J-32 Alternator and Crank Pulley

Progress continues on the J32A2 swap into the S2000.  This post will catch up on some work done over the past several months.

Alternator relocation Phase 1:

I purchased the Prank Parts alternator relocation kit, machined the lower mount to fit the engine mounts, and replaced all the hardware.  This kit drops the alternator down to where the AC compressor once lived.  The advantage is lowering center of gravity and the ability to use a very small belt while eliminating the idler pulley/tensioner.

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Alternator relocation Phase 2:

As an obvious sign that this project has been going on far too long… I decided to make some changes to the alternator relocation even though it would have worked beautifully and I already purchased a brand new Honda alternator, belt, and Prank Parts relocation kit.  The relocation solution was great but I was not happy with the factory crank pulley.  The pulley is large and heavy and I try to reduce MOI wherever possible.  There are aftermarket aluminum replacements but they don’t have the factory female hex detail used to hold the crank for installing and removing the pulley.  Plus they are still large in diameter and accommodate two belts when I’ll only be using one.  It just so happens that an S2000 crank pulley fits perfectly on the end of the J32A2 crankshaft.  This is a single belt pulley and much smaller in diameter.  Because it’s a single belt pulley, it moves the belt closer to the engine.  This requires relocating the alternator to align with the pulley.  The S2000 alternator is slightly smaller and lighter than the base TL alternator that I was using and the pulley diameter is designed to work with the S2000 crank pulley diameter so a new upper and lower bracket was designed, printed for fit check, and then machined out of aluminum.  Total weight decreases and the MOI of the pulley decreases substantially.  It also opens up some options for other pulleys such as the Sector One Design S2000 Pro Crank Pulley, factory Honda S2000 crank pulley, or a Fluidampr pulley.

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Pulley weights:

Acura TL Type S 2002: 3844 grams / 8.47 lbs

Honda S2000: 1986 grams / 4.38 lbs

Sector One Design S2000 Pro Crank Pulley: 349 grams / 0.77 lbs

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Acura TL Type S Pulley

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Honda S2000 Pulley

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Sector One Design S2000 Pro Crank Pulley

Alternator Weights:

Acura TL (base – 105 amp): 6430 grams / 14.18 lbs

Honda S2000: 5450 grams / 12.02 lbs

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Acura TL Alternator

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Honda S2000 Alternator

Total mass saved when using S2000 alternator and Pro Crank Pulley: 4475 grams / 9.87 lbs (mostly rotating mass).

Contact me if you are interested in the brand new TL alternator and Prank Parts relocation kit.

Other progress updates:

Completed the water plumbing.  Aluminum hard-lines to and from radiator plus heater connection.  Coolant runs through a Mocal Laminova oil cooler.

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Completed the oil plumbing using custom braided lines, oil cooler, Accusump, and Trac Tuff Remote Oil Filter Block Off Adapter.

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Fabricated a new clutch hard-line to move it away from the header and fabricated some hard-lines for the fuel pressure regulator and brake booster.

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Designed and printed a new lever for my Accusump control valve.  Installed clutch and assembled transmission (hopefully for the final time).

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Currently working on starter fitment, oil pan clearancing and baffling, fuel lines, exhaust, and wire harness.

Sector One Design: sectoronedesign.com

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WWU Viking 43 – Version 2019 In Pictures

Originally built by WWU FSAE team in 2008.  Reimagined by Sector One Design in 2019.

 

For more blog posts with pictures and videos of Viking 43 click link:  Viking 43

Sector One Design: sectoronedesign.com

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WWU Viking 43 FSAE Racecar – Version 2019

Viking 43 Formula SAE racecar was originally built at the Vehicle Research Institute, Western Washington University for the 2008 FSAE competition where it placed 6th overall at FSAE West.  We chose this car in particular because it has great fundamentals. The carbon tub is stiff, light, and has great ergonomics. It’s a simple car with lots of off-the-shelf components (engine management, display, brake system, etc) for easy repair or replacement. Suspension members are all welded 4130 – strong and easily repaired if damaged. Original roll-out video below:

The car sat in storage for almost 10 years after competition where the intake and ecu were pilfered for use on new FSAE cars.  Trever (who was on the original 2008 FSAE team) and I (Jared) acquired the car with the goal of rebuilding to be a reliable and competitive SCCA auto-x racecar.  This required a lot of work (task list includes well over 100 items).  The main highlights include:

  • Rebuilt differential with hardened steel side plates
  • Reinforced front rocker mounts
  • Reinforced steering rack mount
  • AEM Series 2 ECU, AEM Wideband O2, AEMnet CAN bus Gauge (multi-channel)
  • Custom motorsport grade wiring harness complete with datalogger and sensors (brake pressure F and R, wheel speeds, oil pressure, oil temperature, fuel pressure)
  • New Shorai LFX Lithium battery
  • New Momo steering wheel and quick release hub
  • Cleaned F4i injectors
  • Replumbed fuel system
  • New fuel pump – Walbro
  • New spark plugs – NGK Iridium
  • Gutted and plugged F4i throttle bodies
  • Custom Carbon Fiber intake plenum with AT Power 20mm restrictor and T-Body
  • Triple element carbon fiber unsprung rear wing
  • Carbon splitter with air dam and diffusers

Result:  We raced the car during the 2017 auto-x season prior to adding aero and using the factory ECU with a Power Commander to compensate for the restrictor and it was awesome.  Very reliable and very fast.  Finished with top time of day at nearly every event.  Competed in ~10 events with dual drivers totaling over 120 runs.  This also included SCCA National Tour and Pro-Solo Events.  The only major issue was a failed rod end on the rear suspension.  V43 Auto-X 2017

In 2018, we built the new wiring harness and tuned the AEM ECU.  We only competed in a couple of events but set fastest time of the day at all of them.  V43 Auto-X 2018

In 2019 we added aero and finished 2nd in A-Modified at SCCA National Tour in Packwood, set FTD at most other local events, and took the car to SCCA National Championship in Lincoln Nebraska where we finished 5th and 6th.  The car is competitive and has the speed to win (3rd place on day one) but our lack of practice (especially with the new aero) throughout 2019 resulted in poor driving.  Datalogs show the car was on track to put down the fastest time but driving mistakes ended our chances.  The car is much easier to drive with the the aero.  Very stable and has so much grip.

Specifications:

  • Engine: CBR600F4i – wet sump with baffling/trap doors
  • Carbon fiber monocoque tub with chromoly roll hoop and rear chassis, body is painted Honda Championship White and partially covered with black vinyl graphics
  • Dampers: Penske with Titanium Coil Springs (pull-rod fronts, push-rod rears)
  • Front and rear adjustable ARB’s
  • 10″ 3 piece wheels – 8 wheels
  • Hoosier 10″ R25B tires (4 tires are new with 12 auto-x runs in September 2019, 4 tires are 2-years old with about 50 runs in 2019, 4 Hoosier wets also included)
  • Transmission: 6 speed sequential, lever actuated
  • Fuel: 91+ octane
  • ECU: AEM Series 2
  • Driveshafts: Taylor Race FSAE Tripods (4340 steel)
  • Injectors, fuel rail and regulator from CBR600F4i
  • Differential Internals: Honda OBX Torsen style
  • Chromoly a-arms, billet aluminum uprights and hubs
  • Fits many driver sizes – Trever and I co-drive with no cockpit changes and I’m 6’2″ with a 36″ inseam vs Trever at around 5′ 8″
  • Hindle Titanium muffler with custom removable tip insert that drops 2.5 dBs
  • Ceramic coated custom stainless steel headers
  • Brake System: Wilwood Calipers, dual master cylinders with adjustable balance bar
  • Weight: 518 lbs with full aero and full of fuel (competition weight was around 465 lbs in 2008 – no aero)
  • Horsepower:  85-90 hp (75 hp at the wheels on dynojet)
  • Track Width (center-to-center): 45″
  • Wheel Base: 60″
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Walk around and cold start video below:

In car video below:

For more blog posts with pictures and videos of Viking 43 click link:  Viking 43

Sector One Design: sectoronedesign.com

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Tire Rack Solo National Championship 2019

The Tire Rack SCCA Autocross National Championship – known as “Solo Nationals” –  where 1,325 autocrossers come from across the country to compete in one of the largest motorsports gatherings on the planet and the premier SCCA autocross competition event of the year.  To crown a national champion in each class, drivers get three runs each on two different courses with the fastest times from each course combined for the official results.

With minimal auto-x practice this year and an all new aero package, it only makes sense to drive 30 hours each way and compete in the SCCA Solo Championships in Lincoln Nebraska.  My co-driver, Trever, has competed at the National Championships a few times several years ago but I’ve never been.  With a fresh set of tires and a few last minute car prep activities, we loaded up the trailer and drove to Lincoln.  The trip was fairly uneventful and we arrived on Monday afternoon to high temps, strong winds, and a concrete dust storm.  After registering, sliding through tech, and setting up our site, we walked the East course a few times and then took the car over to Test-n-Tune for 4 laps.  We had reserved the last test session from 6-7 PM but after driving through two time zones, both of our phones were still one hour off so we got there as they were finishing for the night.  They agreed to let us run two back-to-back runs so I jumped right in.  We were using the 2-year old tires to get an idea of chassis balance on the concrete in order to make some setup changes before Tuesday morning competition.  First lap went OK as I was trying to figure out where the course went.  The last turn was a 180 degree tight corner.  As I braked and turned in, I noticed the car hiked up a bit and the rear wheel spun (inside tire spin).  I didn’t think too much of it but as I pulled up to the starter for the second run, he pointed at both tires and then pointed towards the sky.  I waved it off like it was no big deal as we have fought inside tire spin on several occasions but I was now very aware and a bit tentative for the second lap.  The entire lap was great until that final corner where it did it again.  Those watching said both right side tires were airborne – really airborne.  We drove the car back through the white dust storm and cleaned it up.  I was concerned that there was a mechanical failure leading to this two wheeling and that it could lead to a disaster the next morning during competition runs.  Everything appeared OK but it was concerning me all night.  I finally realized that there was a ~20 mph southerly wind that was likely the culprit.  That was the only corner where the wind direction would attempt to blow the car over acting against the massive wing end-plates while the car was fully loaded in a turn.  Mystery solved… I think.  Despite the old tires and two-wheeling, the grip and balance felt amazing.  This is the first time I’ve driven on concrete and will definitely need to lean on this increased grip to achieve fastest results.

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FSAE had 11 entries and ran the East Course on Tuesday and the West Course on Wednesday.  It was really fun checking out the other FSAE cars and talking with the other drivers/team members (mostly university students).  UTA Racing (University of Texas, Arlington) had 2 cars (2019 and 2016) with 4 drivers, Jayhawk Motorsports (University of Kansas) had 2 cars (2019 and 2017) with 4 drivers, Powercat Motorsports (Kansas State University) had one driver in the 2019 car, and Trever and I raced the 2008 WWU Racing (Western Washington University) car.  These are some of the fastest FSAE cars/drivers in the US.

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The East course was fast and long.  Pretty easy course to memorize but a few tricky bits to get right.  With sticker tires and dry conditions, competition started.  Trever was up first and ran a 60.8 on cold tires.  My first run was a 60.9.  Our strategy was to bank one good run each before really pushing on the car in case something fails.  My run felt OK but I drove in too hot in the first big left hand sweeper which caused me to go wide, hit the marbles and loose a bunch of speed getting back on line.  Second run was a 59.7 for Trever and a 59.8 for me.  This time, I had the same mistake on the next big right hand sweeper.  John Price (UTA) and Julian Garfield (KU) both had 57.5 second runs so we needed to pick up some time.  Turns out Price and Garfield are both past National Champions and it shows.  Final run netted a 58.6 for Trever which landed him in 3rd for day one.  My final run was great until the offset in the back slalom where I got sideways and scrubbed a bunch of speed going into the second half of the slalom.  Ended up with a slower 59.9 which put me in 7th or 8th.  I was pretty disappointed to have a major mistake on all three runs.  Reviewing data afterwards showed that my mistake on the third run cost at least 2 seconds and would have been a low 58 or high 57 second run.  Car ran great, aero was working, and the balance was excellent.  My time was over 2 seconds off first and second place.  An impossible deficit to make up on day two.

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On Wednesday, we ran the West course which was slower, tighter, and a bit more technical.  We walked the course Tuesday night and Wednesday morning and I felt confident that I could move up a few positions if I just drove like I normally do.  Trever’s first run was a 60.6 which was, once again, a great first run on cold tires.  My first run was awful and ended up with a 61.5.  As I was driving through the first slalom, I suddenly wasn’t sure if I was in the correct place and started turning the right hand sweeper hoping I was still on course.  It’s sometimes hard to tell when you are going 60 mph and looking up at a sea of cones.  The rest of the lap was done at a moderate pace just trying to make sure I knew where I was going.  Second run Trever ran a 58.4.  I felt confident in where I was going on the second run but went in too hot in the first left hand sweeper which had a big bump on entry and exit which bumped me off line, into the marbles and took out the first cone on the outside wall.  Time was a 59.9 but had a 2 second cone penalty for a total time of 61.9.  On the third run, Trever ran a 58.7 which was a little slower than his second run.  I took it easy as I needed at least one good run.  It felt pretty good but there were two sections where I left lots of time on the table and finished with a 59.1.

Congratulations to the trophy winners.  Well deserved win with some great driving.  Trever finished 5th (0.007 seconds from 4th and final trophy spot) and I finished 6th.  I’m super disappointed in my driving performance.  Not sure if it was the pressure of a national championship event, lack of sleep from the 30 hour drive, or something else but I do know that my mental game was weak.  Very happy with the car and based on reviewing the data, Viking 43 has the speed to compete at the top.  The aero transformed the car, which is now stable and fast.  The car worked perfectly all weekend and we never touched a wrench – just adjusted tire pressures and added fuel.  Overall a fun trip and great experience.

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Sector One Design: sectoronedesign.com

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SCCA National Tour Packwood 2019

The intent was to get some testing of the newly fabricated and installed aero (see this post for more info on the aero: V43 Aero ) prior to the National Tour event. Unfortunately, schedules conflicted with local autocross events and I don’t have access to any test lots. The best I could do was strap on a few GoPros and perform some very tight circles in my driveway and a quick blast up to speed down the road to make sure everything was safe at speed. Everything was working as intended but no way to measure/test aero balance in my driveway. Knowing that the aero balance could be way off and most likely heavily rear biased, I made some air dam extensions from scrap material laying around and bolted them on. The rear wing has lots of adjustment for angle of attack and, as a more drastic measure, the third element can be removed. At least we could run a few practice runs on Friday to make any minor adjustments… until we ran into a pile of traffic on the way to Packwood and arrived just after practice was closed. Here goes something!

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With only myself and Trever in the FSAE class, we decided to bump into the highest PAX class which is A Modified (AMod) which already had 5 drivers signed up. We asked the event officials and they said we could switch classes but before we did, we found all 5 drivers and asked permission. Everyone was very welcoming. AMod is essentially an unlimited class for purpose built autocross cars. A typical AMod car uses a snowmobile engine (2 or 4 stroke) with CVT, often turbocharged with huge multi element wings, full undertrays, and a chassis big enough to hold a driver, engine, and aero. Minimum weight with driver is 900 lbs and there is a minimum wheelbase and that’s about it for rules. The three cars entered in AMod this event were John Haftner’s Tui Vee, Neal Stanley’s custom 2001 LRC LRC AMod, and an Exocet with a K24 and ITB’s. These cars are fascinating.

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John Haftner is a bit of a legend and has raced this car and other similar cars for decades in AMod autocross and hillclimbs. His Tui Vee is a tube chassis with massive 4-element carbon wings designed and fabricated by Simon McBeath. The car uses a large displacement turbocharged air-cooled VW boxer 4 cylinder with water cooled heads and makes around 300 whp from what I hear (not confirmed). John was using Pirelli P ZERO ultrasoft compound tires. This car likely isn’t the fastest AMod car in the nation but is reliable, properly tested and tuned, and John is a great driver.

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Neal Stanley’s AMod car was built from scratch and uses a 4-cylinder snowmobile engine with turbo and CVT. The CVT allows the car to be at peak hp at all times – no shifting gears, no waiting for the powerband. Horsepower was estimated to be around 280. This car also has massive multi-element wings front and rear with leading edge turbulators based on whales. Whale power! Car was on Avon slicks. Neal was a few seconds off the pace of his co-driver, Jeremy Boyer, who was right on the heels of John’s times on Saturday and had fastest time of the day on Sunday but hit a cone.

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John Jobin’s Exocet was the nicest example I have seen. The fabrication and finish work was impeccable. This is not an AMod car as it’s several hundred pounds over the 900 lb minimum weight but it’s the only class where it’s legal. The ITB’d and tuned internally stock K24 makes 240 whp. Car was on Hoosier A7’s and used a Nine Lives Racing aluminum rear wing. The Exocet is based on Miata suspension, brakes, and chassis dimensions so it is essentially a Miata with no bodywork, windows or doors.

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Viking 43 is a Formula SAE car and built to comply with rules from the 2008 competition which it competed in originally. Compared to an AMod car, V43 is underweight by a little over 200 lbs, has a shorter wheelbase and has 70-75 whp. Being shorter and narrower has some advantages in the tighter corners of auto-x.
As we walked the course for Saturday’s event, it felt like a high speed, high horsepower track. Several straights to lay into the power and some large sweeping turns. Lots of offsets but no traditional slaloms. This would favor cars with lots of horsepower and big aero to take advantage of the high speed sweepers.

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Once we drove the track, it wasn’t quite as high speed as we were expecting. Many others experienced the same realization having expected to shift to 3rd gear in multiple spots but staying in second once on track. Our peak speed was only around 65 mph, however, average speed was high which meant that the new aero was very noticeable. For me, it took a few corners to realize I had more grip than expected and started leaning on it. The aero significantly stabilized the car as well which meant I could go full throttle at corner exit almost everywhere vs pre-aero where I would feather the throttle and make constant steering corrections to stay pointed in the right direction. We exceeded the sound limit on the first run. The sound meter was near the finish lights on the right side of the track. The exhaust exits straight out of the right side of the sidepod on V43, aimed directly at the sound meter. Between runs, we added a turn down to help direct the exhaust away from the meter and the next run was right near the 95 dB limit so we decided to lift at the finish to avoid a DQ. Many cars were exceeding the sound limit on Saturday. My three runs were clean and I dropped a full second each run. Despite coasting up to the straight line finish, my last run (41.957) put me in 3rd place at the end of the day on Saturday. First and second place were within 0.004 seconds of each other (40.828) and 1 second faster than my time. That’s a large gap to make up but considering I’m driving this new aero car for the first time and dropping a second each run and coasting to the finish, it might be possible.

On Sunday, Trever took his first run and had a great time (42.933) putting him in 1st. My first run was even faster (41.301) thanks to the pre-heated tires from Trever’s run. My time was enough to bump me into first overall for the moment and my run was sloppy and full of errors so I knew there was more time in it. Trever’s second run was a blistering 40.765 but had a cone. On my second run, I wanted to fix the errors and go through the left hand sweeper with more speed. I did fix the errors on the early part of the course and entered the left hand sweeper with more speed and stayed in the throttle with the intent to stay on the wide line to carry more speed which should equal more downforce and more grip. I ended up wider than expected due to speed and then got into the marbles and washed out, nearly taking out a line of cones. I had to lift and get the car back on line which probably cost a few seconds. Time was 42.212. Trever’s third run was a 41.022 which was slightly slower than his second run but clean. I had one run to get it done. Needed to be a little conservative to bank a good time but also needed to push it. I stayed tight on the left hand sweeper and the run felt good. I was expecting a 40 second or even a 39 which would put me in first overall but ended up with a 41.957 so my first run ended up the fastest for day two. Haftner was in first place and Jeremy Boyer put in a flyer with a raw time of 40.650 which would seal the deal but had a cone which put him in third behind me and in front of Trever. Thank you Hoosier Tire and Hawk brakes for the contingency awards!

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Overall, a fantastic event and the aero exceeded expectations. Trever and I were able to immediately take advantage of the aero and drive faster with more confidence. Initially, I felt like the car was a little tight/pushy on the high-speed sweepers but the more I drove, the better it felt. Need more seat time to dial in the aero balance.  With the downforce and increased grip, the car now feels underpowered as you can run full throttle without wheelspin. It almost feels like it’s bogging the engine down which may be due to the massive increase in aerodynamic drag but I think it’s accelerating fine, we just aren’t used to continuous WOT without wheelspin and steering corrections. We considered making changes to the aero balance, like removing the 3rd element, but opted to focus on driving and learning the car first.

The aero was clearly working by creating more grip and helping to stabilize the car.  Compare the 2019 National Tour video above to the 2017 National Tour below to see how much more stable the car is compared to how twitchy (note the constant steering corrections and throttle lifts) it was previously.  Site and surface are the same.  Weather and course were very similar.

Looking at this years video, it’s clear that my autocross skills are very rusty. I’ve only competed in 4 auto-x events in the past two years and it was evident by the distance to cones. When I should be millimeters from the cones, at this event I was inches if not feet from cones. A bit more seat time required to get back to that level of accuracy and learning to trust the aero is likely worth a few seconds. We have a few minor items to address on the car for the next few events but overall, a very successful first test of the aero.

Sector One Design: sectoronedesign.com

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V43 Aero – Adding downforce

Viking 43 was designed in 2008 for Formula SAE competition. The rules allow some aerodynamic devices but in the interest of time, weight, and cost, the design did not include aero. Many teams choose to run without aero as the grip advantage requires speed and the events run on small low speed tracks. Also, it doesn’t help in the other dynamic events such as acceleration and fuel economy. For SCCA auto-x, the only thing that matters is lap time so if the grip advantages of aero outweighs the weight and drag penalty then it is a net gain.

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Based on lap simulations and real world data, an efficient aero package should be worth a few seconds on a typical 60 second SCCA autocross run.
Ideally, a car is designed around aero from the beginning as packaging is critical. In this case, we have an existing car and a set of rules that bound the aero dimension envelope so we do the best we can within time and budget constraints. Because of the low speeds and relatively low weight of the car, maximum downforce with good aero balance front to rear is the goal. Aerodynamic drag is a concern but more downforce at the expense of drag is a tradeoff we will accept. We decided to use a multi-element wing for the rear to create extreme angles of attack while maintaining attached flow.  For the front we initially considered a similar multi-element wing but ultimately decided against it.

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Instead, the plan was to build a splitter with diffusers and an airdam with end fences to create a stagnation zone.  The intent is to create front downforce with a device that is more robust in terms of cone strikes and doesn’t starve the side pod mounted radiator of cool ambient flow.  For the FSAE 2008 rules, the front aero is limited to 18″ in front of the front tires so there isn’t much room for a large multi-element wing and you’d need to mount it right up against the tire surface which is producing air flow in the counter direction to the wing.  The airflow interaction in that area would create poor results.  The concept is similar to closed wheel hill climb cars with massive splitters and end fences as well as March, Brabham, and Tyrrell F1 cars from the 1970’s.

 

 

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Front Aero:

The splitter/air dam was constructed of birch plywood and balsa cores laminated with carbon fiber/epoxy.  The V43 carbon skinned honeycomb core tub was drilled and metal inserts were bonded in for mounting locations.  The splitter unit has two sets of mounting holes for height adjustment that corresponds to 2″ or 3″ ground clearance.  The splitter was purposefully built to withstand ground and cone strikes.  I added some sacrificial replaceable nylon rub strips to the bottom corners to take ground strike abrasion.

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We tested this front aero before the rear aero was complete at SCCA NWR Region Event #1 autocross in Bremerton.  Conditions were poor for our 2 year old Hoosiers with ambient temps around 45 degrees F.  We couldn’t get much heat into the tires to get them to stick so not a great test of the new front aero.  That said, the front tires were noticeably warmer than the rears despite lots of wheel spin at launch and corner exits and the chassis balance was heavily oversteer biased.  By the end of the day, the tires still had sticker material remaining on the tread (2 years old but never used).  We started the day with the splitter in the low position (2″ ground clearance) but moved it up as we were getting significant ground contact on the bumpy surface.  The car is softly sprung for maximum mechanical grip and we are hoping to keep it that way but will need to sacrifice some splitter height in the process.  I ended up with 3rd fastest time of the day and Trever ended up 5th fastest only 3 tenths behind me.  On the first run in the afternoon entering the slalom, Trever lost control and ended up off course.  The splitter sheared a swath of grass and dirt as it drove straight into the rough run-off.  The good news is that the splitter survived a severe impact test with no issues.  The bad news was that with 4 wheels off, Trever was not allowed to run the remaining sessions.

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A few weeks later, we entered SCCA NWR Region Event #3 also at Bremerton.  Conditions were much better with ambient temps in the 60’s and 70’s with partly sunny sky.  Grip was much higher but balance was still very oversteer biased which was expected with the front downforce and no rear aero to balance it out.  This car has always been oversteer biased and very twitchy and eager to rotate and this made it worse which means the front aero is working.  I finished with FTD (fastest time of the day) with Trever in 2nd about 8 tenths back and the next fastest car about 1.5 seconds behind.

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Rear Aero:

The FSAE 2008 rules limit the rear wing in width (max width equal to outside of front tires) and the trailing edge can’t extend past the rear edge of the rear tires.  In this application, that limits the chord length to the distance between the roll hoop and the back edge of the tires, which is OK as any larger would create too much downforce to balance at the front.  I chose to go with a 3 element wing using an E423 airfoil due to its efficiency at low speeds and thick section which is easier to fabricate and more rigid.

The airfoils were produced by making a hot wire foam cutter and cutting pink insulation foam.  Birch plywood was used for end ribs with threaded inserts pressed in from the inside for attaching the endplates.  These cores were laminated with carbon fiber cloth and epoxy resin, covered in a release film, and cured in a compression mold.  The shucks (leftover foam from the top and bottom of the airfoil profile) were used to create a compression mold tool.  Took some experimenting to get the foam cores to cut accurately but worked out well in the end.

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The wing uprights need to be stout as this wing will be unsprung so it can’t have additional supports such as tension wires supporting the ends.  I decided to make this wing unsprung as it has many advantages including directly loading the suspension/tires rather than the chassis which allows us to continue using very compliant suspension without running into ground clearance issues during high speed/high downforce conditions.  The pushrod/rocker rear suspension on Viking 43 made this fairly easy to incorporate. The uprights will pivot off the roll hoop and the load will be transferred to the rear suspension rockers via push rods.  To make the uprights, I used a birch plywood core laminated with carbon/epoxy.  The core profiles were cut and a wet layup was used to vacuum bag both uprights.  Once cured, the uprights were trimmed and the mounting holes and airfoil holes were cut.  The endplates were produced in the same fashion but using a foam core (cut out with the same hot wire cutter).

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Once everything was fabricated and fit up, the main element and secondary element were bonded to the uprights using epoxy.  The tertiary element can be removed by removing one endplate and sliding it out to decrease the effective drag/downforce at the rear.  Threaded mounts were welded to the roll bar to accept heim joints for the wing pivots.  A stabilizer arm was cut and welded which also pivots off the roll bar.  This arm serves as a pivot for the balance bar that allows the suspension to articulate independently while still being loaded by the wing via push rods.730FD02C-25C1-4931-A4D1-C2FC38C745CB67EB7698-2832-4E19-B5B9-EC3D74B166E1

A quick test in the driveway and down the street demonstrates that it’s working as intended.  Next will be track testing to evaluate the aero balance.

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SCCA Time Trials National Tour PIR 2019

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Trever’s 1995 BWM M3 was built to compete in SCCA Autocross BSP class several years ago. It wasn’t nationally competitive in that class due to other cars in class having more power, less weight and larger tires (S2000’s for example). Because it was never going to be nationally competitive, Trever chose to keep the stock fenders rather than flaring and running super wide tires. The car hasn’t seen competition in a few years but has seen continuous improvements towards a fast and reliable track car. Trever’s goal over the winter was to build a wiring harness and install a Motec display (Motec ECU coming). Some minor engine mods and re-tuning resulted in about 240 whp from the 3.2 liter engine. SCCA announced a Time Trial National Tour series with a stop in Portland Oregon so this became the target. We co-drove this car several years ago at local autocross events and took it to San Diego National Tour and El Toro Pro Solo events so I do have some driving history with the car but haven’t driven it in about 6 years. Trever graciously offered up a co-drive for PIR and I quickly accepted. Because this car wasn’t built with a specific Time Trial class in mind, we picked a class that it would drop into without any changes required. The M3 fits in Prepared 2 although it’s far from optimized for that ruleset. Prepared requires 200 Treadwear tires so Trever bought a fresh set of Bridgestone RE71’s which have had a reputation for one of the fastest “street class” tires available. The new Yokohama A052’s may be faster but also significantly more expensive.
We drove to PIR Friday and made it in time to enter the SCCA Track Night in America also put on by SCCA so we could both get a few sessions in to shake off the driver rust and shake down the car. Trever drove in the intermediate sessions and I drove in advanced so we could both get track time in. Trever was up first and had no issues. About 10 minutes before my group started, the sky turned black, wind started howling, and the clouds opened. It dumped buckets for about 10 minutes and then it cleared up again. There was a slight drizzle still coming down as I entered the drenched track but by the time I got to the opposite end (Turn 4), it was dry. The half wet and half dry track resulted in a few hairy slides until the track was fully dry. Car was great. Brakes needed very little pressure which made it very tricky to heal and toe without upsetting brake pressure during throttle blips. The floor hinged gas pedal didn’t help either as my size 12 feet put my heal right at the pivot instead of at the pedal face. This was my biggest issue initially. PIR has some heavy braking zones with multiple downshifts required. As the night progressed, the brakes required more pedal force which helped and I finally adapted to the floor mounted gas pedal by hitting the gas pedal with the center of my foot rather than the ball. Once I was comfortable with the braking/downshifting, the car drove very well. Finished off with a beautiful sunset and camped at the track.

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Saturday morning started with two 20 minute practice sessions and finished with two 20 minute timed sessions. Fastest lap during the timed sessions counted towards the weekend time total. First practice session, I ran a 1:28.789. Second session a 1:28.835. First timed session resulted in a 1:28.388 followed by a 1:28.964 in the second timed session. The hot track and ambient temp slowed most people down. Overall, the car felt great but the gearing was just slightly off in a few spots which required coasting (staying out of the rev limiter) for a while or upshifting followed immediately by a braking zone and downshift. The hard braking zone into Turn 1 cause the car to dance side-to-side a bit so I left a bit of margin next to the outside wall but the brakes were consistent and strong. After the SCCA provided dinner, we downloaded the data for review. We found some significant differences in driving behavior between us. One of the most significant was brake pressure. My data showed over 80 bar when slowing for Turn 1 where Trever’s data showed about 22 bar. My lap times were consistently about 2 seconds faster and the data displayed exactly where the time was lost/gained.

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Sunday started with a “Track Sprint”. This was basically an auto-x with a standing start near Turn 1, bypassing the festival turns, and stopping the clock exiting Turn 7. You get 4 runs and your fastest is added to the weekend total. This sounded a bit silly to me – to use a small portion of the race track that we are racing on but it was actually very fun and there were much larger time discrepancies between cars/drivers than I expected based on full track lap times. I dropped a tenth of a second off each run and finished with a 42.624 which was 2nd in class. During the Track Sprint, I was downshifting to 2nd gear in Turn 7 which felt better out of the hole, although brief and quickly followed by an upshift. For the last two time sessions, I decided to try this technique. First timed session on Sunday resulted in a 1:28.574 and the last timed session netted a 1:28.695. In both sessions, all except one lap I downshifted to 2nd for Turn 7. In both sessions, the fastest lap was when I didn’t downshift. Lesson learned. Had I not downshifted for the Track Sprint, I may have improved my time – the power of data. The final timed session had me gridded behind a 2018 Civic Type R and in front of a 2006 Porsche Cayman which had been turning 1:27’s. I offered to let the Cayman pass on the out lap so we could all go full tilt without any blocking issues. Both the Type R and Cayman were running street tires and only had a few fast laps before the tires overheat and grip falls off. We all took off, reordered on the out lap and took our flyers. A few laps in, the Cayman pulled off line (left) exiting Turn 8 to cool down and let me pass. At the same time, the Civic Type R pulled off line (right) so I snaked through the traffic for one last flyer before a cool down. On my cool down lap, the V6 powered MR2 that was leading my class caught me on the back straight so I pulled off line and let him by and decided to jump in behind him to see where he is making up time on me. Unfortunately, he went into the next turn too hot and ran off track. Because that happened just before Turn 12, I didn’t have a good run to start a fast timed lap so I drove another cool down lap and let a different Civic Type R pass me on the back straight and started to accelerate to begin a final fast lap when the Type R also ran off track in the same spot and re-entered the track at Turn 12 which again prevented me from starting a new fast lap.

I tried all sorts of things (different lines, sliding vs sticking, shift strategies, etc) to break into the 1:27’s but was stuck at a 1:28 all weekend. I never drove the perfect lap. Every lap had minor mistakes or traffic. Most sessions showed a theoretical best of 1:27.XX. More seat time would help. I was also intentionally conservative with shift points and speed entering Turn 10 and exiting Turn 12. Exit speed at Turn 12 determines your speed all the way down the front straight and is arguably the most critical corner exit for lap time. It is also flanked by concrete walls on both sides with no run-off so no margin of error allowed. Therefore, not my car and the last thing I want to do is go off track in Trever’s project car.

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The last time I drove PIR was in my S2000 and lapped the track with a 1:21.9 which is my personal best. The fastest lap of this weekend was a 1:23.1 in a 2019 Camaro although the most impressive was Tony Rodriguez in a 2004 Honda S2000 in what appeared to be SCCA STR trim with a best lap of 1:26.543. He drove the wheels off that car.

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Overall, I finished in 2nd place 2 seconds behind the V6 swapped 1993 MR2 and Trever finished in 4th place. The car ran great – didn’t touch a wrench all weekend despite 3 days straight with dual drivers. The car is very easy to drive. It’s forgiving and easy to correct a slide. The tires are fairly impressive and took the abuse without protest although they lost a fair amount of life over the three days especially on the left side of the car because PIR is very right turn dominant and the tires are directional so we couldn’t flip sides to even out the wear.

SCCA did a great job with this event. A few glitches with grid position but other than that, a smooth and fun event.  I hope the sport of Time Trials continues to grow.  It’s a fantastic venue for testing your driving skills and car building skills at a much lower risk vs wheel-to-wheel racing.

Thank you Trever for building a great car and letting me race it.

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