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build diary

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August 9, 2005:
On my fastest run, I finally screwed up the courage to take this section flat out.
The back of the car was loose as the tires fought for traction, but it was significantly faster through here.
entry 943
The corner that made all the difference.
Instead of sliding around this corner as I did in the Mini, I relied on grip the last time around and cut it tight. It helped a lot. The open front wheels made it easy to aim, unlike a more enclosed car.
entry 944
New video from the autocross! See it here.
entry 945

August 11, 2005:
Time for a little cleanup after the autocross and prep for the upcoming Flyin' Miata Open House track day.
Those who have been reading for a while will know that the Open House last year was the first time the Seven was run hard! The first item of business is to put the new sub belts on, a bit of a painful process without removing the seats. I have a bruised hand from attempting this last night. I might just have to suck it up and take the seats out again. Argh. An escaped hood latch was reattached last night. It must have been loosening off for some time as it seems much tighter now. A bit of rebending of the fender stays and that should do it. I need to remake those fender stays but it's not going to happen this weekend. I will shamelessly follow the lead of Sam Buchanen's Stalker - he redesigned the ones on his car and I like how they turned out. That's a good build diary, by the way, and really shows the difference between a CMC and a Stalker kit. Someday I'm going to make a collection of all of the pictures of people sitting in their half-finished cars and pretending to drive. I know I've done it enough times, but it's a standard step in the build process.

The local track here is a kart track that operates under the looming cloud of small-town politics. Due to some houses in the area (on the other side of an interstate, underneath an airport approach path) deciding they need a 55 dB ambient noise level in their back yard, the noise regulations are very tight. There's no way the Seven will pass as it is right now. Last year, I ran my "kickstand" diffuser but it would drag on every right turn. This year, I've decided to go a little more high-tech and ordered a Supertrapp "disc-only muffler" from Summit Racing. This has removeable diffuser discs that allow me to tailor the amount of noise and backpressure. I welded up an adaptor yesterday but the fasteners that came with the Supertrapp were weak and had to be replaced. So I don't know how well it works yet. My fingers are crossed.
entry 946

A victim of the autocross - one of my hood latches pulled out.
I taped the hood down. A corner worker handed the missing part to me at the end of the day.
entry 947
My latest attempt to quiet the car for a track day.
This is a Supertrapp "disc-only muffler" slipped on to the exhaust tip.
entry 948

August 12, 2005:
That cursed Fiat.
I've decided to order some nice sticky rubber. A set of Toyo RA-1 tires will be mounted on the Seven for the Open House. Ha ha ha! Not that the Fiat is coming. But in order to fully utilise the ability of the Seven, it needs stick. Now I'll be able to use full throttle.
entry 949

August 15, 2005:
The Seven is sitting outside, waiting to go to the track for noise testing.
In a couple of hours I'll know how well my new Supertrapp tip works. I was reading David Vizard's A-series tuning book over the weekend and he is not a Supertrapp fan. Oh well, there aren't a lot of bolt-on solutions that I could implement this easily. I'm going to continue looking for a better muffler.

Most of the car time this weekend was spent working in Janel's little supercharged Miata, but the Seven got a little love. The glass for the instruments was installed. Unfortunately, the 2001 gauges I'm using now have needles that stand higher than the older style. I had to space the glass off the gauge cluster a fair way. This will let dust get in behind and makes the gauges look ill-fitting . I'll have to come up with a better solution. Putting the glass on the outside of the dash would work but that looks terrible.

A better fit on the instruments is the LED tach. I carefully cut a rectangular hole in the dash and was able to get a press fit for it. It looks good.
entry 950

The new transmission cover.
The welded plate on the sides is painted black and the top is cut off the misfitting one from CMC.
entry 951
The LED tach installed in the dash.
When you turn on the ignition, it does a nice KITT imitation.
entry 952

August 16, 2005:
Thank you Supertrapp!
The sound testing was an interesting process. The way the muffler works is by simply diffusing the sound through a set of discs. The more discs you use, the less muffling goes on and the louder the car is. It seems a little counter-intuitive at first until you realise you're basically opening up more area for the exhaust to escape. Unfortunately as you remove discs to quiet the exhaust, you also increase the backpressure. According to Supertrapp, 24 discs is approximately equivalent to no muffler at all with regards to backpressure and I suspect also with regards to silencing.

The first time out, I set the Supertrapp up with 12 discs. It's the most I had. I wanted the worst-case scenario. After a couple of laps I came in and the track owner looked concerned. Obviously I was too loud.

For the second test, I used 6 discs. This made the car noticeably quieter. I came back in after one lap and the track owner told me he wanted a few more samples. I was to go out and lap the track until he waved me in. Sigh, the hard work I have to do for this car. After about 5 laps, he had all he needed. The 6-disc setup knocked about 7 dB off the peak. Excellent. Since the track owner is also a car nut (why else would you do it?) he wanted me to put some discs back in for maximum performance. Oh well, if I must.

The next test was with 9 discs. I let Bill Cardell take the car out so I could watch it. Well, that was the plan. We were also testing transponders so it was suggested I take out the supercharged Miata so we could check how they worked. The Miata had already come in with overheated brakes and was not set up well for the track at all, so I decided to simply play around. I'm sure the noise peaks from that car came from the tires instead of the engine as I practiced my sideways driving. Hee hee!

While I'd been hooning around in the Miata, the Seven had shown itself to be borderline for sound. So we took out one more disc (to 8) and I went out one last time. I also had three transponders stuck on the back of the car. The sound levels were perfect so I just stayed out to play. The car was right at home - the front end stuck well once I sorted out my entry speeds and the slow track (almost all second gear) allowed me to steer the rear of the car whenever, wherever I wanted. The soft springs meant I could still hammer the berms without upsetting the car but the sway bars kept it flat on corners. There are no high speed corners on the track so I couldn't check out the behaviour at the limit, but for a kart track it's a good little car. The transponders showed that I was lapping fairly consistently, ranging from 1:07.234 to 1:07.888 over four laps. Not too bad considering I'm still learning the track and trying different things. The LED tach worked perfectly, allowing me to judge engine speed easily and also acting as a speedo of sorts.

Do I have a great job or what? This sound testing was done in the middle of the day when I was supposed to be at work. Not only was I allowed to go, but my boss came along to play as well. We'll be going back tonight with the others from the office for more "sound testing". Whee!
entry 953

The datalog from the sound testing.
You can see all four of my test sessions with nice quiet periods in between. The limit at this track is 95 dB. The sound meter could also export a wave file of a peak, giving some nice recordings of the Seven on the track. Cool.
entry 954

August 17, 2005:
More "sound testing" at the track.
Last time was legit, this time was just a chance to play. A few Miatas came along, ranging from Janel's supercharged car to a couple of turbo monsters - and one frustrating little naturally aspirated car with a sick motor that beat a couple of the forced induction cars. It was good fun with a bunch of coworkers. Personally, I dropped down to a 1:06.818 - that's about 3/10ths slower than the fastest car at last year's Open House. That driver isn't coming this year so hopefully I'll be able to take the top spot. The Seven proved to be both solid and fun and I spent most of the lap in a slide and giggling. In the middle of one of my fastest laps, I decided that all the work had been worthwhile.

Interestingly, a coworker took the Seven out (after many subtle hints on his part). He found it a little abrubt in the transition to oversteer and had the front tires go off on him after about 5 laps or so. Neither Bill nor I had the same problem. He also complained about the same thing in his own car so perhaps it was driver-related.
entry 955

More "sound testing".
The Seven and a few Miatas dropped by the track for a little more fun.
entry 956

August 19, 2005:
This weekend is the Flyin' Miata Open House.
Last year, it was the Seven's first real test on a track. I was running on cast-off Toyo tires, there had been no tuning work on the suspension and the fuel pump was clogging up with bits of foam from the tank so there was a bad starvation problem. You can read about it here. This year, I'm a little more prepared and planning on going much faster.

The new Toyo RA-1 race rubber is mounted on the car. They're a 205/55-14 size. Since they fill out the front fenders so much, they really show off the poor fit of the fenders. I'll have to fix that soon. The car's run a wide variety of tires over the past year (mismatched all-seasons, worn-out Toyo T1-S, worn-out BFG R1s, Falken Azenis RT215s and now these) but I'm thinking this should do it. They're street-legal race tires and should let the car reach its full potential. I'll find out in a few hours when I head back to the track. It'll be interesting to see how it handles with the new rubber.

Some disappointing news. The Datatool Revlight that I'm using for a sequential tach is out of production. I have mine so that's good, but it's a pity for anyone else who wants one. It's a good product. The manufacturer says there was no demand.
entry 957

The Seven now has the tires it deserves.
A set of Toyo RA-1 tires in a 205/55-14 size.
entry 958
The Seven has always looked a little under-tired from the back.
Not so much now.
entry 959

August 21, 2005:
Turn two at the track.
It looks as if the rear is going in to positive camber a little, but the car is well balanced at these speeds.
entry 960
I had the chance to watch the car on the track.
It looks very wide from behind and very stubby from the side. The black wheels really set the car off well.
entry 961
Whee! The Seven likes to dance.
entry 962
One of my fastest laps.
I was hammering this berm pretty hard but I didn't realise that I was lifting a front wheel up!
entry 963
This kind of says it all.
It's not the fastest way around the corner, but I'm sure having fun. Sevens love this sort of driving.
entry 964
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