Year: 2017

Where to begin?? Fair warning, this is going to be lengthy. I’ll have to cut this down and simplify for some of the forums but here I’ll post all the details.

For the engine swap, the minimum wiring to get the thing fired up isn’t bad, particularly if you opt to have V8R prep the engine harness for you (I did). You could certainly retain most of the factory wiring on the chassis side and just tie in where needed.

However… I had a few things on the wish list for this car that meant there was more work to do.

Over the years of racing and modifying this car, the wiring has become a bit of a mess with things added, wiring cut to remove things, etc. etc. There’s even been a couple times in the past that I went to modify or fix something in the wiring and found it wasn’t the way the FSM says it should be – I had modified it at some distant time in the past and now I couldn’t remember how or why I did it.

To eliminate any potential for issues for the future, I decided the best approach was to remove all of the existing wiring on the chassis side from the car and start from scratch with good materials, practices, and documentation. This is also the most time consuming approach, but c’est la vie.

Step 1 through 10 of a big wiring project is all planning, long before any tools or wires come out. Drawing up plans, thinking about the systems you want to include and things you may want to incorporate in the future.

Here was my starting point, the electrical diagram for my new chassis wiring:

A diagram like this is the bare minimum to plan out a harness. But as soon as you go down this path, if there’s an issue in the future you can’t just open up a factory service manual to check the wiring diagram. None of that applies any more. The ease or difficulty of service/troubleshooting in the future now comes down entirely to the quality of the documentation you create. With that in mind, I took things a few steps further.

Working off the electrical diagram, I made a spreadsheet listing each individual wire that would be present in the harness – including the wire’s name/purpose and where each end terminates. Each wire is assigned a unique numerical ID. If you’ve ever tried to identify a certain wire in a harness you’ll know the struggle that can be – even with the multitude of wire colors that factories use you still end up with duplicates of certain colors and you end up having to break out the multimeter to test wires and sort out what’s what. By assigning each wire a unique ID and labeling the wire accordingly (more on that later) there is no guesswork left to do, just consult the master sheet and look up the wire number.

Here’s a screenshot of the top of the list. All in, there’s about 100 wires on the chassis side:

A great feature with having this in spreadsheet form means that if you stay consistent with the info you put in each cell then once the list is done you can sort the list alphabetically by whichever column you need. This was really handy during the build as I could easily switch between sorting by harness, numerical order, system, etc.

The remaining piece to the puzzle is knowing how to lay out the harness. The simplest method is to just start laying wires in the car from point A to B to get lengths, but I wanted to be able to build the harness out of the car and also have the plans so that everything is replicable in the future if necessary.

I took measurements on the car and then drew up the build plans:

Now, much of the above is a bit overkill. The key info there is the lengths between splits and the layout. The rest isn’t necessary but I like to be thorough – with this plus the connector diagrams that I show just a bit further down, I could build a matching replacement harness without any need to refer to the car or the original harness.

With the planning sorted it was time to start laying out the harness. I transferred the measurements to a 4’x8′ sheet of particle board with screws placed at each branch split for turning points. Progress shot with the chassis and tail wires being laid out:

The wires are labeled with their ID number on both ends. Here is where the thermal label printer got a workout:

All of the wires used are milspec /32 series with tin plating and very abrasion/temperature resistant insulation. This stuff is a big jump forward from standard cross-link OE wire in terms of durability and is also more conductive and lighter weight. It sounds obvious but the wire is the core of the car’s electonics and nothing else can make up for poor quality wire. IMO this isn’t the place to scrimp.

Most of the materials for this build came from ProwireUSA. Excellent source for professional/milspec wiring materials and the staff is very knowledgeable. They’re local to me but on the other side of town so I can attest to them doing a great job with order processing/shipping times as well.

With all the wires laid out the next step is looming things together. Time for some more materials! Here is all of the shrink tubing used in this build, in several various diameters.

Pictured:
Raychem RT-375; the clear stuff, for covering all the labels.
Raychem SCL; 3:1 shrink ratio, semi-rigid and adhesive lined for sealing bare crimps and also providing strain relief.
Raychem ATUM; massive 4:1 shrink ratio, adhesive lined and flexible
Deray V25; 2:1 shrink ratio, non-adhesive. This is similar to Raychem DR-25 but is a thinner (lighter) version designed specifically for motorsports.
Kapton tape (upper left); super high-heat resistant tape for wiring assembly. Serves as a barrier between the wires and the adhesive shrink tube so if you need to service the harness later you can cleanly cut the tube and tape off and you have like-new wire underneath.

Everything is tagged with its specs. You don’t want to accidentally use an adhesive lined tube where you don’t want it.

NOT pictured above is another loom material that I used in a lot of areas; resin infused braided fiberglass loom. It’s resistant to chemicals and can withstand a massive 1200° F. That’s quadruple what the good heat shrink tube can take, so this was my choice for the bulk of the chassis harness that runs along the trans tunnel and firewall. Overkill? Yep. I weighed the shrink tube vs. fiberglass loom and they are even, there’s no weight penalty for using either one over the other, except in cases of a run of just one or two wires where there is shrink tube available in smaller diameters than the smallest fiberglass loom. For wire runs of ¼” diameter and up it’s a wash.

It’s been quiet for a little while because I’ve been spending long hours building the wiring harness. I wanted to be rid of the hacked up factory wiring mess once and for all so I chose to take the long road and removed every wire from the car, because now was the right opportunity to take the extra time and learn how to build good motorsports wiring from the ground up.

For now, here’s a pic from way back on step 1 with wires laid out for the new chassis harness:

There’s still a bunch of assembly to be done before it’s driving (rear end, suspension, interior, etc.) but we’re close to first test start. All that’s left is wiring… not a small thing but I can feel it getting close!

Current view from the front:

First the hurdle. The factory oil filter setup is a cast aluminum housing that bolts to the left side of the block and extends up to hold the filter canister up near the fill cap. You can see the housing just forwards of the dipstick:

To run an oil cooler we need an inlet and outlet for the lines, but a traditional sandwich plate won’t work here because of the unique shape of the ports where the block and housing meet:

Conveniently, Keisler Automation has been working on a solution. Here is their oil reroute plate:

This plate has a pair of M16x1.5 ports to which I added the metric to -10AN adapters. It also has an ⅛ NPT port for a sensor, but I found its location to be too cramped beside the larger fittings (and the GM oil pressure sensor is M14x1.5 anyways) so after this pic was taken I plugged that port and put the sensor in the remote filter plate:

As I mentioned in the power steering post, the factory oil filter housing can’t be removed without taking the steering pump off because the factory bolts are too long. There’s no getting around this the first time, but when installing the Keisler plate I switched the two forward bolts to shorter ones – this makes it possible to remove/install the plate with the steering pump in place. I forgot to write it down but I believe I used M8x1.25x25mm:

With the in/out for the hoses sorted all that’s left is a remote filter and a cooler. For the remote filter adapter it was important to me for it to be mounted to the engine so that removing the engine requires as little disassembly as possible. I played with a few locations and came up with doubling up the filter adapter on the same bracket that holds the power steering reservoir. Here’s the filter adapter mounted up to that bracket (now powdercoated black) with the steering reservoir not yet mounted:

Here it is with the steering reservoir in place. The filter location ended up mimicking the factory location a bit. Oil changes will be a breeze:

Now for lines and the cooler. For the cooler I chose another Earl’s unit – same depth and length as the power steering unit but taller; 19 rows instead of 7.

Just as I did with the power steering system, in order to make the entire nose assembly quickly removable I chose to add dry breaks here. Staubli -10AN units for the oil lines:

Here’s the full system just before final install. I fit the dry breaks directly to the cooler so that the feed and return lines remained one line each rather than being split into two. Fire sleeves on the portion of the lines that are anywhere near the exhaust. The short line is oil plate outlet to remote filter inlet and the long lines of course go to the cooler:

Installed:

We begin with V8R’s power steering kit. Included are fittings/lines to replace the hard lines that run along the rack itself with steel braided lines as well as fittings and a high pressure braided line for pump to rack. The kit leaves it to the user to sort out the low pressures lines (usually rubber) and reservoir (I’ve heard the factory Miata unit can be used), so that blue 180° hose barb fitting is supplied for the exit from the rack.

I used everything above except the hose barb fitting because this car will use braided lines throughout.

Removed the old lines from the rack and spent a good deal of time cleaning the rack up. The power rack I got from a donor car seemed to have been competing for the coveted title of thickest layer of grime, but it’s shiny now.

Here’s the rack with the V8R lines added. Also pictured is the early version of the rack to cooler line I made which I later added the in-line dry break to:

Closeup shot. This bunch sit close to the pan once installed so best to leave them loose and adjust the angles once both the engine and rack are in place:

Pic of the power steering pump. The black threaded outlet goes to the rack which V8R supplies a fitting for (that’s what I’m holding in the photo). The port above that is the inlet from the reservoir. That port has a barbed end for a rubber hose in the stock GM form, but as seen in this pic I removed that and drilled/tapped the hole to adapt it to an AN fitting:

A note on the power steering pump pulley –
To remove the pump from the engine you must remove the pulley from the pump first. This took us a combination of parts from a rather comprehensive pulley puller kit, something most home garages may not be equipped with. Reinstallation of the pulley is equally difficult. I’d recommend leaving the pump on the engine unless you absolutely have to remove it. However, there is a complication if you’re going to add an engine oil cooler; to remove the factory oil filter housing you have to remove the steering pump first because the filter housing’s bolts are too long and can’t be backed all the way out with the pump in place. For shame, GM! Later, when I installed the Keisler oil reroute plate in place of the stock filter housing I swapped two of the factory bolts out for shorter ones and now the plate can be installed/removed with the steering pump in place. At any rate, if you need to remove the filter housing you’ll have to take the pump off at least once.

Now back to our regularly scheduled programming…
The next piece to the puzzle was the steering fluid reservoir. The reservoir needs to sit higher than the pump as it is a gravity feed. The pump’s position on the motor is high enough that there was a good bit of head scratching and lots of looking around at various reservoir options/shapes/etc. to figure out what to do. The solution I came up with uses a Moroso reservoir mounted directly to the top of the pump NASCAR style. This eliminated the need for a hose and guarantees good flow from the reservoir to pump. This reservoir is actually intended for power steering so it has the appropriate internal baffles.

I don’t have a pic of the reservoir by itself but you’ll see it in following pics. The reservoir had an AN bung in the bottom for the drain so with a couple fittings the pump was set up for the direct-mount:

To hold the reservoir in place requires a bracket. Always up for challenging myself, I decided to make it from aluminum. Here is an in-progress pic about 80% of the way done, just before tack welding the two halves I made together:

It turned out to be a funky looking little thing but it’s nice and light, piggy backs on existing factory bolts, and does just what’s needed:

Here it’s mounted up with the reservoir. Note the factory oil filter housing is still in place behind there, but that is removed later for the oil cooler:

The final piece in the power steering system is the cooler. Most cars doing any sort of performance driving will need one, you don’t want this system overheating and spraying flammable fluid around the engine bay. If you’re doing a more standard street setup with rubber lines there are lots of affordable cooler options with barbed ends built in. For this car I chose Earl’s 40700 cooler, which is a 13”x2”x2” unit, with -6AN ends. I erred on the small side to keep weight down but Earl’s stuff has efficient cores so I think it will do the trick. I’ll be monitoring fluid temp so I’ll know if it is sized well or needs to be upgraded:

Back when I was making the removable nose I made the brackets to hold the cooler in place. With the cooler, pump and reservoir all settled in all that’s left is to connect the dots with the lines. Embracing the idea of having the whole front nose section quickly removable, I picked up a pair of Radium -6AN dry break fittings for the power steering lines:

Long line below is cooler to reservoir, with the dry break junction fixed to the reservoir side. The short one is half of the rack to cooler line:

Here’s the other half of that lower line, I had already fixed it to the rack and didn’t want to remove it for the last pic. This section has a fire sleeve since it’s in the vicinity of the exhaust:

Final setup installed:

That concludes the power steering setup. Tomorrow I’ll write up the oil cooler system.

While waiting on the last fittings to arrive, this past week I’ve been working on wiring plans in the evenings.

Because race car I’m pulling the entire Miata harness on the chassis side as well and will make a new harness for just the essentials. For the record, if this was a street car with many more factory systems I would keep the factory harness and just add things as needed. But since that’s not the case, there’s some planning to be done here if I want to wire everything up in one nice clean harness.

The engine harness itself has already been set up nicely for my needs by V8R. They trimmed out anything unnecessary, converted it from auto to manual, added an OBDII port for me and extended a few wires at my request. They also fused anything that needed it and added a main relay. All that’s left for me to do on that side is carry a few voltage wires from the cabin/battery over to the engine side.

But, that doesn’t get me out of the woods. I still need to sort out a chassis harness which includes several systems like fuel, ignition, etc. as well as the Racepak dash plus the sensor module for the dash. I also need a cooling fan circuit, and I need to get the OBDII port and the drive-by-wire connector into the cabin. To make things easy to service/remove, almost everything will pass through a single bulkhead connector in the firewall.

One unknown I ran into during planning was the question of how much info the digital dash can pull directly from the ECU via the OBDII port. Anything the dash can get straight from the ECU saves me time and wires. The guys at Racepak couldn’t make any guarantees, they said you really just have to plug the dash into the car, start it up and see what data it can pull. Well that’s great except I can’t start my car yet – I need the wiring done before I can start it… but if I want to do the wiring all at once and not have to hack it up and add stuff later I need to know this answer before I do the wiring. Gotta love catch-22’s.

Sean had a great idea for a solution – rent a V6 Camaro and wire the dash up to it.

Turns out it can pull quite a bit of info. I don’t need most of it, but here’s the full list of what the dash is getting from the OBDII port – noteworthy items that I’ll probably be displaying on the dash in bold:

Fuel system status
Engine RPM
Vehicle speed
Calculated engine load value
Short term fuel % trim – Bank 1
Short term fuel % trim – Bank 2
Long term fuel % trim – Bank 1
Long term fuel % trim – Bank 2
Intake air temperature
Intake manifold absolute pressure
Timing advance
Engine coolant temperature
MAF air flow rate
Oxygen sensor Bank 1, Sensor 1
Oxygen sensor Bank 1, Sensor 2
Oxygen sensor Bank 2, Sensor 1
Oxygen sensor Bank 2, Sensor 2
Run time since engine start
Distance traveled with malfunction indicator lamp (MIL) on
Fuel pressure
Fuel rail pressure (diesel)
Fuel level input
Fuel type
Commanded evaporative purge
# of warm-ups since codes cleared
Distance traveled since codes cleared
Evap. system vapor pressure
Barometric pressure
Ambient air temperature
Control module voltage
Absolute load value
Command equivalence ratio
Throttle position
Relative throttle position
Absolute throttle position B
Absolute throttle position D
Absolute throttle position E
Command throttle actuator

In addition to the above bolded items, I’m adding temperature sensors for engine oil, transmission, differential and power steering fluid. These four will tie into a Racepak universal sensor module which transfers the data from those sensors to the dash via one cable. Between the stuff above and these four added sensors the dash should be able to keep an eye on everything important. I can set up warnings on the dash for any of these inputs, so I can focus on driving rather than worrying about checking gauges.

I’m disappointed that oil pressure isn’t on that list. The ECU monitors this, but it appears it doesn’t send that info to the OBDII port. I’ll need to wire up a second OP sensor or figure out if I can piggy-back on the factory sensor’s wires. Not sure yet on that front, but overall some good info gained and I can finish up my wiring plans now.

---

Next morning update:

I spoke with Racepak this morning. Explanation for oil pressure not coming through the OBDII plug is that the Racepak dash can only read the “standard” OBDII PIDs. There are additional “enhanced” PIDs added by GM which are not required part of the standard/required OBDII data. HPTuners and similar can read those enhanced PIDs but the dash cannot.

Worst-case scenario is having to run a second OP sensor for the dash. However, I asked about piggy-backing off the factory sensor and they said because the factory sensor is a 3-wire unit, one of those wires should be a 0-5V signal wire and there shouldn’t be any issues with splicing into that wire to connect to the dash’s OP input wire on its harness. Then, it’s a matter of configuring the dash for that sensor which requires knowing the scaling of the factory sensor – info with should be in the factory service manual. So, sounds hopeful-ish…

If the Radium dry breaks were the appetizers, the entrees just showed up . Staubli -10AN dry breaks for the oil cooler lines:

By themselves they don’t seem too large, but once you add a pair of hose ends the assembly is like 7″ long. It’s actually rather difficult to figure out where to fit these in. After some re-working of some plans I think I have it figured out. Have to order yet MORE fittings to make the new config work, but I THINK this will conclude the many, many rounds of fittings orders.

Aside from doing a bunch of re-puzzling on that front, I did get a few lines hammered out yesterday. I’ll try to do a more comprehensive post about the line layout for each system once I have them all done but here’s some random pics for now.

Power steering from rack to cooler in, including in-line dry break:

Oil line from engine to remote filter, with fire sleeve:

Continuing to wait on a few more parts to arrive, so I took some time to get some of the suspension bits assembled.

Pressed out all of the old polyurethane bushings and now installing for evaluation a spherical bearing kit for the factory control arms from a shop up in Canada.

Spherical bearings within the press-in sleeves:

I’ve run into a couple snags with some of the parts in the kit, shot some feedback to them to get those bits resolved instead of having to machine my own solutions, and hopefully we’ll get things sorted out. Nevertheless, the majority of the kit is installed and ready to rock.

Also going into the arms are Bauer extended lower ball joints and V8Roadsters rebuildable front upper ball joints:

Finally, I’m replacing the rear upper arms with V8R’s tubular Pro series arms. Feedback from Steve about what they’ve seen on other cars, the rear upper arms are the ones responsible for wheel hop and other funkiness when putting big power down as that factory arm twists with enough torque. The tubular arm solves this, and the pro series has spherical bearings to match the rest of my arms.

Oh, and in my recent powdercoating frenzy I had all the factory arms done.

Doing some napkin math for other fun places the car may fit in.

Looking at NASA, when you move above the complicated mess of the lettered classes on up to ST/TT 1, 2, 3 things get much simpler. With a good bit of power taking the tighter-regulated TT4 out of the question it gets even simpler. Basically take a dyno and weight baseline which then applies modifiers for certain mods and you end up with an adjusted power/weight ratio and that’s that. Everything in class is same adjusted ratio. Obviously this favors a wide torque curve, and this motor should be great for that.

TT2 cars have an adjusted wt/hp of 8.00:1 or more (up to 10.00:1 which is TT3)
2300 lbs with driver / 300 whp = 7.67:1
Relevant adjustments:
Comp weight over 2200, less than 2599 = -0.2
Tire size 245 or smaller (DOT approved) = +0.7 or Tire size 275 or smaller (DOT approved) = +0.3
Non-production vehicle = -0.4

A note on the non-production vehicle bit.. have to take that due to the tubular front subframe, but this comes with some benefits. First, I don’t have to take the -0.2 for cutting the rocker for exhaust routing for production vehicles, so it’s really only -0.2 more than if it was considered a production car. But more importantly, with it considered a non-production car there’s no concern about the tubular/removable front nose being OK.

So, with adjustments, 7.77:1 with 245 tires or 7.37:1 with 275’s

Ballasting up to 2375 lbs with 245 hoosiers puts me at an est. adjusted 8.01:1, right at the pointy end of TT2.

While RLTA and GTA are my primary focus… and yeah, TT2 is full of Vettes and Vipers, it could be fun to mix it up there and see how it stacks up. Always love a challenge!

Just before the holidays hit I was deep in connecting hoses and wiring for the final time. Bit of a mess while sorting through what still needs to be figured out, needs to be tweaked, etc. but here’s a quick snapshot of about where we are at the moment:

And, decided to spring for some trick fittings to go hand in hand with the quickly removable front end design, still waiting on parts to arrive but for now here’s a teaser of the dry break fittings that will be going on the power steering lines: