One big item is moving to an aftermarket ECU to control the engine. We picked up a used Megasquirt 3 online for a good price and I handed it over to Luke and Kyle to connect all the spaghetti while I worked on the car.
Kyle sourced some fuel injectors that were 100,000 miles less used than what we had been using so I swapped those in. Additionally, we were given some free hoods, so naturally I cut big ol holes in one so we can vent some of the hot, high pressure air under the hood. Theoretically this will keep the engine running cooler and give the car a little less lift on the front.
Another critical part of a new ECU is telling it how far open the throttle is. The old Miatas have pretty basic electronics so we had to use a BMW style sensor. This upgrade is so common when tuning these cars, popular parts supplier, Flyin Miata even sells an adapter. On top of telling the newer computer more specific information about the throttle, we wired in different air sensors for the intake and exhaust so it will know how much air is flowing through the motor.
At the end of a long Saturday, we plugged the laptop in and got the car to fire up. There is still a bunch of tidying up to do, but we are on track to hand it over to local Miata racing experts, Panic Motorsports in a week to do final tuning on their dyno.
The final cool piece of Miata engine trivia is that the cars originally are programmed to squirt fuel into the combustion chamber in a batch mode. This means that cylinders 1 and 3 squirt fuel at the same time and 2 and 4 squirt at the same time. Unfortunately, those pairs of cylinders don't need fuel at the same time and the stock computer is effectively dumping twice the fuel needed. We are working on setting up sequential fuel injection so we can only send fuel to the cylinder when it is needed. This should allow us to make more power while also improving fuel economy.