Which spark plugs?
- Thread starter Thor
- Start date
The iridium tip is very fine, and technically the iridium allows you to run higher temperatures with less spark jump (and thus better efficiency and throttle response). - The problems with them are that the tip isn't physically part of the plug core; it's welded onto the top (whereas a copper core tends to be a continuous piece of metal), and because it's so fine it's easy to snap that off... giving you a huge gap in the plug and a rogue piece of hardened metal floating around in the bore, which can then damage or get stuck in an exhaust valve.
That doesn't mean it's a common problem, but it has happened to people (I'm sure someone in the N/W).
Usually though, it's that the fine tip gets fouled really easily. If your mixture is a bit rich (as it often is when you're on boost), it doesn't take much to coat the electrode.
Similarly, if you've flooded the engine it's really hard to get them to fire again. - This one I've experience first-hand; it's easier to take the plugs out and put new ones in, than get the old iridium tips to fire. I'm sure if you clean them up they'll work again, but it's very hard to clean such a fine tip without bending/breaking it.
There are plenty of high-powered cars that use a standard copper-core plug.
If you're struggling to find them, I think Boby sells them.
That doesn't mean it's a common problem, but it has happened to people (I'm sure someone in the N/W).
Usually though, it's that the fine tip gets fouled really easily. If your mixture is a bit rich (as it often is when you're on boost), it doesn't take much to coat the electrode.
Similarly, if you've flooded the engine it's really hard to get them to fire again. - This one I've experience first-hand; it's easier to take the plugs out and put new ones in, than get the old iridium tips to fire. I'm sure if you clean them up they'll work again, but it's very hard to clean such a fine tip without bending/breaking it.
There are plenty of high-powered cars that use a standard copper-core plug.
If you're struggling to find them, I think Boby sells them.
skiddusmarkus
Active Member
Got my BCR8's off Ebay, bought 2 sets as they were so cheap.The tip is much more substantial than the NGK's/HKS ones I've used in the past and nto going to be wearing down in a hurry.
All going well car is getting mapped again on wednesday at 1.7bar+ and am thinking of gapping the spare set to 0.9mm.I have an MSD 6A and blaster coil so does this sound about right?
All going well car is getting mapped again on wednesday at 1.7bar+ and am thinking of gapping the spare set to 0.9mm.I have an MSD 6A and blaster coil so does this sound about right?
The Mallory and MSD are both decent pieces of kit and very similar. I used the Mallory.
On my 3071 I found the iridiums could run slightly higher gaps but a tip failed. This is the second tip I'd lost in the life of the car and the last one was running lower boost and much smaller gaps. My experience is the copper plugs are more robust for high boost applications.
@skiddus, in the end I was running BCR9's with a 0.9mm gap with no issues. It improved cold start and low load/rev drivability with no problems at high revs. At 1.1mm gaps they very occasionally misfired so I believe 0.9mm is well with in their capability.
@Sascha, copper is a better conductor than iridium but it is softer and wears out faster (every 6K rather than every 30K) OEM's have moved to iridium and platinum to extend service intervals on cars. Although the conductor is inferior I think their design makes them more efficient and why I was able to run slightly bigger gaps than with coppers plus. The design has also made them less robust too which is why I think they break/melt at high temperatures. As you are already running >500hp and looking for more then I'd recommend the BCR9s. I've run them on my daily commute through winter and didn't have any problems. BCR8's might work but the 9's will be safer.
On my 3071 I found the iridiums could run slightly higher gaps but a tip failed. This is the second tip I'd lost in the life of the car and the last one was running lower boost and much smaller gaps. My experience is the copper plugs are more robust for high boost applications.
@skiddus, in the end I was running BCR9's with a 0.9mm gap with no issues. It improved cold start and low load/rev drivability with no problems at high revs. At 1.1mm gaps they very occasionally misfired so I believe 0.9mm is well with in their capability.
@Sascha, copper is a better conductor than iridium but it is softer and wears out faster (every 6K rather than every 30K) OEM's have moved to iridium and platinum to extend service intervals on cars. Although the conductor is inferior I think their design makes them more efficient and why I was able to run slightly bigger gaps than with coppers plus. The design has also made them less robust too which is why I think they break/melt at high temperatures. As you are already running >500hp and looking for more then I'd recommend the BCR9s. I've run them on my daily commute through winter and didn't have any problems. BCR8's might work but the 9's will be safer.
I don't know. It was a few years since I bought mine.
red reading
Active Member
they dont call them that anymore (bcr9es) i will get the code for you for the plugs i have, mine are non resistor racing plugs
just found this if it helps anyone...
That code doesn't seem to exist for NGK. If you break it down:
BCR9ES
BC = 14mm thread, 16mm Hex
R = Resistor
9 = Heat Rating
E = 19mm Thread reach
S = Standard Copper electrode.
I suggested:
BKR9EIX
BK = 14mm thread, 16mm Hex (ISO Standard)
R = Resistor
9 = Heat Rating
E = 19mm Thread reach
I = Iridium tip
X = Booster gap
here a link for buying them...
http://www.ebay.co.uk/itm/NGK-IRIDI...arts_Vehicles_CarParts_SM&hash=item35b4f9ec43
That code doesn't seem to exist for NGK. If you break it down:
BCR9ES
BC = 14mm thread, 16mm Hex
R = Resistor
9 = Heat Rating
E = 19mm Thread reach
S = Standard Copper electrode.
I suggested:
BKR9EIX
BK = 14mm thread, 16mm Hex (ISO Standard)
R = Resistor
9 = Heat Rating
E = 19mm Thread reach
I = Iridium tip
X = Booster gap
here a link for buying them...
http://www.ebay.co.uk/itm/NGK-IRIDI...arts_Vehicles_CarParts_SM&hash=item35b4f9ec43
Last edited:
red reading
Active Member
personally i would not fit eix plugs as they have a habit of losing there tip and scraping the engine and also if you flood the engine they breakdown.
Copper and paladium are better and softer materials + race plugs have a wider heat range than conventional plugs, you also benefit from not having the resistor.
Copper and paladium are better and softer materials + race plugs have a wider heat range than conventional plugs, you also benefit from not having the resistor.
red reading
Active Member
nope they are r5671a-9, again another racing copper plug
For those with ignition problems on the standard system and don't care about low load/rev dribvability, run smaller gaps. For those who want to run bigger gaps for drivability at low revs fit a stronger amplifier. Simples
So what's the recommended upgrade to the amplifier? I didn't think there was a bolt-on alternative.
I don't think it really applies to me because the only ignition problems I've had were from having too small a gap thus giving a weak spark at high revs. I just use 0.9mm with the standard coil now, and that seem to work for me.
I don't think it really applies to me because the only ignition problems I've had were from having too small a gap thus giving a weak spark at high revs. I just use 0.9mm with the standard coil now, and that seem to work for me.