Wednesday, March 26, 2014

Splitting Airs

Last winter I shifted my splitter forward 2 inches to try to get more front down force, but it seemed to have a very limited effect. This is probably because the main protrusion of that splitter is just in front of the radiator grille. The air flow in the radiator and up over the car is not very significantly restricted, and less so with the AC condenser removed. Thus, the increase in pressure over the splitter vs under is probably minimal there. The sides gained extension too, but the sloped, drag reducing front of the car is probably also fighting the build up of pressure as well.

Since I improved the wing over the winter, I expect to generate more downforce in the back. To make use of that added downforce I will need more front down force. Otherwise I will simply go back to the car plowing on the fast sweepers. To that end, I've ditched the CF splitter and cut myself a much larger plywood one, similar to that used by the other street modified cars in my area. Here are some pictures of the construction process....

Jack it up, prop the board underneath

Scribe a 5.75" offset from the fender (viewed from above). The rule is 6", but leave a bit for safety and interpretation etc.

Painting with Rustoleum to give it a little water resistance...

Initial attachment.  The sides still need trimming, they stick out a little bit too far.

View of bottom attachments. As always I am attaching to hard points, not the fiberglass clam

If air passes above and below an added aero dynamic aid it is considered a wing. Front mounted wings are disallowed in the super street modified class, so trim the ends and put a back plate in to turn it back into a splitter

Another view. It's hard to see because of the paint, but Aluminum angle is used to attach the backplate

The final result from the front

The edges ere a bit floppy and I didn't want to attach to the fiberglass, so I rigged a turnbuckle system attached to the oil-cooler mounting point which is steel.

A slit in the fender liner is required. Re-installation is quite a trick since the top part of the fender liner is actually supposed to slip in first, but that is no longer possible. Really glad that i was conservative on the size of the back plates.

Ever so conveniently the vent for the oil cooler accommodates the turnbuckle! 

The result is that the turnbuckle system is not 100% rigid, so I may need to re-work this if the edges wind up flapping, but it should also work to dissipate and absorb some of the energy from cone impacts. The great thing about this is it was really really easy to install and provides a bit of adjustability if the corners turn out to be pulled upward by the tension (which is not legal if it's more than 3 degrees from level)

Tuesday, February 25, 2014

Antigravity Mounting

Yeah, I wish I had an anti-gravity system. (I'd mount it upside down for downforce!). But all I actually have is an Antigravity Batteries XPS-SC1 battery. Though it can't provide assistance with gravity, it can assist with my inertia. It weighs just 1pound which is a savings of over 21 pounds vs the stock part. However I mentioned all of this in my last post so enough with that.

The great thing about saving weight, is reducing weight allows you to reduce weight elsewhere. The 7lb battery had been held in place with an aluminum bracket I fabbed up out of 1/8" 1x1 aluminum angle and steel brackets. Here's the new bracket for the XPS-SC1:


That bracket is 50g vs the 250g for the previous bracket, a savings of about 9 oz. So weight savings for this mod now go up to ~6.5 lb. To mount it in the car I bolted it to the old air box mounting points. Below you ca see it looking up through the wheel well, tire fender liner and Fujita F5 filter removed. 


I put everything back together and lowered the car. Then I wired it up reaching in from the top where I could be sure I could see the + and - markings on the terminals. According to several folks I've heard it from, getting the leads backwards pops about a dozen fuses some in VERY hard to reach places such as inside the dash, so it's extremely extremely important not to do that. Given the small size of this battery and the resulting proximity of the terminals, I will probably add a cover to the negative side as well so it doesn't get shocked if the car has to be jump started. 

So then came the moment of truth. Would it start... I opened the garage door. I turned the battery cut off switch... the usual whir-click of some misc electronics or relay powering up responded. Good. I opened the door and the cabin light came on. Good. I sat in the seat and turned the key the dash lit up. Good. I stepped on the clutch made sure it was out of gear, and pressed the start button...

Whirr Whirr Whirr...

Hmm, try it with some gas

Whirr Whirr Whir... Whirr Whirr Hic Whir Whirr Whir...

Whirr Whirr Whir

Whirr Whirr Whirr

Ok, Deep breaths... ... So it didn't start. It was an experiment I told myself.... It Hic'd once, so it was close, it was worth a shot, better luck next time (etc... etc... etc.)

Later that night I got to thinking. The car hasn't moved for 4 months. The garage is 40-45 degrees. This is more or less the coldest hardest start possible for a car that doesn't get to play in the snow. I had never doubted that the video of this battery starting a v6 truck engine was a video of a "warm" start. So if I can get it to start when the engine is not almost freezing and not all the oil has drained away from it, I may be ok. But if it never cold starts at all after sitting for a while that may not be good enough. So...

I warmed up the garage to about 60 degrees and let the car bask in that warmth for about a day. I figure if it starts after being still for 4 months at 60 degrees maybe it starts at a spring or fall 45-50 degrees after being still for a few days to a week, and either one of those is good enough. Both at the same time is a once a year affair. For what it's worth, the 7lb Braile battery sometimes required several tries for the first spring start. So with a somewhat warmer engine I tried again...

Whirr Whirr Whirr...

(gas) Whirr Whirr Whirr....

Uh oh...

Whirr Whirr Whirr...

Whir Whir Hic Whir, Hic, Hic *COUGH* HarrROOOOOOMM!!!

SUCCESS!

Whew it does start!! So I shut it off again, and gave it 30 seconds... and tried again...

Hic, HarrRROOOOMM!!

So it starts easy once it's been turned over, which is a really good sign. Good enough that I don't need to de-install the battery just yet, but I've pretty clearly found the bleeding edge. I also suspect it's time to find a suitable case charge the old Braille battery and throw it in my trailer so that I can jump the vehicle if necessary. It will also become more critical to not forget to turn off the battery cut-out switch when the vehicle is parked. Now it's up to the test of time to see if this becomes too annoying. It appears to at least remain theoretically feasible.



Wednesday, February 12, 2014

Vehicular Anorexia

I am always obsessing about weight savings. Maybe it's a side effect of owning a Lotus. Perhaps I am haunted by the ghost of Lotus founder Collin Chapman who said "Power makes you faster on the straights, lightness makes you faster everhwhere." (I wish he would haunt my driving skills a little more and my wallet a little less!). I seem to find inordinate joy any time I can save weight on my Lotus and revulsion deep in my gut any time I have to add weight.

So I'm sure you know where this post is going... :)

This winter I'm looking to shave another dozen or so lbs off of my already featherweight car bringing it close to 1850lbs with 1/3 tank of gas. That 1/3 tank probably weighs 15 lbs or so, which means even if I'm out of gas I will be 30lbs over the minimum weight for my racing class, but here's what my mania has produced to achieve the latest reduction.

The Battery

Batteries are heavy. They often contain lead and lead is heavy. Long ago I switched away from the stock battery which is a 29 lb. monster. That size is mostly needed to support the drain on the system caused by the vehicle alarm system. The little 4 cylinder 2ZZ motor in the elise definitely does not need that kind of capacity to turn over. So 3 years ago I installed a cut-off switch and a 7lb Braille battery. Great! 22lbs saved! Seems good... but not good enough! (I did mention that I might be possessed didn't I?). Enter the Antigravity Battery brand  XPS SC-1.



I've known for some time that lithium batteries are much lighter, but the products available have generally been too expensive. The SC-1 advertises as 12 oz, but my scale says just under 16 oz. If it works I'm not going to complain. The question is... will it start? Too cold to take the car out so I haven't installed it yet. But if it does the job, I get to save 85% of the weight vs the Braile B106 I'm using now, and it's cheaper too! All I need to do now is figure out how to mount it... I'll make that a separate post.

Lightness Added: 6lbs

The Wing

Ever since I built it I knew that I had added a tragic amount of weight when I added the wing. It adds and estimated 25lbs, much of it at the very top of the car, raising the center of gravity. about half that weight is in the supports and attachments to the deck lid. The wing itself weighed 13 lbs. (excluding mounting bolts) when I weighed it a few weeks ago. The construction was entirely 1/8" 1x1 Aluminum Angle, 090 plate aluminum, a 1-1/4" wood dowel for the front edge, steel angle brackets and aluminum rivets with a contact paper skin. I'm actually quite pleased with the contact paper, and the aluminum rivets are probably as light as i can get without a tig welder and a lot of practice time.

After observing the wing in action I believe the 090 aluminum end plates, the wood dowel and the aluminum angle are all over built, or just poor material choice. These are being replaced by much lighter components. The angle is being replaced by 3/64" 1x1 angle (available at Home Depot).



The front rod and end plates are being changed out for carbon fiber. Carbon fiber is not cheap, but I found a discontinued size I can use directly at a steep discount. The end plates won't be as big as I would like, but they will be a little bigger, and the cost is about 1/3 the cost of buying a larger piece in a standard size and cutting it down.



There's a bit of a problem in that I need to have good supports for this CF tube at the front and I need to butt join it to the end plate efficiently. Luckily, I have a friend who just bought himself a Maker Bot 3d printer, and he pointed me to the free OpenSCAD program which renders 3D objects defined in it's own programming language. Since I've got my own software consulting business, this programmatic style is perfect for me. Here are the supports rendered in OpenSCAD


And here are the inserts for the end of the tube (view from inside tube)



So what sort of weight savings does this buy me? Well here's how it works out (orange values are estimates):



BeforeAfterqty
endplates 3982402
front rod 7841551
fastners (all)4504501
center supports1301302
spars6062756
total (g)5,9262,995
total (lbs)13.046.59
lbs/sqft1.650.83
saved (lbs)6.448250.54%


I haven't accounted for the printed parts yet, but they are very light and will probably be offset by a few of the steel angles that I was able to trim down. About 5 oz. was also removed by trimming corners and overhangs from the bracket that mounts the wing to my deck lid.
Lightness added: 6.75 lbs.

Friday, January 17, 2014

2013 in the Mirror

Well, after the Match tour I got busy, and kinda forgot about blogging. Now it's January, and I've got no races and the car is away for the winter, so I might as well do a recap.

The Match Tour was fun and my finish behind Leafy was worrisome but I had a good lead and 4 races to go. Just one race where I came out ahead would seal the deal mathematically. The future looked bright...

Event 6: Racing against Lukemia

This is a funny event. Not funny as in laughing, but funny as in oddball and not much like the other events. For this event we run in a parking lot at NHMS which greatly reduces the length and top speed of the courses. At Devens, we reach highway speeds and each run is about 50-60 seconds. At NHMS, we rarely exceed 45 and average course times are 25-27 seconds for fast cars.

Leafy's car didn't seem to like the course and in the first half of the day I was way ahead and feeling good. My car seemed well suited for it, as I was able to retain 1st gear for the first 60% of the course on account of my 8500rpm 2ZZ engine and gearbox which will do 30-35 in first gear. This meant I always had lots of torque. This was the plus side of things for me. On the down side I was sorting out a suspension change I had added Sector 111's V2 arms and the extra camber made the car turn much more eagerly. On several runs I had to let up a bit to avoid hitting cones after the car turned faster than expected. That and an inadvertent flick of the windshield wipers to the on position probably cost me the day when Leafy Finally figured out how to make his car go fast. On the final run, the extra camber caused me to over-rotate just before the transition to second gear on the final run. I was so busy maintaining control that I forgot to shift. On the back section I, hit the rev limiter, wondered what that unexpected noise was and then proceeded to drift through the final two corners due to the unexpected abundance of torque. Net result Leafy Wins, I take 3rd loosing to Don by 0.076 seconds... That's ok there's 3 more races...

Event 7: Scorched Orange

Back to the usual venue, 60 second courses and 60-70 mph speeds (for cars like min running the extra sticky Hoosier A6 tires). This day was good weather, but in the morning I couldn't seem to find good speed. At this point I don't remember why, but I suspect strongly that I was over-driving and not being smooth since I had some trouble with that this year. The day also had the added complexity that for reasons unknown at the time, I was suddenly failing sound. In the morning I got a warning that I was 90.4 db, perilously close to the limit, and I was asked to make an adjustment. I scrambled for a hose clamp, steel wool and hardware cloth and got it applied.

Despite my efforts it popped off on my first run of the afternoon and I broke the 91 dB limit meaning I had to re-adjust and if I went over again, I was done for the day. After a mad dash and much hasty work with tin snips lent by Brian (thanks!) I made my second run of the afternoon. I didn't break sound and the fix stayed on this time. Problem is, I spun and my previous run had a cone. 2 runs left to find a competitive time. Jenna was leading With Leafy close behind, both way ahead of me.

The next run finally brought my raw time within a second of the lead, but 2 problems... I had a cone, and I broke sound again. Done for the day. Later I found that the metal plug meant to close the hole for a 2nd pre-cat oxygen sensor had fallen out and all the noise was coming from the header before the muffler and my tail pipe remedies had been irrelevant. 3rd place again, but the saving grace was Jena beat Leafy, costing him 3 points so beating Leafy just once was still good enough for the season... with 2 races to go...

Event 8: Attack of the Cones

So once again we were racing at Moore Army Airfield in Ayer Massachusetts, this time in September. I was feeling confident due to an excellent day racing with the Renegade Miata Club. At that event I had been the 7th fastest driver of the day in raw time and on my fun runs I tied the 3rd fastest raw time of Mat Mickle who drives a fully prepared ASP subaru, and drives it quite well. It was also the first day on which I caught Scruffy (who drives a Porsche GT-3 Type RS and had FTD) checking my times.

Event 8 had a wet start but dried out and warmed  up by the second run of the morning. My final run of the morning had a raw time very close to the lead but a cone came along for the ride. In the afternoon my first run fell victim to my inability to recall the layout of the course and I went off course in one of the visually confusing sections. In theory one could read the pointers, but in practice that was difficult at speed and I wound up on the wrong side of several cones. I began to feel the pressure, and on my next run some random bump in the pavement set off my ABS at the hard breaking before the taxiway and there was just no way to recover. I was off course again.

On last run, I got off to a fabulous start and went flying through the first section of the course. I made a small error at the end of the first section which caused me to slide a little just before the turn on to the back stretch, and from there the rest of the run went very well. Leafy was in first with a 62.2, and when I crossed the line the display flashed 61.9! Fist in the air, I drove back to pick up my stuff, but a little voice in the back of my head said... "was it clean?"... and then I thought back to the end of the first section. That little slide would have put me awfully close to a cone. Then I got confirmation from someone standing nearby. The run was dirty. +1 cone. This was really bad news because it left me with no clean fast run. Even with the cone, the final run was my fastest time, putting me in 4th place. Having given up another heap of points, I now had no options. The only way to win the season now was to take first place in the final event...

Event 9: Stirling Moss Championship event. 

The day was uncharacteristically warm for October with temps in the upper 60's. Warm weather is a Boon for me since my car is light and the tires tend to get too cool on cold days. As a point of contrast, I was covering my tires with tire warmers while my opponent was spraying down his. In one way this day marked a sort of milestone. This was the first year I came to the Moss event with a shot of winning the class and becoming eligible to compete in the moss.

However, I also knew from the moment I looked at the registration sheet that my chances were somewhere between slim and none. Leafy, having done the math too had invited an instructor level driver to co-drive with him. If I placed second and Leafy placed 3rd Leafy would still win the season. Totally within the rules, but if you ask me it's kinda lame. I can only assume he was worried I might beat him, and the jacket was more important than the competition. The results of the first three runs were predictable. The hired gun blew away the entire field by 1.8 seconds. On the first two runs I tried too hard and over drove. I had just one do or die run left...

As the final run began, things all seemed to click into place and I ran the front stretch, the runway, and the taxiway the way I do it in my daydreams. It just flowed, and I knew I was running fast. Then came the turn off the taxiway. I remember it crystal clear. I know exactly what happened and why. Eager to get the fastest possible exit from the turn off the taxiway I let off the break slightly earlier than I had before, hoping to just brush past the cone with a little bit of slip to rotate the car. I did this entirely on purpose. It wasn't a bump or a moment of inattention or one of those "why did I do that?" type moves. Unfortunately, although entirely intentional, it turned out to be an error in judgement. The tires didn't hold. I got more rotation than I bargained for. The car slid sideways and the back end started to come around. The car got almost completely sideways and then I caught it and made it around the next cone but my angle was all wrong. I tried to steer away, but I hit the situation was not recoverable, and I took out 2 cones of the subsequent wall. By this point, I was nearly stopped and I knew it was over.  I brought my speed back up to about 80% of race speed and finished the course. My only goal at that point was to not hit more cones and mess up the course for the next guy. Then I saw my time. I was less than 0.4 behind my previous best scratch time.

I'll never know how fast that run might have been, but I'm willing to bet that between getting sideways and nearly stopped and loafing it home I lost at least 2-3 seconds. Maybe more. The hired gun was 3.3 seconds faster than my time on that run. Who knows what might have happened if I had made that turn and remained in control. It was small consolation that by the end of the day in the 3 fun-runs that followed, I came fairly close to Leafy's morning time I did beat Jenna's time for the full day, but the final 3 runs didn't count and so she got the official 2nd place.

Epilogue

Astute readers will notice that many factors contributed to my 4th straight 2nd place in season points. There are emotional errors such as over-driving seeking the win and simple errors in judgment of car control such as the final turn of the final run. There are also some random factors such as the mechanical failure that led to my sound DSQ, and the inadvertent windshield wipers at NHMS. There were also some factors not mentioned above, one was the loss of my co-driver for the second half of the season, and another was the race early in the season where I let Eric Chiang drive my car when his ride broke before he could even get in one run. He took first because he is a much better driver. Those 3 points would have taken a lot of pressure off and if the rest of the season remained unchanged it would have, led to a tiebreaker for season points that I would have won by virtue of more first place finishes. One can also consider the effect of event 2 where I just plain drove like crap. But that's all racing, and if my talents were good enough for a season first place, my times would have been fast enough to overcome those obstacles. A cone here, a tenth there and I come out on top... coulda... woulda... shoulda... but didn't

The history of my second places does not however represent stagnation. The first one was by virtue of attendance and a lack of competition. The second one was by virtue of my car's reliability, more than it's speed or my skill. The third one in 2012 however did involve beating some folks who were actually trying and driving half way decent cars. Similar to this year, in 2012 I developed an early points lead and then lost ground. In 2012, I was mathematically eliminated at the end of event 7.  This year I was a contender through the final event.

This year, I had a few fast runs, one of them winning the first event of the year, but the others marred by cones or mistakes near the end. Reliability and attendance still play a part, but this year unlike previous years the ultimate winner had to work to beat me. And I beat every driver in the field at least once. It's also worth noting that in 2011 I was generally running 5-6 seconds behind the SM national champion car driven by Dave White and PJ Corrales. This year I was usually somewhere around 3-3.5 seconds off their pace. Both cars are somewhat faster machines, than in 2011... so the exact meaning of the decreased gap between me and Dave is unclear but it's definitely not bad.

So now we wait for the 2014 season where the goal will be simple.... Drive faster and cleaner, and try to ignore everything else. I doubt I'll be able to make enough mechanical improvements to catch the SM car's times, but if I can shave another 1-1.5 seconds off that will be a good improvement. Eric Chiang proved that my car can be driven almost as fast as panda (probably about 0.5 seconds on a 60 second course).  The car might be .25 - to .5 seconds faster than when he drove it.

My job for 2014 is to find a big chunk the other 3 seconds... and have at least one race where I get within 2 seconds of the Panda. Another goal is to have at least day where I score above 0.940 pax factor one or hopefully several times. (Eric scored 0.96 when he drove).