I have been using three electrode Bosch plugs for years. They are specified on the 911 3.6
liter Carrera and 911 Turbo. What is really surprising, is the increase to a warmer heat
range. The early 911S and all Turbos used a ridiculous cold and expensive W3DPO spark
plug. This little plug costs about $16.00 each and I have never removed one that
wasnt dark and sooty (indicating too rich or too cold of a plug!) Tuners of these
expensive Turbo and early 911S cars were, and are, reluctant to vary from the factory
specifications. This is a problem. as Porsche can not respecify the older cars without
recertifying the whole engine emission certification all over again. Porsche is not likely
to do this.
What is interesting though, is what has happened to the 911
Turbos. The trend became to increase the power output while meeting tighter emission
standards. The compression ratios were increased to 7.5:1 (from 7.0:1) and even
without knock sensing using a much hotter spark plug, the FR6LDC. This is a copper core,
double ground electrode mini spark plug. The fact that the Porsche factory specifies this
very warm spark plug for the awesome 3.6 Turbo is not so difficult to understand. I have
talked to Bosch, BERU, and NGK about their new applications for old W3DPO spark plugs, and
have been told that those were really too cold even for a
street Turbo. The factory originally specified them in the same way they specified spark
plugs for the special 356 Carrera 4 Cam, 911 S, 2.7RS and other higher performance
"street" Porsches. The factory expected these owner drivers to run the daylights
out of their Porsches and they did not want the engines to "ping" and detonate
from using non-German gasoline. So they specified cold spark plugs. It worked. The
911 Turbo came along at first as a batch of 500 only, to be sold originally for
"Friends of the Factory." They got the same treatment as the earlier specials.
Nothing changed until 1992.
The 3.6 Carrera has used Bosch FR6DTC triple electrode since
1989 and these run great. I started using these 3.6 spec spark plugs in just about all
911s and have had excellent results with them, especially in my own hard run Turbo
motor. I will keep my pile of old "W3DPO", but only for competition events.
In the near future, Ive been told that we may not see
the large inventory and range of spark plugs in our favorite auto parts store anymore, as
the new generation of plugs will be reduced to only a mere dozen or so types. It seems
these new plugs have such a wide range, that one spark plug will work perfectly in dozens
of different engine types.
Trouble with CATs
I got involved with an interesting problem this summer. The
owner complained of a rather sudden loss of power with his 911SC. The owner had the engine
worked on elsewhere and there were lots of new parts installed. Nothing really helped the
problem. I started with the basics: ignition timing, coil output, ignition cable & connector condition and resistance,
fuel pressures and fuel flow quantity, mixture sensitivity. etc. All was perfect. Now
troubleshooting the fun stuff: EGR valve, Aux. air regulator, friction drag
fan, air pump. Nothing there. However during the EGR check I did disconnect the exhaust
line as the exhaust header that supplies hot exhaust to the EGR itself. This line
was removed and with the engine running it positively removes a source of power robbing
exhaust gas from entering the induction system. Well that didnt help anything but
that open line certainly shot a lot of exhaust out. In fact it made quite a blast under
the car. I also noticed that when the car was started the engine caught right away
and seemed very healthy except when loaded down and labored.
I got a tip that the early
catalytic convener cars have had problems with the 'CAT' coming apart. The honeycomb
material incIting and breaking apart and restricting the exhaust flow. I removed the 'CAT'
and cranked it over: Blat. Roar !! No hesitation. No lagging. Just like a little
RSR. It ripped around the block a few times just to make sure. A good cat was installed
and this SC is as sharp as a tack.
The CAT had big pieces broken inside and the
honeycomb material was melted so thanks to Allen Faraballah I came out looking good.
Remember, a good engine should have a good blast from the exhaust pipe.
Installing Later Instruments in an Early
The early 911 and 356s secured their instruments to the
dash panel with 'U brackets and hand tightened screw nuts. This was an excellent
method until the area behind the dash was all filled up with ducts and other components.
The factory started installing instruments from the front in 1969 as access was impossible
without removing the whole ventilation system. You wouldnt want to do that! The
69 cars had a rubber sleeve that slides over the instruments and then the item would
slip nicely into the dash.
For the early cars there have
been all kinds of methods used to install the later instruments. Mostly duct tape wrapped
around the instrument until the right fit could be made. The problem is the duct tape does
not always hold the instrument flush with the dash and removal to replace a bulb becomes a
mess when the tape rolls up and the instrument is half in and half out of the dash.
Relief is on the way. VELCRO kits with a roll
of black fuzzy self sticking velcro. I use the 1/2 inch stuff cut into small
. about 2 inch pieces. Place the velco on the
instrument about 1/8 inch from the outer ring. You should trial fit the instrument without
the wires connected to get the fit right. If the fit is too tight trim off some of the
velcro and if it isnt snug enough add some more.
This idea came to me while browsing in a
hardware store. Ive been wondering why on earth it took so long to finally solve the
problem. I have been using this method since last winter with great results and it is much
easier than anything I have tried in the past.
Trouble with Buying New Tires
After a great Tire Tech last fall I would like to remind all serious Porsche owners to
recall the words of George Lugo from Yokohama Tire Company concerning being a good
customer by knowing and reading tire data of the tires that are going to be installed on
your car before they are installed on your car.
I have a good friend who ordered some new
Yokohamas for his RUF car and became alarmed at what was attempted to be installed on his
new RUF 8 & 10 x 17" wheels. I am impressed that this wise customer took
his curiosity a step further and stopped the installation because something didn't look
right while the tires laid out before him in this San Pedro tire store
To save you a long story, he had ordered four
new Yokohama tires with the rim protector on the side wall. What he got was hard 10
believe. First the next day delivery took two weeks to arrive. Then the two front
tires did not have the rim protectors and the tires themselves looked old. The rear tires
looked old also so he took them out in the sunlight for a good look. He saw that the paint
rings that encircled the outside diameter were nearly gone. The rubber flashing and
whiskers were all gone from the tread and most of the sidewall. The sidewalls had ozone
cracking and there were two small nails in the tread from use. To cap it all off someone
had stuck new tire stickers on the tread!
After his blood pressure receded my good
friend regained his composure and asked for an interpretation of the date of manufacture
code. What was to be installed was over four years old. There was an admittance of some
display use and maybe a prior mounting. An offer to knock off $30 from each tire was as
made. My friend was on his way to another --- any other tire store. A day later this
tire store wanted the prospective customer to pay for shipping the tires to the San Pedro
store. That did not happen.
This RUF owner is now
rolling on a real NEW set of Toyos and has exactly what he needed.
Lesson: Just because it looks new and
is round and shinny, black and smells like a new tire, it does not mean it is one.
You are the person with the
wallet full of hard earned money, so take the time. Ask how is the tire you are
buying rated for wear, wert & dry traction? Ask the sales person how you can
locate and understand the date of manufacture.
I always go to the store and
ask for a copy of the data sheet for the specific tire I want. These are very
helpful when determining the real width and diameter of the installed tire, espeically if
you are upgrading to a new wheel size. A 225 45 x 16 of one manufacturer is very
different in actual size than another manufacturer'st tire. After you pay for the
special order and install them on your wheels, it is too late to return them.
Ask the representative tire
retailer how you can interpret the data codes. If they do not know how to or show no
interest in helping, go somewhere else.
Lastly, the haunting thing that
Yokohama's Georgre Lugo reminded us of is that a brand new high performance tire that has
been stored too long will never perform well and may be unsafe. Tires are life
limited as the rubber ages and deteriorates with time.
My good friend with the RUF car
had a 930 with tires that looked new, but were over nine years old. His airline job
and family took most of his time, so the tires aged-out before they wore-out. One
afternoon while acceleratirng past 60 mph on I-10, the left rear tire exploded. Big
Time. The driver thought the car would flip as he fought to control it. When
he got off the freeway, he found the tire in shreads. He eventually discovered all
four tires were weather cracked through the sidewall and showed signs of tread separation.
His concerns should be a warning to all of us.
Lee Rice writes the monthly Technical & Safety column for the
Orange Coast PCA (zone 8) Newsletter. He has
generously allowed Pelican Parts to republish these articles here for the benefit of
everyone who visits the site.