twin plug z24 head. simultaneous plug firing? any info

[Farshid]

Hi,Dear guys,

 

first I explain that I started to improve my conventional  Z 24 engine  to 8 Plugs.so I purchased the distributor and going to punch the exhaust hole in  the head cylinder.

I have a question about 4 wire E12-83A ignition module Electrical wiring ,exactly on  white wire connection,for cut off

It seems we should use 2 Capacitor that connected individually  on one side to positive side of Intake and exhaust coil and twisted to each other and connect to C pin of module,

Now  my question is: what is the value of these capacitors ???

 

thank you in advance

 

Edited July 28, 2018 by Farshid

[datzenmike]

 

With 4 wire E12 83 module.

 

 

Just leave the white wire disconnected. You would need a vacuum switch to sense heavy load (low vacuum) to operate the shut off. Just run the dual plugs at all times.

 

The capacitors? Probably for RHF noise suppression. Won't affect operation with or without.

 

 

 

 

 

 

 

Leave the white wire and there is no cut off of the exhaust side plugs.

[Farshid]

hi.dear king rat.thank you very much.for your answer.but here I send the electrical diagram that I found these two capacitors.so I concerned about the value of them so I suppose that the value define the advance degree of module in single ignition and double ingnition.

https://drive.google.com/file/d/1ZvqNSAZcTfuBDpF06eJxrY9graPiWWku/view?usp=drivesdk

[Charlie69]

The blue circled condenser is to suppress noise for the radio and surrounding electrical devices like a TV.

[datzenmike]

The vacuum switch grounds the white wire going to the module. This turns off the exhaust side coil so that only the intake side are firing. This is believed to reduce engine noise under heavy load. The module automatically advances the timing to make up for only having one spark plug working. If two plugs are working, less advance is needed. Without the switch everything just keeps working as it should.

 

The capacitors are in no way connected to the single or dual plug operation. I believe it's to reduce noise on the +12 supply that can be heard on the radio as a high pitched whine.

[Farshid]

OK,thank you dear guys,Now I convinced that  these capacitor is for noise suppression only , and I would just fix a manual switch in the car room to manually grounded the C pin, in some circumstances.

but please notice that there is not any electrical connection to white wire directly to earth,wire is between the C pin and the T joint of capacitor only.so how the vacuum switch can grounded the wire.

It seems that the vacuum switch just cut the exhaust coil positive so the module sens for example 0.68 micro farad and hen the exhaust coil is on( Positive potential is present) the two capacitor get parallel and the module senses 0.68 X 2 micro farad,and may be we can adjust the amount of advance degree by deferring the capacitor value  by our self.

 

[datzenmike]

You're right. The switch seems to just open and shut off power to the exhaust coil. Again I would just run without the switch or the capacitors. The engine will run with both plugs firing all the time.

[Farshid]

thank you in advance.dear KING RAT.can you read the value or some thing on the capacitors or send me the pictures,truly yours

[Farshid]

https://t.me/Fmansourbakht

my project on Nissan patrol

[datzenmike]

The Capacitor value I do not know.

[Farshid]

ok,no prob,thank you ?

[Charlie69]

What year Z24 and wiring are you working with?  I have several wiring harnesses and possibly have what you need.

[Farshid]

Hi,dear charlie

My Z24 engine years seems 1975-1980,but please take attention that original Z24 that imported to Iran do not have 8 plugs  head cylinder and so the distributor,also they do not have conventional magnet distributor.

 

so I purchased a new original 4 plug nissan motor head cylinder and going to crated 4 extra hols for exhaust plugs and  finally find a broken 8 plug distributor( that I fixed It).

[Charlie69]

You can buy rebuilt 8 plug Z24 heads on ebay. 

[Charlie69]

Z24 here in the states were 1984 to 1989 in trucks.

[datzenmike]

 NAPS has been around in many forms for a long time but the Z series engines only from '79. In '80 we had Z20 engines with only 4 plugs in two cars the A10 and the S110 200sx. The California models were 8 plug the all were 8 plug in '81. The 720 truck switched from L series to the Z22 engine in '81 and it was 8 plug. I have a couple of 4 and 8 plug heads.

[Farshid]

thank you dear guys

A question: is there any horse power increase in 8 plugs engine compare to 4 plugs z24 really,and how much,what was your sense?

how sense it, in Torque or Horse power??

[distributorguy]

I've only spun up 2 of these distributors, and I recall seeing that they actually did fire 5 degrees apart.  

 

Nonetheless, You can use a single wire for the primary plug set to fire BOTH coils.  This will guarantee that they will fire simultaneously.  Jaguar did this on their V12s. One coil for each bank of plugs, fed by the same trigger wire with a simple jumper.  

[datzenmike]

On 7/29/2018 at 10:05 PM, Farshid said:

thank you dear guys

A question: is there any horse power increase in 8 plugs engine compare to 4 plugs z24 really,and how much,what was your sense?

how sense it, in Torque or Horse power??

 

 Where you set your timing to fire a cylinder is determined by when you want the cylinder pressure to be at maximum to efficiently push down on the piston. Before TDC is pushing backwards. TDC is just pushing down on an aligned piston, rod and crank... it goes nowhere. After TDC the piston is moving away so if too late the expanding gasses are chasing a rapidly accelerating piston and an enlarging space to fill. Generally 17 degrees is the 'sweet spot' where the piston is still quite high and is moving and can efficiently absorb this push downward. 

 

On a single plug head you start the fire well before TDC because the piston is moving very fast and it takes some time for the fire to travel all the way across the combustion chamber. It seems fast but there's time for the piston to travel up to TDC and beyond. The L series uses a single plug and the base timing is 12 degrees BTDC. The Z24 is about 3 +/- 2 degrees (but maybe for emissions) I think some earlier Z22 were 5 +/- 2 degrees. Both are dual plug heads.

 

Now if you have two points of ignition, like lighting a candle at both ends the candle will burn much faster. Now you can reduce your ignition advance because you have less time to work with to catch that 17 degree 'sweet spot'. Less advance means less time for detonation to occur. Shortening the burn time means less time for quench or the absorption of heat by the combustion chamber and piston leaving more to expand the gasses and push on the piston. Less time for peak cylinder temperatures and the formation of oxides of nitrogen. Under certain conditions much more EGR can be used where a single plug would have trouble firing a much diluted gas and air mixture. 

 

Power increase? Some but may not be very noticeable, (probably much more in a performance application) but it will be overall more efficient and cleaner running. It would be hard to compare just by shutting one side off... you would also have to re-time the ignition for the longer burn time.  AA/Fuel dragsters use dual plugs, think about that.

[Farshid]

thank you very much for your complete and full of details information.I appreciate it.

[Spiff]

There is a research paper available online on the effects of one vs two plugs per cylinder, it basically found that two plugs produced slightly more hp and torque. This was some small cc one cylinder engine, but one guy in australia dyno proved and increase in hp and torque on a Z18ET firing 8 plugs vs four. 

It's a subject I'm somewhat intrigued buy as we mostly got the 4 plug heads over here and as my z20e is turbocharged I see the conversion to an 8 plug head(or drilling and tapping my excisting one) as a way of reducing the risk of detonation as I push the limits of this engine. 

[datzenmike]

Dual plugs alters the ignition timing requirements. Dual plugs need less advance than single.

 

Would love to see this dyno proof. Hopefully he altered the timing to be fair.

[banzai510(hainz)]

Doesnt the Iran jeep Safir have a Z24 engine?

[datzenmike]

Yes but outside of N America, maybe Japan and a few others, pollution controls are not as strict and single plug heads are the norm. Here we got single plug Z heads in '80 but the California market ones were dual. In '81 all became dual plug

[Spiff]

There where some dual plug heads over here as well. For the most part the CA20 engine but there where some d21 z24's also. 

 

 

From the discussion in the z18et group

Quote

Ben Diggles I have just started playing with these Z18ETs. On they dyno they pick up around 5% horsepower if you can fire the secondspark plug at the same time as the first (waste spark coil or modified distributor). The hemi combustion chamber obviously needs help with multiple flame fronts to get a quick burn, and thetwin plugs provide exactly that.

Ben Diggles worth 20 kw at the wheels on the engines we are playing with at 6000 rpm. Torque increase is across the board once the engine comes on boost. Timing would depend on your setup so do a timing sweep.

 

I would love to drill and tap the head for a second set of plugs on my z24 engine and do some comparisons myself but it's already assembled and my z20 is smoking like a chimney so I need to swap the engines asap, but maybe in the future.