I don’t have LS1 coils so I can’t contribute much here. But I was wondering if anyone with a desire to test this duty cycle theory could simply hook up two coils instead of 4 to a 13B (1 for leading plugs and 1 for trailing) or if you really want to stress it one coil for all four plugs. If the failure is due to duty cycle that would show it pretty quickly. Not sure if doing that is feasible though – don’t know what the charge time requirement is for these coils.

 

 

 

----- Original Message -----

From: Mark R Steitle

To: Rotary motors in aircraft

Sent: Wednesday, January 18, 2006 11:27 AM

Subject: [FlyRotary] Re: LS1 Coil Failures

 

Ed,

I was thinking about this a while back and was astounded at how many “firings” per second these coils are producing.  Each rotor fires once/revolution of the eccentric shaft.  Cruising along at 6000rpm, that’s 600 sparks/second/coil.  My 5.3L Chevy truck (with LS1 coils), cruising down the highway at 1500 rpm, each coil fires once every other revolution, or 750 times/minute, or 12.5 times/second.  So, we’re really pushing these coils to the limit.  I find it amazing that they don’t fail more often than this.  By the way, in 126,000 miles, I have yet to have a coil fail on my LS1. 

 

Mark S.

 

---

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Wednesday, January 18, 2006 9:09 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] LS1 Coil Failures

 

Hummm, think I will hold off swapping my stock Mazda Coils for the LS1s sitting on my work bench until we have a better handle on the coil "problem".  Have now flow for 300 + hours and over six years with the stock coils with the only problem being the early failure of the leading module because of a resistor opening in its base. 

 

The wattage of the resistor is apparently too low to carry the load of the ignition continuously running at 6000+ rpm.  Replaced the resistor with a higher wattage one and no more problem.  At least three people have had this resistor fail using the stock coils - it may well be that the auto folks don't design for their coils to be run at high continuous rpms unlike the MSD type ignitions for racing. 

 

I wonder what the automobile circle are experiencing with their  LS1 coils - anyone know?

 

 

Ed A

----- Original Message -----

From: al p wick

To: Rotary motors in aircraft

Sent: Wednesday, January 18, 2006 9:57 AM

Subject: [FlyRotary] Re: Coil & Alt cooling, Buly's input shaft

 

I'm wondering if 180f under hood is really the main cause for coil fail? Auto's shut off hot in desert, black steel hood, must see temps way beyond anything we can throw at them. You can't get those puppies to fail regardless of environment. Perhaps there are one or two other significant causes. I'd be real quick to abandon that manufacturer.

 

-al wick
Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on engine/airframe from Portland, Oregon
Prop construct, Subaru install, Risk assessment, Glass panel design info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html

 

On Tue, 17 Jan 2006 22:39:15 -0500 "Tracy Crook" <lors01@msn.com> writes:

During my preflight tests this morning I found the third failed ignition coil in the last 150 hours so I finally got serious about dropping the temps around my coils and alternator.  

 

I've been concerned about this since the under-cowl temps are as high as 180 deg F (delta T through rads is 70 - 90 deg F).  The attached photo shows the solution (hopefully).  The alternator plenum is made from a Tupperware container pirated from the kitchen with a skirt made from sheet silicone rubber.  A 5/8" ID vinyl hose routes cool air from the oil cooler plenum to it.   ( 3/8" ID hose was tried first, not quite good enough)  This was tried prior to today's scrubbed flight and a temp probe shows that air inlet temps to the alternator are only 3 - 5 degrees above ambient.  Nice.

 

I had recently added a cooling plenum around the coils (also made of tupperware) and fed by a 3/8" ID hose but it was pretty leaky and only dropped temps about 10 - 15 degrees.  After replacing the coil today I built a better fitting plenum and fed it with 5/8" ID hose.  This one is made of space-age cardboard and I'll build a more permanent one from fiberglass if it works OK.  Will test tomorrow if wx allows.

 

Input shaft

 

Buly, got your input shaft today and checked it out.  The thrust bearing rollers & races look a little stressed but the roller cage has been completely trashed.  I do not think the .005" out of flatness on your bellhousing would explain this and the odd wear pattern on the plate.  The marks and discoloration (heat) on the bearing and shaft look as if there is misalignment between the E-shaft  and the gear drive.  When you built the plate & bellhousing adapter for the drive, how did you verify concentricity?  This is much harder to do than verifying the parallelism of the bellhousing and plate but is absolutely vital.  There is no question that the drive would have soon failed if you had continued to run it.   Glad this showed up before flight.

 

Tracy  (Happy to hear that Dave L. is safe!  Good flying. )

 

-al wick
Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on engine/airframe from Portland, Oregon
Prop construct, Subaru install, Risk assessment, Glass panel design info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html