2 Weeks Till 24

Next to last weekend before the race. Here's how it went down...

Saturday I got hood pin holes in the new hood, painted it, and added some very home-made louvers. A quick test of the shop fan aimed at the radiator had lots of air flowing out of the new vents. 

Sunday I got to work swapping in a new under-tray to replace the tattered original one, tightened up a few bolts, and spent some time tidying up a lot of the interior wiring. Last weekend there was just a floor full of spaghetti and now it looks like a car again. 

While I finished up all the small jobs around the car, Kyle finished the new ECU wiring so I can take it for professional tuning this week. 

With any luck, next weekend I'll knock out a little theme work and give the car new decorative LED lighting for the night racing and we'll be ready to hit the track. 

3 Weeks Till 24

Hot off the time trial weekend, the Columbia based team is hard at work on a slew of upgrades for the little purple car's second 24 hour race. We are really looking forward to benchmarking our performance at this race since our very first race in the car was a 24 hour at CMP. With fresh pavement, we expect better tire wear and faster lap times across the board, but hopefully we can finish in a top 10 slot. 

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. 

First Time Trial

This past weekend NMS South loaded up and headed four hours north to take on NCCAR. This was going to be my first time trial event, so I had to borrow a transponder from a friend. Similar to racing, each car gets a transponder that sends a signal to timing and scoring every time you cross the start/finish line so they can track, well, timing and scoring. Other than a transponder, the Miata was ready to go!

I arrived Friday and set up next to Lemons teammate, John and later Kyle joined the party and stayed in the NMS trailer for the weekend. With approximately 200 square feet of living space, the trailer is probably just as good as some small apartments.

Saturday we ran the course clockwise and Sunday we ran counter clockwise. Not many tracks are designed to safely run both directions so this was a neat opportunity. The morning each day would be three qualifying/practice sessions and the afternoons would be three timed, competitive sessions. A third timed session was going to be added in for the final scoring but rain and lightning put a damper on the later half of Saturday afternoon. 

In the end the final results would be calculated based on the best time Saturday, plus the best morning time on Sunday, plus the best afternoon time on Sunday to give a final total time. I finished 3rd of 3, but not too far behind 2nd place. The Miata is no way prepared for the time trial rule set, so there was certainly performance left on the table. I had a great time and improved all weekend and brought everything home in one piece. The next few weeks we'll dial in the Lemons Miata and set out for our second 24 hour race in September.