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ARK Design Team America BNR32 GT-R Update

by Mike Kojima and Eric Hsu

The Team America crew has been busy and the car has really come together in the past couple of weeks.  The goal is to be able to have the car dyno tuned and a track test session before it has to go into a shipping container and hopefully end up in Australia this time (if you have been following our story, two years ago, instead of going to WTAC, the car ended up in China for a few months due to the freight forwarder making a huge mistake).

Eric Hsu and Gary Castillo have been working around the clock to get the car done with everyone else on the team pitching in on nights after work and the weekends. The major fabrication is nearly complete and the engine has been started and runs.  What's left is to finish up the top secret Andrew Brilliant designed aero package, the final installation of the wire harnesses, some ducting and to clean up and wrap the car to make it look cool.

Lets take a look at the car's progress.

Read The ARK Design BNR32 Build Stories Here!

The car has come a long way over the past couple of weeks.  The plumbing has been completed and the wiring harness was in place although it had to be removed to troubleshoot.  The engine would not start at first but Eric Hsu obtained some new FPGA settings from the Pectel engineers at Cosworth in the UK and the engine fired right up. Actually to verify that it was not a wiring issue, Tyler at AEM built a Pectel SQ6 to AEM Infinity adapter harness and brought it down one night. Eric was actually tempted to change the ECU to an Infinity, but there was too much that needed changing since the car's electrical system was designed around the Pectel. Since the Pectel engineers pulled through, it was easier to continue with the Pectel. Here you can see the wheel tubs that were fabricated not to look sweet but to help control airflow around the area of the tires and engine compartment.  Nearly every bit of airflow around the car is being put to work to increase downforce.  Yes the probe looking thing on the roof is really a pitot tube.  We will be measuring air speed so downforce can be calculated when looking at how much the suspension is being compressed vs the airspeed. It would have been nice to run strain gauges to measure force on the suspension, but the budget did not allow for them.
I am pretty proud of my department.  The stock BNR32 has a really horrible archaic suspension geometry that was designed by some poor Japanese guy who thought a variable camber curve would be neato while ignoring nearly every other aspect of suspension design.  The biggest problem with the stock suspension among a host of other issues is a super high roll center and a real close inboard lateral instant center.  The car in its previous iteration would jack like you would not believe.  Instead of just rolling the car would also rise due to the jacking.  We managed to come up with a suspension geometry that fixed every issue that the stock car had leaving us with close to classic good geometry. All without overly complicated fabrication and expense while still retaining the stock knuckles. Our design would have kicked ass on the Nismo Group N front suspension back in the day. The only issue that we still had was that bump steer was somewhat compromised because there was a lot of unmovable powertrain stuff in the way of ideal steering rack location.  Although I had some ideas on what to do about it, Gary Castillo came up with a total solution that is pretty fascinating. Additionally, Eric had previously had the stock BNR32 uprights machined for larger wheel bearings to prevent piston knock back.
We call Gary the Filipino MacGyver because he can always come up with some sort of solution to a problem using stuff found lying around the shop.  Gary's steering solution is pretty cool and is very similar to the system found on the Nismo GT-R JGTC car from around 2005 or so.  It starts off with this lightweight and adjustable steering column that he fabricated from scratch. Notice that the factory firewall is still in place. Part of the tunnel was cut out to enable better access to the Holinger gearbox bellhousing. The missing section will be replaced with a sheet metal cover.
The steering shaft leads to this BMW E39 M5 recirculating ball power steering box that is bolted solidly to the firewall and frame rail. It is also tied into the cage on the interior.
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Comments
eeeen
eeeenlink
Monday, September 22, 2014 3:12 AM
Very VERY cool! So great to see this R32 still making progress. Bummer about no test time, but at least it is heading to Au. under its own power..... assuming nothing goes wrong with shipping again. *fingers crossed*

I am beyond excited to see how this build turns out in regards to both the completed aero design and of course the lap times it puts down. I hope this beast is ready to fly with the best of the WTAC fleet.

It is amazing to look back at older Pro Class cars like the CyberEvo and SSE's Christine, rocking H-patterns and looking much more like the Open Class cars now... The WTAC Pro Class has progressed indeed.
Dan DeRosia
Dan DeRosialink
Monday, September 22, 2014 4:28 AM
Okay, the recirculating ball steering solution... wow. As much as I don't like recirculating ball steering, what that enables in packaging and steering geometry is kind of amazing, and I'm not going to pretend I can think of any other good way to do that. Any concerns about whether the cooling stuff will be getting enough air from the back of the wheel wells to work properly? I know some prototype cars have done the same idea, kinda, but that's really apples to watermelons. Obviously you guys have data to suggest it will work, so here's hoping all the wild stuff works as well together as you think it will.
gman
gmanlink
Monday, September 22, 2014 6:11 AM
Good LUCK!!!!!! That car sure has come a long way since our XS days. It looks great! Keep us informed!
gman
gmanlink
Monday, September 22, 2014 6:12 AM
You guys need go pro onboard footage!
rawkus
rawkuslink
Monday, September 22, 2014 6:34 AM
Would someone explain to me how plumbing air on top of your diffuser is helpful? I would think that keep as low of an air pressure zone as possible behind the diffuser would increase flow through the diffuser. Reducing the air pressure zone would hurt, correct?
Dan DeRosia
Dan DeRosialink
Monday, September 22, 2014 7:14 AM
Plumbing air on top of the diffuser probably isn't helpful, but the coolers have to exit into a low pressure area, so there ya go.
jeffball610
jeffball610link
Monday, September 22, 2014 7:52 AM
Can't wait to see this thing on track. I've been watching it since the XS days and following this build here. I hate the anticipation, just get to it already :p
sethulrich
sethulrichlink
Monday, September 22, 2014 8:35 AM
It's not that plumbing air on top of your diffuser is helpful, but plumbing HOT air on top of your diffuser exit is what makes it beneficial, if I understand correctly.
8695Beaters
8695Beaterslink
Monday, September 22, 2014 9:52 AM
That steering system is seriously ingenious...I LOVE IT!!!

You guys are going to turn heads and cause quite the shitting of pants in Australia...best of luck and greatest of speed!!!
gstmike
gstmikelink
Monday, September 22, 2014 10:06 AM
My hats off to you guys, that's a ton of work to get done in an out of hours format (much akin to my own program!)

Love the fab work!
Protodad
Protodadlink
Monday, September 22, 2014 10:19 AM
Amazing. Been waiting years to see this car dominate. Any word on who the driver will be for AU?

Kaane
Kaanelink
Monday, September 22, 2014 11:13 AM
Crazy amount of work in such a short period, the question I have, is it even worth sending a car in this shape to Australia? I mean you guys basically built a whole car from scratch, it happens to use the unibody of a R32, but everything else is custom. The chances of something going wrong are like 100% with no testing.
JM318iS92
JM318iS92link
Monday, September 22, 2014 11:25 AM
Behind the car is a low pressure area, by plumbing air to that area there is a decrease in drag.
Shifter Kart
Shifter Kartlink
Monday, September 22, 2014 2:04 PM
no details about the rear suspension?
Mike Kojima
Mike Kojimalink
Monday, September 22, 2014 2:13 PM
@shifter Kart, the rear suspension was discussed a long time ago in older installments. Basically it is not that radical other than reducing the anti squat and raising the roll center. In the future, time and budget permitting we might build a tubular subframe with a LSA type layout. In it's previous incarnation getting front grip and front jacking were issues so we attacked the weakest end first.
eeeen
eeeenlink
Monday, September 22, 2014 2:29 PM
@ Kaane I would assume the car is not staying in Au. after the event (like AB's car), so I would bet the Team Merica' crew think they can get the car ready for competition. I sure hope so!

At this level, it seems like testing is very important though.
black bnr32
black bnr32link
Monday, September 22, 2014 5:51 PM
Mike,
What can the average guy do to improve the geometry of BNR32s?
Tekdork
Tekdorklink
Monday, September 22, 2014 6:31 PM
There actually is a much easier way to do it assuming you are not going to go wide body. Wide body made it difficult to keep it some what standard.
Mike Kojima
Mike Kojimalink
Monday, September 22, 2014 6:51 PM
@black bnr32 define average. You need to be able to weld and fabricate at least.
Mike Kojima
Mike Kojimalink
Monday, September 22, 2014 6:53 PM
@tekdork, A wide body has nothing to do with why we redid the suspension geometry. Read the articles and we explain why once in detail and mentions why in others.
Tekdork
Tekdorklink
Monday, September 22, 2014 7:23 PM
Oh sorry about that, i should reiterate. A double A-arm set up is possible without going these lengths on a stock body R32 GTR. Not saying that you will have the exact same characteristics as this car but it will get rid of the crazy OEM front suspension with better results then OEM. Yes, there will be welding but it does not have to go as "racecar" as this but a street set up close to this with "minimum" welding is totally possible.
black bnr32
black bnr32link
Monday, September 22, 2014 7:28 PM
Average would ideally mean
-street car ride height
-use as many off-the-shelf parts as possible
-use home-garage fabrication tools
-the goal is to have more fun at local autocrosses and track days

Mike Kojima
Mike Kojimalink
Monday, September 22, 2014 7:47 PM
@teckdork, if it was posible to get close to ideal geometry with less we would have done it. Well we might have had simpler steering and suffered a little bumps steer though. You cannot get proper geometry without fabricating on the chassis side. Once again a wide body has nothing to do with the geometry and why we did the things we did and has no bearing on where the pivot locations are.
Mike Kojima
Mike Kojimalink
Monday, September 22, 2014 7:50 PM
@black bnr32, you can help a little with arms that you can adjust the roll center some at the bottom with adjustable rod ends. Not much though before you start to suffer from jacking. If you try to correct too much the lateral instant center gets too close. If you do this you need adjustable rod ends to fix the change in bump steer you will get. We went this whole route with this car in it's previous incarnations. The car would both roll and rise up in corners from jacking, it sucked. The stock geometry is really bad.
Der Bruce
Der Brucelink
Monday, September 22, 2014 7:59 PM
Gary totally looks like he could be Eric's brother, you know, with hair :-0 !

Do you know what size of tire and wheel you're aiming for this year?

Thanks for the update, so glad to hear it's running!!
Eric Hsu
Eric Hsulink
Tuesday, September 23, 2014 12:42 AM
There will be testing before WTAC, but it will be in Australia.

The fab work will be completed at Hypertune (yes, the beautiful intake manifold and plenum guys) in Australia after the car lands. Gary and I go early to help finish things up and get it ready for testing.

Bruce: the tires are Yokohama Advan A-050 295/35/18 softy softs.

Mike and Gary can answer the other questions. Back to planning for me (damn, there's a lot of planning involved...)
Dan DeRosia
Dan DeRosialink
Tuesday, September 23, 2014 9:57 AM
Oh yeah, two more questions to throw out there... any quick answer on what the Pectel is doing with the FPGA stuff? I have a vague concept for what FPGAs do, and know various motorsports ECUs incorporate them, but not really why or for what. And secondly, noticing the shock pots, is there any viable solution for those short of about $450-500 apiece? I figure you guys would know if anyone did.

I know everyone's busy so I won't be heartbroken if there's no time to do a decent answer.
Micah McMahan
Micah McMahanlink
Tuesday, September 23, 2014 11:21 AM
STACK and AIM both offer the rigid linear pots. The 6" travel AIM one is like $270/per from Pegasus.
I would be curious to learn of any other suppliers before I drop over $1k on mine...Although I have the AIM Evo 3 pro, so the AIM is direct pnp.
Mike Kojima
Mike Kojimalink
Tuesday, September 23, 2014 11:25 AM
I think racepak offer some lower price ones as well. I have learned a lot from these about valving and stuff so it ranks as one of the most useful things to log.
Mike Kojima
Mike Kojimalink
Tuesday, September 23, 2014 11:27 AM
some of my posts are really bad, i can't type on a phone, can't see the screen.
Dan DeRosia
Dan DeRosialink
Tuesday, September 23, 2014 12:29 PM
... man, why was I misremembering the price of the AIM ones from Pegasus? They're even my go-to as their showroom/HQ is 20 minutes from here. Thanks; still pricey but can't really be helped.

After all my shock dyno experiments (which I really do have to rebuild one of these days) I really don't want to run a car for myself without shock pots. Then again, being an engineer working with lots of DAQ in my day job may promote that bias.
Mike Kojima
Mike Kojimalink
Tuesday, September 23, 2014 1:01 PM
@dan, you can learn so much with shock pots, perhaps more than any one single part of suspension logging, at least in my opinion.
Dan DeRosia
Dan DeRosialink
Tuesday, September 23, 2014 6:05 PM
In most SCCA roadrace classes, it's nuts to me how little attention is paid to shocks given all the tools that are available to do so these days. Friend of mine in E Production, one of the biggest classes and one of the most modified for production cars, is running Koni wet converted struts, no shock dyno or development, etc. It's good for consistent top 10 finishes at the national championships, but I'd be willing to bet there's whole seconds at Road America in valving. I'm nowhere near that caliber, but at least I can make the car do its part.
Mike Kojima
Mike Kojimalink
Tuesday, September 23, 2014 6:09 PM
@Dan, are 3-way shocks even legal in E Prod? Koni wetpacks were the shit 15 years ago! They cannot generate much low speed without packing up on high speed. Old school! It's amazing how much modern shocks can do (and how much they can cost!)
Dan DeRosia
Dan DeRosialink
Tuesday, September 23, 2014 6:30 PM
Anything's legal that bolts to the stock upright, or in the 1st gen RX-7's case, "fits into the stock housing" - which is to say is welded to the knuckle's forging. My whole DIY shock dyno project kicked off from the first stages of attempting to make roller bearing struts and realizing I'd need to prove that all the crap worked together but it tapered off with the car getting put into a tire barrier and my dad doing the math on what it would cost to put together another competitive car.

I'm waiting for someone to show up with properly developed Koni 2817s or Ohlins TTX struts (I've seen Motons and Dynamic struts, but the latter not by anyone who knows their business) but with the Runoffs moving away from Road America, I'd say smart money's on Miatas, which have much cheaper solutions.
bigBcraig
bigBcraiglink
Tuesday, September 23, 2014 7:58 PM
Mike,

Can you comment on the frequency you try to log shocks at? I'm ex-FSAE, and we certainly benefited from them, but logged at a fairly low rate (20 Hz or so, I believe)

Had the chance to go back to FSAE Michigan this year to see old friends and had some very interesting discussions about things professionals look at concerning surface and tire behavior at really high frequencies.
Mike Kojima
Mike Kojimalink
Wednesday, September 24, 2014 12:59 AM
We run at 60hz for the drift car, I would probably run 120hz for a road race car.
J Finken
J Finkenlink
Wednesday, September 24, 2014 12:07 PM
Very cool to see an update, cant wait to see it in action at eastern creek!

Mike, concerning the R32s suspension geometry: The R32 GTR was regarded as one of the best handling cars when it came out. It also had a formidable success as a group A car, where minimal modifications on suspension pickup points were allowed, around 20mm from memory.
You say the geometry is horrible, but it must surely be one of the better cars of its era, or..?
It is after all a 25 year old setup.

A bit off topic, but the Z32 and G20/Primera share a similar front suspension, do these cars have the same issues?
Mike Kojima
Mike Kojimalink
Wednesday, September 24, 2014 12:25 PM
When you consider 25 years ago, stock ride height and tire sizes that fit in the stock body work it is sorta ok. Nissan was doing weird experimentation with suspension geometry during this period and doing a lot of stuff I personally think is dumb.
Mike Kojima
Mike Kojimalink
Wednesday, September 24, 2014 12:27 PM
The Z32 and P10 have later iterations of this design that are much better, most notably the mounting location of the upper link and the length of the lower. These cars were designed later.
J Finken
J Finkenlink
Wednesday, September 24, 2014 12:52 PM
Thanks for your reply. I owned a P10 Primera years ago and remember its good handling compared to other cars from the same era. Most cars at least here in Europe only had mcpherson back then.
The geometry sort of went out the window when it was lowered though.
xloki77x
xloki77xlink
Saturday, September 27, 2014 9:33 AM
For a low buck linear shock pot you can use TPS sensors out of nearly any production car. You have to come up with a lever/mounting scheme, but very easy to make it work. No need to spend over $1k on pots, just re-purpose some overlooked ones.
Mike Kojima
Mike Kojimalink
Saturday, September 27, 2014 11:47 AM
Since you have to come up with a linkage to use a TPS, the readings will be non linear unless you created a table in the maths to correct it. Sorta a hassle and since you can be measuring small movements not accurate.
xloki77x
xloki77xlink
Sunday, September 28, 2014 6:16 AM
Sure, you'll need to do some initial setup/calibration to get the system running, but if you're at the level of wanting/needing shock data, then you are more than capable of fabricating a simple mounting system (made from model airplane control rods on the cheap) and turning the data into useful information. Depending on what type of sensors you can find you can manipulate the output data in many ways. And it's something that's built not bought. For people with more time than money, it is a viable option that's been used for years as substitutes for cash money millionaire linear pots.
Dan DeRosia
Dan DeRosialink
Sunday, September 28, 2014 8:58 AM
All gets to your own financial comfort zone. I've heard of Caddy headlight levelling sensor pots used; Summit seems to have them for $29 or so new and actually weather sealed. I'd prefer that to cobbling all of the sensor. At the same time though, god knows what the resolution / repeatability is.

God knows I'm a proponent of building things (I built my own shock dyno that kinda more or less works, started building my own struts and am currently working on home aluminum casting) but there comes a point where you want something that just works without messing around.
Mike Kojima
Mike Kojimalink
Sunday, September 28, 2014 2:37 PM
A good thing about using a TPS is that it would be less damage prone I bet. I would like to see some home casting, do you have one of those cool small induction furnaces or use a torch?
Dan DeRosia
Dan DeRosialink
Sunday, September 28, 2014 3:44 PM
Somewhere in between; its a hot water heater shell lined with homemade refractory and using an oil burner from a furnace. Insert diesel, add electricity, whoosh, fire. Working my way up to casting useful things, but so far have done pours of a couple pounds of aluminum. I sized everything to be able to do maybe 50-100 pounds as I want to move up to cylinder heads eventually. Planning on trying to do a 13B intake manifold in a couple months; mood to get it designed first.
Mike Kojima
Mike Kojimalink
Sunday, September 28, 2014 8:09 PM
Sounds cool, What sort of sand are you gonna use?
Dan DeRosia
Dan DeRosialink
Monday, September 29, 2014 3:20 AM
Started trying a homemade green sand recipe, but that didn't work out all that well. Then just bought some petrobond casting sand, which worked really well on stuff we tried. I'm actually planning on a lot of investment casting though, which is a copy of the piece in something that burns out, coated in plaster or a specialized sort of ceramic slip. Big advantage of that is the details possible, and that my 3d printer spits out a plastic that burns out pretty well; so the path from CAD to metal part is a lot simpler for one-offs anyway. I did a turbo compressor (I had a CAD model for it and the blades are nice and thin) out of zinc a few years back to prove it worked, it's just taken until now to get to where I can do aluminum.
theneil
theneillink
Wednesday, October 01, 2014 7:42 PM
awesome i cant wait to see and hear it run!
Pilun
Pilunlink
Tuesday, December 30, 2014 10:25 AM
This is an amazing build. Can't wait to read about how it does at the next event. I couldn't help but notice something about the wing supports. The cutouts seem to have created a weak spot where a strong sideways gust of wind could bend it sideways.
Mike Kojima
Mike Kojimalink
Tuesday, December 30, 2014 1:05 PM
No they are very strong.
Pilun
Pilunlink
Tuesday, December 30, 2014 4:14 PM
I modeled the wing support and did a stress analysis, if those are 5/16" THK 6061-T6 and those cutouts are 1/2" away from the edge, they will hit yield at around 67 lb sideways force per support or 134 lbs for the combined two supports.
Mike Kojima
Mike Kojimalink
Tuesday, December 30, 2014 4:22 PM
It won't believe me. The chassis mounts and the anchors to the wing elements themselves would yield first.
Tekdork
Tekdorklink
Tuesday, December 30, 2014 5:09 PM
Actually they are 3/8 thick. The original material we had was 5/16". Plus it's double shear on the bottom and top of the support. Lastly, I know that you stated sideway but we had one of my guys and I standing on the wing rocking it up and down and side to side. Can't say that it's more accurate then your software but I weigh 175 and my employee is 150, i realize that's not a ton but it was impressive. If anything i was more worried about the rivets attaching the wing tabs to the wing so we added just a few more in a staggered pattern. That actually helped a bit.
Pilun
Pilunlink
Tuesday, December 30, 2014 6:53 PM
At 3/8" thk, we're looking at 90lbs each, but I think the fact that the assembly is boxed by the wing and chassis helps since the bending of the upright would have to be accompanied by bending of the wing attachment. Anyway didn't mean any of this to come across as criticism. Nice work.
Tekdork
Tekdorklink
Wednesday, December 31, 2014 9:06 AM
Pilun, sorry if I sounded harsh, I didn't mean too, I just don't have computer skills in CAD, Solidworks, CFD crap, email for that matter. I tend to do stuff the old way so I thought I would just explain. no hard feelings.
Mark F
Mark Flink
Wednesday, January 07, 2015 10:38 AM
You should only be spending $1000 on linear pots if they are very special. A normal linear would be around $200 starting price for a P&G. Those are lower end. On a road going car with a lot of vibration isolation compared to an open wheel car or equivalent, they should last a long time. Just keep them clean as well.

You could do hall effect, but the price will go up. The rotary with a gear or toothed wiper so to speak is a very common setup. This also should be relatively simple to fab up as stated.

Hollow shafts are good if you have a pivot point like on a pushrod or pull rod setup. I have always loved the hollow shaft rotaries over shafted, linear or equivalent damper displacement setups.

Hall effect is great, but beware of these truly contactless sensors. I get told that they are the best thing since sliced bread. I will tell you what, if it is for control strategies in your logger, then take a hard look at any electrical interference in the area. We ran a normal 'bodied' hall effect sensor for a couple years in an application with no issues. We then were approached by an engine manufacturer to change to a fully contactless sensor setup. Low and Behold, it was noisy and was picking up noise as signal....this was on an actual throttle pedal too...

Sometimes a simple setup is better than a complex setup. My favorite wheelspeed we sell is cheaper (to million dollar race teams) than almost any wheelspeed sensor on a road going car and can do a high wheel trigger count at 250mph with no issues.
CHEQUERED TUNING
CHEQUERED TUNINGlink
Monday, February 09, 2015 7:01 PM
Fantastic read, not much keeps my attention anymore but once i started on the front suspension i was hooked. We didnt get much of a chance to look over it a WTAC as the boys looked flat out trouble shooting ecu gremlins but Mike was a wealth of information and charming to boot.... so much so i thought id lost my wife :P
Mike Kojima
Mike Kojimalink
Monday, February 09, 2015 7:03 PM
I won't do anything for love.
Protodad
Protodadlink
Monday, February 09, 2015 7:15 PM
Any chance this car will run in CA during 2015. I would love to come and see it (hint:willow springs).
theneil
theneillink
Saturday, January 09, 2016 5:17 PM
What happened? I saw a brief video of this car rolling broken off the track, and a picture of it under its own power at wta, what's the deal? I thought there would be an update even if it was about what didn't work out, or is this car just gone?
Eric Hsu
Eric Hsulink
Monday, January 11, 2016 12:47 PM
Updates coming 2Q 2016.
Micah McMahan
Micah McMahanlink
Tuesday, January 12, 2016 8:15 AM
Are we going to see this run stateside? Go do some shake down on Buttonwillow.
theneil
theneillink
Wednesday, January 13, 2016 12:40 PM
Awesome! Can't wait, I wounder about this car a lot.
Micah McMahan
Micah McMahanlink
Wednesday, August 10, 2016 7:04 AM
So Eric, it's 3Q 2016...what's going on? :)
Micah McMahan
Micah McMahanlink
Wednesday, October 05, 2016 12:38 PM
Fourth quarter bump because IMSA is over, WEC only has three races and I need a break from staring at NASCAR parts, as it Chase time...give me some car porn dang it!! hahaha
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