RX-5 Honda K20A2 Supplement
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The Information and descriptions described herein are the property of MK Sportscars. Such descriptions and information may not be copied or reproduced (duplicated) by any means (in any form) or disseminated or distributed without the express prior written permission (consent) of MK Sportscars. The information contained in this document is subject to change without notice. MK Sportscars assumes no responsibility for any errors that may appear in this document.
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Table of Contents
- Introduction
- IVA
- Safety First
- Forword
- Remove Power Steering Pump & Standard Alternator
- Fitting the Sump Baffle Plate
- Fitting the Gearbox Adapter Plate & Flywheel
- Preparing the Engine Mounts
- Brake Line (Front Brake Light Switch)
- Fuel Line (Front to Back)
- Wiring Harness
- Battery Mounting
- Fitting the Fuel Pump and Fuel Filter
- Fitting the Starter Motor
- Water Pump Delete
- Coolant Plumbing
- Wiring Loom Connection
- Side Panel Exhaust Outlet
1. Introduction
MK Sportscars has produced thousands of cars since the company launched the MK Indy in 2000. We are constantly striving to improve our cars and options list available to further enhance the affordability and desire of the car our main goal driver behind the RX-5 project. The enjoyment of the car should be in its actual construction, This Build manual has been produced to assist with this part of the project. The purpose of building a MK RX-5 140 is to realise a car that will suit the purpose for which it is intended. If this is a Road car or Track-based car, we have many thousands of satisfied owners in all categories both here and overseas who have had the enjoyment of building a MK. MK Sportscars will continue to offer the support to help deliver to you the means and advice of building a car, simply and quickly, with minimum complication and a maximum amount of fun. This manual is for the guidance of building the MK Indy and should also be used alongside the current IVA manual if you are looking at building a road registered car. If at any stage of the build you are unsure, please contact MK Sportscars for guidance or seek professional mechanical knowledge from a reputable and qualified company or individual. MK Sportscars hope you enjoy the experience.
1.1 Manual Conventions
Throughout this manual there are important details which must be followed. These are highlighted with the following icons.
2. IVA
For amateur build IVA compliance, you will need to have photographic evidence throughout the whole build process. Please ensure you take sufficient photographs of each step in the build. These will need to be submitted with your IVA application form. Each section where you need to take photographs will be marked in the manual – but you can never have too many pictures of your build, it’s great to look back on in years to come.
3. Safety First
ALWAYS WEAR:
- GOGGLES OR PROTECTIVE GLASSES AND SUITABLE FOOTWEAR IF YOU ARE USING WELDING OR GRINDING EQUIPMENT, THERE MAY BE OCCASIONS FOR THIS IF YOU ARE OUTSIDE OUT BUILD PARAMETERS,
- PROTECTIVE GLOVES WHEN HANDLING FIBREGLASS OR CARBON.
- DUST MASK AND EAR PROTECTION WHEN WORKING WITH FIBREGLASS OR CARBON.
IT IS ESSENTIAL THAT THE SUPPORTS YOU USE UNDER THE CHASSIS DURING THE BUILD PROCESS ARE SUITABLE AND SAFE FOR USE. DO NOT CONNECT THE BATTERY +VE LEAD UNTIL THE WIRING LOOM HAS BEEN FULLY INSTALLED AND ALL EARTH CABLES HAVE BEEN CONNECTED. THE BATTERY MUST NOT BE CONNECTED UNTIL ALL TESTS HAVE BEEN COMPLETED. DO NOT FILL THE FUEL TANK UNTIL THE CAR IS COMPLETE. PLEASE TAKE CARE WITH BRAKE FLUID AND BRAKE FLUID SPILLAGE AND ALWAYS FOLLOW THE MANUFACTURES GUIDELINES. IT IS ADVISABLE TO HAVE A SUITABLE FIRE EXTINGUISHER AT HAND. ENJOY YOUR BUILD AND BE SAFE AND MOST IMPORTANTLY HAVE FUN
4. Forword
There are several differences between a standard MX-5 based build and the Honda K20A2, noticeably the exhaust manifold exits the vehicle on the opposite side to the standard Mazda MX-5. This means the wiring route will need to change around the manifold area to avoid being exposed to the heat.
The engine and gearbox are slightly wider than the standard MX-5 engine, therefore the fuel pipes will need to be run with slightly more caution and precision.
The inlet for the engine fuel and return are in different places to the MX-5 engine, so again this will need to change.
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All these issues need to be addressed when building the car, so it’s important to read this manual first before trying to build the vehicle using the standard build manuals |
5. Remove Power Steering Pump & Standard Alternator
Remove the power steering pump and the alternator. These are large parts that are not required, and allow the engine package to fit in the car.
** Insert additional details on how to remove them **
6. Fitting the Sump Baffle Plate
• Make sure the oil has been completely drained. It will be required to remove the oil pan to install this product.
• Remove the bolts that secure the oil pan to the engine block
• Once the oil pan has been removed, safely set it aside taking caution not to spill or drip oil on to your floor.
• You can use this time to wipe away any excess oil.
• Remove the bolts securing the factory windage tray to the block.
• Leave the factory windage tray in place.
• Using the provided hardware, locate the (6) studs. Notice that each are threaded at both ends. Next, locate the provided tube of Loctite.
• Apply Loctite to each stud on the end with the short threads.
• Carefully insert each stud in to the bolt holes.
• Locate the aluminium spacers and push nut retainers (washers) in the provided hardware kit.
• Slide one spacer on to the stud, followed by a push nut retainer. If you are working from underneath the vehicle, the push nut retainer will prevent the washer from falling off the stud. Repeat for each remaining stud location.
• At this point, please make sure all studs, washers and retainers have been properly installed.
• Locate the oil baffle and install over studs, washers and retainers. Carefully slide the large opening over the oil pick up. There is no need to disassemble the actual baffle. It is secured by rivets.
• Locate the nuts in the provided hardware kit and use to secure the baffle on to the windage tray. Tighten nuts.
• Locate oil pan and clean the mating surface of old gasket material on the pan and block.
• Apply Hondabond or equivalent gasket sealant to oil pan and reinstall using factory bolts.
• At this point make sure there are no remaining hardware.
• Refill engine with recommended amount of high quality engine oil
7. Fitting the Gearbox Adapter Plate & Flywheel
Remove the gearbox locator lug at the top left hand side of the engine block using a grinder.
The adapter plate and flywheel can be bolted to the engine at this time. Bag 1 includes all bolts to attach the adapter plate to the engine, and Bag 2 contains the bolts to attach the transmission to the adapter plate. The four 30mm bolts in Bag 1 enter the engine block from the transmission side of the adapter plate.
The remaining bolts secure the adapter plate through the engine side. One goes through the starter. Our K20A2 to MX-5 flywheel is designed to work with any 1.8L clutch kit. We prefer the heavy duty clutch that we can supply, but any 1.8L style clutch can be used. It installs on our flywheel just like it would on a stock MX-5.
In order for the Mazda transmission to work with the adapter plate, it has to be modified slightly. The transmission bellhousing needs to be notched since the K20A2 starter is used. The Mazda starter is on the driver’s side of the vehicle, while the K20A2 starter is on the passenger side. The K starter needs to protrude 0.75” into the trans bellhousing. The simplest way to do this is to mock up the adapter plate on the transmission and use a permanent marker to trace where the cut out needs to be.
We used to do this modification with a reciprocating saw, but now we prefer to use an angle grinder for a cleaner cut. Here’s a shot of the final profile.
Once the bellhousing is trimmed, carefully line up the transmission and slide it into place against the adapter plate. Don’t force it or you will damage your pilot bearing. Install the supplied M12 and M10 bolts from Bag 2 to secure the transmission to the adapter.
The adapter plates also come with two custom machined dowels for the transmission side of the adapter. They are installed as shown:
Take care when pressing the engine and transmission together to ensure perfect alignment so the dowels are not damaged.
8 Preparing the Engine Mounts
Note that the top two bolts have a 9mm spacer to spacer the engine mount away from the block on the O/S engine mount.
Note the M8 bolts at the bottom and M10 at the top. N/S engine mount.
9 Brake Lines (Front Brake Light Switch)
While the standard position of the brake light switch should fit (just about), we advise changing the position of the brake light switch to in the middle on the front end of the left to right. Secure the 4 way brake tee to the chassis with an M6 riv nut.
10 Fuel Lines (Front to Back)
The Honda K20A2 engine is quite large and the feed to the engine is on a different side to the standard MX-5 engine. When fitting the fuel lines front to back in the K20A2 installation, they will need to follow the following paths:
Note the fuel lines run down the UK passenger side
11 Wiring Harness
11.1 Engine Bay Routing
Due to the exhaust manifold exiting the bodywork on the UK drivers’ side, the routing of the front section of wiring loom needs changing. In the standard Mazda installation, the front wiring loom is run down the UK drivers’ side, in the K20A2 installation, the wiring will need to be routed down the UK passenger side of the vehicle away from the exhaust manifold and the heat.
This follows the same path, just a mirror what is in the standard RX-5 build manual onto the UK passenger side.
The indicator wires for the appropriate indicator (left and right) is located at pin #5 in the 6 way Econoseal plug. The manual references pin #6. (see section
11.2 Front to Rear Routing
In the same vein, the front to rear wire routing is designed to travel down the UK driver’s side. In Figure 5 you can about make out the wire routing.
Note : It’s a good idea to make sure the wire is protected in split conduit for the IVA.
Note : you may need to extend the wires for the brake pot sensors into the wiring loom for IVA compliance.
12 Battery Mounting
The battery is mounted on the rear the passenger footwell. It’s not possible to mount the battery on the bulk head panel due to the lack of space and the fact that the air filter is going to take up this space.
13 Fitting the Fuel Pump and Fuel Filter
We use an in tank fuel pump, filter and an alignment bracket to position the pump in the correct location in the tank.
The tank is our standard fuel tank using the appropriate top plate for the pump and sender (if required).
14 Fitting the Starter Motor
15 Water Pump Delete
16 Coolant Plumbing
From the water pump delete plate, there is a section of 90° 32mm silicone hose which is connected into the electric water pump output.
The feed in to the water pump is fed from the bottom of the radiator 32mm outlet from a silicone hose into a Y piece into another short piece of silicone hose.
The Y piece is an aluminium filler which is fed from the coolant expansion tank.
17 Wiring Loom Connections
17.1 Alternator
Wire the 4 way plug for the starter and alternator circuit as following with 16 gauge wire. This is either plug CH003 or CH009 which are the same just located on different sides of the engine bay depending on where your starter motor and alternator is.
The alternator has 2 connections (Ignition and L-Terminal)
Connect the alternator plug into the following connections:
| Alternator Plug | Purpose | CH009 (Male) Pin # |
| "L-Terminal" | Alternator Warning Light | 2 |
| "Ignition - Optional" | Ignition | 3 |
18 Side Panel Exhaust Outlet
Please note: these dimensions are from the RX-5 K20A2 installation and may be different with the Indy R and Indy Classic Chassis
