MSD customer Scott Bryce, of Australia, builds 650hp Hummers and races
them in Outback desert. Bryce, who also builds and races a variety of other
off-road vehicles in his spare time, sent a letter to the MSD offices that
tells about his experiences with the 8.5mm Super Conductor Spark Plug Wires. Bryce
was not asked to give MSD an endorsement, but instead simply wanted to share
what he had learned. Read Bryce’s entire letter below.
Are “Low Resistance” Spark Plug Leads all the same?
Scott Bryce – PROFORMANCE
After many months
of annoying black spark plugs, Proformance Motorsport recently changed our
Spark Plug Leads to the Awesome MSD 8.5mm Super Conductor Leads.
The Result – AN
When our new small block Chev engine was screaming
between 5000 and 8000 RPM on the engine Dyno our new race engine showed
absolutely no signs of poor spark or poor performance. The motor sounded
awesome, our crew was excited and we all thought “Job Done”, lets get it bolted
into the race truck!
Our problems started after the
engine was bolted in our truck and the engine was run at idle a few times to manoeuvre
our race truck inside our race shop or when the beast was loaded on or off our
race car transporter.
When driven at slow speeds, or when running at idle
for a few minutes, the motor would start to backfire and run badly (Very
Badly). Our Digital Dash quickly pointed out the problem - the front four
engine cylinders were burning at lower temps than the rear cylinders.
Further investigation showed that the front two front spark
plugs (Cylinders 1 and 3) were completely fouled with thick black carbon,
resulting in absolutely “No Spark”. The next two spark plugs (2 and 3) were removed
and found to be black with carbon, (not quite as bad as 1 and 2) and the rear
most plugs (5-8) were a nice Tan colour as we saw on the Dyno.
A quick change of the front four spark plugs
(Cylinders 1-4) saw the engine come to back life and BOOM, our race truck
engine was again the fire-breathing beast we all saw on the engine Dyno. We
took the Truck out Testing and the engine screamed at high revs, ran for hours of
testing and everyone was again happy.
After loading the truck up on the trailer and moving
it around the workshop (dozens of times) to make way for other vehicles, our
crew began to notice the bad idle and backfiring had returned!
Without even looking at the data logger or exhaust
temps, we quickly removed the first four plugs and sure enough they were again covered
in black soot and carbon, resulting in NO SPARK. We checked the ECU parameters,
Air Fuel Ratio, Computer Settings, we changed coils, checked our ignition wiring,
checked our fuel pressures, checked compression – we checked everything and
found nothing. Every time we put in a new set of plugs, the engine was FINE
when driven hard, but when driven at low speeds, moving the truck back and
forth to car shows and events, and around our property, the front four spark
plugs would simply foul up after 10-20 minutes of low speed driving.
A good friend of mine Kevin happened to be visiting
our race shop whilst I was again busy changing my spark plugs (for the 6th
time in a few short months) and asked me if the problem could be a spark plug
lead. Whilst I appreciate that Kevin is a very smart business person, a race
engine builder he is NOT, so I initially shrugged off his “Silly” idea
suggesting to Kevin that all four front cylinders are playing up and the
chances of me having Four Dead leads in a single batch were pretty low because
the plug leads were brand new only 3 months ago.
Then it hit me! When we had the engine on the Dyno, because
of the longer lead lengths needed to fit the engine and computer harness onto
the Dyno, our team had used some “old” leads from one of our big block Hummer
Engines. The brand new leads I was running on the Small Block were indeed new,
but a Brand and Type I had never used before.
I suggested to Kevin that I thought the longer leads
running to the front cylinders could have a much greater resistance than the
shorter leads (Half the length) that feed the rear cylinders and that the
longer leads are resulting in poor spark at low revs, but could be working ok
at higher revs.
I quickly removed the longest of my now “questionable”
(3 Month Old, Brand XXX) spark plug leads and replaced the spark plug lead with
an old MSD lead that I had lying around on a shelf. Even with the fouled spark
plug, the dead cylinder that was fitted with the MSD Lead fitted came back to
life and the exhaust temp of that cylinder came back to normal. I immediately thought,
“Now we were getting somewhere”. I was super excited and Kevin was feeling a
bit smug knowing it was he that had suggested the lead or leads in the first
place. (Don’t you hate it when one of your mates pops around and solves your 3-month
problem in a few seconds)?
Not satisfied with the test results,
I had to know why one lead worked and the other did not. I measured the leads
and the resistance was low as suggested by both manufacturers.
Anybody that knows me will understand my absolute
passion to get to the bottom of something and I just “had to know” what was
wrong with this questionable lead (And the other three leads that were are
causing the my spark plugs to foul up with carbon.
I then grabbed 3 month old, super duper “low
resistance, Brand XXX “racing plug lead” (I have not mentioned the Brand - it
makes my blood boil) and cut it in half to look inside. I then stripped the
shiny and brightly coloured (Yes they did indeed LOOK like they belong on a
race car) silicon outer layer to reveal the “conductor core” of the plug lead (the
bit that sends the electrical spark to the plug)
Much to my surprise (After spending quite a few of my
Race $$ on this high quality set of “Race Leads”), the plug lead I was holding
in my hand had an “inner core” that I can only describe as a tiny 2.5mm black flexible
rubber “o-ring” stretched out straight. Being an electronics engineer, I
understand that a low resistance lead will result in greater spark at the plug,
but I thought how the hell is electricity ever supposed to travel down this
black rubber stuff? (We are all told at school that rubber is after all an
insulator right?) I know that Spark Plug Lead manufacturers advertise graphite
core, carbon core, low resistance leads etc, but come on, whilst the material
that this core did indeed have a low resistance (As stated by the manufacturer),
the inner core was clearly manufactured from was flexible like rubber substance
and was OBVIOUSLY the cause of my poor spark, my engine problems and my
Now to compare, I then grabbed the old MSD 8.5 Super
Conductor Lead, cut it in half and again stripped the Outer Layer off to reveal
a much larger conductor core that had a tiny wire strand would tightly around the
core. I also noticed that the MSD silicon insulator was manufactured from a few
different layers/colours of silicon AND some sort of white fibreglass looking heatproof
material between each of the silicon layers. Needless to say, I was very
impressed with the MSD Lead, when compared to the “rubbish” lead that I was
holding in my other hand.
Here I was sitting at my bench with a super duper
brand XXX Plug lead with nothing inside it but what appeared to be a black rubber
band and an old MSD lead with multiple layers of insulation, heat proof
fibreglass, large conductor core and some sort of tiny copper wire wound
tightly around the core. I investigated further and pulled at the tiny wire
strands. As it unravelled it revealed a stiff inner core that felt very
different to the rubber feeling core that I found in my “questionable” plug
After a restless night’s sleep (ask my wife) tossing
and turning thinking I have solved one of the world’s greatest mysteries, at
the crack of dawn I jumped in the car and headed straight to the nearest speed
shop to grab a set of MSD Spark Plug Leads to confirm my findings and get the
engine to idle without fouling plugs once and for all. I had a few arguments
with one race shop owner who kept asking me “Why do you specifically want an
MSD leads when my Brand XXX Super Duper Race Lead are even better?” He wanted
to show me chart after chart to explain to me that the resistance per foot of
his Brand XXX leads were lower than the Resistance Per Foot if the MSD leads I had
I then had a strange sense of Déjà vu – I remember
having a similar conversation when I purchased the “questionable” set of leads
a few months earlier from another race shop. I then concluded that whilst the
leads I had purchased previously were indeed low resistance (I even tested them
with a multimeter), the inner core that provided the “low resistance” on
paper, looked like rubber, felt like rubber and performed like crap at
sending a 40,000 Volt spark to my plugs. I was simply not in the mood for
testing another brand of “Super Race Leads”!!
I stood my ground went somewhere
else and purchased a set of MSD 8.5mm Super Conductor Leads and fitted them to
the engine. Even with the fouled plugs, the engine ran fine.
I changed the plugs one more time
and when we took the truck for another test session. We immediately noticed a
dramatic increase in throttle response, much more low-end power & torque
and the engine absolutely screamed at high revs. It simply sounded different - just
like it did on the engine Dyno. I would have NEVER believed that a set of plug
leads could have caused so much frustration and so many headaches to my team. I
have since purchased a 20 Meter length of the MSD 8.5mm wire and the MSD plug
lead “crimps” and I keep them all on my race trailer just in case!!
In summary, don’t get fooled by Brand XXX race lead
with “Super Low” ohms per foot or silly comparison charts showing how great one
lead is compared to the other. Purchase a brand of ignition components that you
know and trust (Not some new brand that comes from china in a shiny box with a
comparison chart). Use what has worked for you in the past and if you are new
to this sort of thing or if you are ever in doubt, use what millions of racers
use worldwide - grab a set of MSD leads and relax knowing that any future engine
“misfires or headaches” will NOT be caused by the spark plug leads!
I hope this has been useful to someone in “race car
land” and prevents the hours of frustration we went through to find the cause
of our problem.
On Friday, May 6th car enthusiasts came out to MSD Ignition's 7th Annual Employee Appreciation Show and Picnic. This year featured a little over 80+ cool cars and customs along with fun and games for the whole MSD family. We would like to thank everybody that came out and made it a successful event. The winners of the car show are as follows: