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Lucas' 1991 Mazda Eunos Roadster


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After accidentally hijacking Gavs/~Slideways~ build thread, thought I should make one of my own. Here is my 1991 hunk-o-junk.

I purchased the car in Whangarei, was driven up to collect it and took it back to Auckland. Did not check for rust as well as I should have, however ended up getting a gem. The car was always meant to be a daily, but we kind of know how that goes. It lasted about 6 months of minor changes here-and-there.


The big issue right from the get go was the plasti-dipped exterior and weird racing strip. It obviously meant the paint would be rough underneath and plasti-dip is a real pain to remove. I've been trying everything possible to remove it, and in the end a good solvent and some elbow grease ended up being the play.

Additionally, the car had no power steering and the A/C was NFG, which is an expensive fix due to being r12 not r134a and not technically legal anymore.

I did all the fun road-trip things you are supposed to do in a newer car.



Engine was running well, gearbox was smooth, clutch was fine (for now). Ended up changing the clutch about 3 months in after being "that guy" merging into a motorway at 60km/h trying to baby the clutch.

Around this time I noticed the diff was playing up, and it wasn't. Turned out I have the mazdaspeed 6" clutch-type LSD (as well as mazdaspeed adjustable dampening shocks and mazdaspeed upgraded swaybars). Turns out the car was a good buy after all!


Also had a run-in with some shitheads thieves. Fortunately they didnt break anything, just my faith in humanity but it was a good lesson to not leave my car parked outside!

Anyway, the positives and negatives:
+It ran and drove
+Mildly upgraded (kinda old) suspension parts
+Clutch-type LSD
+Plenty of boot space
+Mint soft-top with glass window
+Decent interior
-Sounds bad
-Looks bad

Now that we know whats wrong with it, why don't I go ahead and modify literally everything that doesn't help those three points? Good idea...

(Keep in mind I am a student, most of the "Why did you not just pay someone to do it" questions I usually receive can be answered by lack of funds).

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I stumbled across the B6/ZM-DE (2012 below) build thread and decided to do some research into the possibilities of head swaps for the 1.6L B6 that came in the car. These were the only mentions I could find now, but I am sure back when I was first investigating the possibilities of the swap there were more.

Links, oldest to newest:
2004 (mazda3club.com)
2008 (mazdas247.com)
2008 (trinituner.com)
2011 (forum.miata.net)
2012 (miataturbo.net)

Why was this idea so special? Because I could not find anyone who had done it. Also other reasons, which will be revealed later.

I chose to get the ZL-VE head, as it seems it will still work but has the benefit of VVT. Also, rough napkin calculations suggested a minor bump in compression.

Purchasing and Cleaning:

So now that it was an idea I could not get out of my head, the next step was actually attaining one of these heads. PaP it is! Got an absolute steal (unlike my usual trips), I believe I paid $120 for head w/valve cover, intake manifold, injectors, alternator, lower timing pulley and timing covers.


Then the most important step: cleaning...


In the next post I will discuss the "benefits" of this head/swap.

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So now that we have the head and it is somewhat clean (actually maybe I did not clean it until later, but still) we need to look at what this head is and why it is being used.

The elephant in the room is that the ZL-VE head came FWD only, in a Familia. Specifically around 2001-2003 is what I could find, but there are also the 2.0L Familia's, the 1.6L ZM-DE and the 1.5L ZL-DE.

The ZM-DE (Z6) head had been done in the thread linked above (2012). The benefits of the head were larger but steeper port angles, shallower combustion chamber and a few others. I assumed the ZL-VE would have the same steeper port angles and large ports which it did. The lower displacement of the ZL-VE motor was entirely in stroke, but similar compression ratio meant there must be either a difference in pistons or lower combustion chamber volume (both are true).


Here is the ZL-VE intake gasket on the stock B6 head.


There was no longitudinally oriented engine with the same intake/exhaust ports. This meant custom intake, custom exhaust and likely more. I hunted around for a little while for some ITB's from a 4age, as in my mind an ITB adapter would be easier than an intake plenum for a singular throttle body. I chopped up a 4age intake manifold with a hacksaw (never again...) and chopped up the stock ZL-VE intake manifold with a mixture of angle grinder and hacksaw.


We are on our way to an intake manifold. I used JB-weld to attach them together for testing, and skipping forward a few months ended up tig welding them together. I have a HF DC-TIG welder but no AC-TIG, so aluminium welding cannot happen at home. If you spot JB-weld, it was temporary. If you spot shit welding, thats because I'm a shit welder.


Intake manifold complete (ish).

Edited by Themi
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I'll now talk about the exhaust side and show everyone why you should never let me work on your car.


The exhaust ports are not spaced evenly, and does not share pattern with any RWD car so I opted to weld some headers from stainless, more as a learning point than anything. I had some 10mm stainless plate waterjet cut by a friend to match the ports. The 1.25" stainless tube was cheap as chips, and i kid you not the argon + tube + cutoff saw + swearing was cheaper than buying bends to use. Also, it was my first time welding so figured I may as well get some practice in (it is awful, yes, but it was fun). This was the first time the head went into the car, as it is tough to make an exhaust manifold without knowing clearances (turns out there is a lot of space).



I plan on replacing these with some high-rise headers later likely from a B6, 4age, 3sge etc., something I can find from a site like cxracing and chop up without worrying too much about wasting a lot of money.


Next I needed a solution for ignition that was not the factory mazda system, as that uses a coil pack on the back of the block and isn't very good. Opting for the typical Toyota COP's (cheap replicas in the pictures) but then finding out they don't fit in the spark plug wells... I had to get creative.



So that is kind of the hardware for headers and spark done. Horrible, yes, but functional.

Edited by Themi
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36 minutes ago, tigerstyle said:

So what you're saying is there could be piston to head contact? 

Only if your head gasket is too thin. The engine turns over fine with no head gasket at all but once it's running expansion and momentum makes them touch a bit. It'll still run but not well haha. Oops.

The minimum recommended piston to head clearance is 1mm, so a HG that has 1mm or more thickness once compressed is suitable.

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  • 5 months later...
  • 2 weeks later...
  • 5 months later...

A few small updates:

- tidied the heater core hoses using a hacked up VS commodore heater hose (nice 90 and 150° bends)

- shortened the fuel hoses

- plugs, coolant, oil, oil filter... Old oil smelled of petrol and looked dirtier than diesel oil, thinner than water! A lot of unburnt petrol in the oil from test runs, oops

- sanded and primed a small amount of surface rust

- replaced valve cover with one which had baffles (never replaced baffles on old cover)

- tidied up a bit of wiring. Still needs to be wrapped/sleeved/heat shrink.

I'm back at uni full time, and have very busy weekends so progress is slow. Still starts, runs, drives. Tidying up the tune today made it run a fair bit better!20220731_195753.thumb.jpg.8aa4403c6e00427841ca43fe037e63bb.jpg20220731_195829.thumb.jpg.d02ca62076a98667c12e475baad9d995.jpg


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