This article appeared in Racecar Engineering, The International Journal of Motorsport Technology (RCE V19 N12).

As a computer scientist, I find it hard to comprehend that you cannot always quantify engineering. Computers represent, in many respects, a form of perfect engineering, free from the burdens of materials, tolerances and the infinite physics of an environment. In theory, a given operation is entirely predictable whether it is invoked once, twice or a thousand times.

The same cannot be said for most forms of motorsport engineering. Despite absolutely every possible effort being taken to minimise variance, there is no guarantee that two engines, two chassis or two sets of tyres, for example, will ever perform equally – despite being manufactured to an identical specification. And so, I was wondering, if you cannot quantify the manufacturing itself, is it possible to at least quantify the performance gain between different engines?

Formula Ford and the legend of Patch

Ever since the hey day of Formula Ford, there have been stories of engines that have dominated the formula. And the legend that is Patch demonstrates this well.

Patch was a Kent engine with remarkable pedigree. It is most well-known for powering four different drivers to successive Formula Ford Festival wins - Roberto Moreno (1980), Tommy Byrne (1981), Julian Bailey (1982) and Andrew Gilbert-Scott (1983). Additionally in 1981, it also believed to have powered a young 21-year old Ayrton Senna to the RAC and Townsend-Thoreson championships, in the same works-run Van Diemen that Tommy Byrne piloted to victory in the Festival.

However, the origins of Patch are rooted earlier with a young South African driver called Trevor Van Rooyen.  In 1977, Van Rooyen piloted a semi-works run Royale RP24 with a self-built (but Minister badged) engine. That year, Van Rooyen won the RAC championship and in the process won a staggering 33 races. However, the following year (1978), Van Rooyen’s engine was destroyed in a test session and the South African returned to his native land. For the record, Van Rooyen went on to enjoy a distinguished career which included winning the 1985 South African Formula Two championship.

Leading Engine builder Graham Fuller (Minister International) subsequently repaired the broken block, welding a ‘patch’ of aluminium where the block was damaged. The engine then returned to racing during the 1980s and to claim its place in history.

Whilst many would argue that much of the latter successes of ‘Patch’ was due to powering a works Van Diemen chassis, the dominance of which would invariably attract the fastest drivers anyway, the legend of ‘Patch’ continues to be known as the greatest advantage a Formula Ford driver could possibly have.

Formula Ford engine power and torque curves

The following is the dynamometer chart from my Formula Ford (1600 Kent) engine when it is was rebuilt in January 2009.

The vital statistics are that at the time of the rebuilt, this engine produced 105.8 BHP at 5800 RPM and 148.8 NM/torque at 4400 RPM.

The problem is that with only data from a single engine, who is to say whether or not this is a strong engine? What’s more, any comparison would only be valid if it were also from the same dynamometer. However, after a year of racing in Formula Ford I would suggest that immediately after being rebuilt, this engine was average. It was not poor but it was also not great and as the season progressed and the engine ran hotter, it became an obvious disadvantage.

But my question is, what did this disadvantage really do to my laptime?

rFactor for real world simulation

Image Space Incorporated have been producing world class simulations for over a decade and the latest incarnation of which is rFactor. Consumer distribution is almost exclusively online and the success of which is demonstrated by the large, dedicated and vibrant community of contributors it has amassed. GMotor2, the 3D and physics engine behind rFactor is utilised and licensed in many other popular sim racing titles including GTR2, ARCA Sim Racing and RACE – The Official WTCC Game. What’s more, Formula One teams including Williams F1, Red Bull and Ferrari use a (albeit customised) version of rFactor (and gMotor2) for their in-house simulators.

I could have approached this problem using a headless simulation such as Bosch’s LapSim. However, as a driver, the benefits of using an interactive simulation are too attractive. None the less, in the future, I might still do this and it would be interesting to further validate the results.

A more accurate Formula Ford for rFactor

In an attempt to answer this question, I have modelled the physics of a Formula Ford 1600 that is as close to my Swift SC94 Formula Ford as possible. In the process, I have accurately modelled the suspension geometry, imported the power and torque data from my engine and re-profiled the tyre slip curve to one that resembles the Avon ACB10.

To demonstrate its potential, the following is a comparison of two similar laps (within one tenth of a second) of the Silverstone National circuit. The blue trace is the actual speed (mph) sampled from my Swift SC94 on 27 June 2009 whilst the red line is the same speed sampled from a simulated lap of the same circuit.

It would be unrealistic to assume that the two traces would perfectly overlap. This particular lap of data was sampled during race conditions and at the time I was dicing closely with two other competitors. There is also a degree of precision lost in comparing data sampled from two different loggers (one of which being virtual) as there is a small variation in actual sample frequencies. Finally and inevitably, there are small inaccuracies in both the Formula Ford physics and indeed the ISI model of the Silverstone circuit (Formula One teams will have access to much more accurate surface data, for example).

However, for the purposes of answering my question, it is sufficient and accurate somewhere in the region of about 2-5% at terminal speed (comparing speed and RPM).

The following video is two sample laps of Silverstone National circuit using the simulator (one of which produced the simulated data shown above).

One final note before I move on. Whilst I would love to contribute this work to the rFactor community and make it available for download, I can only take credit for remodelling the physics of the car. The artwork and 3D model itself originates from the impressive netkar PRO and doing so would be a violation of their copyright and intellectual property. The original conversion of the car encountered similar problems and for those reasons I will continue to respect the rights of these parties but thank them for their hard work.

Building three more powerful engines – artificially, that is

I have remodelled the engine power and torque curves three times – with two, five and ten more horse power. This is obviously theoretical; a real engine producing more peak power would do so with a entirely different power curve. If anybody has dynamometer data from their own Formula Ford engine please drop me an e-mail.

Running the experiment

I have run four separate 20-minute simulations of Silverstone. In order to minimise driver inconsistency I will be using the worlds best test driver – the computer. This enables me to run four near identical sessions. Internally the rFactor AI uses predefined way-points on the circuit to drive each lap.

A summary of each session is shown in the table below.

The following chart shows the individual lap times for each session run.

Finally, the following two charts show the speed and RPM traces respectively, for the fastest lap in each session.

Making sense of it all

I don’t think there is any particular surprises in the results. The fastest overall lap time was set using the most powerful engine. Ten extra horse power yielded a lap time of 62.626 seconds or 1.105 seconds faster than the best lap time set with the standard engine. Similarly, the average lap time was slightly faster still at 1.113 seconds.

An extra five horse power produced a fastest lap time of 63.298 seconds, 0.433 seconds faster than the standard. On average, it was 0.463 seconds faster.

With just two more horse power, the best lap time was 0.183 seconds faster than standard and on average 0.202 seconds faster.

Broadly speaking in this experiment, one horse power equates to roughly a 0.1 second per lap performance. Obviously, this will vary from circuit to circuit.

Back to reality

During the National Formula Ford race weekend in June I qualified in 7th position with a best time of 63.986. This was 1.216 seconds off the pole position time of 62.770, set by Rory Butcher. For the record, I did not test before this weekend and this qualifying session was the first time I had driven a Formula Ford 1600 around the Silverstone National circuit. I was also driving with a left-rear slow puncture caused by a broken tyre valve core.

If we assume that there was a couple of tenths to be found through familiarisation with the circuit, that brings us close to the fastest simulated time of 63.731. Likewise, Butcher’s pole position time of 62.770 is equally close to the best simulated lap time of 62.626, set with ten extra horse power. However, I would suggest this is probably more coincidence than it is scientific fact. An interesting coincidence, none the less.

Concluding with the caveats

Ultimately, there are many caveats to the conclusions drawn from this experiment. I will reiterate that the remodelled power curves are artificial and in many ways, unrealistic.

There is no allowance for engine wear – at the Silverstone race weekend my engine had run for around 400 miles and probably no longer produced 105.8 BHP at 5800 RPM. However, this works both ways and it could actually mean a horse power differential closer to ten, after all.

The same gear ratios were used for each run (2.40, 1.74, 1.43 and 1.17). These are also the same ratios used during the race weekend. With ten extra horse power, I would expect to run longer gear ratios and suggest this would see a further reduction in lap time. The flat line at the end of the straights on the RPM trace confirms that fourth gear is indeed too short.

Ideally, this experiment would need to be repeated a high number of times before the data is collated and analysed. Unfortunately, one reality of using a real-time simulator such as rFactor is that each 20-minute simulation takes 20-minutes to complete. A headless simulator, such as LapSim, would be able to repeat simulations at a much faster rate and as such produce more reliable results.

As far as I am concerned, this experiment has demonstrated that despite its caveats, a small horse power advantage offers a quantifiable and not insignificant reduction in lap time on the Silverstone National circuit. But even more, it has demonstrated what a brilliant and accurate simulation rFactor really is.

Related posts:

1. Formula Ford (Duratec): Snetterton testing
2. Formula Vee: Pole Position, Fastest Lap and 2nd at Silverstone
3. Articles

Almost 10 years passed and you could argue it was spent waiting for the hardware to catch up. In Ë92, Crammond again set the benchmark when Formula One Grand Prix was released. It marked another milestone for the genre whereby 3D environments became more elaborate and for the first time, a player could change the setup of the car. The success of Crammond’s Grand Prix series saw three further sequels, appropriately published as Grand Prix 2, 3 and 4.

As the Grand Prix series grew, so did the genre and other publishers began to show innovation through their own titles. Papyrus, already an established player with its IndyCar Racing and NASCAR series was, in 1998, to significantly raise expectations once more. Grand Prix Legends (GPL) portrayed the heroic 1967 Formula One World Championship with immaculate attention to detail, far surpassing anything at the time and probably for the next few years too.

Aside from one of the best handling models ever written and an incredibly versatile graphics engine (variants have been used as recently as 2003) GPL introduced the world to online multiplayer racing and sparked an enthusiastic community still proficient today.

Crammond was not done and in 2000 published the much anticipated Grand Prix 3. However, unlike it’s predecessors, Grand Prix 3 was immediately criticized and whilst it still provided ultra-realistic car handling, its graphics and sound were dated.

The short-comings of Grand Prix 2 and 3 created opportunities for others, the most important of which being Image Space Incorporated (ISI). Shortly after Grand Prix 3, EA Sports introduced the first of its F1 Series. ISI took charge of development whilst EA Sports used their weight to ensure distribution and some much needed license negotiation. Whether consciously or not, ISI had delivered the community another important milestone – modding. For the first time, the community was able to take advantage of the game without relying on a handful of individuals who could reverse engineer the games proprietary formats – as was the case with Grand Prix and GPL.

The success of EA Sport’s F1 series largely overshadowed the last of Crammond’s titles and almost certainly was a contributing factor in the demise of his series. Grand Prix 4 arrived in stores in late 2002 and featured a much improved graphics engine. However, licensing difficulties meant it still lacked online play and it offered nothing more to the modding community than its predecessors. Despite this, Grand Prix 4 largely stood the test of time and there is still a vibrant community of players today.

That would be the last we’d see from Crammond, the Grand Prix series was discontinued and Micropose went into submission in early 2003. What was once the pioneering force in race simulation dissolved through a sequence of strategic errors. First, they were unable to negotiate a full Formula One license and therefore could not offer online play. Second, Crammond did not see the potential in providing a more open platform, one which would encourage the modding community. Crammond, fatally, had missed two of the most important milestones.

Unfortunately, EA Sports would suffer a similar fate as in 2003, Sony Computer Entertainment Europe entered a multi-year deal with the Formula One Administration to develop the exclusive Formula One game. Consequently, Formula One simulation on the PC has become stagnent and both EA Sport’s F1 Challenge and Geoff Crammond’s Grand Prix 4 live on as the last and best of the genre.

Why have I only talked about Formula One simulators? Firstly, it gives historical context to the genre. Perhaps more importantly, it allows me to demonstrate the legacy it has created.

Ever since Formula One was effectively retired on the PC, the genre has become polarised. At one end of the spectrum, the rise of console gaming has given birth to many titles like ToCA Race Driver or Gran Turismo which sit between arcade game and simulator. They’re superb for what they are but they’re not serious racing simulators.

At the other end, it gets interesting. ISI, developers of F1 Challenge for EA Sports, now lead the market with their own title, rFactor. Learning from the strengths of F1 Challenge, rFactor provides unprecedented levels of customisation and its success heavily depends on how much the community gets involved.

ISI has chosen to not pursue licenses for official cars or tracks. A stock rFactor includes two categories of cars, open wheel or sedan (touring) all of which are heavily inspired by their real world counterparts. The open wheel “trainers are Skip Barber Dodge cars, the “rF3³ is a Dallara and “FormulaIS has an obvious synergy with Formula One. In addition to this, since October 2006 and in celebration of Intel’s latest processor, rFactor provides an official BMW-Sauber Formula One car and licenses for Silverstone and Nurburgring circuits.

The fact that ISI has chosen not to purchase licenses itself is not restricting. The modding community they’ve created largely supplements what is missing. It’s rare that lawyers get involved with non-commercial developers and so much of what ISI would like to publish themselves can be downloaded at rFactor Central. Stand out examples being CTDP F1 2005 and Grand Prix 1979.

ISI, too, realised the next major milestone, this time with its distribution (a distribution model pioneered by LFS, see below). Without EA Sports, rFactor lacks a commercial publisher. Consequently, ISI distribute rFactor themselves, entirely from their website. The full game can be downloaded but the purchase of an activation key is required to unlock the major features. Whilst this naturally means the overall profile of the title is reduced, it is plausible that a traditional distributor would restrict growth which so heavily depends on third party modifications and the Internet.

ISI doesn’t have it easy and other similar simulators look promising. UK-based Live For Speed (LFS) stands to challenge rFactor’s supremacy and it’s latest release, S2, is certainly of no less quality. LFS focuses almost entirely on the online play in an attempt to bring more organisation to the experience. Like rFactor, there are no official cars nor tracks but with a little imagination, their real world equivalents are immediately obvious. Similarly, an official BMW Sauber Formula One car arrived in late 2006 and a lack of a commercial publisher means distribution of LFS is exclusive to their website.

Whilst both rFactor and LFS continue to explore new markets, the commercial future of both is a little less sure.

In 2005, a new development studio arrived on the scene and quickly gained notoriety for its efforts. SimBin released GTR in March and it was exactly what the genre needed. SimBin acquired the official license for the FIA GT Championship and through Atari distributed the game worldwide. Suddenly, there was another player and like Papyrus and Crammond before them, SimBin committed to ultra-realistic products.

The success of GTR was good news for rFactor too as much of what SimBin have achieved is largely due to ISI technology. GTR, its sequel GTR2, GT Legends and now RACE – The Official World Touring Car Game all use variants of the graphics and physics engines used in rFactor: gMotor2. The association, no doubt, has provided ISI with a much needed revenue stream to continue the development of its own title.

Furthermore, some still feel that even rFactor and GTR have sacrificed gameplay over realism. Up until recently, Italian Kunos Simulazioni single handedly created a simulation more realistic than anything I’d expect to find on the general market. netKar PRO, or nkPRO as it’s more commonly known, is, like Live For Speed, intended purely as an online simulator. What makes it special, however, is the most complex tyre model ever produced. Tyres are able to wear, pick up dirt, be flat spotted and are sensitive to heat cycles. Each factor has a dynamic effect on the handling characteristics of the cars, which presently includes just single-seaters.

nkPRO really is unique. You should think of nkPRO as you would a commercial flight simulator at Boeing. nkPRO is a technology, it’s an engineering tool. nkPRO can be used not only to train drivers in a particular environment but also to provide accurate data to how tyres or different setup parameters would affect the handling charactistics of a real car. The Marangoni Group recognise this and have recently negotiated tyre evaluation for the Italian Speed Hillclimbing Championship through a partnership with nkPRO.

The original Geoff Crammond genre no longer exists. Instead, it’s fractured into smaller but equally thriving subgenres: console simulators (ToCA Race Driver, Gran Turismo), online simulators (rFactor, Live For Speed), the championship endorsed simluators (GTR, RACE) and finally the reality simulators (nkPRO, iRacing.com).

2007 should see the addition of two more simulators entering someway between the online and reality genres. Papyrus co-founder David Kaemmer has recently announced his intention to release iRacing.com and its development is impressive although no concrete information is available about its release. Likewise, Drivers Republic should also make its debut in 2007, this time crafted by Eero Piitulainen, previously an architect on Richard Burns Rally.

I will leave you with the following chart. I have tried to give a visual overview of the PC simulator sphere as it is today and show associations where possible. Need For Speed and Test Drive Unlimited are included to give the chart context whilst iRacing.com and Drivers Republic have lower opacity to indicate they are yet to materialize. Moving your cursor over the different emblems will reveal information about each respective title.

Related posts:

1. Simulating Formula Ford Engine Performance with rFactor
2. Race Report: Castle Combe (UK Formula Vee)
3. Formula Ford: Anglesey Review