[s-cars] Re. Spark plug

Tue Dec 14 09:07:46 PST 2010

So in my case, where I installed a set of NGK BKR7E coppers (replaced 30K mile NGK BKR7EIX iridiums) doing some troubleshooting of a random "hiccup" under load (which is still ongoing) in an unchipped AAN, what do you suppose the change interval would be, or should I just pull them and switch back to Iridiums?

Wylie Bean
TheRingmeister at triad.rr.com
90 cq
91 90q20v
92 UrS4
08 Q7 3.6
via BlackBerry®

-----Original Message-----
From: qshipq at aol.com
Sender: s-car-list-bounces at audifans.com
Date: Tue, 14 Dec 2010 11:31:26 
To: <benswann at verizon.net>; <djdawson2 at aol.com>; <cody at 5000tq.com>
Cc: <s-car-list at audifans.com>
Subject: [s-cars] Re. Spark plug

 Hmmm, discussed this with Dave and many others for years.  The F5DPOR used to be the cats meow (market introduction ~1989), and developed specifically *for* the I520vt in the 1991 200q20vt.  Then time and technology caught up with it two ways.  IMO Bosch quality control on their platinum spark plugs went down the terlitt (was it the P+4 junk habit?), so bad that when I was ordering them in batches of 50 back in the mid to late 90's, I was *guaranteed* to have at least 2 defective out of the box.  They also have a propensity to burn small holes in the ceramic that deforms the spark, and for high boost applications, they absolutely will drop electrodes, btst on a couple different S cars.  On one, it happened not long after I replaced a set of plugs, and I thought for sure it had blown a coil.  Pulled the plugs, #3 had no electrode or evidence of it. When I got my first set of problems with the F5D's I started using single and triple coppers in all turbo applications, and just accepted the increased wear as par for the course, they were better built plugs.

Since the NGK iridiums came out in 2000, I use them almost exclusively for ALL coil on plug applications, because that's what the plug material was specifically designed for.  Even Audi started using them in the 2.7tt applications.  I acquired the 1999 Denso SAE White Paper  (SAE 1999-01-0796) on the comparison of Platinum to Iridium to help me understand the real differences in the materials in terms of performance.  The iridum electrode is stronger, harder and has less wear than platinum, and iridium in a C-O-P application surpasses platinum in every measured performance benchmark.  All good things for a high-ouput coil on plug application.   That said, if using a single coil, you will likely have a stronger spark with Platinum or Copper.  

Now, I still have customers that *insist* on the F5D's which I am then obligated to install, and with 5 working plugs in a stock I520vt, they will last 25k miles, usually without issue.  In those cases, I insist on a 25k mile change interval for them, as well as, dictate the 22lb/ft torque spec be followed to the letter.  With those caveats, they are absolutely adequate.  You top 20psi, you shouldn't be using the platinums IMO.  Because the iridium is a better application for that performance environment.  IME with the iridiums, I have yet to have one to outright fail after installation, and their service life is easily double the platinum.  I put them in my Supercharged Toyota LC, and finally just gave up and replaced them at 60k, because of habit, not necessity.

I won't dish the F5DPOR, it was a great turbo app plug in the 1990's....  Three things have happened since the time those were the standard:  First, Audi went to coil on plug which increased the performance requirements of the plug.   2) the aftermarket tweeksters started into the 20psi+ boost territories with reckless abandon, which increased the required performance/duty of the plug.  3) Denso/NGK saw 1 coming to all production cars (and wanted increased change interval, since many of the Japanese v6 cars require water cooled intake manifold removal to change plugs), and introduced the iridium plug.  There is no question in my mind that anyone that understands the differences between the plug design and engineering, will never buy a F5 again, no matter what your opinion or 'experience' otherwise.

Ben, if you've never had a Bosch plug failures, you just haven't done many installations.  Talk to ANY shop that routinely installs them, it's almost a joke, and a known given.

And I use whatever synthetic oil is on sale, what do I know?

Cheers

Scott Justusson
QSHIPQ 

-----Original Message-----
From: Ben Swann <benswann at verizon.net>
To: djdawson2 at aol.com; cody at 5000tq.com
Cc: s-car-list at audifans.com
Sent: Tue, Dec 14, 2010 12:32 am
Subject: [s-cars] Re. Spark plug

Dave,

I digress.  I have never had a Bosch failure - the recommended F5DPOR plugs go 

for the

duration and get replaced as a matter of course.  

The NGK plugs  on the other hand - several were pretty much DOA causing me a 

real

troubleshooting nightmare.  I put the 100kmile Bosch back in place of the 

defective NGK

and engine runs fine at over 3 Bar.

The NGK weren't that cheap either.

Go figure.

Ben

[Date: Mon, 13 Dec 2010 23:30:06 -0500 (EST)

From: djdawson2 at aol.com

Subject: Re: [s-cars] Spark plug

To: qweblog at gmail.com, cody at 5000tq.com

Cc: s-car-list at audifans.com

Message-ID: <8CD695EB7CD02F2-159C-6016 at webmail-d038.sysops.aol.com>

Content-Type: text/plain; charset="us-ascii"

 yeah, it is a dead horse, and seems to be personal preference.  Me... I will 

never

install a Bosch plug in one of my cars again, not when there is an NGK 

alternative.

I've dropped one too many Bosch electrodes into the cylinder on high boost 

applications.

Dave]

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