autocross

WWU Viking 43 Resurrection

Last winter, my friend Trever and I acquired an incomplete WWU Viking 43 Formula SAE racecar with the intent to rebuild and race it at SCCA Auto-X events.  V43 was originally designed and built for FSAE competition in 2008.  Check out this promotional video for details:

V43 uses a carbon fiber monocoque tub and tubular steel rear frame, pushrod/pullrod inboard dampers, and a Honda CRB600 F4i engine.  This is a fundamentally good car with intelligent design and execution.  It performed well at FSAE competition and was optimized over an extensive testing period (extensive for a volunteer student designed/built/raced in one year effort).  As received, the car was missing the ECU, intake system (intake manifold, T-body, restrictor, etc), fuel system, steering wheel, battery, jack bar, and several other components and systems.

Photo of Viking 43 from 2008

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First step was to get the car operational.  We decided to get the car running with the factory Honda intake/injection/ECU system and once running, test and fix the other vehicle systems.  To compete in FSAE or SCCA FSAE competition, the intake charge must pass through a 20mm restrictor.  This limits power to roughly 80-90 hp.  With the stock engine and intake system, the engine produces over 100 hp.  With a total car weight of approximately 450 lbs, this makes for a very fast vehicle.  After modifying a factory wire harness to work in the car, rebuilding the differential, rebuilding the oil pan, and plumbing a new fuel filler tube, fuel pump, and fuel filter, the cars maiden voyage was in the snow.  We still had V26 at the shop so we jumped into both cars and ran some laps down the driveway – the Hoosier Wets worked much better in the snow than the slicks.

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A few additional modifications would be required before competing.  To build a seat, we used two-part expandable foam poured into a heavy garbage bag and let it form around the seated driver.  We ended up making a seat base and a left and right upper seat insert.  Despite a 5-6″ height difference in drivers, the seat and controls work for both.  The shifter is mounted to the left side of the driver for the most direct cable routing.  Feels a bit odd but pretty easy to use as it’s sequential.  I manually machined a spacer for the steering wheel as my hands would hit the shifter when turning.  This makes the cockpit very cramped for me as I’m 6’2″ with long arms but lock-to-lock is minimal so I can manage.  I also modified the clutch and accelerator pedal to optimize both cable travel and cable orientation.  A lift bar is required per rules and was missing so I tig welded one up and formed a stainless steel chain guard also required by the rules.

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We sourced new sprockets based on clearance and the gearing from V26 which worked well for auto-x speeds.  2nd gear is used the majority of the time with 1st and 3rd used in spurts depending on track layout.

Car was aligned and corner balanced.  At this point, we joined the WWU FSAE Team in a test session at a local airport.  Car ran great for the most part after bedding in some new brake pads.  The steering rack kept coming loose which required some fastener modifications while there for a temporary fix.

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To address the intake restrictor rules, I initially designed a new intake plenum for use with the factory injector bosses and an AT-Power throttle body with integrated 20 mm restrictor.

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My plan was to 3D print the intake plenum in two parts with a bolted flange interface.  After seeing the very expensive quotes for the printed part, I opted to fabricate something similar using part of the factory airbox modified with a carbon fiber transition.  I cut the airbox top and bottom in half and welded in some plastic walls.  I then turned some wood on the lathe to match the restrictor diffuser taper on the AT-Power T-body.  Clay was used to sculpt the transition.  Carbon/epoxy was hand laid and vacuum bagged.  Once the shape was cured, the wood/clay was removed and the carbon top was bonded to the plastic airbox top.  Not pretty but effective.  I also created an epoxy cradle for the steering rack to distribute the side loads into the chassis rather than bend/stretch the rack bolts.

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We planned to use the factory ECU along with a Power Commander for the first several events.  I designed a TPS sensor adaptor that allows the factory Honda TPS sensor to be used on the AT-Power T-Body.  We used a chassis dyno to run loaded pulls and fine tune the Air Fuel Ratio.

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At this point, we completed over 70 tasks.  Some were minor details and some required significant design and fabrication.  Next up, we go racing!

Sector One Design: https://sectoronedesign.com/

Instagram: https://www.instagram.com/sectoronedesign/

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