Archive for category: Technical

An essential stage when designing a crankshaft is to ensure that it is as well-balanced as possible. This is normally done with the addition of counterweights, which will counteract the inertia forces and couples created by the rotating and reciprocating masses. If a crankshaft is not correctly balanced then it can lead to excessive vibration, which will have a detrimental effect on reliability.

At the heart of every piston-powered engine sits a crankshaft, to convert the reciprocating motion of the pistons into rotational movement. The movement of these piston assemblies, connecting rod assemblies and the crankshaft itself creates large inertia forces and couples, which in most engine configurations have to be balanced out with webs and counterweights on the crankshaft. These forces and couples will manifest themselves as vibration, which if ignored can drastically reduce the reliability of both the engine and the car.

Bad Vibrations

A poorly balanced crankshaft can drastically reduce the reliability and performance of an engine. First of all, the out of balance forces will subject the main journal bearings to higher loads than they are designed for. Most main journal bearings are plain bearings, relying on a constant film of oil for lubrication; an increase in load will reduce the oil film present, which in turn will lead to a loss of power. Should the oil film start to break down under excessive loading, then the bearings will wear out quicker than intended.

The imbalance within the crankshaft may cause it to distort (both in bending and in torsion). This distortion also has a negative effect on main journal bearing performance as the edge loading of the bearing is increased.

Externally, the loads from the crankshaft are transmitted to the mating chassis through the engine mounts. It is often not possible to incorporate any damping into these mounts, particularly when an engine is installed onto the back of a single-seater monocoque, so these vibrating loads are passed through to the driver; in the past, drivers have been known to suffer from visibility issues when racing because of badly balanced crankshafts.

Vibration from the engine will also affect the reliability of components mounted to the chassis, from minor ancillary parts through to important structural members. So a car’s reliability can sometimes be greatly improved just by better crank balancing.

Calculation of Balancing Forces

While the primary objective of the crankshaft is to convert the reciprocating motion of the pistons into a rotation movement that will turn the engine’s output shaft, it also has another job to do: to provide opposing forces and couples to balance the forces from the moving parts in the crankcase, thereby reducing the amount of engine vibration.

A perfectly balanced engine would exhibit no vibration, such that it could be suspended in mid-air and not move. Of course, in reality that is almost impossible; however, the dynamic forces and couples can be virtually eliminated for some engine configurations.

As mentioned, the dynamic forces are due to the movement of the internal masses within the crankcase. The masses attached to the crankpins can be broken down into two categories: rotating and reciprocating.

Rotating masses consist of the crankpin bearings, big-end bolts and a proportion of the connecting rod mass that is centred on the crankpin. Also not to be forgotten when considering the rotating mass is that of the crankpin itself, plus any lightening hole bungs that might be present. The reciprocating masses will include those of the piston, gudgeon pin, bush, rings and clips, plus the rest of the connecting rod.

The proportions of rotating and reciprocating masses of the connecting rod are normally expressed as the rod’s big-end and small-end masses, and are derived by taking moments about the rod’s centre of gravity. Assuming that a 3D CAD model of the connecting rod exists then most CAD software packages can quickly give the position of the centre of gravity for the rod. Alternatively, before the advent of CAD, the traditional method to determine the big- and small-end masses would have been to weigh the connecting rod on two scales, with one scale on the split line between the rod and cap and the other on the small-end centreline, whilst keeping the connecting rod centreline horizontal.

Next, consider the reciprocating motion of the piston. The acceleration of the piston can be broken down into a series of sinusoidal waves, which can be expressed as:

where θ is the crank angle from the cylinder centreline, r is the crank throw, n is the crank throw divided by the rod length and ω is the angular velocity of the crankshaft. There are higher-order cosine terms, but these are not normally considered.

It follows that the inertial force F_rec created by the reciprocating motion of the piston is:

where m_rec is the mass of the reciprocating parts. The first half of this equation is termed as the primary reciprocating force, and the second half the secondary reciprocating force. As these primary and secondary forces act along the cylinder centreline, they will create a corresponding primary couple and secondary couple about the front and rear main journals.

There is also an inertial force F_rot and associated couple created by the rotating components, which can be found from the equation:

where m_rot is the mass of the rotating parts.

In a similar manner, the inertial forces F_web from the rotating webs (including counterweights) can also be found, as:

where m_web is the mass of the web (including counterweight) and r_web is the distance from the centre of gravity to the crankshaft centreline. A 3D CAD model can give a very good measure of both the mass and the position of the centre of gravity of each web.

The inertial forces and couples from the webs will only be able to balance out the forces that are occurring at once times engine speed. The secondary forces are occurring at twice engine speed, and so would need to be balanced out by external balance shafts rotating at twice engine speed.

As it is not possible to completely balance out the secondary forces and couples, crankshaft designers often cite a balance factor, usually as a percentage. That is the percentage of the reciprocating mass that when added to 100% of the rotating mass will be balanced by the webs (including counterweights).

Typical values for balance factors are around 50% for most crankshafts; anything lower will give a lighter crankshaft but at the detriment of balance. Ultimately, the chosen balance factor is a compromise between crankshaft weight, main journal bearing performance and engine vibration.

Aside from the design of the crankshaft webs, the other crucial factor in engine balancing is the configuration of the cylinders in the engine. The number of cylinders, and for vee arrangements the angle between the two banks of cylinders, will have an enormous effect on the summation of the inertia forces and couples. In some layouts, particularly those where two banks of cylinders are opposing one another (usually termed a ‘boxer’ layout), the first- and second-order forces can cancel one another out.

The Bosch Automotive Handbook gives a very concise summary of the first- and second-order forces and couples for a number of popular cylinder arrangements. The configurations that will have zero first- and second-order forces include the inline three-cylinder, four-cylinder opposed, inline five-cylinder, six-cylinder 90° vee, six-cylinder 60° vee and eight-cylinder 90° vee layouts. Even better are those arrangements that also have zero second-order forces and couples, which include inline six-cylinder, six-cylinder opposed, and 12-cylinder 60° vee layouts.

Its worth mentioning that crankshafts are normally also dynamically balanced after manufacture. The out-of-balance forces and couples can be measured by spinning the crankshaft on a balancing machine, and material can be removed from highlighted areas on the crankshaft to bring these forces and couples down to below preset targets.

Introducing the Modatek Crank Calculator

There are many different methods used by crankshaft designers to ascertain the required balancing and then decide on the shape of the webs. Using the theory shown above, it is possible to construct a spreadsheet in Microsoft Excel to calculate the reciprocating and rotating inertial forces acting on the crankshaft at a given crank angle and engine speed for each cylinder and web along the length of the crankshaft. Taking moments about the main journal centre positions, the spreadsheet can then be used to determine the inertial forces and couples that are transmitted to the main journals.

At Modatek, we’ve gone one step further (well, quite a few steps actually). We’ve combined the crank balance calculations with our own crankshaft torsional calculator, to create a tool that can predict rod and main bearing loads, front and rear net forces, torsional frequency and torsional ampltitude.

We’ve been gradually developing this tool, and its now available for a number of different engine configurations, including inline-4 and V6 layouts.

If you’d like to learn more about our crankshaft calculator then get in touch!

This feature on crankshaft balancing is based on an article written by Modatek’s Matt Grant for Race Engine Technology, issue 99, and back copies of this publication are still available.

In our recent email newsletter we looked at the latest controversy to grip Formula 1, which is the subject of compression ratio. We were deluged with enquiries from people who had missed out on this newsletter, so we decided to republish it here. (If you haven’t already subscribed to our weekly email newsletter then you’re missing out!)

The 2026 Formula 1 technical regulations are the most heavily prescribed set of rules in the history of Formula 1 (writes Modatek’s Matt Grant). As an example, 40 years ago the rules that defined the engine barely covered half a page. Conversely, the rules for the 2026 Formula 1 powertrain are over 70 pages long.

Nevertheless, every engine manufacturer will be doing their upmost best to find hidden loopholes in the rules. And the recent news that two manufacturers (Mercedes HPP and Red Bull Powertrains) might have been able to exploit some poorly-defined wording in the rules comes as no surprise.

Rival manufacturers are claiming that both companies have found a way to increase the compression ratio when the engine is running. At the heart of this controversy is article C5.4.3, which states: “No cylinder of the engine may have a geometric compression ratio higher than 16.0. The procedure to measure this value will be detailed by each PU Manufacturer according to the Guidance Document FIA-F1-DOC-C042 and executed at ambient temperature. This procedure must be approved by the FIA Technical Department and included in the PU Manufacturer homologation dossier.”

(Incidentally, the first clue that the FIA might have not properly thought about this rule is their inaccurate definition of the compression ratio number. 16.0 on it’s own is meaningless, it has to be relative to another number, so one has to assume that they mean 16.0:1)

Rival manufacturers have claimed that both Mercedes and Red Bull have found a way to increase the compression ratio to around 18.0:1 when the engine is running. They point to another regulation, article C1.5, which is a long-standing rule that says: “Formula 1 Cars must comply with these regulations in their entirety at all times during a Competition.”

The argument they make is that whilst the engine might be legal when it is measured at ambient temperature, it breaches article C5.4.3 when it is running on the track, and there is no way to measure compression ratio during running.

I’ve been asked by a number of people about this, so here are my thoughts. I should point out that I don’t have any insider information, and as Baz Lurhmann once wrote, “my advice has no basis more reliable than my own meandering experience,” so feel free to ignore this.

Personally, I think the FIA were already aware that engine manufacturers were actively trying to increase the compression ratio during running, which is why they decided to drop the limit from 18.0:1 in 2025 to 16.0:1 this year. They probably reasoned that this allowed sufficient headroom to ensure that nobody exceeded the previous limit of 18.0:1 when the engines are running.

But the question everyone is asking is just how are Mercedes and Red Bull able to increase the compression ratio during running? Do they have some clever trick bit of kit that can circumvent the rules?

In actual fact, I think manufacturers have been able to increase the compression ratio during running for years, often inadvertently. The compression ratio is defined as the ratio of the the maximum cylinder volume (when the piston is at bottom dead center, BDC) to the minimum cylinder volume (when the piston is at top dead center, TDC). So if the volume of the combustion chamber at TDC is reduced, then the compression ratio is increased.

One way to reduce the volume at TDC is to increase the length of the connecting rod, which happens naturally on every engine, and which explains why I think everyone has been doing this for years. On Formula 1 engines that I have worked on, at maximum engine speed the rod stretches by around 0.2mm due to the inertial load from the piston, so there is an inherent increase in compression ratio, whether you want it or not.

There is talk by some that Mercedes and Red Bull are reaching 18.0:1, which would equate to a rod stretch of around 0.5mm. I wouldn’t be surprised to find out that they have cleverly designed the rod to expand in length due to a combination of the piston inertial load and thermal expansion. This would almost certainly be legal, as there is no regulation about the longitudinal stiffness or thermal expansion coefficient of the connecting rod.

Like I said though, these are just the ramblings of an ex-Formula 1 engine designer, with no factual evidence. But I’d love to hear your thoughts on this controversy. How do you think they’ve been able to raise the compression ratio during running? Is it even a controversy, if everyone has been doing it for years anyway? And is this just a distraction from other loopholes that we’re all missing?

Are H-section con rods any good? There seems to be a lot of false information on various social media channels. We take a look at why you shouldn’t trust everything you read on the internet, and offer our opinion on this much-maligned engine component.

A couple of weeks ago we received an ‘interesting’ comment on one of our Facebook posts (writes Modatek’s Matt Grant). The post featured a photo of one of our Arrows Precision connecting rods for the Cosworth YB engine.

The comment caught our attention, mainly because it was completely untrue:

(An H-section or H-beam rod resembles the letter H when looking down the rod with the journal axis horizontal, whereas an I-section rod looks like the letter I. To put it another way, an H-section rod has the lightening pockets on the sides, and an I section rod has the lightening pockets on the front and rear.)

The comment was accompanied by a photo of a bent con rod attached to a cracked piston. I did a Google reverse image search, and I discovered that the first use of this image didn’t attribute the failure to the con rod design (it was probably caused due to a hydraulic event). But someone else then used this photo and claimed that the failure was because the con rod was H-section. Then another armchair expert claimed that “all H-section rods are made in China”, and the myth has then snowballed across the internet.

Now, as far as debates go, this one is probably not that important in the grand scheme of things, but I thought it was interesting to see how some people can latch on to untruths on the internet, and then profess to know everything there is about, in this case, con rod design.

In my experience, I’ve not seen any evidence to say that all H-section rods are bad, or that they are infinitely inferior to I-section rods. A great number of engines that I have worked on have used H-section rods, and with no failures that can be traced back to the con rod design. In fact, some designs, like the Cosworth CA Formula 1 con rod, transition between the H-and I-style designs along its length to provide optimal weight reduction and distribution.

But some might say that I’m going to biased, given that we sell H-section rods, so I thought it might be handy to refer to an in-depth article in Race Engine Technology issue 75, written by David Cooper. Here’s what the article has to say about con rod sections:

“The most obvious variation in con rod design is in the cross-sectional shape used for the main beam section. While a wide range of possible section shapes are available, and can be used – including solid sections of various geometry – the current preferred choice is between either H-beam or I-beam sectional shapes, with virtually all manufacturers queried on the topic for this article supplying either or both types.

“Both can be engineered to provide sufficient strength and stiffness for virtually any application, although neither shape lends itself particularly to higher load applications, for example, than the other.

“Instead it is a case of optimising the chosen section to match the end use. For example, an I-beam rod may have a slightly lower weight for similar stiffness in some applications, whereas an H-beam rod will typically be narrower for a similar stiffness, especially if arranging the rod onto the crankshaft is a significant concern, as in a single-cylinder engine where crank cheeks are close together.

“Ultimately though, comparable performance is achievable with both designs, and the devil is really in the particular design details, the materials used and the manufacturing route/cost requirements.”

The article goes into more detail about the merits of H- and I-section designs, so I won’t reproduce all of it here, but if you do want to learn more then I highly recommend getting hold of a copy.

So there you have it, not everything you read on social media is true. And maybe give H-section rods an easier time next time you see them posted on a company’s social media channels.

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We are Cosworth’s official distributor for their historic engine parts, and we supply a wide range of parts for a number of different Cosworth historic engines, from BD, YB and DFV through to the more recent F1 engines like the CK, TJ and CA. Our mission is to help our customers build better engines by supplying high quality parts backed up with a design consultancy that utilises over 25 years experience in top level motorsport.

If someone asked you what the most complicated part in a Formula 1 engine is, you probably wouldn’t instantly think of the connecting rod bolt. But this humble-looking fastener is in fact incredibly complex.

(By the way, we’ve just received a handful of con rod bolts that Cosworth had removed from one of their TJ Formula 1 race engines that are now available for sale.)

When I started as an engine designer at Cosworth way back in the mid-1990s, one of the first parts that I got to design was the con rod bolt for the VJ Formula 1 engine.

On the face of it, this might seem like just another fastener, albeit one that is highly loaded. But I was told in no uncertain terms that this is no ordinary bolt. In fact, I remember being told to add the words “THIS IS THE MOST IMPORTANT PART OF THE ENGINE” to the drawing.

As a measure of just how complicated the con rod bolt for an F1 engine was, the size of drawing ended up being A1 (eight times the area of an A4 drawing), which seems like a lot of space for a part that is less than 2 inches long. But over half of the drawing was devoted to long lists of instructions that detailed how the bolt was to be forged, machined, finished, inspected and handled.

All of this care and attention was necessary because these rod bolts were the only components that were stopping the piston from being ejected upwards every time it reached TDC. In an F1 engine that was revving to 20,000 rpm (which is what the Cosworth CA could reach in 2006), that was over 300 times per second.

In addition to this insane frequency, the loading on the rod bolt was huge. At 20,000 rpm the piston has a deceleration of over 10,000 G. Even for a 250g piston, that’s equivalent to it weighing 2.5 metric tons – that’s like hanging a Range Rover from just two rod bolts!

(This was the best image that AI could generate. I think our jobs are safe for now.)

So to make the bolt as strong as possible, there were loads of steps that had to be carried out. First of all, the material was the best multiphase steel alloy that was available at the time. The head of the bolt was then forged, giving the optimum grain flow.

The downside to the specialist material and the need for forging was the lead time. It could take as long as 9 months to produce the bolts, which often meant that the rod bolt was one of the first components to be designed, before even the cylinder block and heads were started.

Secondly, the threads ended up being a custom size. The radius in the roots of the threads was meticulously defined by an international standard, so the actual thread naming convention was MJ9x1.0 4h-6h to BS6293 Parts 1 & 2, to be exact.

The pitch in the corresponding threads in the con rod weren’t the same as the pitch of the bolt thread. It was deliberately ‘depitched’, so that when the threads in the rod were stretched under load they would match up with the shape of the threads on the bolt. This in turn helped to even out the stresses in all of the threads.

There was also additional instructions to make sure that the shank of the bolt was as smooth as possible and free from any scratches, which might otherwise act as a stress razor. Later bolts, like the ones from the TJ engine, were superfinished to give them a mirror-like finish.

On top of that, there were incredibly tight geometric and dimensional (GD&T) tolerances that ensured that the face of the bolt was as perpendicular as possible to the bolt axis and thread (the maximum allowable runout was just 76 microns).

So all in all, the Formula 1 con rod bolt ended up being one of the most complicated parts in the entire engine.

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Don’t forget, you can get hold of one of these rod bolts from the Memorabilia section of our on-line shop.

We are Cosworth’s official distributor for their historic engine parts, and we supply a wide range of parts for a number of different Cosworth historic engines, from BD, YB and DFV through to the more recent F1 engines like the CK, TJ and CA. Our mission is to help our customers build better engines by supplying high quality parts backed up with a design consultancy that utilises over 25 years experience in top level motorsport.

Back in July last year, a 1972 McLaren M19 circulated around a very wet Silverstone circuit. This might not seem so remarkable, except for the fact that this represented a significant milestone for the future of historic motorsport. Why? Because the Cosworth DFV engine in the McLaren was being fed with fully synthetic petrol, a sustainable fuel from Zero Petroleum that promises to be the replacement for fossil fuels in the years to come. But what are sustainable fuels and lubricants, and why are they so important?

Sustainable synthetic and bio-synthetic fuels and lubricants could be the solution to the growing need to decarbonise motorsport. They are one of a number of different tactics that we can employ today to reduce carbon emissions. And unlike other methods such as electrification or switching to hydrogen fuels, the use of sustainable fuels and oils requires virtually no modifications to existing IC (internal combustion) engines.

Indeed, as part of the FIA’s desire to become ‘carbon net zero’ by 2030, a number of its top tier categories have already started to mandate the use of these sustainable fuels. WRC switched over to 100% sustainable fuel in 2022, and Formula Two and Formula Three began to ramp up the percentage of sustainable fuel used in their cars in 2023. But perhaps the most noticeable move to sustainable fuel will be when Formula 1 switches over in 2026.

In the world of historic motorsport, the use of these sustainable fuels will become even more necessary if we want to continue to use the existing IC engines that the historic cars are famous for. Who would want to contemplate replacing the iconic Cosworth DFV in the aforementioned McLaren M19 with a battery pack, inverter and electric motor, for example?

A couple of years ago I wrote an article for Race Engine Technology that looked at how these sustainable fuels and lubricants are manufactured (1). Without wanting to sound arrogant, I’ve written dozens of articles for this publication but this was in my mind probably the most important subject that I’d tackled in my 10 years of writing.

There is so much misunderstanding and misinformation in the media today about decarbonising vehicles that I thought it would be interesting to write a blog post about sustainable fuels and lubricants, and with kind permission from Race Engine Technology, I’ve been able to reuse some of the original article.

Why Do We Need Sustainable Fuels & Lubricants?

When it comes to rising carbon levels in the atmosphere, it is usually the IC engine that is maligned and not the fossil fuels themselves.

I spoke with Rebecca Mann of Coryton, who are already supplying sustainable fuel into main stream motorsport. “All too often, we demonise the IC engine,” says Mann, “but it’s the fossil fuels we put in them that cause the environmental problems. And, if we want to look at the actual environmental impact that we are making we really need to look at the bigger picture. The life cycles of the vehicle and fuel runs from its production to its disposal, and the various stages involved in this cycle can also include the creation of pollutants.

“If we want to weigh up what’s best for our planet, we need to explore the environmental impact of all these stages. Making the most of our existing vehicles whilst we develop wider solutions, such as EV, really could make a big difference.

“What’s more, sustainable fuel is ready to hit the ground running using our existing infrastructure. This means we can continue to utilise the existing fleet that we have on roads, along with the existing refuelling infrastructure.”

There are numerous arguments for and against the transition to sustainable fuels and lubricants, but probably one of the biggest advantages lie in the shear volume of IC engines that are in use on today’s roads.

“There are 36 million existing cars on the UK’s roads”, continues Mann, “and only 0.5% of which are currently fully electric. And there are 275 million passenger vehicles in Europe. We would rather be making moves to immediately improve these vehicles, rather than just waiting for the entire fleet to be replaced with electric vehicles or other new technologies.

“According to the UK government’s own statistics, sustainable fuel could reduce emissions by up to 80% compared to fossil fuels. Even a staged introduction could remove 130 million tonnes of carbon dioxide in Europe by 2030  – almost the same amount as 33 coal fired power stations would produce in a year.

“And, given sustainable fuel could be introduced much more rapidly than the transition to all-electric vehicles, we believe this is something we should be looking at very seriously to help tackle the climate emergency, whilst the infrastructure for electrification is put in place.”

But just how are sustainable fuels better for the environment than fossil fuels? “Sustainable fuel works by, effectively, recycling carbon,” answers Mann. “The carbon that a sustainable fuel contains is captured or absorbed from the atmosphere during the production process – for example, the agricultural products absorb carbon dioxide whilst they grow.

“Once it is turned into fuel and burnt, that same carbon is then released back into the atmosphere. Fossil fuel, on the other hand, has held its carbon safe for millions of years. Burning it releases additional carbon dioxide into the atmosphere that was not there before.”

There are two different ways to make sustainable fuels and lubricants. Bio-synthetic fuels and lubricants are processed from organic material, whilst synthetic fuels and lubricants are created by a number of chemical processes that use the existing carbon dioxide in the atmosphere. Both categories have their own advantages and drawbacks, such as cost and difficulty. Some fuel and lubricant manufacturers combine both bio-synthetic and synthetic products, whilst others continue to use fossil fuels or oils that are mixed with these sustainable fuels and lubricants.

What are Biofuels?

Bio-synthetic fuels, sometimes referred to as biofuels, and lubricants are manufactured by processing biomass – biomass is term for an organic material such as crops (like corn, soybeans and sugar cane), algae or microbial culture. These organic materials use photosynthesis to capture the carbon dioxide in the air. Burning bio-synthetic fuels is carbon-neutral, as the carbon dioxide that is produced from combustion is balanced out by the carbon dioxide that is required to produce the fuel.

The ‘first generation’ of bio-synthetic fuels and lubricants used arable land to grow the required biomass. However, the downside to this approach is that an intensive amount of land is required – one study (2) estimated that to meet the USA transportation fuel usage requirement, 25% of the total land used for agriculture in the USA would have to be converted over to fuel production.

Consequently, this production of these first generation bio-synthetic fuels and lubricants competes head on with food production, and as a result is not a viable solution. Instead, the solution to conflict with food production is found with ‘second generation’ bio-synthetic fuels (known as advanced biofuels) and lubricants, which are manufactured from non-food crops.

Second generation bio-synthetic fuels and lubricants uses waste biomass such as waste agricultural material or food crops that are no longer fit for human consumption. Second generation bio-synthetic fuels and lubricants are created by either thermochemical conversion or biochemical conversion.

There are a number of thermochemical conversion processes. The first is known as gasification and is a process that has been used with conventional fossil fuels for decades. The gasification process converts carbon-based materials into carbon monoxide, hydrogen, and carbon dioxide.

A second thermochemical process is pyrolysis, which has also been used with fossil fuels in the past and is carried out in the presence of an inert gas like halogen. One other thermochemical reaction called torrefaction is similar to pyrolysis but is carried out at lower temperatures.

The other process for the production of second generation bio-synthetic fuels and lubricants is biochemical conversion, which consists of a number of biological and chemical processes. One popular example of biochemical conversion is fermentation with unique or genetically modified bacteria.

Rebecca Mann of Coryton says, “Whilst we can call upon many technologies to create our products, we focus mainly on second generation biofuels. This involves us using biological waste such as feedstock, agricultural waste (straw, for example) and forestry waste (such as wood pulp).

“After the crops have been harvested, we can ferment the waste matter that is left over and process it to make bio-ethanol. We then use this bio-ethanol to produce bio-gasoline, a sustainable fuel that can be pumped straight into cars without any modifications to the engine.

“We make over 4,000 blends a year using a range of techniques and sources to create bespoke products for our partners’ individual needs. We also have a range of sustainable fuels developed specifically for the motorsport industry.”

Some companies are now beginning to refer to a ‘third generation’ to refer to biofuel that has been derived from algae, which had previously been classed as part of the second generation group. This reclassification is due to the potential of algae biomass, which can provide much higher yields with lower resource inputs than other feedstock.

Rick Lee of Evolve Lubricants, a company that has created a range of bio-synthetic lubricants, explains the chemical processes that they employ. “We achieve excellent performance through molecular dynamics that enable precise control over branch length position and the proximity and the degree of branching for higher performance in a finished lubricant.

“This is achieved through control of the average double bond position in the molecule. Through the oligomerisation process we have precise control over the linear alpha-olefin chain length, average branching point and alkyl branch formation. Selective isomerization allows for an optimized final product structure properties with methyl branch addition.

“The result is critical control over fluid properties such as viscosity, vapour pressure, traction/friction coefficient and pressure-viscosity relationship resulting in energy efficiency and wear protection.

“Our products were designed to deliver the highest performance with narrow molecular weight resulting in higher flashpoints, initial boiling point and low volatility. The presence of a high molecular weight in the tail allows for low temperature optimization. Increased branching proximity and reduced branching index (more linear) delivers a reduced friction coefficient. These enhanced friction properties reduce shear heating and maintain film thickness at elevated temperatures, more so than fossil-based lubricants.”

What are Synthetic Fuels?

The creation of synthetic fuel in a laboratory or factory using just water, air and renewable electricity could potentially change the course of direction for powertrains, both on the road and on the track. Whilst the processes involved in the manufacture of synthetic fuels are well established, the development of such techniques has appeared to have ramped up over the last few years.

Synthetic fuels are manufactured by capturing carbon dioxide from the air which is then synthesised with hydrogen that has been extracted from water. As with biofuels, the carbon dioxide that is produced from combustion is cancelled out by the carbon dioxide that has been used to make the fuel. The processes involved in the production of synthetic fuels rely on the supply of electricity, hence if the electricity is from a renewable source then the fuel can rightly claim to be carbon neutral.

In the absence of any singular word that can be used to define the complete synthetic fuel production process, Zero Petroleum has coined the word ‘petrosynthesis’. The company provides the following definition of petrosynthesis as follows:

“Petrosynthesis (noun) – the artificial creation of organic compounds (synthetic petroleum/petrochemicals) and oxygen from inorganic precursors (principally water and carbon-dioxide) using non-biological energy (such as hydro, wind, solar, tidal, nuclear, geothermal); the industrial equivalent of photosynthesis, using neither energy nor material produced by either concurrent photosynthesis (plants) or legacy photosynthesis (fossil fuels).”

Similarly, there isn’t yet a widely accepted name for the fuel that is produced. “The fuel that is created goes by a number of different names, such as synthetic fuel, e-fuel and power-to-liquid”, says Paddy Lowe, who established the company after leaving Formula 1.

“Synthetic fuels are made using renewable power like wind and solar energy and the efficient industrial processes (carbon capture, electrolysis, thermal reactions), and should not be confused with biofuels or fuels made from waste.

“Using an industrial non-biological process is controlled, efficient, reliable, secure and scalable. Manufacture can be co-located in territory – self-contained energy generation without dependence on any foreign supply of raw materials. The process of manufacture and consumption is fully circular, creating an industrial carbon cycle which can continue indefinitely in balance with the environment, just as the biological carbon cycle has done for billions of years.”

There are a number of discrete steps in the production of synthetic fuels. The first step is to capture, remove and store carbon dioxide from the air. One such method is known as direct air capture (DAC).

Air is pulled into an air contactor by one or more large fans, and it is then introduced to a potassium hydroxide solution. This solution creates chemical bonds with the carbon dioxide in the air, creating a carbonate salt that is captured in the solution.

A number of chemical processes are then carried out on this carbonate solution in a pellet reactor to turn the salt into small solid pellets, which are then heat treated in a calciner to release the pure carbon dioxide gas. The left-over pellets can be hydrated and then re-used.

The next step is to convert this carbon dioxide into carbon monoxide. This is done by a process that is referred to as ‘reverse water gas shift’ (RWGS). The RWGS process converts carbon dioxide and hydrogen into carbon monoxide and water, as per the following chemical equation:

Note that this process requires a significant amount of heat and note also that the reaction of carbon dioxide with hydrogen can also produce methane, which has to be suppressed with a selective catalyst.

The other ingredient for synthetic fuel production is hydrogen, which is obtained by the electrolysis of water. This process takes place in an electrolyser and involves the use of electricity to break water down into hydrogen and oxygen.

The final step is to carry out a catalytic chemical process that takes the carbon dioxide that has been captured from the air and turned into carbon monoxide via the RWGS reaction, adds it to the hydrogen that has been obtained by electrolysis of water, and creates the required hydrocarbon (plus a number of other by-products, such as water).

This chemical process is called Fischer-Tropsch synthesis, in recognition of two German inventors, Franz Fischer and Hans Tropsch, who pioneered this process in the 1920s.

The underlying chemical formula for this process is:

where n is an integer. Different hydrocarbons can be created, by changing the value of n – for example, if n is 1 then methane is produced. Changing the catalyst, temperature and type of process will create different hydrocarbons. Almost any hydrocarbon can be manufactured, such as plastics, gasoline and lubricants.

The catalyst is based on what are called transition metals, which are typically nickel, iron, cobalt and ruthenium. Nickel is used for the formation of methane, whereas iron is used for the production of hydrocarbons that are created with a lower ratio of hydrogen to carbon monoxide. Ruthenium is usually prohibitively expensive for use as a catalyst in most applications.

Lowe reports that cobalt is commonly chosen as a catalyst for the production of gasoline but would not disclose its own choice of catalyst – this would appear to be part of the company’s ‘secret formula’.

The Fischer-Tropsch process is highly exothermic, creating a large amount of heat. As a result, the company mentions that the overall efficiency of the chemical energy that is created in the synthetic fuel is only around 40 to 45%.

The other issue is of course cost. At the moment the cost of the production of synthetic fuel is higher than that of fossil fuel. As an example, Lowe mentioned that their SAF (sustainable aviation fuel) is currently four times the price of regular jet fuel. This high price is largely down to the relatively low volume that sustainable fuel is currently made in. Lowe drew a parallel with the excessive costs of energy that was derived from the early wind farms, again due to the initial low number of such power sources. Lowe was confident that the costs of its fuel will drop when the volume of fuel produced is increased.

Aside from the carbon-neutral aspect with sustainable fuels, there is one other advantage with regards to emissions from combustion of such fuels in an IC engine. Obviously, the combustion of this fuel creates the primary products of water and carbon dioxide, but as there are no non-hydrocarbons present in the combustion, there are lower levels of particulates and nitrous oxide present in the emissions. Also, as there is no sulphur present, there have been favourable comments about the improvements in the smell of the fuel.

Summary

Sustainable fuels and lubricants will play a pivotal role in the decarbonising of our transportation in the coming years and decades. Rebecca Mann of Coryton observes that 1 tonne of carbon dioxide that is saved today is equivalent to having to save 30 tonnes in 2050. The long term benefits of reducing the carbon footprint of vehicles on the road today will be extremely powerful.

Bio-synthetic fuels and lubricants use biomass that has captured carbon dioxide from the atmosphere. Synthetic fuels and lubricants replicate the process of photosynthesis that was used to create fossil fuels – Paddy Lowe of Zero Petroleum notes that they can complete a task in 3 minutes that nature took six million years to do!

Motorsport will play a vital role in the transition to these sustainable fuels and lubricants. Jean-François Toulisse of TotalEnergies says, “In terms of motorsport activities, we can see that more and more championships are looking for sustainable fuels and lubricants for the near future of their series. This is clearly a beneficial solution to the environment, whilst also keeping the spirit of IC engines alive with the fans.

“EV powertrains won’t be the only solution for motorsport. We are not here to say which energy will be the best on track, but we will see all kind of solutions (biofuels, synthetic fuels and electricity) on the track in the years to come!”

Mann leaves us with a parting word on the future for IC engines that sustainable fuels and lubricants could be a significant part of. “It’s our belief that we need a range of solutions working together to help meet our net-zero target and that sustainable fuels could play a significant role in the mix.

“Across the world there are lots of great examples of sustainable fuels and lubricants working well in action, and there’s a great deal of development work underway. Much of what we’re working on we can’t disclose. But we’re constantly exploring new innovations and ideas to push the sector forward. We’re driven by our mission to create a better future.”

References

1. Race Engine Technology issue 144, January 2023. https://www.highpowermedia.com/Product/race-engine-technology-issue-144

2. Savage, D. F., Way, J., Silver, P. A. (2008) “Defossiling Fuel: How Synthetic Biology Can Transform Biofuel Production” ACS Chemical Biology 3(1):12-16.

Acknowledgements

I’d like to thank Rebecca Mann of Coryton, Jean-François Toulisse of TotalEnergies, Mike Bassett of MAHLE Powertrain, Rick Lee of Evolve Lubricants, Benjamin Cuyt of P1 Fuels, Paddy Lowe of Zero Petroleum, and Yann Labia of Haltermann Carless for their help with researching this article.

You might notice that we stock two types of Cosworth YB piston: the first is for the standard length connecting rod, and the second is for the long rod. The long rod is 7.5mm longer that the standard rod, which is a significant increase. But why would you want to increase the rod length?

Rod length is defined as the distance between the small end and big end bore centres. Combined with the stroke, which is the distance that the piston travels, the rod length is an important parameter in the kinematics of the cranktrain. The rod length and stroke for an engine are sometimes expressed as the ‘rod ratio’, which is the rod length divided by the stroke.

It seems counterintuitive to increase the rod length. After all, this means that the deck height increases and the engine gets taller. But if the engine has already been designed, then one common aftermarket trick to get more power is to try and increase the rod length.

Here are four reasons why a longer rod length can help improve performance.

1. Longer Dwell

An increase in rod length allows the piston to spend more time near TDC (top dead centre). The change in geometry means that the compression can be held for around half a degree longer. It might not sound much, but that small increase in time can improve combustion efficiency and eek out a bit more power from the combustion process. This effect is normally more pronounced above the mid-range RPM.

2. Reduced Skirt Load

Increasing the rod length will reduce what is called “rod angularity”, which is the angle of the rod to the cylinder axis. This reduces the side load on the piston skirt, which helps in a number of ways. For a start, there will be less frictional losses between the skirt and the cylinder wall, which means that there will be more power transmitted to the crankshaft.

Another beneficial by-product that comes from reduced skirt load is an improvement in NVH (noise, vibration and harmonics). The YB piston already has an offset pin bore to help stop it sounding like a diesel tractor engine on a cold day, and long rods do a similar thing.

3. Reduced Secondary Forces

The secondary forces that are created by the reciprocating mass (which is a proportion of the rod mass plus the piston mass) are inversely proportional to the rod ratio. If the stroke is fixed and the rod length is increased then the rod ratio goes up and the secondary forces come down.

These secondary forces act at twice engine speed and as such can’t be balanced out by the crankshaft counterweights. Reducing the secondary forces by increasing the rod length helps to improve the balancing of the bottom end forces, which will reduce vibration.

4. Reduced Piston Mass

For a given deck height, increasing the rod length means that the pin bore needs to be pushed higher up in the piston. This can often lead to a lighter piston – in the case of our YB pistons, the mass reduces by 38g.

Of course, the rod mass will increase so there might not be an overall weight saving, but reducing the piston mass has a knock-on reduction in the inertia forces that the piston imparts on the gudgeon pin when the piston reaches TDC.

This means that there is less load, and hence less stress, in the pin bore, which can help to increase the durability of the piston.

The Long & The Short of It

Of course, the proof is in the pudding. Does running a longer rod actually give more performance? Well, one of our customers kindly tested the YB engine in both standard rod length and long rod length forms, and gave us this feedback. “We saw around between 5% and 10% increase in torque between the midrange and the top end of the power curve”, says the customer.

Running a longer rod length not only offers the potential of extra torque, but also can improve reliability and reduce NVH.

If you’d like to know more about the benefits of switching to a longer con rod then please get in touch.