I was asked this question at work, and could only come up with three engines; I’m sure there are more, so I therefore turn the question over to you, our astonishingly-well-read commentariat, to provide more answers.
Alfa-Romeo made a marketing point of this feature, so I am removing them as the low-hanging fruit. In their “Twin-Spark” engines, they utilized a dual spark-plug configuration, or eight spark plugs in a four-cylinder engine. The idea behind this is that it allows the engine’s timing to be set much more accurately, and allows for a more efficient fuel burn, and therefore an engine that can be run on a much more lean setting, using less gasoline.
This was actually a fairly common practice with Alfa-Romeo, so by all rights I should be removing their engines altogether, but let’s face it, Alfas are gorgeous, so feel free to list them all off with beautiful high-resolution images.
I can think of one other very common engine, and one not-so-common engine that used this technology. After that, it’s up to you guys!
[Remember the rules, lurk before leaping, and width=”500″ is your friend.]
Robert Crespo 
Jeff Glucker 
Kamil Kaluski
Low hanging fruit indeed.
Ford 2.3L OHC Pinto engine came with 8 plugs in the Mustang and Ranger. It produced a whopping 105hp.
<img src="http://carphotos.cardomain.com/ride_images/3/3344/61/33357530009_large.jpg" width="500">
I have one of those, minus the A/C.
It many only put out 105 bhp, but with the right gearing (5-speed stick and a 4.10 rear) it goes pretty good.
A college pal pranked his coworker by pulling the caps off the Ranger. He was pretty surprised to see that thing fire up and sputter away.
Harley Davidson has used this technology for ages in a single spark, dual work load application… Harley's spark on the intake and exhaust stroke to burn all the leftover fuel and this is also what gives it that unique loud sound and vibration. Does that count?
If I'm not mistaken, most of the engines produced by Maserati in the 1950's and 60's had twin plug heads. The same is true for Aston Martin's twin-cam 6.
They indeed did. The straight 6 was based on the Tipo 350 racing engine and was available with fuel injection in the early 60s. Back when I was an apprentice mechanic, we had a customer with a 3500 GT that had previously been owned by Tony Curtis.
It was a very cool car. I loved working on it – changing 12 plugs all standing in a row was a unique experience. One day it spun a bearing; I can still hear the metal bits flowing out as I removed the oil drain plug.
<img src="http://www.maserati-alfieri.co.uk/3500gt/3500gt-21a.jpg" >
I feel like this is going to be fairly common, but without resorting to The Google or The
GuideWiki, the only things that come to mind are top-fuel motors and extra plugs in the turbos of WRC cars.Goddammit, you're right, I didn't limit it to production road-going cars. Ah well, guess that means everyone is going to have a billion answers.
If I recall correctly, the Porsche 964 3.6L was twin plug. However, you didn't actually mention it had to be a road going vehicle, so:
<img src="http://upload.wikimedia.org/wikipedia/commons/thumb/2/27/Porsche_917-16_Spyder_1970_engine_2009-03-14_A.JPG/800px-Porsche_917-16_Spyder_1970_engine_2009-03-14_A.JPG" width=500 /> I think most of their racing engines were dual plug.
God damn, but that's pretty.
Yep, the stock NA flat six in a 964 was twin spark:
<img src="http://porschebahn.files.wordpress.com/2009/12/100_5718.jpg" width=400 />
Seems like a lot of cars around the late '80s/early '90s went twin plug for emissions.
The 200sx, as mentioned above, among many other Nissans of the 80's, had the NAPS-Z engine–a twin spark 4.
I had a NAP-Z 4 cylinder in my 86 Nissan truck, awesomely fun hoonage!
Can't believe I actually have an answer to a technical question but I've spent enough time on Allpar to vaguely remember that the current 5.7 hemi has twin spark. One fires after the other to burn the hydrocarbons more thoroughly for better emissions. Not sure if it was Mercedes-influenced, but here you can see where the spark plugs go:
<img src="http://image.moparmusclemagazine.com/f/9604909+w750+st0/mopp_0602_03z+hemi_engine+plugs.jpg" width="500">
I had a '95 Ford Ranger with the 2.3 I-4 that had 8 spark plugs. Doesn't that count?
Chrysler 4.7L V8 for 2008 and later model years.
A lot of racing Hemis are set up with dual plugs.
<img src="http://www.moparengineswest.com/images/EFI_16plug_drysump_HEMI_2.jpg">
Merc S600 V12. Friend was complaining how at $20+ per spark plug, it quickly adds up…
MGB!
Wait, what?
<img src="http://www.shoyer.com/mgb/pictures/fire4.jpg" />
MGB are very efficient – that was likely accomplished with a single spark.
The Panhard 2-cyclinder horizontally opposed engine. Only the Tigre version had twin-spark, producing a whopping 50 horsepower. <img src="http://studiotimecapsule.com/yahoo_site_admin/assets/images/P1010015.176204804_std.JPG" alt="Panhard" /> <img src="http://studiotimecapsule.com/yahoo_site_admin/assets/images/P1010002.192232347_std.JPG" alt="Panhard2" />
Does the Mazda Rotary Engine count as a twin spark? It does have two spark plugs per rotor housing.
How has the rotary engine not been touched on?
Renesis rotary.
<img src="http://nicemazdapics.info/pictures/car/images/87/RotaryEngine.jpg">
First thing that came to my mind when i read Twin-Spark
I know of a certain MR2 (very limited production) that is a twin spark…. http://forums.24hoursoflemons.com/viewtopic.php?i…
Honda has dual ignition in the engine that powers the Jazz/Fit in some markets. They call it intelligent dual sequential ignition, iDSI. It is a low emission, high mileage option rather than a performance engine. Two plugs, two valves, and two coils per cylinder with a 10.8:1 compression ratio and a single camshaft making for 83 hp with a 119NM torque peak at 2,800 rpm from 1,339 cc isn’t really exciting.
I tore down a Honda VT500 Shadow, and was surprised that it had twin spark plugs per cylinder.
Yep, those Honda v-twin heads had 2 spark plugs and 3 valves, and the 500 had a WAY better combustion chamber than the bigger ones. VT700/750/800/1100 had hydraulic lash adjusters…
Nash used twin spark engines in the thirties for quite a few years.
Do extra spark plugs need to be located in the cylinder head(s) to count?
<img src="http://farm3.static.flickr.com/2468/3568168155_38973d9d36.jpg">
I'd vote no, because apparently some had the second plug mounted in the block itself, although I can't find a particular example…
Fireball madness?
I had one in my 86, the year before the hardbody one, fun truck to hoon!
I just read in Hemmings about the 1909 Pierce Arrow with twin spark ignition. Also, my Kawasaki Vulcan has it.
http://images.hemmings.com/wp-content/uploads/200…
Ferrari 410 Superamerica. Rather dashing, eh?
<img src="http://www.carstyling.ru/resources/studio/large/56ghia_ferrari_410_superamerica_31.jpg" width="600">
Of course if they built one with a displacement similar to your typical sports car of today (3-4L) it would be incredibly powerful.
Rumor has it they kept it at sewing machine size for the mild manered hairstylists that would be driving them.
Would a 3 or 4 liter rotary get single-digit fuel economy or would we have to measure it in gallons per mile?
Honestly I don't care, all I can think about is the sheer power potential from that. the rotors would probably be the size of my body, that or the engine would be 5 feet long and contain 7 rotors.
In the JC Cosmo they used a triple-rotor twin-turbo engine with each rotor having the same dimensions as the 13b used in the FD RX-7.
Mazda will tell you that a 20b is a "two litre rotary" in the same way that a 13b/Renesis is a "1.3L rotary" but that ignores that you can't directly compare rotary engines with piston engines. In Australia, most racing classes double (sometimes 1.7/1.8 times) the Mazda-stated capacity for a rough equivalency. Using that method the 20b works like a 4 litre engine. Mazda, per the agreement at the time said that the 20btt engines produced 206Kw but people who have dyno'd stock JC Cosmos say they get closer to 400hp. They also measure fuel-economy is single-digit mpg.
BMW 650 with rotax engine, both on same side of the cylinder.
<img src="http://www.bmbikes.co.uk/photos/mechanicalphotos/f650%20engine%20cutaway.jpg">
Does the second plug have to fire for it to be considered twin-spark?
<img src="http://shanelindsay.com/files/gimgs/12_1972yamaha360rt-2.jpg"width=500>
Had one of these back in the dark ages. It had a second plug for quick change over, in the event the first one became fouled.
Here's a song about Fort Wayne: [youtube fUKrQej4C3Q http://www.youtube.com/watch?v=fUKrQej4C3Q youtube]
This 1927 Seagrave fire truck has a twin-spark straight six with 17 liter displacement.
<img src="http://www.jalopyjournal.com/forum/attachment.php?attachmentid=1275615&d=1300843435" width=500>
Some guy on the HAMB is turning it into a gigantic speedster: http://www.jalopyjournal.com/forum/showthread.php…
man that would be loud!!!
Toyota 3T-GTE.
Probably had a CA-18 or CA-20 engine, most of the NA variants of this engine (common in a lot of 1980's Nissans) had a twin-plug head.