Spark Plugs - Too hot, Too Cold or just about right?

[MyM8V8]

I just found out that the plugs in my new stroker are the same as fitted to the Aston 5.3 supercharged motor.

I'm running rich while logging and fouled them up on tickover and low rev stuff.

Found a set on fleabay for £14 inc inc. Copper cores NGK BCR8ES.

Is this too cold a plug for a 11-1 CR motor?

Any rec's on gap size?

Edited by MyM8V8 on Friday 3rd October 15:18

[007 VXR]

I use the LS9 plugs on mine.

[MadMaxHSV]

I'd say that's a little on the cold size. 5's are stock and I run a 6 in the blown motor.
I used to get my plugs from Halfrauds. BPR6EF's set of 8 for £11 with a trade card
Coil packs are strong on these so you can go quite big on the gap, can't recall exactly what i've set mine to currently though (around 40 thou rings a bell)

Edited by MadMaxHSV on Friday 3rd October 16:10

[gsd2000]

from a quick google search a heat range of 8-9 is recommended for an 11:1 ls motor

[ringram]

What google are you looking at mate, that makes no sense. 11:1 NA is OEM LS2 spec. Do they run 9's!? No they run 5's..

Im with Piers on the 6 range as being best.

If the ones in there are fouled Id suggest you need at least 2 ranges hotter.
If it was only 1 out I doubt they would look overly fouled.

[stevieturbo]

MyM8V8 said:

I just found out that the plugs in my new stroker are the same as fitted to the Aston 5.3 supercharged motor.

I'm running rich while logging and fouled them up on tickover and low rev stuff.

Found a set on fleabay for £14 inc inc. Copper cores NGK BCR8ES.

Is this too cold a plug for a 11-1 CR motor?

Any rec's on gap size?

Edited by MyM8V8 on Friday 3rd October 15:18

That's just an old RS Turbo plug.

I used them for a while as well as some other 8's, never had any fouling issues
Sort the tuning and they'll be fine....whether you need or benefit from an 8 though ? Harder to say. Plus I'm not overly keen on the retracted nose which is one reason I went back to a more normal type 7.

Some like a retracted nose, so probably isnt a big deal either way

I'm only using 7's now.

[ringram]

Gareth has a 255/263 cam I think, so its not as if that would be nice and clean at idle.

Rule of thumb is to pull plugs after a spirited run. Look for the mark on the heatstrap etc.

[jameshsv]

ringram said:

Gareth has a 255/263 cam I think, so its not as if that would be nice and clean at idle.

Rule of thumb is to pull plugs after a spirited run. Look for the mark on the heatstrap etc.

That's a nice size cam

[stevieturbo]

ringram said:

Gareth has a 255/263 cam I think, so its not as if that would be nice and clean at idle.

Rule of thumb is to pull plugs after a spirited run. Look for the mark on the heatstrap etc.

probably all the more reason to run a hotter plug then

[ringram]

Exactly my point

[MyM8V8]

ringram said:

Exactly my point

What makes me ponder is the fact that the engine builder fitted those plugs, but I don't know if he gapped them properly? Was a huge gap.

[TheRealFingers99]

If it's rich at idle, (assuming it has injection -- you may have to live with it if carbed), it needs mapping.

You might look at the recommended plug (I'd avoid anything other than copper as rare metal plugs tend to wet foul very easily and often won't recover) and go up a grade to be on the safe side. One grade in NGK is quite a big step.

As a (very) rough guide, MR2 Turbos tend to use 7s as a hard plug. Anything above a 7 is bike territory, probably useless on a road car.

0.8mm would be a decent gap to start with.

[ringram]

LS OEM spec is either 11 or 13mm from memory.
I run 13mm in my heap. Which is 0.055 IIRC.

The ignition is strong in these cars so you can easily run a larger gap NA.

[stevieturbo]

ringram said:

LS OEM spec is either 11 or 13mm from memory.
I run 13mm in my heap. Which is 0.055 IIRC.

The ignition is strong in these cars so you can easily run a larger gap NA.

13mm gap....must be arcing of the piston ! lol

It's hard to judge plugs by other engines.

RS Turbo uses 8's and makes no power at all, Cossie equally uses very cold plugs.
Modern Jap turbos making more power might tend to use 6's

Even the yanks on LS's seem to stick with 6's even to rather high boost/power levels.

But I wouldnt see a problem with either 7's or 8's in almost all LS applications. I've used a variety of types of plugs in those heat ranges in mine and never had a problem.

Gap...I'm around 25thou, not sure if there is actually any real world benefit from a larger gap if more spark isnt actually needed.
But even with decent amounts of boost on occasion, I've never had any spark related problems, so the OEM coils have more than enough power.

[MyM8V8]

TheRealFingers99 said:

If it's rich at idle, (assuming it has injection -- you may have to live with it if carbed), it needs mapping.

You might look at the recommended plug (I'd avoid anything other than copper as rare metal plugs tend to wet foul very easily and often won't recover) and go up a grade to be on the safe side. One grade in NGK is quite a big step.

As a (very) rough guide, MR2 Turbos tend to use 7s as a hard plug. Anything above a 7 is bike territory, probably useless on a road car.

0.8mm would be a decent gap to start with.

Cheers Bud, it is being logged/mapped at the moment and it is heavily rich on the base map (purposely?)The plug fitted by the engine builder happens to be OEM for a S/C Aston 5.3 apparently.

I am 7.5 litre NA.

Thanks for all your input guys. I will see how we go with plugs once the tune is dialled in. Just need to keep it running while we get some data.

Edited by MyM8V8 on Saturday 4th October 12:59

[TheLeatherman]

I actually use the ZEX triple prong plug in my ute - made more power on the dyno, idles smoother and ran well with them in Oz on regular 98 octane on the blacktop. When we threw some 105 in there we went to an NGK race plug that was at a 7 heat rating. Anything higher and it just kept fouling unless you were idling over 3K rpm.

At TR I had TR6's in the Monaro - all good.

Best of luck with it!!!

Cheers

Leatherman