MY WCM Ultralite S2K
The new car is a World Class Motorsports (WCM) Ultralite S2K. It is a modern rendering of a Lotus Super 7, which was designed by Colin Champan and originally sold by Lotus Engineering in England from about 1957-1973. Lotus then sold the rights to the design to Caterham Cars, who still produces them today, but their popularity has led to imitation, and there are a number of Super 7 "replica" cars being produced and sold (often as "kit cars") by companies like Birken, Westfield, Locost, Rotus and WCM. You can learn a lot about the history of these cars at this website.
My WCM Ultralite was designed and built by a fellow named Brian Anderson in Lancaster, Texas, in 2002. It is a front/mid-engined design (the 4-cylinder, 2-liter motor sits in front of the driver but behind the front axle) with a steel and aluminum space-frame chassis and a fiberglass hood. It actually has fenders, so it is not really an "open wheel" car, but the front fenders are a "cycle" type which turn with the wheels. Some Lotus Sevens had a "wing" front fender which was attached to the body, arched over the wheel, and extended back, swooping downward past the cockpit.
The engine and 6-speed transmission are from a salvaged Honda S2000, and the rear end is from a Subaru WRX. It has 4-wheel, independent, coil-over suspension and billet aluminum Wilwood 4-piston calipers clamping 12" rotors. It weighs about 1350 lbs. wet, and makes about 200 HP in its current state of tune. Brian also builds the Ultralite using either a Mazda Miata drive train (called the "Clubman") or the 1300cc 4-cylinder motor and 6-speed sequential transmission from a Suzuki Hayabusa motorcycle (which is the lightest version) called the "Ultrabusa". The S2K model with the Honda S2000 drivetrain weighs a couple of hundred pounds more than the Hayabusa version, but has a little more power. His web site is here if you want to read more about him, the cars and WCM.
I bought the car used (with 700 miles on it) last March from the original owner, a collector in Oklahoma, to replace my Formula Ford, which was a true open wheel, mid-engined race car that I ran in SCCA Solo2 in the C-Modified class. While this car weighs 400 lbs. more than the FF, it has twice the power and runs much larger tires. It qualifies for the D-Mod class in SCCA Solo2 in its current configuration. If I added 200 lbs. of ballast, I could supercharge the engine and run in E-Mod at 1550 lbs. with about 350 HP. While it may not handle quite as well as the FF, the WCM S2K is quicker under acceleration and corners very well, but the real beauty of this car is that it can carry two people and be street licensed, which are two attributes the FF could never have.
The picture above and on my home page was from the first time I ran it in a PCA autox on street tires in exhibition class, just to get a feel for the car. It did pretty well, beating all the Porsches that were running on street tires by a couple of seconds, but it could not keep up with the full race cars. Since then, I have added some custom 10 & 12" alloy wheels from Rich Bogart and mounted some Hoosier slicks on them, and the grip is much better. I also added an updated exhaust from WCM as the original was leaking around the welds in the engine compartment.
So far, from the few outings at speed I have had in it, I have found that there is still a great deal of preparation and tuning to be done to get the most out of the car, but that's true of any vehicle. When Steve Grosekemper did the first setup on the car, it was with the taller 17" wheels and street tires mounted. With the shorter slicks on, it is really low, and the stock springs and shocks are not stiff enough. I found myself "bottoming-out" over bumps, especially in the braking zones. I have already gotten some new springs with 100 lb./in. higher rates, and am looking into having my shocks revalved to match.
I also need to solve a fuel starvation problem from the gas sloshing in the tank from high G-loads in cornering, which causes the engine to stumble occasionally, and fix some problems with the electronic engine management which are keeping it from making maximum power. I have fabricated a surge tank to take care of the first problem and will be installing it this week, and I have studied the manuals and acquired some knowledge of the SDS ECU, as well as bought and installed a wideband A/F meter now to monitor changes, and have already had some success in tuning the engine to run smoother and stronger.
My goal is to get the whole package competitive with the other Super 7's that run locally in D-Mod, and then perhaps try some national SCCA competition with it sometime in the future.
Update: 02/13/04
I installed the custom surge tank and have not had another problem with consistent fuel supply to the engine since, even with low tank levels which allow a lot of fuel slosh in the main tank. I used a $40 Facet high volume/low pressure, self-priming pump (4 psi) to supply the surge tank from the fuel tank, using the existing filter before the new pump. This, combined with routing the FI return line from the engine to the surge tank, insures that the small tank is always full and cannot slosh enough to interrupt the supply to the high pressure FI pump, which comes out of the bottom of the surge tank. Any excess fuel in the surge tank is returned out of the top connection to the main fuel tank using the original return line entrance. The pic below shows the installation in the rear bay of the S2K.
Just before Xmas I was able to run the car with the PCA in a non-points "bring your other car" autox, and even with the too-soft suspension setup, it was able to post the 3rd fastest times for the day. The only cars that were faster were Steve's full race 914-6 and Gary Thomason's ASP 'vette. Since Steve and his car are perennial TTOD finishers at our PCA-SDR autocrosses and Gary is a multi-time National Solo2 and ProSolo champion, I am going to guess it's the driver's fault I didn't catch them, not the car's! Here's a couple of low-res pics taken by the PCA newsletter editor, Greg Phillips, that day.
New adjustable shocks are on order and I already have the heavier coilover springs in hand to revise the suspension, so maybe I can catch those guys next time.
UPDATE- 05/04/04
I installed the new set of QA1 single-adjustable aluminum coil over shocks last month, and paired them up with some new 450#F/350#R springs from Suspension Specialties.
I was anxious to see what they felt like, so I ran a practice Solo2 event with the SCCA with the new setup without getting the car aligned and cornerbalanced, since I couldn't get in to see Steve before the event (he was too busy prepping cars for the PCA club race at Fontana.)
I started with the new shocks on full soft settings, and the new, stiffer springs felt much better at resisting diving under braking and squatting on acceleration, and rolling in corners. I didn't bottom out over bumps at all, but I had the ride height set pretty high. There was a little bit of a push in slow corners, so I dialed in two clicks of adjustment in the rear shocks and it handled much better. I think my toe and camber settings were off, though, as I ended up with some heavy inside tread wear on the front right tire. All the others looked OK. I got my times down to within 2 seconds of the fastest cars on the last runs.
I had Steve set the ride height a little lower and corner balance and align all 4 corners, and I'm looking forward to the next practice event. I have finally unwrapped the whole wiring harness loom and found the wiriing fault that was keeping my throttle position sensor from working (one wire was hooked up incorrectly in the harness), so now I should be able to finish the engine tuning. I'm getting it all dialed in finally, and can't wait to try it out once I reprogram the ECU.
UPDATE- 12/24/04
Well, I have had a lot of success using the Innovate LM-1 wideband A/F meter to tune the fuel injection system. The Porsche Club held a Driver's Ed event at Qualcomm in Sept., so I took out the S2K and was able to run continuous laps in 3, 20-minute sessions with the O2 sensor hooked up and led back to the instrument temporarily mounted on the dash. I had done some tuning on the street already, and had the SDS programming module mounted on the dash next to it. This way, I could run some laps, watch the readouts, and pull into the hot pits and re-program on the spot, then go out again to check the results.
I just ran on street tires to save the rubber on the slicks, because it wasn't a timed competition, just a testing opportunity.
(You can see the 5-wire lead from the Bosch LSU-4 O2 sensor leading back to the cockpit in these pics, with some blue masking tape holding it down to the body. In the center pic, you can see the LM-i instrument and the programmer module temporarily mounted to the dashboard, with some little cardboard shade-screens over the top to make the LCD displays more readable in the bright sunlight.)
On Dec. 18th, 2004, PCA-SDR held their last autox of the season, and it was a non-points event. Everyone was encouraged to bring their "other car" (non-Porsche) for this event, since it didn't count for the 2004 season results. I had already wrapped up the season championship in the GS/S class in my '67 911S, so I took the opportunity to run the S2K and compare the improvements. I was happy to find that I was only 3-tenths of a second slower than Steve in his 914-6, who took the TTOD, as I was a full 2 seconds off his time at this same event last year. It's getting faster all the time! Out of all the cars there, including Porsche GT-3 and Turbo models, Boxster S, etc., only the 914-6 in full race trim was faster. There were Ferraris at the event, including a 360 Modena, a Viper Coupe, Mini-Cooper S models, BMW M-cars, and even a 600+HP Mercedes SL65 (twin turbo V-12) that were all slower. OK, the Viper did have a lap faster than mine, but it wasn't clean! Cones were flying, the driver said!
Two pics from that event taken by Greg Phillips:
