Building a modified Mazda MX-5/ Miata to beat a new Porsche Boxster (Pt 1)

Building a modified Mazda MX-5/ Miata to beat a new Porsche Boxster (Pt 1)

It’s the Mazda Mx-5’s 25th birthday this year
and that gave us an idea. Can you, with a budget of £5,000, buy an old MX-5, get it
modified and end up with a car that’s as exciting to drive as a brand new Porsche Boxster? Which,
incidentally is the current Auto Express Roadster of the Year. To find out, we’ll be racing
a modified MX-5 around our test circuit against the Boxster. To see how close it can get to
the Porsche’s lap time. It’s going to be tough though. The Boxster has a mid-mounted 2.7-litre
flat six engine with 265 horsepower and is built to be great on road and also ruthlessly
quick round the track. We’re going to try and beat with a sixteen year old mark 2 MX-5
1.8is with 86,000 miles on the clock. Are we mad? This is actually my own MX-5. It’s
probably worth around £1,000. IN fact, you can pick up a decent condition Mark 1 or mark
2, such as this, for around a grand, so, that would leave you £4,000 to spend on tuning
and you’ll see how we spend that money later on, but first, we’ve got to see what this
car can do as standard round our track. And I’ve got a feeling it’s not going to be particularly
quick. Indeed it wasn’t. When our resident racing driver, Owen Mildenhall, did a flying
lap in my standard MX-5, he said it was fun, but it lacked power, brakes and had a lot
of body roll. In the end, he recorded a time of one minute, twenty-three point seven seconds,
the slowest, by far, of any car he’d ever tested. Obviously we’re going to need to bring
the lap time down by quite a lot if we’re going to compete with a Boxster, but I don’t
want to do it in a way that’s going to spoil the car’s original character, so we’re not
going to strip it al lout and make it into some track-focused special. It still needs
to be usable on the road every day, much in the same way the Boxster is. You can get lots
of information about tuning MX-5s on internet forums such as the Mx-5 owners club and Mx-5
nuts, and find used parts and tuned cars for sale on them, too. However, we wanted to build
our own tuned car, so headed to MX-5 experts Scuzzle Motorsport in Winchester for some
help. We’ve had this car on the rolling road, and it’s made 113 horsepower on the wheels,
which is about 140 at the fly. Unfortunately, you’re going to need a lot more than that
to beat a Boxster. The easiest way for big power gains on an Mx-5 is with a turbocharger.
It can take the stock engine to 250 horsepower really easily. The other option is supercharger,
you won’t get as big gains from it, but it’s a lot more linear power delivery and you’ve
got boost straight away as soon as you press the throttle and bucket loads of torque all
the way through the rev range. In the end, I decided to go for a supercharger because
you get a more progressive power delivery, and it’s more in keeping with the original
concept of the MX-5 and people say it’s like you’ve got your normal MX-5 but with a bigger
engine in it. I found one, for a grand, an N45 Jackson Racing supercharger with lots
of bits, an intercooler, bigger injectors, a standalone ECU for emission control of the
fuelling, we’ve also got an exhaust manifold and hopefully all that should be good for
between 180 and 200bhp. You can also get a more powerful NP62 supercharger for the MX-5,
but they are harder to find and they cost more as well, and I wanted to save money for
other upgrades. The handling of the MX-5 out of the factory is actually really good, but
it can be improved upon. A decent set of coil-over suspension, adjustable so you can tweak it
for the track you’re driving. One of the best options out there at the moment is the MeisterR coil-overs. You can have them quite soft for the road so they’re really nice to ride,
or you can stiffen them up for the track and for the money you really can’t get much better.
The stock brakes are actually a pretty decent size for the MX-5. It’s a little lightweight
car, they’re plenty to stop the car, but it can be improved so what we’re going to recommend
is the EBC yellow stuff pads. A fast road and track day pad. The turbo groove discs,
they work really well with the EBC pads and then the braided brake lines – they will give
a much better pedal feel. We can also add a master cylinder stopper, it’ll give you
a much better feel through the pedal and much more braking effort. People often forget the
key to a fast car is the tyres. It’s the only contact patch you’ve got with the road so
they need to be good. A great tyre is the Yokohoma Ad08Rs. They’re a fantastic tyre,
they’ve got a really nice compound that will keep them nice and sticky, they’ll be fantastic
on the track. They’re also really good road tyres, they’ve got a nice stiff sidewall so
you’ll get a nice sharp steering response. Overall they’re a great blend of track performance
and road performance. With everything we’re doing to this car, I reckon we’re going to
save about ten seconds off your lap time, so that’s going to be quite a big improvement,
you’ll be able to notice that. Seeing as the car’s going to have more power, I decided
to uprate the clutch because the current one will probably start slipping And while i was
at it I thought, I know, I’ll have a lightened flywheel to make the engine a bit freer revving.
I got these parts from FlyMiata in the US and even when you take into account VAT and
shipping, they’re still pretty reasonable and they’re about the best Mazda MX-5 parts
you can get. WHen you add it all up, we spent three thousand and six pounds on parts and
nine hundred and seventy pounds on labour. Add in the one thousand pound value for the
car and the total comes to four thousand nine hundred and seventy-six pounds. Of course,
you could save some cash by doing some of the work yourself. Probably the easiest part
of the car to do yourself would be the brakes. They’re relatively straightforward, jus a
few nuts and bolts. A lot of people have a problem with touching their brakes because
obviously its a vital safety feature, but they’re really not that bad. The suspension
is probably the hardest part of the car to fit yourself because you really need to get
the car into the air and you’re probably going to struggle with some fused bolts where they’ve
been exposed to the elements for a few years. The Jackson Racer supercharging kit is a relatively
straightforward piece of kit to fit so a couple of brackets need to be bolted on and the supercharger
bolts to those brackets. ANybody can do that with just a small tool set. No matter how
much of this you can do yourself at home, you are still going to have to go and visit
a rolling road. That’s because you’re going to need someone like Nick to tune the car
so it runs properly and doesn’t blow up. We decided to run the car on Shell V-Power Nitro
plus as this would allow him to push the performance as far as he could. And, as this before and
after graph shows, our performance increased from 113 to 196 horspeower. So let’s see what
that difference feels like. Ok then so, it’s the first time I’ve driven this car with a
supercharger on it, we’ve got a bit of open stretch of road. Let’s put it in second, and
see what the performance is like. So, Oh yes! That is a lot faster than it was before! Whether
it’s fast enough to beat a Boxster, I don’t know. I don’t know, it’s definitely going
to be close. To find out exactly what happened, you;;; have to tune in for our modified MX-5
versus Boxster track battle. Also, you can click on the video windows to watch our drag
race between a tuned Renaultsport Megane and a Ford Focus RS and our Porsche Boxster S
video review. Click on the play icon to watch our latest videos and click on our logo to
subscribe to our channel.

About the Author: Michael Flood


  1. No matter how much you spend, or how much work you do, it will never be a Porsche. A Mazda will never have the street cred of a Porsche. MX5 is alright for hairdressers, but no more than that.

  2. The people who are saying that you can get a decent MX-5 for $1500 anywhere in the U.S. either don't know what they are looking at or they're lying or they're engaged in an insane amount of wishful thinking. The mechanic is right about the brakes being easy. Even without a lift the suspension shouldn't be too hard either. If you've got some reasonable mechanical skills and a logical mind most of the other things really wouldn't be too difficult either, if you've got the right tools that is. I really expected a lot more horsepower than 196 from a supercharged engine.

  3. Set the average Porsche driver behind the Boxster's wheel, and you need no modifications to the Miata at all to beat it.

  4. Even in 2019, the cheapest Miata I can find similar to his is going for about $4,000-5,000…. (though remaining examples have probably depreciated fully by now, and may be going up in price!)

  5. When I was shopping for cars I actually ended up buying a used MX-5 over a used Boxter. Once I found out what a nightmare the Boxters are to work on, I'm really glad I made that choice. Never regretted the choice of a stock MX-5. Simple to repair, cheap to repair and it only cost me $4000. Best purchase ever.

  6. In my youth I modified and tuned a 1.6 Sierra that could beat XR4's. I ended up with a highly strung 2.1 that did at times 16 mpg. It also ate clutches and gearboxes on a regular basis. The cost of putting 176 hp into a 65 hp car was massive, because everything would break. In the end, on paper, I owned a messed around 1.6. The average XR4 owner had a car that was still desirable when it came to selling it, and lost a lot less money. I must admit though, I kept the exterior standard, including the 1.6 badge, and the pure joy of out dragging an over confident Golf GTI pushing in at the lights made it all seem worthwhile at the time.

  7. You don't need to do anything to a functioning Miata to have more fun in it than in a Porsche. Higher speed and fancier carpeting doesn't necessarily mean more fun. It's the old Alfa Bertone-coupè/Spitfire-thing. And a Miata's fast enough for the road; Porsche's are for posers, Miata's are for drivers!

  8. Not as much boost.. why not just put a smaller pulley on and then you have more boost, all the time? 👌🏼

  9. You guys are so lucky…that MX-5 would cost a minimum $8k here in Canada. One I looked at yesterday looked just like yours but had only 35k on it, guy wanted $12k for it.

  10. This is such bs you cant call this a sub $5000 build. That car is worth way more than 1k and you got a super cheap labor cost.

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