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586 Posts
Discussion Starter · #1 · (Edited)
Hey all.

My previous car was a Nissan S15, built for track and street duties. Served me well but I sold so I could get an RX-7. Well instead of doing that, I've invested the money and bought an MX-5 instead. Should keep me entertained for the next 6 months or so, that's when I'll hopefully get my rotary fix.

Modifications so far:
  • 1.6L Engine from the NB6 (solid lifters, cam/crank angle sensors, etc...)
  • Extensively ported head
  • 280 degree camshafts with 10.5mm lift
  • Oversized valves
  • Stronger valve springs
  • Toda adjustable cam pulleys/gears
  • HKS headers
  • Toyota AE101 ITBs
  • Garage Star/T3 ITB adapter
  • T3 Velocity Stacks
  • UNI filters
  • Outwears filter booties
  • Innovate MTX-L
  • Relocated brake prop valve
  • NB 5-Speed gearbox
  • Lightened flywheel 3.5kg
  • Cusco 1.5way LSD
  • 4.778 diff ratio
  • Every nut and bolt re-zinc plated
  • Painted block
  • MegaSquirt DIYPNP ECU
  • Bluetooth ECU Connection
  • Custom ECU mounting
  • Toyota COPs
  • CNC cut COPs bracket
  • OBX dual feed fuel rail
  • Aeromotive FPR
  • Short shifter
  • Custom wiring harness, body and engine
  • FD3S RX-7 fuse folder
  • Dedicated engine fuse/relay panel
  • Flex-a-lite 16" thermofan
  • 42 Draft Designs Catch Can
  • GarageStar radiator cooling panel
  • 52mm aluminium radiator
  • MX-5 Plus custom exhaust
  • Yellowspeed Racing coilovers
  • Broadway Mirror
  • Frame Rail Braces
  • Low-Profile Headlights
  • Garage Vary front lip
  • Project-G Bikini Top
  • Carbon fibre side mirrors
  • Side Skirt Diffusers -
  • R-Package rear lip
  • MX-5 Plus offset number plate bracket
  • Genuine hard top
  • Hard top brackets
  • KG-Works cluster
  • Vented front window
  • Momo Team 280mm steering wheel
  • Sparco Sprint V fixed back seat
  • MX-5 Plus Tall Boy roll bar
  • Whiteline sway bars
  • Genuine strut tower brace
  • Hankook RS-3 225/45/15 tyres
  • OG-San 15x8 +25mm with 5mm spacers to make it +20mm

My blog -

How she currently sits (page 9):


· Registered
586 Posts
Discussion Starter · #2 ·
Re: mrpham's summer build

Had all four guards rolled yesterday, so the inner lip is now flat. Work was done by FineFitment and I can definitely recommend them to anyone that needs some extra clearance for wheels.

Car jacked up ready for some guard work =)

Also took a quick photo of the MX-5 Plus exhaust, love the lobster tail TIG welding!

Guard roller mounted up ready for action.

Before and after shots of guard inner lip.

MY BRAND NEW WHEELS!!!!! Axis OG-San 15x8 +25
I ordered Axis OG-San wheels from JDMYard, they were by far the cheapest I could find. Email response was fast and shipped out the next day. Definitely recommend them =) . The Axis OG-San wheels are replicas of the SSR Formula Mesh, which are the replicas of some BBS wheels. I ordered them in 15x8 +25 gold finish.

For tyres, I've again chosen to go for maximum rubber instead (like my S15) of the stretched look. But I also wanted to avoid getting semi-slicks or R-Compound tyres for a car that I will most likely drive on a daily basis. So I decided on the Hankook R-S3 in 225/45 R15. These were hard to source in Australia and they sell for $335AUD, compared to $110AUD from TireRack in the US. After shipping and other fees, the tyres cost me just under $200AUD each landed at my door. Total saving of $540!!


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586 Posts
Discussion Starter · #5 ·
Re: mrpham's summer build


how can you get on the track without helmets? doesnt seem safe. car looks good, keep up the work
Thanks mate. The photo was taken during some "happy lap" sessions, not a timed sprint, so helmets weren't neccessary and passengers were allowed.

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586 Posts
Discussion Starter · #7 ·
Re: mrpham's summer build

Thought I'd take a few photos of the interior to show off. I spent half the day cleaning it up with a friend and it turned out pretty good. Kudos to the original owner for maintaining the interior so well.

In other news, did some more work on the car =)

I'm a bit OCD when it comes to wiring, I like everything to be neat and tidy. That means all wires bundled together, all connections soldered and heatshrinked. So every time I get a new car, I go through all the wiring to make sure everything was done right. Unfortunately, this is never the case...

While cleaning up the engine bay wiring, I found something really strange. Check out the photos below:

Had to do some intense detective work to figure this out. Turns out it's a 1.5kOhm resitor that is in series with the coolant temp sensor for the ECU. This temp sensor's function is tell the ECU when to use the cold map (rich fuel mixture), this resistor in series tricks the ECU into thinking that the engine is actually cold.

In parralel with the resitor is a thermoswitch which closes when temperature rises to a specific point (not sure what temp though), this then shorts out the resistor and everything is back to normal so the ECU now thinks that the engine is warm.

I believe whoever did this wanted the engine to run on the cold map for longer because of Mazda's stupid coolant routing desing. This design flaw causes the rear of the engine to be hotter then the front. Meaning that the coolant temp sensor at the rear of the engine is reading warm when the engine is actually still a bit cold.

Although the mod works, there is no reason to have it. After removing all that junk, the car runs normal and no longer runs rich. So confused why they did this.... so silly!

The thermoswitch used -

Also spent the weekend replacing all the hoses and flushing out the coolant. Pretty happy to brand new hoses in the engine bay =)

Intake and hoses removed.

All back together and happy again =)

Look what arrived today! Quickly fitted them up too, need more adjustments tomorrow.


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586 Posts
Discussion Starter · #9 ·
Re: mrpham's summer build

So a small update, some good news and some bad....

Bad news first.
Turns out that the valve stem seals are starting to leak, after doing a Mt. Nebo run it lost around 800ml of oil.... When engine braking/overunning, it causes a lot of vacuum and this sucks oil past the leaky valve stem seals and into the cylinders. As soon as a I step on it again, big puff of blue smoke escapes as the combusttion burns up the oil. As you can imagine, this happens a lot during a mountain cruise =)

Have added up all the costs for gaskets/seals and it is very doable, I will be removing and installing the head myself but all head work will be left to the machine shop. Quickly did a compression test yesterday and everything is well, helps rule out piston rings.

Now the good part...

Recently decided to order some wheel spacers, 5mm to be exact. Nothing crazy but they came up for cheap so I took the opportunity. They are made specifically for the MX-5 and are hub-centric too, sit perfectly flush against the hub with no play at all.

Just some photos of the spacer and how the car now sits.

Visited MX-5 Plus today, like nearly every weekend, and picked up some offset number plate brackets. The standard number plate bracket is flimsy and often bashes against the front bumper, leaving behind scars/scratches. The MX-5 Plus bracket is thick as well as placing the number plate to the side, definitely over-engineered.

Richard unpacking the freshly laser-cut bracketsm, mmmmm tasty.

The bracket is all it's glory, plus hardware.

Original bracket removed, and the MX-5 Plus bracket installed. Mounts to the left tow-hook.

All done and looking good =)​

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586 Posts
Discussion Starter · #11 ·
Re: mrpham's summer build

Awesome build thread, I am thikning on going for those rs3's instead of kumho xs's. 225 instead of 205 being the main reason.
I had 245 front and 265 rear Kumhos on my S15, they performed very well but poor in the wet.

· Registered
586 Posts
Discussion Starter · #12 ·
Re: mrpham's summer build

So a pretty big update =)

After doing a cruise through Mt. Nebo, I had lost about 800mL of oil. There were no leaks so the oil simply burnt up in combustion. This is usually caused by old piston rings or valve stem seals.

A quick compression test showed all cylinders produced identical compression readings, this rules out piston rings as the cause. When valve stem seals leak, blue smoke is usually seen when you start the car up first thing in the morning. Oil slowly leaks past the seals into the cylinders overnight, then burns up as you start the car up. My MX-5 did something different though... Under engine braking/over-run, the crank case vacuum sucks oil past the seals. Then as soon as you step on the throttle again, huge amounts of blue smoke escapes from your exhaust.

Was thinking about blowing up my engine and putting a new one in, but did my research and found that it's fairly cheap to fix.
So here it goes =)

Firstly, I drained all the coolant and removed the top water hose as well as the intake piping. May as well remove the filter and air flow meter so you have more access to the exhaust manifold bolts. Everything was set to TDC, no need to though since the head is coming off.

Valve cover removed and showing the nice clean insides.

Cam pulleys removed and exhaust manifold un-bolted.

Camshafts and cam caps removed.

BOOOYAHHH! The head is off =)

I decided to keep the intake manifold on the head to make removal easier. But will be removed before I send it to the engine machine shop.


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586 Posts
Discussion Starter · #16 ·
Re: mrpham's summer build

Engine Out -

After receiving my cylinder head back from Chilton Engineering, they informed me that my head was no good. The head tested too soft, which meant it overheated some time in the past, valve springs were damaged, valve seats were damaged. Pretty much scrap metal... To purchase a second hand head would cost around $500-$600, whereas buying an entire engine would cost $800 and also means I'll be replacing this "short nose crank" engine with a later model "big nose crank" engine. I obviously decided to go with a replacement engine =)

I was initially planning to remove just the engine and leave the gearbox in but this proved to be more difficult, so both engine and gearbox will be removed as a unit. The following had to be disconnected from the gearbox:

  • neutral switch wiring
  • reverse light switch wiring
  • speedo drive cable
  • clutch line
  • Power Plant Frame
  • shifter

While under the car, I also drained the transmission fluid so that it doesn't leak too much as we tilt the gearbox out of the engine bay.

Some photos now:

Bonnet removed to make it easier to work one.

Radiator and fans removed.

Exhaust headers removed.

Shifter removed revealing ripped shifter boot.

The damaged head... =(​

· Registered
586 Posts
Discussion Starter · #17 ·
Re: mrpham's summer build

She's Heartless -

Had some time today so went ahead with removing the engine out, I like to call it a heart transplant. Was a pretty straight forward process and easy enough to do by my self. Tried to take as many photos as I could remember, enjoy =)

Before I could start, had to remove the front lip because it couldn't clear the engine crane. Stupid ride height...

Chained up and slowly lift and tilt it out.

And it's out!!!!!

Once the engine was safely outside of the engine bay, I split the gearbox away from the engine. Once that ws done, I saw that the clutch was getting old so decided to replace it while everything was out.

Picked up a Exedy Heavy Duty clutch kit from NPC. Price was awesome and came with the clutch, pressure plate and throwout bearing.

That's it for now, should be picking up the replacement engine tomorrow. Then more fun =)

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586 Posts
Discussion Starter · #18 ·
Re: mrpham's summer build

So instead of buying a replacement NA6 engine, I bought a NB6 engine. Still 1.6L but was taken from a JDM 2002 NB Roadster. Has solid lifters instead of hydraulic lash adjusters and makes about 10HP more, uses my original wiring etc... More details later.


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586 Posts
Discussion Starter · #19 ·
Re: mrpham's summer build

My New Engine... NB6 -

Bought my replacement engine on Saturday from MX-5 Plus, but instead of picking up a regular 1.6L B6 engine from a NA6 I purchased a 1.6L long engine from the NB6. In Japan, the NB series Roadster (MX-5) had the 1.6L engine up until 2005. The cast iron block is identical, but the head and intake are different. The hydraulic lash adjusters are replaced with solid lifters and cams have more lift. The CAS is no longer used and replaced with a cam position sensor and crank angle sensor. The NB6 also uses the crank-shaft nose/pulley/cog, water pump and oil pump from the 1.8L BP engine.

To run the NB6 engine in a NA6, there are two options. First option is to swap the entire NB6 wiring and ECU into the NA6, the other option is to use the following NA6 items on your NB6 head/block.

  • intake
  • exhaust
  • CAS
  • rear water outlet
  • front water outlet
  • alternator (using the NB6 pulley)
  • air con (if you have it)
  • power steering (if you have it)

In addition to this, you will need a modified intake cam-shaft. The NB6 intake cam-shaft doesn't have a slot for the CAS, so the NA6 cam-shaft end is cut off and pressed into the NB6 cam-shaft. Pretty straight forward and costs $100 to do.

Now all that info is out of the way, here are some photos of my progress so far.

Showing the revised crank nose, difference between the short nose crank-shaft bolt (right) and the revised crank bolt.

Removing the old front seal, new front seal in. May as well replace all the seals and gaskets while the engine is out.

Removing the sump was a bitch because the baffle is bolted under the oil pickup, and this results in the sump being "stuck" until you seperate the baffle from the sump.

Brand spanking new water pump =)

Pulley boss attached, and most of the external parts attached.

Engine finally off the stand =)

New rear main seal in and flywheel on (nearly anyways).​

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586 Posts
Discussion Starter · #20 ·
Re: mrpham's summer build

New Radiator -

After finding out my radiator was leaking, I ordered a eBay special China radiator. Bought one for my S15 and it was pretty decent, especially for under $200. I ordered the 52mm dual core aluminium design for a low low cost of $175 delivered to my door from Melbourne.

Test fitting it, a bit of squeeze because its 52mm thick. But so worth it =)​

Also I took my valve cover and water outlets to get blasted at Chilton Engineering, they turned out looking brand new! Much better then paying over $300 for brand new items through Mazda.

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