The charm of a bud­get turbo

Total MX-5 - - CONTENTS -

Michael Gwyn bought a mk1 for £600 then tur­bocharged it him­self us­ing mostly sec­ond­hand parts that cost him about £1700

The BBR mk4 MX-5 Turbo was al­ways des­tined to be one of our favourite cars of the year. Mazda’s fab­u­lous sports car chas­sis teamed with 250bhp couldn’t fail to be a win­ning com­bi­na­tion. Here’s a car with the abil­ity to em­bar­rass cars cost­ing tens of thou­sands of pounds more. If only we had the spare cash…

That’s a com­mon cry, of course. A lament you’ve prob­a­bly ut­tered your­self at some stage.yet it is pos­si­ble to avail your­self of tur­bocharged MX-5 per­for­mance for not much more than the cost of a sec­ond­hand learner car for your kids. Pro­vided, that is, you’re pre­pared and able to do most of the span­ner­ing your­self and have the wil­i­ness to track down good qual­ity used com­po­nents off the in­ter­net. And prob­a­bly best to strike up a re­la­tion­ship with some­one who has in­stalled a tur­bocharger be­fore.

Suf­folk-based Michael Gwyn did just that. His turbo pro­ject be­gan by ac­ci­dent, when he spot­ted a red mk1 for sale on the road­side for £600. Couldn’t re­sist.who could? The no­tion of fit­ting it with a tur­bocharger came a bit later, though, fol­low­ing a track­day when he was of­fered a few laps in ‘our’ Michael Clev­er­ley’s mk1 tur­bocharged demo car: ac­tu­ally, it might have been more than just a few laps…

A man who rel­ishes a chal­lenge, Michael de­cided he wanted to in­stall a tur­bocharger of his own, on a tight bud­get, and with the (freely and en­cour­ag­ingly given) help of Mr Clev­er­ley and his crew. And so the pro­ject be­gan.

The whirring, chunter­ing, wheez­ing heart of the con­ver­sion is a Mit­subishi­man­u­fac­tured TD04 tur­bocharger, which de­spite its parent­age was sourced sec­ond­hand from a Subaru Im­preza Turbo mo­tor. Cru­cial to the smooth in­te­gra­tion of the turbo onto the stock

1.6 mo­tor is a Me­gasquirt MS2 ECU sup­plied by Dim­itri at MS Labs. An­other cru­cial piece of elec­tron­ics is a wide­band Lambda sen­sor from In­no­vate.

An area in which you don’t want to skimp is the ex­haust man­i­fold, and Michael bought a welded steel unit, plus down­pipe, from what is now called Revent but was pre­vi­ously, and more fa­mously, known as Stur­ovo. Big­ger in­jec­tors from a Mazda RX-8 help feed the en­gine’s new­found hunger for fuel, while an ebay pur­chase in­ter­cooler keeps coolant tem­per­a­tures in check.

The Clev­er­ley crew helped Michael with the ECU set-up and tun­ing, but as yet only on the road – a dyno ses­sion is on the cards for the near fu­ture to re­ally nail down the map­ping. Un­til that date with the dyno, a power out­put is a mat­ter for learned spec­u­la­tion, but Mr

Clev­er­ley is con­fi­dent that there’s

BBR’S lat­est tur­bocharged mk4 MX-5 is a bel­ter, but what if your fi­nances won’t stretch that far? Well, there are cheaper paths to a boosted life­style… Words and pho­tos: Brett Fraser

200bhp at least. And all for some­thing in the re­gion of £1600–£1700.

Michael has spent a lit­tle ex­tra, though, up­rat­ing other ar­eas of the car to cope with the ad­di­tional power. The clutch has been up­rated to an Exedy Stage 2 item, though if you’re not a re­ally hard driver and stay away from tracks, the stan­dard clutch should suf­fice. The orig­i­nal sus­pen­sion has been swapped for V-maxx coilovers (as cheap as you should go, ad­vises Clev­er­ley), and the stan­dard brakes up­rated to mk2.5 Sport discs with EBC Yel­low Stuff pads on the front, stan­dard EBC pads on the rear.

This con­ver­sion may have been done at home, but there’s noth­ing home­spun about the car’s per­for­mance. The turbo spools up with­out un­due fan­fare from about 2500rpm, helps build the ac­cel­er­a­tion ro­bustly un­til 4500rpm, and from thereon up to 6500rpm thrusts the mk1 for­ward with thump­ing en­ergy and verve. This up­per-end punch is com­ple­mented by crisp throt­tle re­sponse and the el­e­va­tion of fifth to an over­tak­ing gear on open roads. Third is for an­gry at­tacks on tightly gnarled back roads; fourth is for chas­ing down sports cars worth 10 times more on twist­ing, flow­ing, cross-coun­try sec­on­daries.

And while mod­ern tur­bocharged mod­els barely alert you to the man­ner of their in­duc­tion, Michael’s MX-5 shrieks and hollers and chat­ters and blows off its boost with all the ma­ni­a­cal mu­si­cal ac­com­pa­ni­ment of the blown beasts of yore. It’s a vis­ceral, en­gag­ing, en­velop­ing ex­pe­ri­ence that turns mi­nor out­ings into ma­jor ad­ven­tures. That said, it’s not un­ac­cept­ably an­i­ could just about use it as your ev­ery­day mo­tor. If you didn’t live in a city or town: that would be frus­trat­ing.

But if you’ve got the skills and time to in­stall a tur­bocharger on your own MX-5, it’s a mag­nif­i­cent way to go very fast, very cheaply.

Welded steel man­i­fold and down­pipe from Revent

Dump valve adds to the un­der­bon­net orches­tra

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