[s-cars] Re. Spark plug

Tue Dec 14 18:07:32 PST 2010

You can add me to the list of dropped electrodes.  I had one ruin a coilpack
for me as it basically created a short.
--Calvin

-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com]On Behalf Of qshipq at aol.com
Sent: Tuesday, December 14, 2010 9:31 AM
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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