We had a race car that didn’t run. The engine was toast. Rebuilding it was going to cost three to four times what our whole $500 racer was supposed to be worth. We gathered at a nearby family eatery to discuss options over breakfast. Was this engine-less project worth continuing with? Or should we just give up and go home?
We discussed re-powering the car with something other than a rotary. I was imagining something really nuts: A ford straight six like the one in my craptastic Maverick I’d had in high school. I wisely kept my mouth shut. Ed told us that he knew where he could lay hands on a Miata 1.6 engine for cheap. Given that there were four Miata owners sitting around the table, someone was bound to suggest that engine. After some discussion about how crazy we might all be, we agreed to do the engine swap. I left the meeting wondering what the hell I’d gotten myself into. A quick side conversation with Brian confirmed that at least some of my team mates were thinking the same thing.
While we were waiting for Ed to get the new-to-us engine, we started working on the cage. The previous owner of the car must not have been tall, because when I sat in the car my head rested right up against the side of the cage’s halo. Not comfortable. No way this was going to pass tech with me in the car.
For a while, we had Mick on our team. Mick’s an expert welder. Dennis bought bent dom tubing. We all took turns fitting and notching tubing and Mick welded it in place.
Mick welds in a new halo tube for our roll cage while Ed and Dennis hold it in place
We had a basic cage structure in the car, but no door bars. In the end, nearly every existing tube would have to be removed, replaced, repositioned, or totally re-thought. So much for having a car that came with a cage.
Crisis? What Crisis?
Well at least we had a clean starting place. It would be clean once Brian “Mr. Clean” got a hold of it. Brian’s spent a lot of years working on cars, and he’s gotten tired of being covered in grease. I don’t blame him, I’m just more tolerant of being dirty because all things automotive are a hobby for me.
At this point, frankly I wasn’t taking this build very seriously. I’d never done an engine swap. There were a bunch of guys on the team who were much more expert at working on cars than I. They were all focused on the logistics of getting the engine in. There was an abundance of cooks working on this piston powered RX-7 recipe. In truth, I wasn’t 100% convinced that this car was ever going to run. So I decided to stay the hell out of their way. I worked on the roll cage instead.
There were skirmishes about how the engine mounts would be created, whether to use the RX or Miata steering rack, etc. etc. I avoided most of this and got reasonably good at notching tubing with a grinder. My one joy during this part of the build, is that my bench grinder made so damn much noise that I could not only drown out the sound of bickering mechanics at will, I could make it quite difficult for them to hear each other speak. Passive aggressive? Who me?
Sparks fly during the MX7 build
Pistons are for pussies — That’s what the words painted on the hood of the car said
Oh darn, the epithet isn't even spelled correctly. Never buy a car from someone who can't swear good.
We were installing a 115 horsepower piston engine in a car that used to have a 146 horsepower rotary. The previous owner of the car was apparently proud of fact that the car was rotary powered. We knew this upon reading “Pistons are for pussies” — that’s what the words painted on the hood of the car said. Was he right?
The Miata our new-to-us engine came out of would have weighed about 2100 pounds. A stock 1986 RX-7 weighs 525 pounds more than that. The 1986 RX-7 was named Motor Trend’s Import Car of the Year. Would it still have won that award if Mazda had fitted it with a 115 horsepower four banger? I doubt it. The engine was now bolted into the car. Would it run? If it did, how much would this car suck with 31 fewer horsepower and 38 fewer torques than stock?
Congratulations, It's a girl! Our Maz-mongrel now with engine in place
The engine went in with less drama than I expected. I have no idea how much drama the cooks expected. Next, a radiator support and radiator was hastily added. The cooks were moving quickly and frequently stepping on each others toes. Fuel lines connected. Intake and air box installed. Wiring. Oh crap. What were we going to do about wiring? Ed was of the opinion that we should completely remove the RX-7 harness and use the Miata harness. Mark wanted to keep much of the RX harness. Two, perhaps three weekends of working on the car came and went with no sign of the car actually starting.
As the car now lived at Ed’s shop, when Mark wasn’t looking, Ed ripped out all of the RX wiring, installed the Miata harness and had the car very nearly start-able by the next weekend. After 45 minutes of connecting wires, Ed turned the key, and the car started!
Almost a year later, I’m still grateful that Ed decided to take over the wiring. The level of enthusiasm about doing wiring was a lot lower than it was about getting the engine installed. He put the hours into getting the wiring sorted at a time when as a team, our enthusiasm was low.
The beast now ran. The drive shaft was fitted and we were ready for the MX-7 first drive. Ed lives way out in the sticks. This gave us the chance to test drive the car with minimal muffling. Is actually ran, drove and didn’t immediately catch fire!
Our enthusiasm for this project went way, way up. Next we attended to getting the rollbar completed (or what we though was completed). We got the seat bolted to the floor.
Having never really raced anything faster than a sailboat, I had some fear that I might actually hurt myself in this car. Given this, I insisted that we make the shoulder harness attachment mounting points as by-the-book as possible, given the geometry of the cage. I spent hours getting two short pieces of dom tubing the correct shape to fit the “V” of rear of the cage. The shoulder harnesses would wrap around these short tubes. It was fussy, but it made me more comfortable about driving the car.
I missed a couple of work weekends. During that time an exhaust system was built, the Miata instrument cluster was made to work. Wiring was tidied up. We installed a master power switch. ChumpCar rules state that there can be no glass in the car besides the windshield. The door glass was already gone. We removed the rear hatch glass.
We were now ready to test the car on a track.