Twin Spark, who's done it? how? Options

[brer]

I have seen the twin spark dizzies. Straight forward.

Then there are the crank fire twin pack setups. ok.


what else can be used?
Piggyback systems?




(picture is for entertainment purposes only. this is not my motor)

[Jake Raby]

We perfected it last year with the 257 HP, 2.3L "Mighty Spyder" engine after about 6 months of cutting, fixturing and testing the procedures and plug placement.

Here is an example(IMG:http://www.aircooledtechnology.com/galleries/msheads/slides/Arnett%20manx%20058.jpg)

This is serious business, not to be attemted by those that lack fixturing/machining experience. It requires extensive preheating, welding and post cooling of the head castings, these heads pictured has 9 hours of solid weld time into them.

(IMG:http://www.aircooledtechnology.com/galleries/msheads/slides/Arnett%20manx%20065.jpg)

(IMG:http://www.aircooledtechnology.com/galleries/msheads/slides/Arnett%20manx%20052.jpg)

To do these first heads was a HUGE task, even for Len and myself to tackle. It required buying a dozen different spark plugs andseeing what worked best physically and then we had to work out the heat ranges. The fixturing process sacrificed 4-5 heads that needed to be cut up to provide the necessary approach angle to get the spark plug out of the way of the pushrod tube, exhaust stub and allow the plug wire to be installed- all of this was done with a 10mm spark plug- nothing else will fit and provide clearance.

When we finished these heads we had them digitized fully, so now all twin plug engines are completed from these tool paths and programs via 5 axis CNC machining which is a requirement to repeat these processes at anything less than a 2,000 buck expenditure...

Now here are my thoughts on this modification.
1- If you don't intend running more than 10;1 CR on pump gas or 13:1 on race gas don't bother with the mods because you'll never gain the benefit they'll offer

2- If you have a bore smaller than 96mm you won't be able to fit both plugs, nor will the flame front of the smaller bore lend it's self to the mods

3- If you plan on doing this mod, but retaining a dizzy you need to reconsider where to spend your money and thats because direct ignition with ONE plug would be a better choice all around than spending money on a dual plug mod only to slap 1970s technology on it for firing purposes!

4- Big bores love it, all my engines with larger than 102mm bore are getting this as standard, we are building two of them now- one N/A 2.9L and another 2.5 EFI/Intercooled boosted engine. The differences that can be seen with big bores and dual plugs are apparent, even at idle. The 2.3l ENGINE THAT MADE 257hp DID SO WITH ONLY A 34 POUND FUEL INJECTOR!!!Thats totally unheard of with single plugs.

5- He who thinks that conventional timing will work optimum with these arrangements has another thing coming, we have seen engines that need as little as 18 degrees of full advance to have optimum EGT/CHT and BSFC, normally these engines with a single plug would require at least TEN more degrees of advance to reach this point. That yells efficiency loud and clear and it also means that EVERYTHING about tuning the dual plug equipped engine changes and you'll be hard pressed to ever tune one without a very well equipped dyno.

So with that being said our LE 200 N/A and LE 220/LE 230 Turbo/large cc N/A heads heads have the option of dual plugging. It adds 1K to their price tag, but the work is done spot on with CNC repeatability.

I have a custom dizzy made from a Nissan Z22 engine set up that offers twin plugs, but I'd never try it without direct fire... Why???

Well this is why, in our experience a dizzy simply cannot offer the ignition manipulation that these mods work best with. The advance curve of a conventionally fired engine is linear as RPM increases, these plugs don't like advance at higher RPM and with a dizzy its difficult to accurately pull timing away from the engine as RPM increases...

The "Mighty Spyder" engine utilized RAT/SDS Engine management with our custom dual coil pack enhancement. With this set up a standard SDS "F" system can be made to fire twin plugs easily with a clean installation...

Its a great mod if you accept the alterations it requires. I'll be happy to help anyone accomplish this mod if they purchase our CNC twin plug heads, I have several combos cooked up that work very well with these mods.

Don't think that a local machinist can do this simply, or easily- doing it correctly gave us a workout and these engines are all we touch.

Tuning the "Mighty Spyder" took us 3 solid days, the first pulls were only 200HP, we tuned another SIXTY into it.