Most 911 enthusiasts are well aware of the company that is Tuthill Porsche in the UK. Its latest creation is arguably one of their most subtle, yet most exciting projects.
Words: Wilhelm Lutjeharms
Photography: Charlie Brenninkmeijer
Tuthill Porsche is arguably one of the most respected specialists of the marque in the United Kingdom. The company has vast experience in terms of air-cooled Porsches, especially when it comes to building rally cars, engine development, restorations and other development work. But, how do you develop and improve on one of the best air-cooled Porsche 911s manufactured by the factory? This story started a couple of years ago.
Background
Two years ago Tuthill Porsche launched its sensational 911 K. This was a beautifully simplistic air-cooled 911 that tipped the scales at less than 900 kg and revved to 11 000 rpm. Needless to say, a fair amount of development and engineering expertise went into the engine and the special 24-valve head that made these high engine speeds possible. Fast-forward to 2024, and one of its latest products, the 993 RSK, has again attracted serious interest from enthusiasts.
Having already purchased a fantastic 911 (in the shape of the 993 Carrera RS), one client was longing for a little more in terms of performance. After some in-depth discussions, the idea of a complete resto-mod was pushed aside and the decision taken to build the RSK to be all about small improvements on every level. One of the most significant upgrades becomes obvious when you look at the tilted rev counter with a redline that now starts at a lofty 8 000 rpm! If the green exterior colour appeals to you, you have Ferrari to thank: the colour is called Verde Francesca, while that flying pink pig is painted on and not merely a sticker!
We had a chat with Richard Tuthill himself about the detail of this project and the ultimate goals.
The details
“A friend of mine, who is also a client, is the owner of a 911 K. He was my partner in crime in creating that original gold-coloured car. One of the great ideas from the 911 K was that we could use the top end on bigger engines like that from the 964 and 993 to create 4-valve (per cylinder), higher revving engines in larger capacities. I always said the 993 Carrera RS, if not the best 911 Porsche ever made, is one of the best – but this is my opinion. So, my friend bought himself a 993 RS. The only criticism one might choose to level at the 993 Carrera RS is that it is a bit underpowered. However, I would argue that an underpowered car is not necessarily a bad thing, in fact, in some ways it is a good thing because you can drive the door handles off it and get a whole load of alternative enjoyment. Other people might say that they want a bit more power.
“What we essentially did was to take a standard 993 Carrera RS and strip it back to the bare shell as we do with all our proper builds. We re-assembled it mostly originally, but we added our own suspension and carbon brakes. We gave it a beautiful re-trim and the engine rebuild resulted in the new 4-valve head on a larger 4.0-litre engine. We also shortened the gear ratios.”
Richard goes on to explain that what they ended up with is a 993 Carrera RS that should realistically be compared to cars that would normally not even be mentioned in the same sentence as a standard 993 Carrera RS.
“It still comes back to our core values, which is ‘how does it handle on a B-road’ and ‘is there any emotion in the engine’. I really don’t want to talk about horsepower figures, but I am keen to talk about all these ingredients that we put in that make for a more holistically enjoyable car.”
Power and weight
Although the aim of this car was never headline power figures, maximum power delivery is still notably up from the standard 3.8-litre engine’s 224 kW, a conservative 275 kW has been mentioned before. The increase in capacity has been achieved by enlarging both the bore and stroke, but improvements are not confined to the innards only: finer details such as the beautiful new custom intake, to name only one element of a completely new engine, provides a feast for the eyes.
Touching on the topic of weight, Richard explains that the RSK is slightly lighter than a standard 993 Carrera RS (1 270 kg). “The carbon brakes significantly lower the un-sprung weight. It not only weighs less, but it weighs less in the right places. Then there is the beautiful Inconel exhaust which further lowers the weight at the rear. One of our aims is typically to take weight out, but it doesn’t need to be to the extreme. If you can marginally improve everything, you end up with a huge and impressive result.”
The callipers are machined from billet aluminium. “In nearly all our projects we now use our own callipers. This is mostly to improve packaging, because in some cases I want a smaller wheel to lower the weight, for example. It is very nice to be able to control what is fitted to a car. We will try to design and engineer parts to be not only an improvement on the original, but also serviceable, promising a long life.”
The suspension
“As has been the case before, we developed our own suspension in conjunction with a company called MCS, Motion Control Suspension. We worked very closely with them on our 911 K and SCRS projects. This is the only way to achieve what we require for damping. It includes lots of test driving and working with our in-house engineer. It is not always necessary to design your own stuff from scratch. We can take something that exists from a company or an individual which we think is great, and then we evolve their base product to our specification. With the 911 K, SCRS and now the 993 RSK, we were able to implement three different philosophies for damping.”
“Because of our rally heritage, I want cars to be able to handle well on our B-roads in the UK. I drive cars every single day and it is very seldom that I get out of a car and think ‘that is good’. That is not to say anything against anyone else, it all depends on what your focus is. For me it is to make these cars handle bumpy roads expertly.”
Steering feel
A 993 Carrera RS’s steering feel and feedback is quite good, but an upgrade was made to it. “We still use the 993’s steering rack, but with a 997 steering pump. In fitting our 911 K heads, you also disable the power steering pump on the standard engine. We had to come up with a new solution. A 997’s steering pump we’ve used on lots of cars before. It works really well and you still have brilliant feel.”
Going forward, any 993 Carrera owner will be able to bring their car to Tuthill Porsche and have these updates or engine build done – it doesn’t need to be a 993 Carrera RS.
“Anything Porsche did was very well thought out and developed. I’ve so often seen people changing stuff just for the sake of changing stuff. Porsche is an amazing car company and their engineers are very clever. In most cases much of the package is brilliant, we would just like to subtly improve some areas. Unless you understand where you want to get to with changing everything, I believe you can often stick with the good standard elements and enhance whatever needs to be enhanced. We are not into selling things you don’t need. I have no aim to fill up my workshop, it is already full. In the case of the 993 Carrera RS, leave it alone where you can as it is already such a good product.”
The 993 RSK is so neatly done inside and out that it will really take a true enthusiast to spot the mechanical differences. Most of these improvements are hidden away and are parts that have been keenly developed to enhance the experience for the lucky person behind the wheel. It is truly a piece of well thought-out mechanical art.
As our interview comes to an end, I ask Richard his opinion on the various companies and individuals globally that re-design, re-imagine and re-engineer the 911.
“I think it is great, what everyone is getting up to. There are some concerns from manufacturers of people modifying their cars. My view is that this kind of thing is brilliant for any brand. We all love their work and we are doing what we can to keep the cars running in whatever form. Sometimes these custom-built cars will attract a whole new audience that might not have known what Porsche or the specific model or model range stood for before, but now they know. Long may it continue.”