Spark plugs

Road-race engines and ancillaries - general discussion
MinorTC
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Spark plugs

Post by MinorTC » Tue Aug 17, 2010 1:37 pm

I was wondering if there is a generally accepted best spark plug to use in the Fiat twin-cams (specifically the 2-litre)?

I have a batch of NGK ZGR5A spark plugs, normally used in 1980s BMWs - would they be of any use in a Fiat engine? The NGK website recommends ZGR5A for earlier BMW E30 325i and BPR6E for the later E30 325i, coincidentally the BPR6E is also recommended for the Fiat 2-litre TC. So, presumably the ZGR5A could be safely used in the Fiat engine, but has anyone on the forum actually done this?

Thanks for any advice,
Maurice.
Maurice,
East Kent.

WhizzMan
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Re: Spark plugs

Post by WhizzMan » Tue Aug 17, 2010 6:23 pm

Personally, I'd go for BPR6E-IX. Iridiums last longer and give a better spark, especially on a cold engine. Technology has moved on the last 25 years. Even the BPR6E is more modern and since it became available, BMW has stopped using the ZGR5A. I've tried matching the WR9LS that BMW uses OE to the BPR6E and the closest NGK match I found was the GR4. I think you have a mismatch and I would advice against it. If they were interchangeable, I'm sure both would be in the replacement tables. I wouldn't put them in, but maybe others know more?
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MinorTC
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Re: Spark plugs

Post by MinorTC » Tue Aug 17, 2010 9:28 pm

I used to run BMW E30 320i and 325i models, and couldn't notice any real difference between ZGR5A and BPR6E plugs, even though some swore by the later BPR6E plugs. I just happen to have twelve spare ZGR5A plugs, and would like to use them if possible!
Maurice,
East Kent.

Guy Croft
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Re: Spark plugs

Post by Guy Croft » Wed Aug 18, 2010 8:05 am

Depends on stat_of_tune. Selection of the right plug for the in-cylinder condition is vital.

Recommended reading:

http://www.ngkntk.co.uk/working/RunScri ... \Pg100.asp

GC

Sandro
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Re: Spark plugs

Post by Sandro » Wed Aug 18, 2010 8:22 am

Guys,

the NGK spark plugs you have will be too hot a heat range. I am a design engineer for Champion and know the heat range of these two designs well.

The ZGR5A is a hotter design than the BPR6E and you may have issues with pre-ignition even on a std tune TC. I would stick with the BPR6E in terms of heat range....the key item in the part number is "6" this determines the heat range. As Guy say though as the state of tune increases you may need to go colder again, ie 7 or 8 NGK.....

For optimal ignitability in an engine you need fine wire electrodes (and a relatively large starting gap), ie Iridium / or platinum and they do last a lot longer.

Hope that helps. I do have an ignitability video I can show you guys but it is very big..approx 750Mb...I would gladly share but I dont know how we can upload on to here something this size - this shows the difference in start of combustion based on different spark plug designs.

Guy if there is anything I can share on the subject of spark plugs let me know..I can prepare some information and share if needed.

regards

Sandro
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Guy Croft
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Re: Spark plugs

Post by Guy Croft » Wed Aug 18, 2010 8:41 am

MODEL POST!

Thanks Sandro.

Now - about that link to Champion Racing Division..?

G

MinorTC
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Re: Spark plugs

Post by MinorTC » Wed Aug 18, 2010 1:34 pm

Interesting stuff, thanks guys! Think I'll donate the plugs to the Beemer boys then...
Maurice,
East Kent.

WhizzMan
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Re: Spark plugs

Post by WhizzMan » Wed Aug 18, 2010 7:25 pm

http://www.ngkntk.co.uk/working/RunScri ... /pg100.asp should work better?

The heat range is obviously important, but to replace a BPR6E that is functioning fine, I would just go to the IX version and not change to another heat range.

Sandro, maybe you can convert the video to another format and upload it to a video hosting site? If Guy approves, a link to that would be marvelous. There are several good guides on converting video using free or trial software packages to be found on the Internet.
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Sandro
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Re: Spark plugs

Post by Sandro » Fri Aug 20, 2010 12:30 pm

Guy,

I have the spark plug movie file down to just under 3Mb - what do you think?

This shows the start of combustion in a pressure chamber using different spark plug firing end designs.

Plug 1 - std spark plug with no precious metal, centre electrode diameter 2.5mm or 2mm, eg NGK BPR6E, Champion RC8YCC
Plug 2 - std precious metal spark plug with Platinum or Iridium tip 0.8mm diameter
Plug 3 - high end precious metal design with platinum or Iridium tip 0.4mm diameter. Please also note the reduced ground electrode coverage that improves combustion compared to 2
Plug 4 - multi ground electrode design


Sandro
Attachments

[The extension wmv has been deactivated and can no longer be displayed.]

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WhizzMan
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Re: Spark plugs

Post by WhizzMan » Sat Aug 21, 2010 11:36 am

I think I have some ground electrodes to modify. ;)

Very nice to see the differences.
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4v6
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Re: Spark plugs

Post by 4v6 » Sat Aug 21, 2010 3:31 pm

Fascinating to see that!
Tony Warren. GC #96.

Sandro
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Re: Spark plugs

Post by Sandro » Mon Aug 23, 2010 8:32 am

Huys,

yes the difference is interesting between designs....but remember this work has been done for OE customers developing new engines where Ignitability improvement of the air fuel mixture is extrememly important. The reason for this is so they can make use of the better ignitability, ie they can make the engine run leaner and hence save fuel / emmissions / change ignition timing as well as other parameters to make best use of it.

On an engine that is already developed, ie the TC engine fitting these fine wire plugs will not yield any significant benefits unless you do the same. What you will notice is that the engine will feel smoother but dont expect any great power gains etc just by simply swapping the plugs. We have done this testing on dyno to prove / disprove other aftermarket spark plug manufacturer claims.

I would suggest the best design for a TC would be an Iridium / Platinum fine centre wire design with a gap around 0.9 to 1mm. Well that is what I will be doing on my engine. The spark plug allows engine builders to improve perfomance by changing engne operating parameters but it is not an instant bolt on power accessory.

Once you move into race engines then a different design is used than that used on road engines so please dont confuse the two.

to sum up Ignitability effect of spark plugs is down to the following:

1) gap size (ie longer spark). Dont open the gap up too big or it will misfire or puncture the ceramic). You need to understand what is the available voltage that can be delivered to the spark plug and the coils on these cars are pretty old pls have to go through a distributor that are not very efficient. 1mm start gap is the max I would recommend on these engines.
2) volume of electrode material in the chamber (ie fine wire centre electrodes are better than the std 2mm ones)
3) making the spark as visible as possible to the incoming mixture (ie cutting the ground electrode back so it just covers the centre electrode)
4) pushing the spark position further in to the chamberso its further away for the top of the cylinder head
5) energy delivered to the spark ( on a TC this cannot be changed as it is ignition coil dependant)

I will try and get some photos of plug designs up on this site...

hope this helps...

Sandro
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Guy Croft
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Re: Spark plugs

Post by Guy Croft » Mon Aug 23, 2010 8:48 am

"I would suggest the best design for a TC would be an Iridium / Platinum fine centre wire design.."

Does that signal the end of my sales of NGK B9EGV that I have used and recommended since 1992?

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Sandro
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Re: Spark plugs

Post by Sandro » Mon Aug 23, 2010 9:10 am

Guy

I am sorry I was referring to twin cams in std tune not modified ones

apologies

sandro
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Sandro
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Re: Spark plugs

Post by Sandro » Mon Aug 23, 2010 9:26 am

Guy,

I have just checked up on the reference you gave as I did not recognise it.

It is specified with a Gold Palladium centre elctrode that is usually fine wire too....what I should have said in my earlier post, is precious metal electrodes, that covers, Platinum, Iridium and Gold Palladium. The 9 in the code is a cool heat range and makes it safe for all tune in terms of heat range. The discussion revolved around BP6ES earlier in the thread that is a std OE heat range.
I was trying to explain how we recommend a design for an original equipment specification and not contradict any of your recommendations...although what you recommend is what I was trying to say. Its just we (Champion) dont do Gold Palladium any more thats why i mentioned Platinum and Iridium, much to my annoyance as it is very good, I have used these in my cars over the years but Champion sprk plug versions...

sorry for any confusion Guy....
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