Simple reliable cheap ignition source

[hosedup]

I wanted to share my current ignition upgrade for the engine Mr.Coffee and I built. When I was younger, I was a bit fascinated by playing with high voltage. Biggest problem I had was generating it in a way that was reliable and cheap. I tried lots of things, even wound my own transformers and built pulser circuits to drive them. It just wasn't that reliable and I spent more time fixing my HV power supply than I did using it.

Then I discovered the General Motors High Energy Ignition. Also known as the GM HEI. It came out in the mid 70's and is one of the first, and arguably the best mass produced electronic ignition systems ever made. Most modern systems are based on it in some way.

Anyway, on to how to use it in our engines. To use it in our engines, you need a few basic components: a coil, ignition module, pulser, spark plug and spark plug wire. For $50 or less, all of those can be obtained from a junk yard, with the exception of the pulser. The generator is a simple device built from a 555 timer.

Putting this together is rather simple. Basically you duplicate the way it was wired when in a car. The most complex part is the pulser but I would say that most anyone here who has built a jet from a turbo could do it.

I like this approach because you are using purpose built components for their intended purposes and they are available off the shelf as new from an auto parts store or junk yard. Also, these components are designed to last the life of the car in an inhospitable environment.

If people are interested, I'll post a write up on how to build the entire system.

[turboron]

hosedup, yes I am very interested. Please share your information on the GM HEI.

Thanks, Ron

[hosedup]

May 11, 2020 7:25:26 GMT -5 turboron said:

hosedup, yes I am very interested. Please share your information on the GM HEI.

Thanks, Ron

The GM HEI ignition is relatively easy to turn into a high voltage power supply with minimal effort. 



First thing you need is a coil.  I suggest mid 80's to late 90's small block V8s and V6s.  They did not have coil over plug arrangements and this type is generally unsuitable for what were doing.  If you are running 2 spark plugs or want to, there is an easy to do it.  GM did a distributor-less system that fired 2 plugs at the same time (known as lost spark).  In the pic, its the coil on the left with 2 HV towers.  Keep in mind that the secondary of this type of coil is NOT grounded.  If you use this coil, you must run 2 plugs.   If your running a single plug, then the coil like what is in the middle.  

Next thing you need is an HEI module.  They usually live inside the distributor down by the reluctor.  The module takes pulses from the reluctor and amplifies them into the coil.  A module generally looks like what is on the left.  There are many different flavors of these modules but in general, simpler the better.  The module in the pic is from a late 80s GM V8.  It has 5 electrical terminals, 4 pins and case ground.  The terminals are B C P N and G (case).  Its whats known as a 4 wire module.  There are others that have more pins and they incorporate electronic advance.  Though they will work, we don't need it.

And finally you need a pulse generator circuit.  I made mine from a 555 timer IC.  The pulser simulates a running engine.  My circuit gives about 0.5 mS pulses at ~80Hz.

To wire it up, first bolt the module to a heatsink and ground it to your chassis.  Next connect the 12V neg to chassis ground.  Connect +12V on the B terminal.  Next put +12 on one of the coil input terminals.  The other input terminal connects to the C terminal.  The pulser connects to the P terminal and it grounds to chassis ground.  

Its important that you use a spark plug wire as opposed to a normal piece of wire.  Long story short, it works better.  It is also important that everything is well grounded to the metal chassis of the engine.  

If all goes well, this is what you get:



I do not have a drawing of this circuit currently but I'll get it drawn up in a day or 2.

[racket]

Have you checked these out ............ www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=high+voltage+generators&_sacat=0

[hosedup]

May 11, 2020 23:29:36 GMT -5 racket said:

Have you checked these out ............ www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=high+voltage+generators&_sacat=0

No, did not know they existed. When I was much younger, such devices simply were not cheap and readily available, especially to teenagers. (probably a good thing) The jet currently is using a HV brick similar to what you linked but was designed for a small laser.

I wanted to return the brick to its original purpose so I can use the laser for another project. It is what Mr.Coffee and I had at the time. He used it to build the ignition system and it served its purpose well.

When upgrading the ignition, I went with what I had experience with and and what was available. I came across the HEI parts from some old boxes when cleaning up some old junk. Also because of safety and reliability. A car ignition system is inherently safe and reliable when used how its intended.

But you bring an interesting point with those items on ebay. I never considered them.

[racket]

They're interesting little devices and only seem to have become readily available in the last few years or so .

Yep , I tend to use auto bits as well , simple and available , my first setup on the bike was a car coil and flasher unit type system, the one on my teststand is a small electric motor with a homemade cam on the shaft and a set of points to activate a car coil .

[ausjet]

I made something quite similar to yours back in the day. Consisted of an ignition coil, condenser and a latching relay. Pulsed something like 100 times a second which gave a very strong constant spark even with the ground electrode opened up as far as it would bend outwards

[slittlewing]

Hi Gents,

Having done quite a lot of messing about with ignition of late, these are my findings:

I previously used a Bosch car ignition coil with a VW ignition module and a relay, capacitor and resistor to provide an oscillator that switched between open and ground. It worked on my mk1 engine with propane but was quite heavy and needs a fair bit of wiring - not simple enough.

Then I tried the Ebay high voltage generators (12v version), the one with the circular body with a flat on it, part number LG-801. They make very nice big fat sparks but overheat and die after about 30seconds continuous. I blew one up whilst testing this (I was also using a spark gap to get more voltage).

Then I tried one of the “20kv negative ion generator”. It was rubbish and made one little spark.

Then I tried a rectangular version of the 12v high voltage generator which is rectangular and bigger. Coupled with a 20kv diode on the output (£2 on eBay), it only sparks half as often which I assume to aid in not overheating it. So far I haven’t blown one up despite sparking for over a minute. Haven’t tested one to destruction as don’t have a spare but this is my recommendation!

www.ebay.co.uk/itm/352692469280

The ones I got were from amazon (£7 each)


After mounting in box they look like this:







Cheers

Scott

[hosedup]

So here is a schematic of what I built. Its a pulse generator based on a 555 timer that drives an HEI module from an early 80's S10 pickup (2.8L V6). The module fires the coil that came from a late 80's Chevy V8. I've done a bit of testing with this setup and found it to be very reliable. I did a 48 hour test and it never skipped a beat. This circuit runs at ~100hz (about 100 sparks per second). Adjustments can be made to change the pulse rate and dwell but its completely unnecessary. Simply apply 12VDC and you get sparks.

The hardest part is building the circuit board with the 555 IC but considering the skills of the people here turning old car parts into jet engines, I don't think it'll be that hard. One thing to note is the case of the HEI module must be grounded and mounted to a heatsink of some sort. It doesn't produce a lot of heat but it will overheat if just sitting on a bench. Because its based on car parts, it runs on 12 volts DC.  

In other tests, the spark will ignite fuel sprayed at it as well as start the turbojet that Mr.Coffee and I built.