The Definitive S2 Spark Plug Thread

[terrybullwon]

^^^^^ so long they are not Denso's. I've seen more molten heads than you can shake a stick at with Denso's fitted.

I have been through about 5 sets of IK27's i would not bother with them any more

[RichLV]

Plug change time upon me. Wanted to hear some opinions. I want to go for BKR7/8EIX-11 (1.1mm gap), this is a native gap for FSI coils (which I run). Will the old 5-banger be OK with that?

[mcandmar]

Plug change time upon me. Wanted to hear some opinions. I want to go for BKR7/8EIX-11 (1.1m gap), this is a native gap for FSI coils (which I run). Will the old 5-banger be OK with that?

I don't see any need for such a large gap, do as JP said above and gap them to .6mm

[Thuppu]

Yes, I would also say 1.1 meter is little bit too big gap.

[RichLV]

I don't see any need for such a large gap, do as JP said above and gap them to .6mm

I stumbled upon a thread somewhere in the web, that to take advantage of the increased spark from FSI coils, a plug gap of atleast .040 inch is required.

*EDIT*
Found it - http://www.audizine.com/forum/showth...FSI-coil-packs

Is this true or I can stick to smaller gap? Currently running BCPR7ET with 0.9mm, runs like a clockwork.

[Thuppu]

0.6-0.7mm is good. I think they are pre-gapped from factory to 0.7mm.

[RichLV]

0.6-0.7mm is good. I think they are pre-gapped from factory to 0.7mm.

Great, thanks!

*EDIT*

Looked at the specs of the plugs again, turns out I'm running 0.9mm.

[Tridac]

I put in a set of NGK PFR7B, recently and all ok so far, no misfiring, but the engine is completely stock and not exactly driven at the limit.

One thing to consider about using a larger than spec gap is that the timing will be retarded a little. It requires a higher voltage to fire the plug and the coil output takes a finite time to reach that point anyway. Don't know if this is significant, but perhaps at red line. May be worh sticking a scope to sense (not directly connected !) the rise time of the coil voltage...

Chris

Edited: Part number incorrect

[RichLV]

I put in a set of NGK BCPR7ET recently and all ok so far, no misfiring, but the engine is completely stock and not exactly driven at the limit.

One thing to consider about using a larger than spec gap is that the timing will be retarded a little. It requires a higher voltage to fire the plug and the coil output takes a finite time to reach that point anyway. Don't know if this is significant, but perhaps at red line. May be worh sticking a scope to sense (not directly connected !) the rise time of the coil voltage...

Chris

Mine is stock too, for now.

That's a fair point, but at this stage, with stock coil dwell times, FSI coils are getting overcharged. Might that balance it out?

[Tridac]

Haven't measured it here, but it's not the dwell time so much as the fact that when the coil is energised, it takes time for the voltage to rise to plug breakdown level. Think of it as a graph of a rising voltage against time. At 6000 rpm, 1 degree of crank rotation takes 27 microseconds, (6000 / 60 = 10mS per revolution) / 360), not very much, so depending on the coil rise time, a larger than spec plug gap could retard the ignition.

Whatever, may not be significant, but the plug gap and delay would have been factored in to the design of the original ecu map, irrespective of what plugs you are using. What does the manual say is the correct plug gap ?...

Chris

[RichLV]

Never thought of it that way...
OEM Bosch plugs are 0.6mm.


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[Tridac]

The dwell time is set in software by the ecu, so I guess it's enough to store enough enargy in the coil, but what's interesting is what happens after the circuit is broken. I tried to find out typical voltage rise times on break, but there's very little info online. Looks like it could be in the 10's of microseconds range for a standard coil and less for a low inductance type. Anyway, plug gap for the NGK plugs is specified as 0.6mm, or 0.024". Will leave it at that, as the ecu has no way to compensate for a non standard gap in terms of timing...

[Greg_S]

Just looking around at plugs, I have F5DPOR fitted now, but been looking at BKR7EIX which work out at about £6.56 a plug. Are these working well for people?
Any retailers recommended her in UK?

[oilman]

I can't say how well they work for people, but we have them and you get 10% off the website prices with the club discount code.

http://www.opieoils.co.uk/p-63603-ng...electrode.aspx

Regards

Tim

[Greg_S]

Thanks Tim, will take a look