ABS, a healthy winter project.

This post is primarily going to be a photo-montage of the ABS system that I added before spring, 2016.  With that said, requests for more details in the comments section may result in wiring diagrams.

The ABS module is a Bosch 5.3 unit from an NB Miata.  The Miata 5.3 is a 3 channel system and can run in standalone applications.  My experience with using this system at several open track events is that it’s reliable and sufficiently indifferent to my aftermarket calipers to still perform reasonably well.  The tires chirp some under max effort braking suggesting that the system maintains slight longitudinal slip, a good thing when you seek to slow down expeditiously.  My phone, mounted in a way that will not flatter the readings because of cross axis contamination, says that I consistently hit about 1g in braking.  I’ve never had a wheel lock up with the system active.  I chose to put the module behind the passenger seat to help offset driver mass, improve the f/r weight distribution, keep the CG low, and to keep clutter out of my engine bay.  ABS is not permitted in Spec Miata.  Shops that prep Spec Miatas tend to have an abundance of these modules on hand and will part with them for ~$50.  Second hand wheel speed sensors go for ~$20 each.

The OEM mount was used, and welded directly to the chassis.
The OEM mount was used, and welded directly to the chassis.

 

The ABS module in place.  This is essentially behind the passenger seat.
The ABS module in place. This is essentially behind the passenger seat.

 

Some freshened up components, plus a wheel speed sensor.
Some freshened up components, plus a wheel speed sensor.

 

Wheel speed sensor and tone ring.
Wheel speed sensor and tone ring.

 

Things and stuff to support the operation of the pulsey-stoppy-brick.
Things and stuff to support the operation of the magic pulsey-stoppy-brick.

Keeping it cool with science and stuff.

If you’re like many others, and your most pressing issue is the need for an increase in the efficiency of your vehicle’s cooling system, then it’s your lucky day! Increase the pressure differential across your radiator, and reduce your front end lift, with simple vents and flaps.

My cooling system works fine, however with the more is better philosophy, I decided to experiment with a few different configurations and try to quantify their effects. The best configuration yielded a 24% increase in pressure differential across the radiator than the control, at the 50mph test speed.

 

Configuration 1: Sealed hood, no vents.
This test is representative of what you’d see with your stock hood. For the purpose of this test, it served as a control, a baseline to which the other configurations were compared. I blocked off my existing vents as shown below. An early indication that the vents work is that the paper I used to block off the vents lifted in the back and started flapping around shortly after reaching my test speed, which was 50mph. That suggests that the pressure under the hood was greater than the pressure on the top side, at least in that region.  Maybe that’s why I put my vents there.

The pressure differential across the radiator was .55 in H2O.

Don’t be deceived, my car isn’t drinking from a crazy straw. The tube in the picture samples the air pressure in front of the radiator.

 

Configuration 2: Vented hood.
This test was performed with the vents unobstructed.

The pressure differential across the radiator was .625 in H2O.
That’s a 12.8% increase over a vent-less hood.

 

Configuration 3: Vented hood with flaps.
This test was performed with the vents unobstructed, and 1.5″ aluminum flaps at the leading edge of the vents. The flaps manipulate the air to produce a pressure differential of their own. The pressure forward of the flaps becomes greater and the pressure rear of them is decreased. The reduction in pressure behind the flaps helps to draw air out through the vents.

The pressure differential across the radiator was .7 in H2O.
That’s a 24.0% increase over a vent-less hood.

 

Lift Reduction:

These increases in pressure differential across the radiator are a result of reduced pressure in the engine compartment. Less pressure in the engine compartment translates to less pressure pushing up on the hood, and consequently less lift.

The reduction in lift can be approximated by multiplying the reduction in pressure across the surface area of the hood. The listed values are for 50mph.
The reduction in lift due to the addition of the vents was ~5 pounds.
The reduction in lift due to the addition of the vents and flaps was ~10.1 pounds.

 

Observation: The pressure differential generated by the cooling fans on the stationary vehicle was not great enough to register on my gauge.  This emphasizes the importance of not overly relying on fans, as their effect, short of using large power hungry ones, is insignificant relative to what can be achieved with a well placed radiator and proper ducting.

 

The following photos are to provide insight on my methods:

The high pressure reference, forward of the radiator.

The low pressure reference, rear of the radiator.

My pressure differential gauge, and the reason why I’m using inches of water as units.

Adaptive Bi-Xenon Headlights in a ’94 Miata

I’ve built a few sets of headlights now. The first was pretty good however I ended up selling them. The second was a flop. These, I think, are a winner.

The headlights that I built, last minute, before I did my road trip to California from Michigan seemed pretty good…but then I tried to do some night time canyon driving and quickly realized that they were grossly inadequate in that setting. My primary gripe was that the projectors did not put enough light out to the sides. I was entering turns blind, which isn’t safe or confidence inspiring. I had to come up with something better.

Adaptive headlights have been on my radar for a while. Driving cars that are equipped with them has always been a treat. Making a set just wasn’t a high priority. Then I was an idiot and forgot to reinstall my hood pins after washing the car. The hood flew up and I needed a new one. Putting headlights behind the windshield was something that I had also been contemplating because getting the performance I desired from the stock headlight location seemed unlikely, so I had a new hood made that blocked off the stock headlight openings and that put things into motion for high mounted adaptive lights to actually happen.

Anyway, photos….

Covers to block out glare:

Pulley, bored out for the steering column.

A 10 turn pot went on the small pulley. This proved to be a cheap and easy way to track my steering inputs.

The belt driven steering angle sensor ended up having a propensity to skip and applying enough tension to prevent that would have been hard on the potentiometer.  I switched to this gear driven setup and haven't had a problem since, even after a few thousand miles.  The downside is that this approach is incompatible with the stock ignition switch, steering lock, and stalk controls, which had to be displaced via angle grinder, mini-sledge, and chisel.
The belt driven steering angle sensor ended up having a propensity to skip and applying enough tension to prevent that would have been hard on the potentiometer. I switched to this gear driven setup and haven’t had a problem since, even after a few thousand miles. The downside is that this approach is incompatible with the stock ignition switch, steering lock, and stalk controls, which had to be displaced via angle grinder, mini-sledge, and chisel.  #Flint

To answer the most likely questions….

-No, I haven’t been pulled over with these yet. That said, I keep an excerpt from the Michigan motor vehicle code and a tape measure in the car so that I can prove that at least as far as mounting height goes, they’re legal. They’re aimed to be fairly courteous to other drivers.

-They do not obstruct my view in any appreciable way. I sit low and am only 5′ 9″. Taller people would have a tough time driving my car, which is fine because I don’t really pass my keys around.

-They’re controlled by an Arduino. Servos, equivalent to what you’d find on an RC car, move the projectors.

-Glare is negligible.

-This is what they’re like in heavy rain. It sucks but I expected that. That’s why I have the LED spot lights in the front bumper. They make the car plenty drivable in poor weather.

-I intend to eventually read the VSS output so that I can scale the headlight movements based on vehicle speed.

-They work great. I went to the tightest and most twisty local road that I know of. They threw tons of light where I needed it most.

7,200 Mile Road Trip in the Fun Facilitator

Over the course of about three weeks, I drove 7,200 miles, to California and back, with a number of stops along the way to visit friends and do cool things. My Miata probably wouldn’t be most people’s first choice of vehicle for such a trip but when you consider that people used to go out west on horseback, gaining sustenance via the consumption of rattle snakes sprinkled with gun powder, my car, with special amenities such as a seat…and another seat that I sat a cooler on…made the trip not only bearable but genuinely pleasant. *Not applicable were the two instances where I encountered flash flooding and had to wade through literally a few inches of water. That was quite unpleasant. But even so, the thing was pretty damn reliable and I’d totally do it again.

Auto-x in Nebraska. I dominated X Prepared, which just consisted of myself and a rough looking z3.

Claiming victims

American muscle……bro…

Utah salt flats. No I didn’t drive on them.

This is the street we stayed on in San Fran

Prepping our cars for the track in a cul de sac. A track day at Laguna Seca was the following day.

After the car meet pictured above I went to the Wal Mart parking lot that my friends were at, trying to fix the Camaro. The torque arm mount fell off. Using what was available to us at 1am, that being a clothes line from a nearby grocery store, I employed my eagle scout knot skills and some redneck engineering tactics and lashed the torque arm to the crossmember. Then we drove from LA to Vegas…and eventually on to San Antonio where the yarn was replaced with a new mount. This didn’t budge at all.

We all wore these for the drive to Vegas because not doing so would have been pretty silly IMO.

Then we water skied through New Mexico…

2014-2015 Off Season Upgrades

First up, the engine… What started out as concern for the sustained well being of my stock valve springs ended with me installing ported ls6 heads, with some nice stiff springs that shouldn’t be phased by what I subject them to, and a more aggressive cam. The lift on my cam isn’t particularly high, a decision I made for reliability, however the duration and overlap have gone up drastically. It’s now a full embodiment of of the things that people who hate v8’s hate about v8’s. Loud, lopey, and very much not epa friendly…which I’m not proud of but on toy like this I’ll let it slide. Still not a power monster(in v8 terms, not Miata terms), but based on what’s done the wheels should rotate with the strength of nearly 400 horses, or unicorns since this is a Miata. Also for reliability I installed an ls2 timing chain. It’s a bit beefier and less apt to break when I occasionally scrape the rev limiter.

While I was at it I cleaned the hell out of everything that I encountered. Selective OCD at work…

I’ve also picked up ABS components from an NB. This project isn’t complete and is moving slowly. So far, there’s a mount for the ABS module and I’ve switched to ABS compatible front hubs and uprights. Next up is figuring out the mounting for the rear wheel speed sensors and tone wheels. I may have to stick my axles in a lathe to bring the OD down to the ID of the oem tone wheels but I still need to investigate the viability of that. Then wiring harness which is easy and plumbing which is just tedious.

I touched on the cooling system as well. Last season I ran a universal radiator that had been modified to work with my setup. The welds ended up being kind of dirty and there were some pinhole leaks that I repaired, by redneck definition, with some epoxy. That got me though the season. I have too many teeth and not enough flannel to leave the system in such a state so I had a new radiator made, by somebody capable of making welds that don’t leak, to fit my specifications. It’s nice–whether on track or sitting in traffic in a 105 degree desert, my water temp won’t budge.

Water pump bracket:

I’ve also installed Xida Clubsport v2’s. I chose 800 front 500 rear. The car may be a little over-sprung right now but I chose those spring rates with the intent to add some down force in the not too distant future and also because the F/R wheel rate ratio is about the same as what I had with my previous setup, which actually provided a pretty satisfactory balance. Also, I think my unibody must be in really awesome shape because I made literally zero adjustments to achieve 50% wedge. I just set the collars to be an equal number of threads up from the bottom and stuck them on the car.

2013-2014 Off Season Upgrades

Several months elapsed between the completion of the swap in August 2013 and the end of the 2013 season. The car was subjected to autocrosses, open track days, thousands of miles of street driving, and the kind of treatment that I’d normally reserve for Nazis and members of ISIS. Nothing catastrophic happened, however plenty of potential for improvement was found.

The car proved itself to be quick, so working to wring out every last ounce of performance was not the priority–at least not yet. Rather, I focused on tackling the things that made me uneasy as a driver. The cooling system, the brakes, and the clutch topped the list.

The cooling system worked well when the car was in motion however a defective radiator led the temperature to climb at low speeds. Typical radiators consist of two end takes that are connected to one another by rows of flat tubes. Fins are connected to, and located between, the tubes. The tubes on my radiator expanded, ceasing to be flat, and crushed many of the fins. Air needs to flow through those fins. Airflow through the radiator was decreased due to a greater pressure differential being required to overcome the resistance introduced by the crushed fins. Replacing the radiator would have fixed this. I replaced the radiator along with most of what was nearby.

The objectives for the new cooling system were less weight and ample cooling performance for all foreseeable conditions. The weight was reduced by using a smaller radiator and an electric water pump that happened to weigh less than the original mechanical pump. For functionality, low speed performance was improved, likely at the cost of some high speed performance. The flow of the electric water pump is not dependent on the speed of the engine as the mechanical pump is, so the system can operate at 100% at idle. Low speed performance was also improved by ducting that forces the fans to draw air through all of the available surface area of the radiator core. This change allows a greater volume of air to be drawn through the core per unit of time without actually changing the fans.

A standalone controller, a Tecomotive TinyCWA, controls the water pump and fans. The water pump is a Pierburg CWA-200. This pump is OEM on some BMW’s and the speed is controlled by a PWM input. The controller attempts to maintain a user-defined target temperature. Mine is set for 185 F. This system works wonderfully in moderate to warm weather. Heat retention in cold weather is a problem, but one that I can live with by partially covering the air inlet late in the season.

Supporting changes include a different air intake, accessory drive, and swaybar mounts. An air intake from a C6 Corvette is now being used with a newer blade style MAF sensor in place of the much clunkier old style MAF sensor. The alternator is the only belt driven accessory now. While not totally necessary, the sway bar was replaced and moved back some. The stock sway bar mounts have a number of documented failures. The mounts that I made have no failures, documented or otherwise. Yes, I just built them. No, I do not expect for that to change.

These blocks adapt from a 1.5″ hose to a pair of 12an hose ends. They allow the water pump and radiator to interface with the AN adapters that are bolted to the engine block.

The pedal effort for the brakes was higher than I would have liked and I experienced some fade on the track. Fixing this was simple. I switched to 1″ bore master cylinders, which are one size down from what I had been using. That reduced braking effort to an acceptable level. Fade was addressed by switching to different brake pads. Hawk DTC-70′s were used in place of Hawk HP+’s. This change helped considerably however brake cooling ducts are still on the agenda.

The stock clutch that was included with my powertrain pullout did not respond well to rapid shifting, even with an aftermarket master cylinder and hydraulic line. After one or two shifts in rapid succession, the next would grind. Apparently this is a common issue, and one that can be addressed with an aftermarket clutch. I chose a Monster stage 2 clutch with a light weight flywheel. My shifting woes went away. Yay!

Track for days

I like to drive quickly. That interest manifested itself in my registering for two track days on consecutive weekends at Waterford Hills Road Racing. The weather forecast for the first one was nasty. I drove my Subaru instead instead of the Miata. The Subaru has Dunlop Direzzas, which are awesome in the rain, and I could absolutely flog the Ru without having to worry about much. Conversely, the Miata would have been a scary white-nuckle experience. That’s fun too, but not on a track that provides very little distance between you and concrete walls.

My Subaru had a serious power disadvantage. It’s a naturally aspirated, all wheel drive, station wagon from 2002. Everything is stock. That said, when the track was wet, I had no trouble hanging with the big guys, and even passed a C6 Vette. The most fun thing about the Subaru is I can push it extremely hard, giving it my all as a driver, and rarely ever get stuck behind people. Every time I see somebody in the distance, it’s a battle to see if I can gain ground. In the Miata, those same people become road blocks–people who I have to crawl behind until they move over for me to pass. Additionally, slow cars grant you plenty of time to focus on your lines and hone your technique. Oh, and the brake pads that I installed the previous night were totally gone by the end of the event. My passenger side rotor was severely gouged by the caliper.

Okay, onto the next weekend. To this event, I took the Miata. The weather stayed nice and I had an absolute blast. I was constantly stuck in traffic during the first part of the event, however as the day progressed, the slowest people in my group were moved to other groups so the average pace picked up. I still frequently got stuck in traffic, but I was at least able to put down the occasional uninterrupted lap before encountering someone new. The car performed well, was fast, and will be even faster once I install my smaller bore brake master cylinders and cooling ducts. I feel like my stopping distances will improve quite a bit once the pedal ceases to require monumental force as I couldn’t lock the brakes if I tried once the tires were making peak grip. I’m thrilled that the car performs as well as it does without much in the way of development, and the changes that I plan to make this winter should be transformational. I’m excited to see what happens next season!

Miata road trip

It all started on a Monday night, when I was hanging out with some friends after a bike ride. Somebody brought up a music festival that was taking place in Georgia that upcoming weekend. The conversation shifted from a mutual understanding of its existence, to “hey we should go to that”, and finally to “lets take the Miata”. Anyway, after talking to people and trolling Craigslist, we had tickets lined up and a loose plan. Friday came before we knew it, and after a morning job interview, I got the car packed up, met my friend, and we were on our way from Detroit to Atlanta.

Being strapped into fixed back racing seats via six-point harnesses for hours on end wasn’t particularly comfortable, but that’s not important. The same things that make this car so horribly unsuitable for road trips are the same things that make it perfect. Let me explain. Now that a few weeks have passed, my butt and back have fully recovered, however the memories of driving a race car to Georgia for a festival, and the shenanigans that took place along the way, will be with me forever.

Fun facts:
-The car averaged 27mpg on the highway. We were trying to make good time and packed the car in a manner which harmed aerodynamics. Not too shabby.
-Roll bars are practical. Mine served beautifully as a cargo rack.
-There were zero mechanical mishaps.
-A Miata with an engine and trans from an 04 GTO is much faster than an 04 GTO.
-This car can handle minor off-roading. The trail to the festival parking and camp site was severely rutted.

The aftermath:

And that there, is the appearance of a car that has been genuinely enjoyed. Would I do it again? Absolutely!

Going fast: don’t we all love it?

It’s been a good week for racing, and both vehicles have taken quite a beating. I started last Saturday by attending a rally-x in the Subaru. Myself and the guy who codrove my car left with second and first respectively in a class of 12. Not bad, and I’d have won if I hadn’t hit two cones during my parade lap. :facepalm:

I had an auto-x on the agenda for last Sunday. My original plan was to take the Miata, but the weather forecast motivated me to take the Subaru instead. This was a mistake as the course resembled a drag strip and it didn’t end up raining during the first run group. Even so, good times were had and I won in my class of one. They gave me a beer mug.

I went to a track day at Gingerman on Tuesday, and put some work into air management before that.

Radiator ducting:

Under tray and splitter:

The radiator ducting worked great–the temps stayed rock solid no matter how hard I pushed. The splitter worked too well. The car gained a tendency to oversteer and I had to shift my brake bias more towards the front. In hind sight, the brake bias adjustment may have also been required because I was cooking the front brakes.

Then……pretty early on, I went off and met some tires. A combination of my forgetting about a turn that’s obscured by a crest and the brakes being too hot to do much with such late notice resulted in an off track excursion. The car is fine, however I lost all of my aero stuff and blew out the alignment. I’m kind of bummed, but **** happens and the car handled better without the splitter. After removing the mangled aluminum and performing a trackside alignment, I was up and running again, and finished the day strong.

Anyway, this car is tremendously fun on the track and I can’t wait to take it out again. The biggest problem that I can fault the car with is brake fade, and that should be easy to fix with ducts and some more serious pads. I was running Hawk HP+’s. Here’s some video of part of one of my last sessions. Watch the brake fluid reservoirs for a rudimentary G meter.

Yesterday, I went to an auto-x in Lansing, and it was about the most fun I’ve had in this car to date. My strategy for the day was to take it easy, avoid cones, and really focus on my driving. That strategy paid off as I won my class of one(woohoo), and got the second FTD. A guy in an ASP Corvette, with massive Hoosier A6′s, was faster by a second. I’m thrilled with the results, although a set of 275 A6′s would be fun to play around with.

I’m happy with the way that the car handled, too. I had an understeer problem at the first event I went to. Installing the rear swaybar made that problem go away and the car feels quite neutral now. Throwing the car into turns is extremely satisfying.

I’d consistently smoke the inside tire under braking. Kind of aggravating as I think it’s largely unavoidable unless I install ABS.

Here’s a video of my fastest run. I ran a 49.9.