| MIATA BUILD |
|
|
 | |  | July 25, 2008 - A very interesting picture provided by a fellow racer.
He's entering a corner at about 40 mph. This car is fitted with the AFCO suspension, but with much higher spring rates and big fat Hoosier 275s. Check out that lifted rear wheel!
Cory reports that his car is sitting higher than he'd like, about the same as the Targa car is. This is because he's running 800 lb springs in the front and they're not compressing as much as my 375s, thus he ran out of adjustment. You can really see that in how high the car's sitting even in this position, the front still has another couple of inches of travel left. Some shorter springs will solve that, and it will give him some more droop travel.
He's also not running much swaybar at all when compared to his springs. It's a 7/8" bar up front, and he reports lots of oversteer. So he's going to try dropping the car by about an inch and sticking a much larger bar up front.
I find this interesting because it may be related to my wheelspin problem. I've never seen a picture of my car with such unbalanced cornering though. I'll be playing with ride height a bit at the track tomorrow to see if I can alter the behavior - or even to see if the car wheelspins in that environment.
entry 502 - tags: suspension | | | July 25, 2008 - I've been dealing with stacks of paperwork for the Targa.
Is it a good sign when you email a photo of the car (for the program) and the registrar responds "SWEET!"?
entry 503 | | |  | July 28, 2008 - The final high-speed testing took place on Saturday.
In short, the car performed well. I had a brace of sway bars along with me to do some tuning, but it wasn't necessary. The overall balance of the car is pretty good. On long sweepers, it can be balanced on the throttle well. I've set the car up to be a little bit softer on turn-in than I usually do for a track-only car, in order to give myself a little more margin for error. Still, it'll rotate nicely if I set the car up properly on corner entry.
I did play with the ride height a bit to see what that affected. The car's a bit sharper and less prone to understeer at the lower height, which is about the same height that we use for street Miatas at Flyin' Miata. It's easy to adjust so I'll leave that as an adjustment option once we get to Newfoundland.
I tried driving a few different lines around the track to see how the car would react. It's amazing how much slower you get when you're driving like a normal person instead of a racer who knows every little bump in the course. Still, it was good practice and the car was a good tool - mobile and friendly. Even a fast entry into the fastest corner on the track, with a different line than usual, was dealt with well.
The car ran flawlessly and cool despite 30+ minute sessions in brutal heat. I need to spend a bit more time on the dyno to tune the engine but overall it's pretty good. I declared it finished at the track.
Well, finished except for one thing. The tight corners on this track tend to be lefts. There's one relatively tight right hand 180 degree corner, and on that one I could get the inside rear to spin up once in a while if I was brutal on the berms. This was without a passenger, so it probably wouldn't happen on the Targa - but I've decided it's time to solve this problem once and for all. I'll pull the Guru differential out of my Seven and install it in this car. The Guru is a helical-style diff like the Torsen, but with preload so it won't act like an open diff when one wheel loses significant traction. I'll swap that over this week. I'm just trying to decide if I should have it changed to a 4.10 ring and pinion or stick with the 4.30 that's on it already. I do prefer to drive the taller setup, so I'll probably go with that.
The trailer towed really nicely, and when we hit lots of rain on the way home I was happy to think that my little car was safe and sound inside. It's not cheap to tow, but that's life.
entry 504 - tags: testing, suspension | | |  | August 1, 2008 - The differential is out again.
I'm going to use velcro to put the goofy thing back in again.
It's out so that it can be replaced with the Guru from the Seven. What the heck, even if I don't need it I'll have it. The Guru is currently set up with a 4.3 so I'm having the gears swapped around. I was tempted to try it myself, but this close to the race and with such an expensive part at risk I decided to try it some other time.
While underneath, I noticed that the last alignment tech set two of the four rear alignment bolts upside down - you can see one at the far left. I'm not sure if this is going to be a problem or not, but I'm not impressed regardless. My usual long-time alignment guy seems to have retired.
entry 505 - tags: suspension | | |  | August 6, 2008 - The Underground Miata Network logo is proudly displayed in the hardtop window.
I'm hoping to get together with the club to thank them for their support on my way home from the race.
entry 506 - tags: sponsors | | |  | August 6, 2008 - The Guru diff, freshly wrapped in a 4.10 ring and pinion.
It's a beefy thing, rated for 600 hp or so. With the number of diffs I've been juggling, I've started identifying them with a silver marker on the housing. Makes life a lot easier, and this way you don't accidentally install an open 4.30 diff in your rally car. To pick a random example.
entry 507 - tags: differential | | |  | August 6, 2008 - I love that blue.
The last time I installed the diff, I experimented with using Hylomar HPF instead of the usual RTV. Hylomar never really sets up, but stays tacky. This makes it really easy to separate later and to clean up. The old Land Rover guys use this a lot, and when I came across it in my toolbox I decided to give it a shot in something a little newer and hopefully more oil-tight. I'm pretty happy with the results, it's much cleaner to work with than RTV.
While writing this, I decided to check out the suggested uses of Hylomar from the manufacturer. And will you look at that, they recommend it for "differential covers". So there you go.
entry 508 - tags: differential | | |  | August 6, 2008 - I've been working behind the scenes on the website.
It's now easier for me to post updates - something that will be important on the road during the race! I am hoping to keep everyone up to date while the really exciting stuff is going on.
What's up with the picture? Well, I need to make sure the picture uploading is working. So that's what the car looked like a year ago. The Martini paint had been unwrapped just a couple of days earlier. It didn't even have a windshield or rear hardtop window yet.
entry 509 | | |  | August 9, 2008 - A great shot from the last trackday at Pueblo.
The car's sitting nicely - this is a fairly fast corner with a quick dab of the brakes on entry, a bit of rotation and then back on the throttle. At least, that's how I do it. And I always exit this corner saying "next time, faster on entry..."
Back to the present day - the diff is in and working nicely. I'll know just how nicely after tomorrow. A surprise track day has come up at the Woody Creek track in Aspen, courtesy of the 25th anniversary gathering of the original quattro. This isn't a track we get a chance to drive very often. It's relatively short but is bumpy in spots and has a couple of challenging corners. I've only been on it once before. I'm going primarily because Janel has to work and because the weather forecast is poor. Hopefully it'll rain. It's not the usual wish for track work, but I don't have much experience in fast driving in the rain and I need the practice!
I have my new race tires all mounted and balanced. If it's rainy, I'll scrub them in and see how full-depth RA1s work in the wet stuff. Quite well by all accounts. If it's damp or dry, I'll use my well-seasoned test tires. I'm also going to drive the car out to see how the new padding works in the seat.
There's a Sport Quattro in attendance at the event. I can't wait to see one in person.
entry 510 - tags: testing, suspension, ergonomics | | |  | August 10, 2008 - In terms of rain, the trackday at Aspen was a failure.
For me, anyhow. One run group of Audis was lucky enough to get wet. I was the only one disappointed, however. Nobody else is any fun.
The day started with a really early morning (8 am driver's meeting and a 2.25 hour drive to the track). The good news? The new foam in the seats makes all the difference. No numb bum at all. That's a big win for the "backsaver" pad from Pegasus racing. Insert glowing testimonial here.
The bad news? The 8 am driver's meeting was at 9:50. My car was given a tech inspection four times. This kinda gives you an idea of the level of organization present. Still, we finally worked out way out to the track. I was staged right behind three Formula Fords that had me a little spooked - Aspen's track is a little on the small side, and I didn't want to accidentally squash one that had sneaked into my mirrors. That wasn't a concern. My biggest problem was trying to get one to give me a point-by. I had the same acceleration, better cornering and vastly better brakes than the driver in front of me, but he apparently didn't have mirrors. After seriously considering using the old "chrome horn" on an open-wheeled car, I ducked into the pits to get some clear track.
The car was okay, but it was hunting for grip. Both ends were skating. I checked the tire pressures and found I had them too high. The next session was better, but still too much hot pressure. Finally things settled down a bit. The car's quite safe right now, giving me lots of warning of what it's about to do. For a track car, I think there's still just a bit too much understeer. Of course, that means it will understeer, even mildly, on occasion. I can throttle steer the car fairly well. But given the unknown nature of most corners in the rally, that's a good setup. In my opinion, anyhow! I'll have the ability to tweak it at the rally if required.
And while it may not have been my preferred setup, a chicane at the fastest part of the track was handled very nicely, a high speed right-left jink that could have been a real problem if the car oversteered too much. Instead, it just screamed right through and surprised a few cars. I was also informed that my lap times were very good for running two-up with a chicane on the straight. Considering my lack of knowledge of this track, I'll take that as an endorsement.
So, despite the lack of rain, a good day. I had fun playing with some purpose-built race cars (who were a little surprised to see how fast this particular Miata could squirt out of corners) and Brandon had an excellent time bonding with his new Locost. Smiles all around.
entry 511 - tags: suspension, ergonomics, testing | | |  | August 18, 2008 - The Flyin' Miata Open House track day was last weekend.
It's always been my plan to have the car finished by this point. Last year, the Open House marked the first track outing of the car. Since then, of course, I've done a whole lot of work!
I'm a little conflicted. The car didn't feel that great to drive, with a soft turn-in and a steady-state cornering balance that was slightly biased towards understeer. Just like last weekend, naturally. This time I had a passenger every time I went out and the car was happier putting down power.
However, the car was fast. Really fast. The fastest Miata out there despite a big power gap.
I was a full 3.230 seconds faster than last year. Granted, everyone was going 1 or 2 seconds faster this year, either due to track conditions or improved cars. But still - over 3 seconds. Some of that is engine, some of it is driver, and the majority of it is setup. I also picked up 0.2 seconds over my time on the same track in April, and the track was fast that day.
I'm going to check the toe on the car and then call it finished. There's another track day next weekend, but I'm going to resist the urge to keep tweaking. It's time to concentrate on final preparation for the race. After all, I have to hit the road in less than three weeks!
One of the other drivers there did note that the fastest Spec Miatas aren't as fun to drive as the slower ones due to their setup. I suspect that I have the same problem. Don't get me wrong, the car is still a lot of fun. The first corner on the track shows off the light weight of the car as the nose dives for the apex, and it's still quite faithful. I've probably given the impression that the car understeers badly, when really it is fairly neutral. Never does the front end wash out on me, and I can always get the back end to step out if I try. A couple of times on the day, I got the rear end out a little too far! So it's a good balance, especially as I'm not a hero rally driver.
entry 512 - tags: testing | | |  | August 19, 2008 - Okay, we know the car's set up.
So it's time to start working on the other aspects of preparing for the race. The countdown is on.
First, it's time to fit a spare tire in the trunk. I couldn't do this before I had a full-depth tire on hand. It'll change the handling slightly but not enough to worry me. A bigger worry was making it fit! A little bit of clearancing on the rear of the trunk (ie, I sawed a slot in it and hit it with a hammer) lets me slide the wheel right into place. A stud was attached to the bottom of the trunk so a wingnut can hold the wheel in place.
entry 513 | | |  | August 19, 2008 - Continuing with tire preparation - I put some tape over the wheelweights.
This will theoretically prevent them from coming off. I don't know if that's a legitimate thought or not, but it's a trick I've learned from other racers. It can't hurt!
entry 514 | | |  | August 19, 2008 - We're only allowed six tires for the race.
Theoretically we can carry a space-saver spare as well, but we can't run closed stages with one. Since our wheel/tire combo isn't much heavier than a space saver, there's no point.
Anyhow, thanks to this tire restriction, we'll need to be able to track which tires have been used. I marked the sidewalls with 1, 2 or 3 as well as L or R depending on the direction of the tread.
It's worth noting that the rotation direction really only matters with full tread depth in wet conditions. When the tire's worn or it's dry outside, the direction doesn't matter to the RA1 anymore.
entry 515 | | | August 21, 2008 - I had a bit of a close call yesterday.
I was mountain biking (it's world-class stuff around here) and, while dropping off a ledge, I went over the handlebars. It was a pretty good crash, really, and I landed hard on both hands before doing a shoulder roll. Other than some deep bruises on my palms and a bit of scraped up skin on a shoulder, I'm fine. I was hurt enough that we had to back-track out of the trail instead of continuing though. I'm sore now but I should be healed in a few days.
But all I could think about was the potential consequences. If I'd damaged myself, I might not be able to run the Targa. Ask Sebastien Loeb about that!
So, it's easier rides only for the next few weeks.
entry 516 | | |  | August 24, 2008 - Another track day.
Yes, August has been a busy month! This time, the Targa car stayed in the garage. There was no need to beat on it any more, and I was busy defending my shiny new lap record in the Seven. So I took the old race rubber off the Targa car and stuck them on Janel's little Miata so she could have some fun. She did pretty well, taking a second off her previous best time.
I took her car out for a few laps to show her how much she could trust the race tires, and it was an interesting drive. Her car is fitted with a small, responsive turbocharger (an FM Voodoo II with the smallest turbo) and has a number of chassis braces installed as well as a Flyin' Miata Stage 2.5 suspension. Peak power isn't much different than the Targa car although it's a more civilized drive due to the full interior and a bit of extra sound deadening. But other than the lack of a full cage, it would be a good specification for the Targa for much less work and cost than our purpose-built racer. It uses off-the-shelf components and the whole car would cost less to duplicate than building a Spec Miata. It would have to run in the Unlimited class thanks to the turbo, however.
On the track, the car felt softer. The suspension dealt well with the berms, although I wasn't taking anywhere near as many liberties with them! The car had good power that was easy to control, friendly handling and nice brakes. But everything was just turned down and softened a bit. The brakes were nowhere near as aggressive, the power response wasn't as hyperactive and the car just didn't have the sharp reflexes of the full-on race car. I didn't have a transponder on the car so I didn't get times, but I'd guess it would be at least a couple of seconds a lap slower. That will translate to a lot of time over the course of a Targa stage. This isn't a big shock and I was quite happy with how friendly the blue car was to drive. It's under full braking in the picture, in case you're wondering. That's Janel setting a personal best.
One piece of good news: while the bruising to my hands did make things a little less comfortable and meant I didn't have much grip strength in my right, it didn't seem to slow me down. By the time the Targa rolls around, I'll be just fine.
entry 517 - tags: skills, suspension, other cars | | | August 26, 2008 - With the car finished, other aspects of preparation are moving into high gear.
I'm busy gathering up documentation and tools, and starting to wonder about things like having cellphones that don't cost $1/minute in Canada. The truck should be serviced before it goes into harness. I need a haircut. Janel and I will be taking our First Aid certification in a couple of days. Do I have everything? Have we thought of everything?
All through the build of the car, I've had the luxury of time. Lots of time. And now I'm aware that there's only a little bit of time left and little room for error if I forget something.
And I lied about the car being ready. It's on the dyno today, making sure the engine is happy. Then it's time for a bit of heat insulation and an oil change, and I need to scrub in the race tires. But it's close.
So close.
entry 518 - tags: preparation | | |  | August 27, 2008 - I spent some time under the car last night.
An oil change, a quick nut-and-bolt check and a general under-car inspection. Remember that red PPF?
I also decided to add a bit of heatshielding. You can see the factory heat shield that I've added above the catalytic converter in this picture. It weighs next to nothing so I'm not sure why I never put this in before. Probably because it's the sort of sharp, oddly shaped piece of metal that always gets first squashed flat by accident and then eventually thrown away.
There's also some Reflectix insulation inside the transmission tunnel. It's not very visible here, but it's near the white header. I attached it with waterproof foil tape which has been very effective in other applications, but which seems to disapprove of the particular texture of the bottom of the car. So while I'm happy with the effect of this shield, a quick peek under the car when I arrived home showed that the bottom tape had separated. Shame. The material itself is pretty neat, just a double layer of bubble wrap with a Mylar coating on each side. It weighs next to nothing (a 24"x25' roll is about 3 lbs) and can withstand 180F in direct contact. That's borderline for this use but the air space will help a lot. A good thing about it for under-car use is that it's also completely unaffected by water. I'll probably end up removing it if I can't manage to adhere it. Still, given the lower temperatures in Newfoundland, the heat shouldn't be too big a problem.
entry 519 - tags: ergonomics | | | August 27, 2008 - Dyno run!
The car spent some time on the dyno yesterday, making sure that it was safe and ready to go. Jeremy at Flyin' Miata managed to pick up a bit of top-end power but more importantly he was able to confirm that everything was in good shape and ready to go.
The chart is interesting. There's a big dip in the curve at around 4000 rpm. I don't feel it when driving, but the car would be faster without it of course! Jeremy spent some time trying to tune it out but didn't have much luck. If I was building the car now, I'd probably use a VVT head from a 2001-05 Miata instead of the 1999-00 one I used. They have much better torque curves down low. But if you don't learn something over the course of a project, you're not trying hard enough.
I waffled a little bit about whether I should put this chart online as it will invariably get held up on various forums for ridicule and taken out of context, but what the heck. Here goes.
This is Janel's little blue car vs the race car. She has a Flyin' Miata Voodoo II turbo installed on a stock 110,000 mile 1.6 engine. The turbocharger itself is the smaller 2554 unit, chosen for response instead of ultimate power. Since her power level is limited by the injectors in the car regardless of altitude, I used an uncorrected chart for her. Since I'll be able to make more power at sea level (close to 20% more), I used the SAE standard correction. This chart should be accurate for the relative behaviors of the two cars at sea level. The biggest change will be that the turbo will spool up a bit quicker.
What's interesting about the chart is how similar the power curves are, once you hit 3700 rpm. Two very different ways of making power but with surprisingly consistent results. Below 3700, the big displacement of the naturally aspirated car really helps. It's no wonder people comment on how quickly it squirts out of corners, with almost full torque available at 3200 rpm. That's more important than some sort of headline horsepower number. The dip that bothers me (intellectually, I've never noticed it driving) in the race car is there in the turbo car as well, but it's not as noticeable because it doesn't have the big torque swell earlier in the range.
I've always known that I chose a more difficult way of making power. If I was using that little turbo 1.6 in the Targa, I'd be running in the Unlimited class and would have to drive much faster to avoid penalties. But really, it was an excuse to build a cool engine. I love the response of a good naturally aspirated motor. I'll do more development on the engine when I return from the race, trying to open up the breathing on the intake side and maybe swapping a VVT head on. For the race, reliability and tractability are more important and I didn't want to have to babysit a fussy mill. Focusing on the handling and suspension of the car will pay greater dividends, so that's why I spent my time there.
I'm looking forward to feeling how the race engine feels at sea level with a 20% power boost. I think it's going to be a very good tool for the job at hand - dealing with unknown roads as expeditiously as possible.
Dyno chart
entry 520 - tags: engine, dyno | | |  | August 29, 2008 - Janel and I took a First Aid course yesterday.
Both of us have had fairly extensive training in the past - I used to be a swimming instructor, her job in the construction industry opens up the option for all sorts of gruesome problems - so it wasn't a difficult thing. Still, it's good to shake the dust off those skills again.
While going through the regulations one last time to avoid problems at scrutineering, I discovered that our first aid kit (supplied by the good folks at Rallylights.com) needed to be in the cockpit instead of in the trunk where I'd mounted it earlier. Finding room for the big white box was a bit tricky, so I stuffed everything in a small tool bag. This is strapped up under the dashboard where it can be in Janel's hands in seconds, but it's out of the way. It's also less than half the weight it used to be!
entry 521 - tags: skills, preparation, safety | | |
|
THE DIARY