly.

That led me to a 2 - 1 arrangement on the back baffle.
 

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Here are the coils installed with nominal cable routing. I will need to order custom spark plug wire lengths to complete the installation. I think this will provide a neat installation with the plug wires running along the outside of the cylinders, aft to the back baffle, and center to the coils. The coaxial coil inputs will penetrate through the normal plug wire location on the back baffle and tie-wrap to the bolts along the aft end of the coils.
 

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And here is a view of all six coils mounted. I like the high, central locations for cooling airflow, and neat cable routing to both sets of coils. With these coils mounted I'm now ready to route the fuel and oil hoses.
 

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I'm nearly done upgrading my RV10 this week. Replaced the impulse coupling Mag with a Lightspeed Plasma III. After over thinking mounting of the coils, I decided on simply mounting them to the engine mounts using MS21919-12 / -14 Adel clamps. I'd have to be more clever/efficient with space if I had twice the number of coils with a dual system. With a simply spacer, I could double up two coils per adel clamp pair though.

Love all the other solutions shared on this thread! We need to supply Klaus with these pictures to add to his website.

Can't wait for engine start tomorrow!
 

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