September 13, 2014 - Miatas at Mazda Raceway! This is always a big event, but this year it was massive with the public reveal of the 2016 MX-5, a world record attempt, a showing of Racing The Rock under the stars and nearly 2000 cars. The paddock was mobbed and the track time was full.
It was also my first time to really let the new engine rip at sea level. I'm still in awe, it's a spectacular thing. Every time we got on the straight, I'd just power past every car in sight. Sure, it may not be as cool as catching a high power car in the corners and working out a clever way to get in front, but the big hammer is still pretty gratifying. Here's what it looked like from inside one of the other cars - I make an appearance at 2:00.
I was taking it a bit easy in the corners. Mostly because there's no prize for being the fastest at an event like this, and I did not want to crash. I was also backing off the throttle as I went over the crest halfway down the straight because the cars entering the next turn had no idea I was coming. With the closing speeds, I was essentially coming out of nowhere. This was a particular problem in the slower Group B, where I had one exciting moment as a Spec Miata moved over close to the wall as I came barreling up with about a 40 mph closing speed. I thought I was going to lose both door mirrors, one on him and one on the wall. The car was actually really well balanced, with a bit of inherent high speed understeer from the aero that could be counteracted with throttle.
The car, unfortunately, was not rock solid. When I had it down at Road Atlanta this spring for display purposes, it went into some sort of limp-home mode on me. I was never able to duplicate it and the car's been great ever since. Well, it started doing the same thing at Laguna Seca. I'd be powering along, and all of a sudden my drive-by-wire throttle would disable after a shift. It's not a fun experience, losing all power just when you're hitting the next gear. I found I could bring it back if I turned off the main battery switch, resetting the ECU. Of course, this wiped any error codes. Eventually, it failed on the way up the hill to the Corkscrew and I was able to coast back to the pits without resorting to the reset. It had to do with the electronic throttle.
Lots of theories bandied about and I tried to eliminate potential interference by wrapping the wiring harness, swapped out the pedal for another and generally got frustrated. It seemed to be heat related - and it alway happened on a shift. So eventually I just left it in fourth gear and avoided shifting all together. Still, I didn't trust the car so I parked it early. A bit of a letdown after the buildup to the event.
My current thinking is that I was hitting an airflow limit on the car's programming. There's one particular table that has to do with the amount of airflow expected for a given throttle opening, and I may have been exceeding it. That would explain why it's never been a problem with high altitude use, and why it happened when I was shifting and getting a big gulp of air when the throttle smacked open again. I'm going to mess with the table and see if I can duplicate the problem at altitude, then we'll see what happens next time it goes down to sea level again. Unfortunately, that probably won't be for another year, and I really don't want any questions around the car at that time. Some troubleshooting lies ahead.
Photo by Ben Sale. It's definitely not the classic Corkscrew shot, I love the different take on it. entry 1130 - tags: MRLS, laguna
December 15, 2014 - It's time for some traction. Maxxis has just introduced a new size of their RC-1 track tire: a nice fat 245/45-15. It's been a long time coming. The tire is aimed at the track day crowd, promising a long life and good traction. I'll be mounting them on a set of Jongbloed 15x10 wheels.
I'll have to do some work to make them fit under the fenders, that's for sure. But I'm looking forward to the first track day in the spring! entry 1131 - tags: tires, maxxis
January 15, 2015 - The new track rubber is mounted and ready to try out. Those are 245/40-15 Maxxis RC-1 tires wrapped around a 15x10 Jongbloed wheel. It's a lot of rubber, and it's going to be a real challenge to get it to fit. I'm a bit worried about the fenders. entry 1132
January 21, 2015 - Test fit of the new Maxxis RC-1 tires! And it's a problem. In the front, I could probably get them to just barely clear with a hard pull of the fenders. Probably. entry 1133 - tags: wheels
January 21, 2015 - The tire fitment on the rear is a bigger problem. I don't think I can pull that fender enough to clear the tire. Almost all of the extra width of the big 245/40-15 ends up on the outside. So it's time to look at some real body modifications. entry 1134 - tags: tires, maxxis
July 1, 2015 - Track day! I was back at High Plains Raceway with the Z Car Club. Usually, this event attracts some pretty fast cars. But attendance was down and the top echelon didn't show up. There was one notable exception - a 60's 911 that had a bunch of modifications, including a MAST-built 7.0 l LS7 V8 stuck in the tail. We had some fun. I was quicker than he was on sweepers and I think I had the edge on him on high speed acceleration, but he had me under braking and on acceleration out of corners. It's hard to beat having all your weight on the rear wheels sometimes.
Otherwise, it was an exercise in passing and passing and passing. No worries, it's kind of fun to be Godzilla once in a while, and I had enough of a challenge dealing with my driving. The car was a rock star and didn't miss a beat all day.
The biggest problem was heat. It was a hot day - somewhere around 100F - and I was generating a lot of heat. Enough that I measured the temperature of the transmission tunnel at 196F and the heel of my shoe at 147. Yes, that was uncomfortable. After about 6 hard laps, I'd see the temp gauge start to move a bit on the dash, but that's still a very happy range for LS motors like mine. Even with 20 minutes on, 20 minutes off the track the car never flagged.
The brakes were much improved from a year ago. That's when I was boiling fluid and having to be very conservative. I've upgraded my brake ducting from 2" diameter to 3" and gone to 660F fluid. The brakes were still pretty hot and I wore out a set of front pads, but they never went away. I wasn't as aggressive as I could have been under braking at times - never my strongest point - but it wasn't due to a lack of braking power.
I love this engine. My maximum speed with the old one at this track was 197 kmh. Last time I was here, I had a headwind and peaked at 215 or 217. This time, I saw 222 kmh. That's a full 25 kmh faster than I ever managed with the old engine.
I had the prototype FOX suspension on the car. The Targa Miata was used as one of the development platforms, and this was the chance to get it out on the really fast stuff. After two sessions, I had it pretty dialed in and the car just felt fast and balanced. It's got great stability and fast turn-in, making the old rally-bred AFCO stuff feel surprisingly soft and wooly. I like it.
Video! Here's a clean lap, followed by the one lap I spent behind the 911. I had him on the straight, but decided to hang back and watch. Then he overheated.
This video is just a compilation of passes. NSX, Noble (or the new equivalent), new Corvette, WRX and a bunch of minnows.
THE DIARY
