4AGE four plugs firing at once

[thruthefence]

Any thoughts about a Toyota 4AGE 20 valve engine, that fires a coil-on-plug ignition system, ALL AT THE SAME TIME? I'm not referring to an alternating "wasted spark" system, that fires two-and-two, but one that all four at the same timing point. The coil/plugs are in parallel with the igniter. A pair will always be firing at the start of the intake stroke. These guys swear its an operating concept, no loss of power, normal throttle response, ect.

http://forums.club4ag.com/zerothread?id=18900&page=6

about 1/4 way down the page, there is a schematic.

please don't shoot the messenger, I am seeking understanding.

 

[BrianPetersen]

There is certainly no advantage to doing it that way, and surely it's a recipe for backfiring through the intake system. Just because something can be done, doesn't mean you should.

 

[patprimmer]

Yep

I can hop on one leg and simultaneously sing the British national anthem. I always choose not to.

Regards
Pat
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[Pud]

Pat, got a youtube link?

http://www.tynevalleyplastics.co.uk

 

[patprimmer]

Pud

Not likely unless someone slips me some powerful mind altering drugs

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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[WGJ]

Sounds like you may already have used them to dream that trick up

Bill

 

[jmw]

Didn't the 2CV plugs fire on both ignition and exhaust?

http://www.netcarshow.com/citroen/1963-2cv_berline/

The reliability of the car was increased by the fact that, being air-cooled, it had no coolant, radiator, water pump or thermostat. It had no distributor either because both spark plugs were fired at the same time, on every two strokes.

and

The 2cv also pioneered the use of the now common Wasted spark Ignition System, also known as the DIS (Distributorless Ignition System) ignition using a double ended coil fired on each revolution, (on the exhaust and compression stroke), by just a contact breaker.

JMW

http://www.ViscoAnalyser.com

 

[BrianPetersen]

Yes, and so do most engines with distributorless ignition (every motorcycle engine is like this). But those fire the plugs on every approach of the piston to top-dead-centre. This means they fire the spark plug (usefully) near the end of compression stroke, and (wasted but harmlessly) near the end of exhaust stroke.

With a 4-banger 4-stroke engine, if you fire ALL the plugs at the same time, you will have to do the above, but also fire the plugs approaching *bottom* dead centre, since that occurs simultaneously with the other cylinders approaching top dead centre. Firing the spark plug nearing the end of the power stroke won't do anything bad, but firing it near the end of the intake stroke, when the cylinder is full of fresh air/fuel mixture and the intake valve is still open, has a rather high risk of igniting the whole thing and backfiring out the intake system.

 

[thruthefence]

So it would seem - Why aren't these guys shooting fire out of their 'velocity stacks'?

 

[patprimmer]

If they are doing what you say, they would be.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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[bigpaul]

looking at the second drawing all cylinders will fire together so nominly every tdc and bdc which means it will attempt to fire the cylinder @ bdc of the induction stroke.which will cause a big bang through the inlet
an ingition amplifier desgined to run 1 coil could not run four for very long.

 

[Nemesis4]

After looking at the original forum this idea came from I don't think there is any point in saying that it doesn't work; will shoot fire out the intake etc. - it does work.
Why doesn't the wrongly timed spark ignite the mixture?
Maybe the petrol/air mixture at normal pressure and temperature cannot be ignited by a spark. Several years ago I attempted to make a heating torch by attaching a carby to the intake side of an old compressor and ran a hose from the outlet - there was no way in the world the mixture coming out would ignite. The mixture appeared to be far too lean to burn - it didn't even smell "petrolly". Quite possibly the mixture needs to be made much denser and heated to 100/150 degrees C (as it is at the end of the compression stroke) before a spark will ignite it.
Also, with a conventional crank-fired "wasted spark" system the spark that occurs towards the end of the exhaust stroke also occurs when air/fuel mixture is flowing into the cylinder and is exposed to the spark - but it does not ignite. This is a very interesting question that shouldn't have mostly been dismissed as "It doesn't work".

 

[patprimmer]

It could work if the cam was changed so that the pistons acted in pairs with two cylinders inducting at the same time. It then effectivly becomes a two cylinder engine with two cylinders per cylinder, well kind of.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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[thruthefence]

This particular engine has variable cam timing, but if you read through the thread, the reports are that it runs strong across the rpm range and power band. Again reading the thread, the Boy-Racers themselves seem incredulous that such a thing is possible, then cobble up their COP's and report back with successful results.

And apparently the "why would anyone do this" is answered by the desire of some folks to install this engine into older RWD Toyota Corollas- there are problems with the cam driven distributor, you have to ding the firewall for clearance.

 

[MikeHalloran]

A very, very long time ago, the cover feature on HRM was a Buick V8 with all the plugs wired in parallel. It was said to run just fine.

.. but there was a trick; a Kaehni ignition. I.e., the coil was run by a vibrator and fired continuously.

That's not the trick. The trick is that the heads had been equipped with precombustion chambers in which the plugs fired, and the precombustion chambers communicated with the combustion chambers only by short capillary passages.

The mixture in the p/c chambers changed with the gas dynamics in the combustion chambers, but the combustion chambers only 'fired' when there was a combustible mixture in the capillaries, which allegedly occurred naturally at exactly the right time to light the combustion chamber's mixture.

So, the timing was generated by the gas dynamics, and hence, always optimal. .. allegedly.

Given timed fuel injection, continuous firing plugs might work in a modern engine, at least well enough to say 'it works', though probably not well enough to satisfy the smog police.



Mike Halloran
Pembroke Pines, FL, USA

 

[Nemesis4]

I remember seeing a picture in HRM of the Buick at a car show - I wondered how it worked.
Assuming the system works on a 4-cylinder engine - it should also work on a "flat" crank V-8.

 

[thruthefence]

This HRM picture, had to be from the 60's, right? I recall seeing the same picture, and showing it to my father, an auto mechanic, who advised ( like some on here ) "that can't work. It's impossible, it's for 'show' only". I had forgotten all about that until y'all mentioned it.