Mazda MX-5 with a Turbo 4G63
I always enjoy writing about a neglected vehicle being reborn into an exciting and loved project. This Mazda MX-5 NA might have been destined to a short life rotting away until a talented builder decided to give it a second chance.
The project started in 2013 with a goal to build a capable track car on a limited budget that would still be street legal. All modifications would be performed with serviceability in mind. Nothing would be changed if it meant a lot of time or money to be repaired. Also every change would be for a purpose. No changes just because it looked good.
After everything was removed from the car the builder started with fabricating a roll cage. The builder cut, bent and welded every piece from straight tubing. To allow the roll cage to sit much tighter in the car a lot of interior metal was cut away.
Since the owner built this car to be driven and wanted a dependable turbo inline-four he went with one of the most bulletproof ever built, Mitsubishi’s 2.0 L 4G63T from an Evo 8. The engine was upgraded with a Speed Density Conversion which is capable of handling 17-20 psi (1.2-1.4 bar) of boost. The engine makes 300 horsepower and 310 lb-ft of torque on a low boost of 14.5 psi (1 bar).
Since the 4G63 can suffer from oil starvation under right turning in the factory configuration, it means in a longitudinal layout it could suffer under acceleration. The owner corrected this by switching to a dry sump oil system.
The engine was mounted using a set of Cosworth engine mounts from Vibra-Technics. A custom mounting plate was fabricated and boxed in on the subframe.
A lot of time and effort was put into this build but probably some of the most tedious was put into the fabrication of the exhaust headers and turbo piping. I don’t need to tell you the time it takes to make that many cuts and then weld it all back up.
A custom bellhousing adapter was ordered from the United States which allows the Toyota W-series manual transmission to connect to the Mitsubishi engine. The resulting placement of the transmission lined up perfectly with the factory shifter location.
Aside from engine mapping and paint the owner completed all the work by himself over the past three years. There is still some improvements planned for the suspension and aero but the MX-5 has been on the track and performed well. Looking through the build thread that shouldn’t be a surprise.
Source: MX5Nutz (build thread) via Owner/Builder