Do any 16 valve engines have 8 spark plugs? - Team Camaro Tech
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post #1 of 18 (permalink) Old Sep 26th, 04, 03:43 PM Thread Starter
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My roomate told me there are many 16 valve engines that he has seen with 8 spark plugs, two in each cylinder, one firing at the bottom of the stroke and once at the top. I never heard of such a thing but wanted to make sure before I continue our arguement with some facts.

Jared
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post #2 of 18 (permalink) Old Sep 26th, 04, 03:59 PM
 
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Sure there are some ricer 4-bangers that have four valves and 2 sparkplugs.

I have seen a couple of them but I have never really paid that much attention to the names and models, sorry..

AND there are even AA/FD's that have three sparkplugs, but only two valves!! One on each side where the valves are close at the top of the Hemi dome shaped combustion chamber and the third down around the bottom of the exhaust valve.

It's done this way to, (I think), make sure all the Nitro gets burned??

I think they all fire at TDC, but I think what your buddy is talking about is that they fire every stroke instead of every other stroke like most four-stroke motors do just b/c of the way the firing trigger is made, that's all....

That just means that one fire is at TDC on the power stroke and the other fire is on the exhaust TDC is all..

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post #3 of 18 (permalink) Old Sep 26th, 04, 04:00 PM
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Yes, he is right, its an emissions thing. One plug fires late to start a second burn or something like that.

Can't tell you what cars exactly other than I seem to remember them being foreign high-end type jobs.

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post #4 of 18 (permalink) Old Sep 26th, 04, 04:25 PM
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Ummm...all my 16 valve engines have 8 spark plugs. Oh, you meant...nevermind

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post #5 of 18 (permalink) Old Sep 26th, 04, 04:41 PM
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I've seen a few Nissan pickups with that. Not a performance deal by any means.

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post #6 of 18 (permalink) Old Sep 26th, 04, 05:08 PM Thread Starter
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Hey thanks for the quick replies. It just seems so weird to do something like that.
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post #7 of 18 (permalink) Old Sep 26th, 04, 06:38 PM
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1980 Nissan 200SX, California models have 2 spark plugs per cylinder, but only 8 Valves.
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post #8 of 18 (permalink) Old Sep 26th, 04, 09:18 PM
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nissan trucks also. i had an 84 nissan 4X4 with a 2.4 (they called it a Z24), and it had two plugs per cylinder. it was purely an emissions thing as was said, one lagged the other by a bit, a few degrees i believe, ensure it burnt all the fuel/by products. it was a cluster **** of cap rotor and wires, cost as much as a V8 to tune up as well. the ignition sytem was real sensitive to moisture and abuse, and thats pretty much all i did with this thing, get it wet and abuse the hell out of it, it was purely bought to beat on and 4by. in its defense, that little 2.4 was a pretty darn good motor, plenty of power, and got great mileage, which is nice when your miles in the woods from anywhere.

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post #9 of 18 (permalink) Old Sep 27th, 04, 07:40 AM
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I have to agree with Travis on this one...
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post #10 of 18 (permalink) Old Sep 27th, 04, 10:17 PM
 
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Years ago I saw a 32' Ford 3 window coupe, sporting a Ford flat head V8 with brass heads that had 2 spark plugs per cylinder; the second being over the exhaust port. The theory was that when the second plug fired on the exhuast stroke, the spark ignited any unburned gases on the way out, thus evacuating the cylinder more efficiently. This in turn, help create a "ram" effect that pulled the air/fuel charge in faster on the next intake stroke. I was told these were "marine" heads. The engine also had 3 deuces and twin magnetos. I've never seen another one like it.
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post #11 of 18 (permalink) Old Sep 28th, 04, 12:20 AM
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some Mustangs and Rangers in the late 80's/early 90's got a dual plug SOHC 2.3 4 popper in them. i think they made all of 140 HP on a good day. i think they also used that as the base for the T-Bird Turbo coupe engines, as well.

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post #12 of 18 (permalink) Old Sep 28th, 04, 07:49 AM
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Here in Europe we have a few I think.
The Alfa Romeo 146 Twin-spark has 4 cylinders, 16 valves, and 8 spark-plugs. I think it is a performance and environmental issue....

There is also the Alfa Romeo 155 Twin Spark, the GTV twinspark...
Probably more Alfa's (the latest and performance orientated) and other cars here, but can't remember them now.
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post #13 of 18 (permalink) Old Sep 29th, 04, 12:18 AM
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My b/b has 16 valves and 8 spark lugs
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post #14 of 18 (permalink) Old Sep 29th, 04, 05:30 AM
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So does my 327...lol

I think having a plug fire on the exhaust stroke is more of a packaging thing than anything else. I used to play with motorcycle engines... this is very common there, because the ignition runs off the end of the crank, twice normal spped. While it can't hurt anything to fire with the exhaust valce open, I doubt it helps anything either.

Example would be an old honda 750... has 2 sets of points and 2 coils, each coil has 2 plug wires, all at crank speed. each pair of cylinders gets 1 spark per rev, for each spark, one hole fires, the other is on exhaust.





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post #15 of 18 (permalink) Old Sep 30th, 04, 07:23 AM
 
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New stealth 2nd spark plug technology: all distributorless ingnition systems(crank trigger) fire 2 plugs at a time; one on the combustion stroke cylinder and one on the exhaust stroke of another cylinder. :&gt
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