24 Mar 2013

Shakedown/test drives have started. A lot of people have been bugging me about why I bother, just drive it instead of these wimpy baby steps. The thing is, driving a freshly-built car is kind of taking up running, you don’t just sign up for a marathon, you build up to it. The day started with a bunch of laps around the block, then venturing  out further, finding a few issues along the way:

1. The clutch anomaly is still present. It may be due to not having a check-nut on the clutch – my goof – or perhaps the clutch has to break in. Regardless, twice it had to be adjusted and while I’m not too worried, yet, the Concern Meter is up off its zero peg…

2. The fuel level sensor was calibrated using a 12V power supply, but a fully-charged battery is more like 14V, making the readings wrong by a fair amount at the low end. The fuel tank will be pumped out and one gallon at a time added, recording sensor output each time. That equation will be entered into the dash and then there won’t be any guessing how much it’s really holding – I don’t like inaccurate dash readings.

3. Part way through one drive, the oil temperature and pressure suddenly shot up, with oil pressure indicating about 420 lbs… sure. Thinking it through, since both sensors are located on the dual remote oil filter housing, the suspicion was that the aluminum housing had become ungrounded from the chassis (necessary for the one-wire sensors to generate readings.) Sure enough, the filter block didn’t have a reliable ground so some powdercoat was ground off and a split-lock nut added under a mounting bolt – fixed.

4. The alarm kept getting flagged by oil pressure dropping below the 20 psi threshold. The problem is that the alarms are very simple-minded; they’re just a value below which a warning is flagged. The problem of course is that how low oil pressure gets very much depends on both engine rpm and oil temperature, both of which the dash knows, but the software doesn’t allow for more complex alarm conditions. Oh well.

5. The engine really wanted to run but it was being limited by the ECU. The setup is in place to have boost-by-gear, which means literally that; each gear can have its own boost level, sort of a poor-man’s traction-control. For now it’s disabled, expecting that boost would be limited by the springs inside the wastegates, but it isn’t. It may be because the solenoid is normally-closed; perhaps it’s trapped air above the diaphragm which is keeping boost pressure from opening the wastegate valve. I unscrewed the top hose from the wastegates so that the air vents directly to the atmosphere but didn’t have time to try it. The point of this long explanation is that the ECU cut off fuel at 11 psi (I set it there as protection against me overdoing things… good thing.) The result was that at around 4000 rpm, the ECU shut off fuel – hard – which was like kicking the engine in the nuts… not glamorous for seeing how well the engine would pull, with the party being over before it even started. Given that the engine’s built for 8300 rpm, it’s not even half way there!

That said, I wanted a wild engine and I got it, kind of like having a crazy redhead for a girlfriend, one with tats, piercings and owning a sportbike – or so I imagine. Between the boost and straight-cut gears, she’s going to take some getting used to.

I went around a few corners at maybe 30 mph and it’s very clear that Midlana corners really well; it’ll be interesting to see how things go at higher speed 🙂  For the above reason regarding the engine, I never really get on it from a stand-still since it would only barely get going before having the fuel pulled out. Still, the one time I did, it didn’t spin the tires. That’s very promising and confirms that having much of the weight over the rear-driven wheels provides great traction. It’s one reason why I’m going to run without boost-by-gear for now and see how it goes.

So why no video? It’s boring! Between all the above issues there just isn’t anything interesting. That, and driving down our local Highway 101 wasn’t any fun as there was a lot of bumper-to-bumper traffic. Not much to see except license plates at eye-level…