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Practical Wiring - Professional Motorsport: Step 10 - Final Installation

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Step 10 - Final Installation

06.12

00:00 - The 10th and final step of our HPA 10 step professional motorsport harness construction process is the one that we've really been waiting for, and that is doing the final installation of our completed harness into our vehicle.
00:14 We're out here in the workshop next to the engine bay of our RX7 to have a look and check on the final fit and finish of our completed harness.
00:21 But if you remember back to the beginning when we were designing the routing of our harness, there were three crucial details that we were looking for.
00:28 We needed to ensure that the harness was going to have an amount of slack between our soft mounted engine and our rigid chassis to ensure that as the engine moves, the harness isn't going to be put under any strain, we needed to ensure that the harness was going to be protected from extreme sources of heat which in a rotary engine vehicle is actually really critically important as they do output an awful lot of exhaust heat.
00:50 And we also needed to make sure that our harness was going to be protected as much as possible from the harsh vibrations that are apparent in a vehicle that's being used and driven very hard like we expect our RX7 to be.
01:03 So if we have a look at those three elements now.
01:06 The first we can see here is that we've got a bulkhead mounting plate machined up which is going to make an attachment to the original point on the bulkhead here where the OEM wiring harness came through.
01:18 Now that bulkhead mounting plate is simply going to attach onto our firewall here with three riv nuts and it will mount, give a good mounting place for our connectors there.
01:29 With those connectors in place we can see that we've got a good amount of slack apparent between our soft mounted engine and the rigid chassis here, and that's going to ensure that as our engine moves back and forth as we accelerate and decelerate the vehicle, it's not going to put this section of the harness under any strain.
01:46 Now for protecting our harness from extreme sources of heat, with the rotary engine here we are actually in a little bit of an advantageous situation as we've got the exhaust and the intake ports on the same side of the engine.
01:58 So we can use our intake manifold here to shield us from a lot of the heat from that extreme exhaust system.
02:05 Now this vehicle is getting a conversion to a single turbo system.
02:08 We've still got the twins in place at the moment.
02:11 So that is why, one of the reasons why we've used an interface connector for our exhaust connections.
02:17 So that's going to be for our wastegate position sensors, boost control, exhaust gas thermocouple sensors, and the wideband O2 as well.
02:23 That interface connector is right here and that's going to connect to the engine here via a sheet metal bracket off a bolt hole just on the top of the engine here.
02:33 Now to protect our harness from the harsh vibrations that it's likely to see, because it's fitted to a vehicle here that is going to be used in quite a harsh manner, it's going to see a lot of time at high revs on our dyno and it is going to be used for street sprint events as well, we've gone with rubber mounted p clips on the engine here just for keeping the harness organised and in place.
02:56 Now those rubber p clips are not completely tight on the harness.
02:59 We can actually still move it back and forth slightly in here, and that amount of movement really is quite important.
03:05 It's gonna keep it really well supported but it's gonna make sure that if anything needs to move, it'll move in those mounts, and it's not actually going to put our harness under a large amount of strain.
03:15 The rubber isolation on those p clips is what's going to give us that protection from vibration.
03:21 Just having a look at how the harness physically fits the top of the engine here, we can see we've got runs with nice gentle curving radii that aren't putting the harness under too much strain and it's run in a reasonably logical manner which actually parallels how the OEM harness runs on top of one of these engines as well.
03:40 We've got our fuel and our ignition interface connectors here on top of the engine which will pick up off this bolt hole location on the top of the engine here for a sheet metal bracket that'll mount these flanged connectors, giving good access to them to allow either rapid dissasembly or just ease of assembly.
03:57 Once again, the reason we've gone with interface connectors for those sub systems are that we're striking the situation that you do extremely often when you're building a car is that not all the pieces of the puzzle have arrived yet.
04:08 We had to get on with our harness build to meet our deadlines for this project, before those parts were actually in place.
04:15 But using those interface connectors is going to allow us to quickly and easily just build sub harnesses once those parts arrive, and quite often it can allow you to get a better fit and finish overall as well.
04:27 The downside is of course the extra cost as we now have an extra connector in the middle of our harness which we've had to buy that connector and the booting materials as well.
04:37 But I definitely would suggest it as an option to look at, it really can save a lot of time when building your main harness and that ease of getting a nicer fit and finish once all the pieces of the puzzle are in place are typically definitely worth it.
04:51 This brings us to the end of the HPA 10 step professional motorsport wiring harness construction process.
04:57 By this stage you should have a clear idea of how a motorsport orientated harness is going to differ from a harness that we might build for a more club or street orientated vehicle.
05:07 You should have a really good understanding of the key techniques and materials, differences and how we apply those to a harness build for those motorsport projects.
05:16 Now a really key point that I want to make clear here is that undertaking a harness build to this level is a big time investment.
05:25 You really need to give a lot of thought before you commit to the project as to whether this level fo harness is actually applicable for the project that you're working on.
05:34 As an example of time frames here, the relatively simple harness that we have built for our FD3S RX7 here would still be a time investment of at least three weeks of full time work.
05:45 Not to mention the financial cost as well, it can really stack up and quickly become one of the most expensive parts of your race car.