Author Topic: Electronic Ignition Design  (Read 60676 times)

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Offline FlatheadPuller

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Re: Electronic Ignition Design
« Reply #30 on: December 20, 2010, 03:53:30 pm »
Bill the ford module and the gm hei module will fail. I have used the chrysler with a single cannister style coil and a 2 post gm v-6 coil to fire an opposed twin briggs. As long as you have an internally resisited 12vlt coil and a ballast resistor to down the voltage to the chrysler box to 9vlts your good to go. The proxy switch is an eaton fuller out put shaft sensor. Its a little big though but works great. I can get you a part number if you like but it will have to wait till tommorrow when I get back to work. I work on class 8 trucks for a living. That is were I found the proxy switch. I have never had a problem with the chrysler box. The other two I have never gotten to work or last more importantly. My cost on the proxy switch is in $40-50.
Dennis Bazzett
Grandville Michigan

Offline Rocket Ron

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Re: Electronic Ignition Design
« Reply #31 on: December 20, 2010, 04:08:54 pm »
I have a LOW COST digital ignition available for lawnmower racing use. It is in retard mode to aid your firebreather in starting, and as the RPM's increase, the ignition automaticly advances. The bracket shown in the photo is a rough prototype, the finised product will of course be made of billet aluminum.
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Offline Goeytex

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Re: Electronic Ignition Design
« Reply #32 on: December 20, 2010, 06:13:04 pm »
Like I said,  the GM HEI and Duraspark units fail on mower engines because ......

1.  Too much dwell  ( inherent in single cylinder crank trigger setup)
     a. Only 4ms of dwell is needed. With a single crank trigger in a Briggs
         there will be 4 ms at 10,000 RPM and  well over 15 ms at 3000 RPM
         This is way more than 180 degrees of dwell.  The coil and box gets hot   
 
2.  Wrong Coil / Ballast

3.  No heat sink  (GM HEI) 
    GM HEI  MUST have a heat sink and white heat sink compound between the box and
    the heat sink plate.

There is nothing inherently wrong or weak with the GM or Ford modules,  they are simply
being used incorrectly.  Fix the dwell problem and ALL of these will work correctly.

I have a GM unit working now on an OHV Single and it barely gets warm.  Why ?  I have the dwell
controlled with a  simple circuit that limits dwell to 4ms.

Bill
Bill Roth
12405 Blossomwood Dr
Austin, TX.
Email: bill.roth@comtrotech.com

Offline Goeytex

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Re: Electronic Ignition Design
« Reply #33 on: December 21, 2010, 07:45:42 am »
A real cool Ignition can be done with a "coil with ignitor".  This is a coil with a built in 15 =20 amp IGBT driver.  Used on Delphi ignitions with 1 coil per cylinder, like 2006 GM trucks. These are very high energy coils with a spark duration of over 2ms !

This unit triggers with a logic signal.


What you get is a high output coil AND the equivalent of an updated Chrysler module built into one small package.  Price = $35 - $70 depending upon manufacturer.   Accel makes a racing version for about $60.

To make this work on a mower engine you need a trigger and a control box (ECU) that controls dwell and timing.  The trigger can be a hall sensor or magnetic pickup  and the "box" is little more than a $5.00 microprocessor programmed to control dwell and timing. A rev limiter could be easily incorporated into the programming code.    

Do not use this without dwell control !
Bill Roth
12405 Blossomwood Dr
Austin, TX.
Email: bill.roth@comtrotech.com

Offline birdman_express

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Re: Electronic Ignition Design
« Reply #34 on: December 21, 2010, 08:44:19 am »
One thing to think about is the power drain on a battery that is not being recharged
as the ignition is taking power away. The hotter these things are, are they going to
be hungrier and sap the battery dry?
Marc Baker

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Offline Goeytex

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Re: Electronic Ignition Design
« Reply #35 on: December 21, 2010, 10:17:06 am »
One thing to think about is the power drain on a battery that is not being recharged
as the ignition is taking power away. The hotter these things are, are they going to
be hungrier and sap the battery dry?

The battery absolutely needs to be well maintained and charged. With the dwell properly set
average current draw will vary from 2 - 6 amps depending upon RPM.

So for a 30 amp hour Garden Tractor Battery battery, a fully charged battery would
last about 6 hours with the engine running  at 8000 RPM.  This assumes proper dwell
control.

This type of ignition is not for those too busy or too lazy to charge a battery between races or
to keep a spare fully charged battery on hand.

Bill    
Bill Roth
12405 Blossomwood Dr
Austin, TX.
Email: bill.roth@comtrotech.com

Offline birdman_express

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Re: Electronic Ignition Design
« Reply #36 on: December 21, 2010, 10:20:57 am »
The battery absolutely needs to be well maintained and charged. With the dwell properly set
average current draw will vary from 2 - 6 amps depending upon RPM.

So for a 30 amp hour Garden Tractor Battery battery a fully charged the battery would
last about 6 hours with the engine running  at 8000 RPM.  This assumes proper dwell
control.

This type of ignition is not for those too busy or too lazy to charge a battery between races or
to keep a spare fully charged battery on hand.

Bill     

Good info, thanks.
Marc Baker

ARC Dealer

Marc from ARC.... "Billet Billet"

Powered by a Full Bug E.C. 20HP Vanguard!!!!

Offline Goeytex

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Re: Electronic Ignition Design
« Reply #37 on: December 21, 2010, 10:32:41 am »
Simple Microprocessor Ignition Control Unit . 

This is not an Ignition Module coil driver !   It it an ECM that triggers an LS1 coil.  It can also trigger a Chrysler,
GM HEI, or DuraSpark Ignition Module while maintaining correct dwell control.   This microprocessor
is a Picaxe 14M running at 32 mhz.     Now I gotta go build some rev limiters ..... 
Bill Roth
12405 Blossomwood Dr
Austin, TX.
Email: bill.roth@comtrotech.com

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Re: Electronic Ignition Design
« Reply #38 on: December 21, 2010, 04:29:09 pm »
So when is the GoeyTex Rev Limiting, ECM tach going to be available?????
Bert stole my cookies!!
 I think he used them to bribe Ed into something naughty?

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Offline Goeytex

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Re: Electronic Ignition Design
« Reply #39 on: December 21, 2010, 05:54:17 pm »
So when is the GoeyTex Rev Limiting, ECM tach going to be available?????

LOL,

I underestimated the time required on the Rev Limiter, so I am not gonna do that again.
This should be quicker though, because I have good suppliers already lined up.

I will make a couple for myself and then put couple out there with some National level racers
to try out on the track.  If there is enough interest  I "MAY" make some for sale.

My best guess is somewhere around the end of January.

Bill
Bill Roth
12405 Blossomwood Dr
Austin, TX.
Email: bill.roth@comtrotech.com

Offline Rooster

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Re: Electronic Ignition Design
« Reply #40 on: December 21, 2010, 06:08:16 pm »
So here's the plan.

  When the microprocessor sees the engine running for 5 seconds, the delay is removed and the normal timing kicks in.  This could also be done by detecting RPMs over 1000 or so.  After the plug fires the capacitor is recharged  and the cycle repeats for each engine revolution.

That 5 seconds is a long time on a race track. assuming USLMRA LeMans starts, that could put you coming out of turn 2 with the retarded timing, and that is a critical corner. Could this time be knocked down any?
Bert stole my cookies!!
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Offline George Herrin

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Re: Electronic Ignition Design
« Reply #41 on: December 21, 2010, 07:16:09 pm »
The RPM would probably be the best setup to cover those doing lemans.
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Offline Goeytex

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Re: Electronic Ignition Design
« Reply #42 on: December 21, 2010, 07:29:40 pm »
That 5 seconds is a long time on a race track. assuming USLMRA LeMans starts, that could put you coming out of turn 2 with the retarded timing, and that is a critical corner. Could this time be knocked down any?

It can be set to anything.  But I will go the RPM route.  Timing advances to normal after starting and hitting 2000 RPM . 
Bill Roth
12405 Blossomwood Dr
Austin, TX.
Email: bill.roth@comtrotech.com

Offline Goeytex

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Re: Electronic Ignition Design
« Reply #43 on: December 23, 2010, 03:45:20 am »
Modified Design  ( per request)

Added WOT throttle switch Input.  IF this is connected then timing is retarded when ...

1. RPM > 5500 and
2. Throttle is wide open

RPM and amount of timing retard are adjustable
Bill Roth
12405 Blossomwood Dr
Austin, TX.
Email: bill.roth@comtrotech.com

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Re: Electronic Ignition Design
« Reply #44 on: December 23, 2010, 05:22:44 am »
Why?
Not questioning it, jsut wanting edumacated ...lol
Wouldn't that act as somewhat of a rev limiter...so to speak?
Bert stole my cookies!!
 I think he used them to bribe Ed into something naughty?

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