My ITB MX5 Build, So far...

In late 2017 I decided to take my neglected mx5 off the road to turn it into a project. At this point I had no idea what i wanted to do. But a little over a year later and I’m nearing the “end” of my project (note, end in inverted commas, we all know that projects never end!) and some substantial progress has been made, but there is still a fair amount to be done.

The first step was to remove the old, and knackered engine and decide what to do next, new BP 1.8 and turbo? Full forge? Honda K series swap? V6 Swap? It was at this point, my friend suggested the VVT engine from a MK 2.5 and add ITB’s. I wasn’t sold immediately, but once I had summed up cost and ease of the conversion, this actually seemed like a pretty good plan, and it wasn’t going to be too hard on the bank (ha ha ha, yeah, right!). So after a few months of searching, I sourced a nice little engine, with on 54k miles on it. The first thing we did when the engine arrived was take the head off and have a good look down the bores and a good inspection. I figured while the head was off that I had may as well have it skimmed, and a good tidy and polish up of the ports!

So that’s exactly what I did! skimmed around 0.5mm from the deck surface, tidied the ports of the nasty casting marks and smoothed out the combustion chambers. With all this done, valve stem seals changed and valves replaced it was a case of putting it all back together and in the car, or so was the plan. Originally there was no plane to change the cams, but after winning a competition from piper for a free set of reground cams, that plan soon changed! Which brought with it a whole new set of problems, as the later model BP engines that went into the MK2 mx5 all had solid lifters, which use shim over bucket type lifters. These were replaced with some shim under bucket lifters provided my Maruha Motors in Japan. Which bring us up to current events, with the valve clearances measured I am yet to order new shims for the lifters. But the engine is now in and mounted up, with some of the wiring now modified to run the VVT from the new ECU, along with the wiring from the crank and cam position sensors, instead of the CAS found on the MK1 engine.

For the engine side of things, that is it so far, with few things left to do. Like get the ITBs ordered, get some minor welding done to the rear arches, and new shiny exhaust manifold. However none of this to this point would have been possible without various people, the main source of information for me has been from Greg Peters at Car passion channel, as he has done a similar conversion to his NA mx5, and has a full write up (https://www.thecarpassionchannel.com/vvt-wiring) on things that need to be done to complete the VVT conversion into an NA mx5 1.6 or 1.8. And of of course I can’t forget my good friend who has let me keep my mx5 in his workshop and leant many a hand with getting some jobs done!

I know that this doesn’t sound like a lot of progress for a year, but work only gets done at weekends on the mx5 as I spend all week working away.