Mazda Eunos RS-Ltd - Turbo-charged

[goodwoodmx5]

One of the most common group of questions I get asked by MX5 owners is about turbo-charging their car. Does it really make such a big difference? How much does it cost? Whats it like to drive?

Well this is the latest addition to my own collection: its a 1994 Eunos 1.8 RS-Ltd. In fact this is the third time I have owned this car. I think I first bought it back in 2012/2013 and I ran it as my daily driver for quite a while. Someone made me an offer I couldn’t refuse and I sold it, regretting it pretty well immediately. That chap ran it for 3 years and offered to sell it back to me, an offer I snapped up as I was short of stock. It sold again pretty well immediately to a chap in Scotland.
Meanwhile, RS-Ltd prices continued to rise and I regretted not having one as part of my own small collection. I had a feeling that I may have missed the boat on this one.

Move on to 2021 and I couldn’t get rid of this urge to buy a decent turbo-charged MX5. The trouble is that so many conversions are badly done, making the cars unreliable or resulting in one that just doesn’t drive very well. If I was going to do it, I wanted it done properly. Unfortunately I knew this wouldn’t be cheap. I happened to have a chat with Matt from Mtech Automotive who do a decent turbo conversion and he reckoned I should budget for around £4000-£4500 to get the spec I wanted. Hmm, thats a lot of money…

While I was mulling over the above, I was browsing the minefield that is Ebay and spotted my old RS-Ltd, up for sale yet again. And would you believe it, it had recently had a turbo conversion by Mtech. The price was substantially less than the cost of a decent car plus a turbo conversion and I felt it was too good an opportunity to pass up and got a deal done very quickly.

Apart from the turbo conversion, it had recently had sills repaired to very high standard by The MX5 Restorer in Pevensey and also had two brand new front wings fitted. It was sitting on an odd set of alloy wheels but still had the 4 point roll bar and front lip spoiler that I had fitted back in 2012.

I could see that with a bit of work, this could be an ideal fun/track day/hill climb/sprint car. First job was to replace the Pedders suspension with a set of Meister Rs. I came across a set of 15” BBS RG04 alloys that to my mind are even better than the original BBS fitted. I also fitted my race seat and harnesses, fitted an alloy radiator, gave the car a service and thorough check over and attended to 101 small jobs that needed doing. I did away with the soft top preferring to run it with a permanent hard top. There’s quite a lot more I want to do yet such as a coolant reroute and I really need to find some better seats – it currently has a Motamec driver’s bucket seat and a standard Eunos passenger seat. I also have a plan to improve the brakes - more on that another time.

The highlights of the turbo set up are as follows:
TD04 turbo mounted on a G19 cast manifold, an Mtech intercooler, yellow RX8 injectors, Mazdaspeed stainless exhaust and I have just had a new BOFI Racing uprated clutch fitted.
It has a two stage boost control switch with the lower setting giving around 180bhp while full power is 226bhp.

This doesn’t sound completely wild but it gives a similar power to weight ratio as my Porsche Carrera 4 (996). If you watch plenty of YouTube videos of people having their first drive in a turbo’d 5, you’ll notice lots of uncontrollable giggling – the acceleration really is that daft. For me, I prefer uncontrollable swearing, especially at the way it picks up speed from 40-50mph onwards – properly exhilarating and an utter handful in the wet. Brilliant fun though.

I'll expand on some of the work done so far and what its like to drive (I've covered probably 1000+ miles so far) in later posts. But I can already tell you, its even better than I thought it was going to be.

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[goodwoodmx5]

One of the very first things I did on my RS-Ltd was to change the wheels. The wheels that came with the car when I bought it were some unattractive aftermarket alloys. When new, an RS-Ltd would have been fitted with 15” BBS wheels and that was what I wanted. However while researching these, I came across something a bit more interesting. On the face of it, these are 15” BBS alloys which look near identical to the originals. However these were designated ‘RG034’ by BBS which signifies that they were manufactured to a higher standard and are forged for extra strength and are some 20% lighter too. When I say lighter, we’re talking just 12kg each including the tyres (which are Toyo Proxes) compared to 15-18kg each for a typical set of standard Mazda alloys. I reckon it means each BBS bare wheel is no more than 5kg which is very light indeed.

The car looks terrific on these but as I intended to use the car on track, I know they will be tricky to replace if damaged. So for track use I have fitted a set of 15” Enkeis (as originally fitted to various MX5 models) along with Toyo 888 tyres . They are quite light and are readily available if I damage one. I wanted to give them a ‘JDM’ feel and paint them in a bronze/gold colour often seen on Rotas etc. A good colour match turned out to be BMW Sepang Bronze and surprisingly, it suits the Montego Blue body colour quite well.

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[goodwoodmx5]

So we here we are 15 months later and I haven't updated anything on here. The car has changed quite a bit over this time so I intend to document the various improvements/problems solved on here.
The first problem appeared very quickly and its one that many turbo'd MX5 owners will know all about - clutch slip. A older standard clutch simply won't cope with the amount of torque now being delivered. In my case, this was bit odd as the previous owner was adamant that a new uprated clutch had already been fitted. And they were right though it was quite worn and was of an unknown make and strength. It turned out that part of the problem was actually down to a failing rubber hose from the master cylinder to the slave cylinder: it was simply collapsing inside and restricting fluid flow. A new braided clutch hose was fitted but by the time this was discovered, I had already bought a Stage 2 clutch from the guys at BOFI Racing so I thought I may as well fit this too and that was the problem cured.
Next job was the suspension. The car came with a new set of Pedders Motorsport coilovers fitted. Pedders are pretty well unknown in the MX5 world but they are a big deal in places like Australia, the Subaru tuning world and actually produce some good quality stuff. However I had a set of Meister Rs ready to go on this one. I have used Meisters on so many MX5s and just love them so I was always going to fit them to this one. Once set up, they are just brilliant and the car feels perfect. I can take dips and bumps in the road as hard and fast as I want with no bottoming out or anything else untoward.
The whole point of this car is to look at the real world performance on the road as a complete thing, something a lot of owners of turbo-charged cars ignore. Building a 300BHP+ car doesn't necessarily make it fast to drive on either the public roads or on track. A car can be fast in a straight line but I wanted mine to be reasonably quick everywhere and hopefully better to drive. the suspension was a big part of this.

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