Uprated ignition and coil packs

campbellju

campbellju

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I run a Mallory system and use a 3071 at 1.8Bar. I've been running 0.7mm plug gaps for fear of over working the igntion system at high boost. It worked so I've never tried to stretch it any further.

I was chatting to Stu and a quick internet search later showed 200sx's and GTR's running 1.1mm due to their coil packs but only with mild boost increases.

As I am commuting in my car, getting it running smoothly at low loads is as important as ehat it does at WOT .

I've set the gaps to 0.9mm today so I'll see how it goes tomorrow but was wondering if anyone else had experience of using larger plug gaps on a >400hp car?
 
P

pulsarboby

Guest
on standard ign and those gaps you could experience spark blowout at that boost level jim (assuming you nailed it), but with the mallory system i dont know tbh, but if its driven non harshly i guess it would be ok
 
GTIR-LOZ

GTIR-LOZ

New Member
i ran the crane hi-6 at those gaps and it was fine, makes the car smoother and supposidly you will get better fuel consumption and more power
 
campbellju

campbellju

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Staff member
Thanks Lawrence. Did you try anything bigger than 0.9mm or did you leave them at that as it worked?
 
campbellju

campbellju

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Staff member
The 0.9mm on the way to work was smoother and didn't misfire on a quick 2nd and 3rd gear blast. When I next get the chance I will gap to 1.1mm. Assuming no immediate problems I'll try it for a few weeks and check the plugs for wear.

So far so good :thumbsup:
 
Smo

Smo

Active Member
I'd be interested to see how you get on mate - my car will be running BCR8ES plugs with an MSD 6a Ignition box and SS Blaster coil so if you get on well with a bigger gap I'll give it a try.
 
stumo

stumo

Active Member
Smo said:
I'd be interested to see how you get on mate - my car will be running BCR8ES plugs with an MSD 6a Ignition box and SS Blaster coil so if you get on well with a bigger gap I'll give it a try.
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have you seen the sparks that your setup produces?

get the king lead about 30-40mm away from metal and short out the white wire :shock:
 
Fusion Ed

Fusion Ed

Active Member
[nerd]
lol, I made a Jacobs ladder using a SS blaster coil, although it seemed to provided more current, I found I could get better longer sparks (higher voltage) from a oem coil, HOWEVER I think my SS blaster coil may have had and internal breakdown problem, that I never knew about previously.
[/nerd]
 
stumo

stumo

Active Member
Fusion Ed said:
[nerd]
lol, I made a Jacobs ladder using a SS blaster coil, although it seemed to provided more current, I found I could get better longer sparks (higher voltage) from a oem coil, HOWEVER I think my SS blaster coil may have had and internal breakdown problem, that I never knew about previously.
[/nerd]
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I'd not tried a normal coil v's a SS coil with the MSD6 unit as it was a new build but it would be interesting to see what the differences are.
 
Fusion Ed

Fusion Ed

Active Member
campbellju

campbellju

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Staff member
From the last time I looked into this I measured the leads to hand.

Nissan OE leads resistance are between 6K - 11K (About 20K/m)
Magnecor 8mm (blue) leads resistance are between 3K - 6K (About 11K/m)
Magnecor 8.5mm (Red) leads resistance are between 6K - 11K (About 20K/m)

The reason for the range of resitances is the lead to cylinder 4 is short where as cylinder 1 is much longer. So in terms of stuff you can measure, the resistances are similar.

However a higher resistance gives a slightly longer spark duration which is helpful at low loads. A lower resistance cable will have minimal effect on the ability to jump the plug gap. In the practical world this is a function of the plug gap only
 
campbellju

campbellju

Moderators
Staff member
To answer Stu's question, the spark will jump a 6" air gap quite happily from inside the leads.

The problem is in the cylinder the air is compressed 8:1 so you can have up to 8 times the air in the gap.

The main problem though is petrol is an insulator so at 12:1 afr you have to bridge this too.

If you are running nearly 2.0bar of boost then you have 3 times as much petrol insulating the plug gap too than on an NA

You add all this together and it explains why you can fire a spark 6" in open air but far far less in a cylinder.
 
Fusion Ed

Fusion Ed

Active Member
MSD blaster wouldn't jump that when I tried to see how far it would go, HOWEVER MSD specifically say not to try this as it can damage the coils. (I think mine already was judging by my results I got at the time)
 
stumo

stumo

Active Member
campbellju said:
To answer Stu's question, the spark will jump a 6" air gap quite happily from inside the leads.

The problem is in the cylinder the air is compressed 8:1 so you can have up to 8 times the air in the gap.

The main problem though is petrol is an insulator so at 12:1 afr you have to bridge this too.

If you are running nearly 2.0bar of boost then you have 3 times as much petrol insulating the plug gap too than on an NA

You add all this together and it explains why you can fire a spark 6" in open air but far far less in a cylinder.
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It was a rhetorical question but i'd still like to see the difference between coils when attached to a MSD or Mallory etc CDI unit in a working engine.

Obviously the coil that goes with the CDI unit would hopefully be matched and in theory be better than the stock coil......
 
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