Conrods and Pistons

Do I need to rebalance my engine if I fit Atomic conrods to my XR6-T?

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. 

Are Atomic conrods made heavy to make them stronger?

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 conrod. 

Why do Atomic conrods have numbers on them?

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. 

Why do some forged pistons make noise?

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 July 2010.

What is the torque setting for the conrod bolts?

Please refer to the instructions that come with the conrods or refer to our Tech Department for detailed instructions.

Your Superleggera conrod was 600kW rated but I saw they are now 698kW rated. Why?

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.

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.

Which face is the front of the conrod?

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. 

Ford uses a stronger conrod in the Typhoon, why can't I put a set of those rods in my engine?

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. 

What are your Nissan RB30 Conrods rated to?

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 cylinder. 

I got a set of conrods and the gudgeon pins don't fit in the bushes. What's wrong with them?

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. 

Is it OK to use a rattle gun set at 45 ft lbs to tighten the conrod bolts?

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. 

What's the small hole for in the side of a standard Ford conrod? My engine guy said it stops detonation.

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.

Which way does the cap fit on the conrod?

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 tunnel.

What is the purpose of piston crown cooling?

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

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?

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 line.

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.

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. 

What is the difference between an Atomic performance short motor and an Atomic performance long motor?

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. 

If you were to rebuild my engine, how would I get it to you?

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. 

Will Atomic conrods fit pre BA "Barra" engines?

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. 

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.

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.

Do XR6-T Ford 6 cylinder engines suffer from crankshaft problems when making big power?

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.

Why do many DOHC Ford engines have problems with #5 piston and/or conrod once an aftermarket plenum is fitted?

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

Why did the scrutineers at the drags tell me to get a new harmonic balancer for my car before I come back next time?

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 requirements. 

Does my new Atomic balancer require rebalancing before being fitted?

No - it has been balanced to zero and can be fitted as is. 

How much does the Atomic balancer for the XR6-T weigh?

It weighs 3.6kg, which is approximately 300 grams less than a stock balancer. 

Why do you make a pulley for the RB26 Nissan that is oversize?

To slow down the water pump by approximately 8%. This reduces the horsepower losses at the pump and reduces water cavitation at high engine RPM. 

Why do some companies sell a lightweight alloy hub for the Subaru WRX to replace the factory harmonic balancer?

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

Can I reuse the old head bolts in my Ford 6 cyl turbo when the head is being refitted?

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.


My mate makes hi flow injectors at home by drilling out stock injectors. Are these OK to use with your engines?

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

What is a windage tray?

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!

Why do some XR6-T engines suffer oil pump failure? Does Atomic have a fix?

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 gears.
  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

Do Atomic valve springs for the XR6-T fit straight in or does the head require machining?

The springs are a drop-in replacement and no machining is required. 

Can I fit a set of your cams to my BA engine without changing the valve springs?

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. 

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?

No, it is not. Our springs are priced from $396/set and the labour to install should be around $450-500.

Why do you produce 3 different valve springs for the Ford DOHC engine?

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.

Cylinder Heads and Valvetrain

What is detonation or pinging?

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 under control. Click here to view a report from Metallurgical Testing & Consulting Engineers in relation to a customer's engine failure.


What is a torque plate and what is torque plate honing?

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.

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Durability and performance are our focus at Atomic Performance Products

With years of experience developing and testing our products, you know you'll get high quality performance products that are built professionally.

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