Month: May 2025

Turbo Lines, Oil Coolers & Timing

I finally dummy-fit the turbo up and tried to fit up per the HKS ZC31S turbo kit manual but I really wasn’t happy with the setup, particularly with the length of the feed line.

The feed line is “AN4″ or 7/16” JIC and the return line is “AN10″ or 7/8″ JIC. If you’re a hydraulically inclined like me these sizes suits 1/4″ and 5/8” tube OD/hose ID respectively.

Personally, I hate how “AN” centric car plumbing is. You pay an insane premium for the anodized pretty parts. The hose fittings are nice and the way all the off the shelf hose options align to AN size is convenient given all the big automotive retailers sell both the fittings and hoses to suit a range of applications. Still, as a mechanical engineer/hydraulic engineer (depending on the day) it still irks me in a weird way. I can’t complain too much though – at work, our fitter and I both like using thread sizing as opposed to tube od/hose id dash sizing. Tomato tomato?

Side note, I love the Taipan Thread Identification Chart. It’s a great point of reference and I use it almost daily at work.

Below is my mud map of how I plan to run the oil lines. The water lines will make use of the lines that formerly served the OEM oil cooler (a very simple, leak-prone, heat exchanger). Excuse the horrible paint work, this was only really used for ordering bits – which have arrived!

The OEM oil cooler as mentioned above isn’t the greatest, the HKS manual calls for it to be rotated but removing it makes much more sense given I’m running a decent size oil cooler anyway. It’s worth noting with the oil cooler I hardly saw temps above 85C, even on 30C+ ambient track days. Unfortunately, removing the factory cooler reveals no “stud”, luckily, I found an option online that should do the trick nicely.

Apart from that I was fairly unwell during the tail end of this week. Today I did bolt up all the timing gear, new sprocket, guides and tensioner. I reused the chain as it looked to be in good condition and the manual states it is OK to reuse.

Once I make the new oil lines, it should all start coming together!

Cometic Head Gasket & ARP Studs

This weekend I removed my head, installed the almost new head, ARP studs and a cometic head gasket.

After removing the head I was generally very happy with the condition of the cylinders, hatching still looks good and for 121,xxx kms, I would say the carbon buildup is pretty good.

Before removing the head, I aligned the timing marks per the manual, for reference, here is what the alignment looks like.

I have new timing components on the way; I will leave the water pump undisturbed as it still turns freely. Will I change my mind in the next week? Probably!

The original head gasket was also in OK shape, not that I expected anything different. Here is a photo of the cometic gasket (1mm) and OEM gasket (?mm) side by side.

The cometic gasket bore diameter is a bit over 2mm bigger than the OEM gasket. As mentioned in a previous post – nobody thinks this is an issue. For shits and giggles, I drew up the difference to see it better visually – agreed – no issues.
– 78.5mm ID is the OEM gasket bore
– 81.2mm is the Cometic gasket bore
both as measured

Installing the head gasket and ARP studs was easy enough, I always hate doing up head studs but thankfully I had experience x4 from the Galant. Interestingly, the ZC32S final torque spec per ARP is 75 ft-lb (102 Nm), the Galant was only 60 ft-lb!

ECU Wiring

As promised, this post will document ECU wiring. I will be wiring in a Link G4X MonsoonX in a “piggyback” style. Below is a wiring table on what I plan to do.

I have seperated the loom and marked the cam and crank sensor. There will be some figuring out to do on the cam and potentially crank signals as I know they differ from the ZC32S (which Haltech has documentation on).

Unfortunately, there is very little information on aftermarket ECUs in these cars and a lot of people report odd issues with cheaper options like AEM and GReddy E-manage (E-Mangle).

I’ll also need to decide what I do about the variable intake runners either:
a) try to remove it
b) replace with ZC31S intake (may require further head drilling, new intake piping)
c) use the Link to control it (looks doable)

If you made it this far, below are images of the ZC32S ECU wiring for your reference. I found these extremely hard to find, hopefully this helps others. I cross checked a lot of the wire colours and it all aligns, will need to check with a multimeter to be sure.

To view in full resolution, right click and open image in new tab.