Conrods and Pistons
Q: Do I need to rebalance my engine if I fit
Atomic conrods to my XR6-T?
A: As the engine is an inline configuration, the
conrod and piston weights are not a function of
the balance factor of the engine (as they are in
a V configuration engine), so they can be
installed without rebalancing the engine.
Q: Are Atomic conrods made heavy to make them
A: Atomic conrods are machined from high quality
alloy steel with a tensile strength many times
greater than standard conrods. Part #306200
“Superleggera” as the name suggests, is lighter
than the stock BF conrods by approximately 30
grams. The brutally tough “FatRod” is
approximately 50 grams heavier than a stock
Q: Why do Atomic conrods have numbers on them?
A: This is to identify the conrod and its
matching cap - they are machined together so a
cap will only fit its matching conrod. We number
them so you don't have to.
Q: Why do some forged pistons make noise?
A: Forged pistons expand more when hot so they
require a greater physical clearance than a cast
piston. From 2004 to 20006 we used custom forged
pistons made to our specifications from a
proprietary aerospace aluminium alloy, which
operated at the industry's tightest piston to
bore clearances. They were reasonably quiet and
very durable, but when cold they made a slight
operational noise. There were some other pistons
on the market which were quieter but were not as
durable, so we believed it was better to install
the strongest piston available and accept a
small amount of operational noise. In 2005 we
began working with Mahle Motorsport and in 2006
we released a forged piston for the Ford DOHC
engine. This was a good piston but it developed
cracks in the skirts over time. Unable to
achieve a satisfactory product to handle the
power we sought, we went straight to the
ultimate in piston engine manufacturers,
Cosworth Engineering in the UK. They evaluated
our current problems and designed a true racing
piston for the Ford. Taking cues directly from
the current Cosworth V8 F1 engine, our piston is
forged from the very same material as used in
Formula One pistons, and have all the F1 tricks
like hi-leverage skirts, anti-detonation bands,
pressure fed gudgeons, coated skirts and make no
operational noise whatsoever. We believe these
are the best pistons ever made for the Ford
inline 6 cyl and will be ann integral part of
all SOHC and DOHC engines and rebuild kits since
Q: What is the torque setting for the conrod
A: Please refer to the instructions that come
with the conrods or refer to our Tech Department
for detailed instructions.
Q: Your Superleggera conrod
was 600kW rated but I saw they are now 698kW
A: From 2008 all our #306200 Superleggera
conrods are rated to 698kW because in 2007 we
redesigned them to provide pressure fed oil to
the gudgeon pins and, as a consequence, the
beams of the conrods were widened. This
increased the yield strength of the conrod by
12% approx, hence the increase.
Q: What is pressurised gudgeon pin oiling?
This is another Atomic innovation, borrowed from
diesel engine technology. We redesigned our
conrods in 2007 to provide a pressure feed of
engine oil to the load side of the gudgeon pin
bush, thereby providing oil directly to the
gudgeon pins and bushes. As turbo/supercharged
engines make more power than their normally
aspirated cousins, the forces of combustion are
far greater which leads to excessive pin/bush
wear. Providing pressurised oil feed to the pins
increases life of the engine considerably.
Q: Which face is the front of the conrod?
A: It is a symmetrical design so can be
installed in either way - most engine builders
install them with the bearing nips facing the
passenger side of the engine, or with our logo
to the front.
Q: Ford uses a stronger conrod in the Typhoon, why can't I put a set of those rods in my
A: Ford identified the XR6-T needed a stronger
rod very early on with the BA, but due to cost
constraints they could not afford to fit a set
of rods like ours to every vehicle, so they
chose to fit the LPG conrod. It is marginally
stronger than the stock XR6-T conrod, but they
still fail. Conrods are even failing in standard
vehicles, which are usually due to detonation
and often occurs due to an overboost situation
or the use of low octane/poor quality fuel.
Excessive cylinder pressures of
detonation/pinging fatigues the conrod, which
results in it bending or breaking, or both.
Q: What are your Nissan RB30 Conrods rated to?
A: We make two models for the RB - our #356200
is designed for a 21mm (std size) gudgeon pin
and are rated to 100kW per cylinder. Our #356201 conrod has a 22mm pin and is rated to 120kW per
Q: I got a set of conrods and the gudgeon pins
don't fit in the bushes. What's wrong with them?
A: Nothing is probably wrong with either - you
probably have a set of semi-finished conrods.
Atomic supply them (part #306200 and #306201-SF)
undersize so professional engine builders can
hone the big and little ends to provide the
exact clearances they require. Please contact
Atomic and we will recommend an Engine
builder/machine shop in your area that can
finish-hone the rods to size, or we can do it
for you free of charge.
Q: Is it OK to use a rattle gun set at 45 ft lbs
to tighten the conrod bolts?
A: No - you should NEVER use a rattle gun to
tighten any engine fasteners. Please refer to
the installation instructions or contact Atomic
Tech department for further information.
Q: What's the small
hole for in the side of a standard Ford conrod?
My engine guy said it
A: The small hole is an oil spit hole to provide
oil to the major thrust side only of the
cylinders and has nothing to do with detonation
whatsoever. We provide oil to both major and
minor thrust sides by way of conrod side
clearance, alleviating the need to put a hole in
the side of the conrod, which weakens it
considerably. I would be very wary of an “engine
builder” who was not familiar with the purpose
of a spit hole in a conrod. Ford have included
them since 1964 in 6 cyl engines.
Q: Which way does the cap fit on the conrod?
A: The cap is to be fitted with the numbers on
the side of the conrod and the side of the cap
aligning with each other. This can also be
checked by ensuring the bearing nips (cut into
the big end tunnel) are on the same side of the
Q: What is the purpose of piston crown cooling?
A: This is designed to help remove heat from the
piston by spraying oil onto the underside of the
piston. It is common practise in many high
performance engines such as the Nissan Godzilla
2.6Ltr engine, Sierra Cosworth, Porsches, etc.
We are the first manufacturer to offer this
feature in Ford DOHC engines and it will be
included in all of our Ford engines and rebuild
kits from 2008.
Engines and Rebuilding
Q: My XR6-T is stock except for a high flow air
filter, yet I had an engine blow up due to a
broken conrod. Ford replaced the motor under
warranty and it happened a second time. Why
doesn't Ford fit your conrods to their engines?
A: Ford identified the problem with the conrods
and fitted the LPG conrod to the Typhoons, which
are marginally stronger, but still break. The
main problem of conrod failure in stock vehicles
is pinging/detonation due to poor quality, the
wrong type of fuel or poor tuning. Atomic
conrods are machined from premium quality alloy
steel and are made far stronger than they need
be to provide an extra margin of durability. The
bottom line is they are too expensive to be
fitted to every vehicle coming off the assembly
Q: Can you rebuild my Ford XR6-T engine, or do I
need to buy a whole new performance short motor?
My engine has a knocking noise but still runs.
A: We can rebuild your engine if it is running
or not. Once the conrod breaks the serious
damage occurs, so if this has not happened as
yet we can remanufacture your engine with all
the same high performance internals as fitted to
our performance short and long motors. It works
out to be less expensive than buying a new short
motor, as replacing the block and/or crankshaft
and sump is not required. All of your original
engine parts will be magnaflux (crack) and
ultrasonic tested to ensure that are as good as
new, or we will not re-use them.
Q: What is the difference between an Atomic
performance short motor and an Atomic
performance long motor?
A: A short motor comprises a block, crankshaft,
conrods, pistons, rings, bearings and windage
tray as a balanced, clearanced and assembled
package. It does not include the cylinder head
or sump, and subsequently is "shorter" in
stature than a complete engine, hence the term.
A long engine is just that; a short engine with
a cylinder head, valvetrain, rocker cover,
camshaft drive system, oil pump, timing cover,
harmonic balancer and sump fitted. All you then
need to do is fit the external accessories, such
as manifolds, alternator, engine mounts, etc
before re-fitting to vehicle.
Q: If you were to rebuild my engine, how would I
get it to you?
A: We have palletised shipping arrangements in
place across Australia and can arrange
transportation of your engine to us and back, or
get one of our engines to you at very
competitive rates. We can also recommend a
number of specialist workshops in most States to
undertake the removal, reinstallation and
retuning if required. We also work closely with
a number of Ford Dealers across Australia and
can ship engines and/or parts directly to any
Ford Dealer no problems, should your vehicle be
located there for repairs.
Q: Will Atomic conrods fit pre BA "Barra"
A: Yes they will - the inline Ford engine comes
in various configurations and most share the
same crankpin diameter of 2.1234". In engines
other than the Barra, they require the use of a
custom piston due to Ford using a range of
different diameter gudgeon pins. Our conrods are
designed to accept a .866" dia gudgeon pin and
we can supply bulletproof rod/piston combos for
EB and AU Ford 6 cylinder engines.
Q: Which is the major thrust side of the
cylinder wall and why did my block crack in a
non thrust related position? I expected it to
split across the block due to heavy loading from
the skirt of the piston.
A: The major thrust side on an engine that
rotates clockwise is the drivers (left) side of
the cylinder, as viewed from the front of the
car with the engine in place. The common cause
of bore splitting is usually due to detonation,
and this "abnormal" combustion is more akin to
dynamite being ignited in the cylinder rather
than normal combustion pushing the piston down
in a controlled fashion. This explosive force
sends shock waves in all directions and the
thinnest part of the cylinder usually fails.
This is why we ultrasonic test cylinder wall
thicknesses in all cylinders in 4 locations - to
determine if a block has suffered from core
shift when manufactured and rejecting ones that
do not meet minimal thickness requirements.
Q: Do XR6-T Ford 6 cylinder engines suffer from
crankshaft problems when making big power?
A: We have never experienced a total crankshaft
failure in any of our engines and have only seen
total crank failures as a result of hydraulicing.
The problem of bottom end strength is in the
lack of rigidity of the main bearing caps. Even
though the caps are tied into the alloy sump via
cross-bolts (turning the cast alloy sump into a
stressed member), it does little to keep the
tunnels in alignment when making upwards of
400+kW. We now have a range of steel main cap
girdles to alleviate main cap "walk" - please
contact our Sales Dept for further information.
Q: Why do many DOHC Ford engines have problems
with #5 piston and/or conrod once an aftermarket
plenum is fitted?
A: This is because of the plenum design and the
placement of the throttle body to the front.
Flow bench testing has revealed there can be a
flow difference of 10+cfm per runner, which
equates to a leaner mixture in the cylinders
with the higher flow. These are the cylinders
toward the rear of the engine and vary depending
on the manufacturer of the plenum. We find the
factory plenum is very even in flow (all runners
within 5%) due to the central intake location.
However the runner length and plenum volume is
too small to support power greater than 550kW.
Harmonic Balancers, Pulleys etc
Q: Why did the scrutineers at the drags tell me
to get a new harmonic balancer for my car before
I come back next time?
A: If your vehicle can run quicker than 12
seconds in the quarter mile it is mandatory to
fit a balancer that satisfies ANDRA
requirements. All Atomic balancers satisfy ANDRA
Q: Does my new Atomic balancer require
rebalancing before being fitted?
A: No - it has been balanced to zero and can be
fitted as is.
Q: How much does the Atomic balancer for the
A: It weighs 3.6kg, which is approximately 300
grams less than a stock balancer.
Q: Why do you make a pulley for the RB26 Nissan
that is oversize?
A: To slow down the water pump by approximately
8%. This reduces the horsepower losses at the
pump and reduces water cavitation at high engine
Q: Why do some companies sell a lightweight
alloy hub for the Subaru WRX to replace the
factory harmonic balancer?
A: These hubs do not function as a vibration
absorption device and lead to premature
crankshaft failure. If a harmonic balancer was
not required, Subaru engineers would have not
put one there in the first place. Our balancers
do a superb job of absorbing torsional vibration
and satisfy all ANDRA requirements.
Studs and Bolts
Q: Can I reuse the old head bolts in my Ford 6
cyl turbo when the head is being refitted?
A: No you boxhead, you cannot - the OE bolts are
TTY (Torque to yield bolts) and once they have
been torqued in place they have “yielded” which
means they have exceeded the “plastic”
deformation state - in other words they are
stretched. We suggest you fit a set of
Atomic head studs. They can be reused many times
and apply approximately 30% more clamping force
(at the same torque) than a bolt. If you are
really going to crank things up we suggest you
upgrade to a set of our 14.3mm head studs. They
require drilling and tapping of the block to
fit, plus enlarging of the clearance holes in
the head, gasket plus a set of our oversize head
to block dowels.
Q: My mate makes hi flow injectors at home by
drilling out stock injectors. Are these OK to
use with your engines?
A: We do not recommend the use of drilled
injectors under any circumstances. Injectors are
very precisely machined components and we have
found it is impossible to replicate the exact
entry/exit profiles and orifice cross sections
when drilling out the original holes. We only
recommend the use of new injectors manufactured
with the flow volume you require.
Oil Pumps etc
Q: What is a windage tray?
A: A windage tray is a louvered or contoured
sheet metal device that fits between the rotating
components of the engine (crankshaft and conrods)
and the oil in the sump. It acts as a barrier to
prevent oil being whipped up by the spinning
crank mass, thereby creating heavily aerated oil
in the engine. It has a twofold advantage; the
parasitic losses created by the whipped up oil
cloud are quite high, costing horsepower; and
the second advantage is that the oil is kept in
a more liquid state in the sump rather than a
frothy, aerated mix so therefore your oil pump
can supply the engine with a plentiful supply of
liquid oil rather than a gaseous oil/air mix -
your bearings will love you for it!
Q: Why do some XR6-T engines suffer oil pump
failure? Does Atomic have a fix?
A: Oil pumps fail in turbo engines (mainly
manual transmission cars) due to torsional
vibrations of the crankshaft being transferred
to the oil pump gears, which are driven directly
off the front of the crankshaft. The Original
equipment (OE) gears are made from powdered
metal and lack the ability to withstand the
additional torsional moments generated by high
horsepower engines. Hydraulic pressure also
splits the oil pump housings open when engines
are revved beyond the standard rev limit.
We have two fixes for the problem:
1. #306100 Hi-Mass harmonic balancers absorb
more damaging torsional vibration therefore
reducing harmonics transmitted to the oil pump
2. #306751 billet gear oil pump. Our gears are
made from EN-26 steel, heat treated and black
oxide coated for both durability and appearance
and are virtually indestructible. The oil pump
also has a high flow pressure bypass circuit to
ensure oil pressure is maintained at the correct
levels, irrespective of RPM. The pump is a
bolt-up replacement item with no modifications
required to fit. These are bullet-proof!
Cylinder Heads and Valvetrain
Q: Do Atomic valve
springs for the XR6-T fit
straight in or does the head require machining?
A: The springs are a drop-in replacement and no
machining is required.
Q: Can I fit a set of your cams to my BA engine
without changing the valve springs?
A: No you can not. Our camshafts open the valves
a little earlier, close them a little later and
the rate of valve lift is quicker compared to
the original cams, thereby allowing greater
volumes of intake charge and exhaust gas to be
passed. As the valves lift further off the seat,
the original valve springs do not possess
sufficient tension or free length to allow the
valves to move in accordance with our camshafts.
Q: I was quoted $1400 to supply and fit a set of
H/D valve springs to a Ford Turbo 6 cylinder - is
this the usual cost for this job?
A: No, it is not. Our springs are priced from
$396/set and the labour to install should be
Q: Why do you produce 3 different
for the Ford DOHC engine?
A: This is because different customers have
different requirements - our #306800 spring
works perfectly up to 1.4bar boost. #306801 and
802 are for high boost applications.
Q: What is detonation or pinging?
A: Pinging, knocking or detonation are terms for
a rattling sound that emanates from the engine
when under load and sounds like nuts/bolts
rattling around in a hubcap. It is the sound of
destructive, abnormal combustion and severely
shocks the conrods, pistons and crankshaft. You
may or may not be able to hear the noise, which
means that damage can occur to your engine
without you knowing about it. Detonation is
another name for pinging. Higher octane fuels
and quality tuning is required to keep pinging
Q: What is a torque plate and what is torque
A: A torque plate is a large steel plate that is
bolted (and torqued up with a head gasket) to
the top of the cylinder block when machining
operations such as cylinder boring/honing etc
are carried out. Its purpose it to simulate the
stresses applied to the block when the cylinder
head if fitted, making machining operations far
more accurate. It is quite surprising how much a
torqued cylinder head will distort the bores,
especially in engines with only 4 bolts per
cylinder (such as Ford 6 & 8 cyl engines). We
have witnessed bore ovality of .0005" to .001”
occur when torquing the plate in place, so its
use is mandatory in performance machining
operations. At Atomic we manufactured our own
torque plates and they are used on each and
every one of our performance engines when honing
cylinders to the required finished size.