ZR/ZS 1.8 K Turbo conversion guide

Essential k-series 1.8 Turbo conversion guide by Luke Chapman

4y ago
27.7K

Luke has kindly let me post his guide from the MG K Series Turbo Owners group on facebook www.facebook.com/groups/499316600163267/

1.4 to 1.8T K series conversion (for both ZR and ZS)
I apologise for no pics, I forgot to take them as I was going along, and I aint doing it all over again for this! It’s a boring essay walkthrough of an engine conversion.
Also, I’m a bit of a cowboy, if you can see a safer method in doing whatever, I suggest you do it, I will not be held responsible for any injuries from copying me!
And please bare in mind I’m sat at my dining room table typing this up, around a year after doing this conversion myself.. This is being done fully from memory. Even the last engine removal I did was around 3 months ago. Also A/C is a pain in the ass and will add a good paragraph every time I mention it so this is for a non A/C conversion. Just remember to get it drained by a “competent person” in the “legal method” before disconnecting. You can be fined lots of money if you get caught venting it to atmosphere. The green people on this world love their O zone.
Oh, and the order isn’t particularly good.. You may want to read the whole guide before cracking on with your own conversion, and possibly re-jig it to suit you.

Everyone is under some sort of illusion that the 1.4>1.8T K series engine swap is a straight swap, because they are both K series engines. This is not the case, there are lots of little surprises that will jump out along the way, such as the different fuel rails, drivers side engine mount and flywheel to name a few.
While all these can be sorted fairly easily by using the old engine as a donor, there are a few things that can’t.
Before doing the conversion you should have;
• 1.8T k series engine
• K series turbo exhaust manifold
• Suitable turbo (standard turbo is a GT2052)
• Custom made turbo downpipe (AMW Motorsport can make to order, or weld the turbo downpipe and standard downpipe together
• 1.8T injectors (usually easier to buy a whole inlet manifold though)
• 1.8T Throttle body (it’s different from its NASP equivalent)
• Cambelt kit (optional)
Usually when buying a “Complete 1.8T engine” this will all be included, but sometimes best to specify!

(Ideally, but not necessary. R65/IB5 gearboxes won’t normally last long on a turbo engine due to torque)
• PG1 gearbox
• Flywheel
• Clutch kit (new one??)
• Drive shafts
• Mount
• Gear linkage
• Starter motor
This will all be included in a “PG1 conversion kit” but if buying separately, they are the individual items you’ll need.

• Intercooler
• Intercooler piping
• PRT system (or cooler running thermostat)
• VVC subframe
• ZandF 1.8T mapped ECU (Or standalone system if you’re going for more power)
• AFPR (Adjustable Fuel Pressure Regulator)
• (Not necessary, but ideal) Oil catch can
• Boost control
• Boost gauge
• 282 Brake upgrade minimum

Removing the engine is surprisingly easy, and can be done in around an hour if you don’t come across any issues and you know what you’re doing.
Remove the battery, slacken the wheel nuts, jack her up and tug the wheels off. Start draining all the vital fluids out the engine, coolant, engine oil and gearbox oil. Bang her in gear, get someone to apply the brakes (or something if you’ve got no mates) and crack off the hub nut. You’re removing the driveshafts so if you know how to do that then you can skip on! If not, I have found the easiest way to remove them is by, un doing and removing the steering ball joint, the 2 bolts at the bottom of the hub that connect the hub to the tie rod and then the 3 bolts at the top of the strut. Fully remove the hub nut now and then I just pull the whole strut down and tug as in to almost remove it, I generally get to the point where the top of the strut is out of the arch... Put some cardboard there or something to protect your paint! When doing the driver’s side you will find that you need to remove the lower stabilising arm that is on the back of the sump.. Otherwise the drive shaft will foul on it and you won’t get the strut low enough to remove it properly. Then a few love taps with a hammer and the drive shaft will come out of the hub. Hopefully by now the gearbox will have finished draining so you can tug the shaft(s) out of the gearbox too. I find they are generally quite well in there and end up using a ball joint splitter fork to prise them out.
Right, on to the engine! It’s not hard to get out, a few nuts and bolts and a couple of plugs and vacuum lines! And you should have already undone the lower stabiliser arm, so that’s 1 engine mount down! Happy days.
Under the throttle body there is a large multi plug, unclip that. You also need to undo the power steering pump from the rack, it’s located down around the back of the engine on the opposite side to the throttle body, it’ll make a bit of a mess so I’d put something down... Spill pads or something if you have them.. Or old clothes.. Whatever floats your boat?
The brake booster servo that pokes out the back centre of the inlet manifold, pull that out, also the vacuum lines going into it just after the throttle body. Undo the exhaust down pipe, and then the fuel feed and return lines. These can be found in the form of quick release connectors if you follow the lines back from the rail. Green and orange, pretty easy to find. Undo the coolant lines to the radiator and heater matrix.. And any others that look like they will need to be removed! And you’ll probably find a few electrical cables too! Like the starter motor cables and stuff! Climb underneath and disconnect the gear linkage from the box.. If you’re already running a PG1 you don’t want to damage those bars! And if you aren’t.. Well.. Yeah. Now crack off the gearbox mount to the chassis, and the engine mount. When they’re fully removed you should be ready to remove the engine! This is where my cowboy-ish ways come in... I got a seatbelt and tied it around the inlet and exhaust manifolds, and hooked it up to a crane, I would suggest using a proper engine lifting rig to raise it out.
When you have both engines out, put them next to each other! Compare! Everything that was on your original engine needs to go over onto the turbo lump.
• Power steering pump
• Alternator
• A/C compressor (if you have it and are keeping it)
• Drivers side engine mount
• Injectors (NOTE: The fuel rails are not the same. ZR/ZS use a fuel return system, the 75/ZT do not. You need to use your original fuel rail so just swap the injectors over!)
• Throttle body (notice the turbo lump doesn’t have the link between rocker cover and TB)
• Any and all sensors, and the engine loom. (75/ZT use a lot of BMW crap, not compatible with ZR/ZS)
If you already have a PG1 fitted (ie you’re running a 1.8, or a converted 1.4/1.6) you then need to remove the DMF (duel mass flywheel) from the engine, and fit your PG1 flywheel, clutch etc..
If you’re going to man it and stick with your R65/IB5 kit, then fit that instead. But beware you’ll probably be changing the box again soon, either to another weak gearbox or upgrading to a PG1. But whatever gearbox you have, whack it on and you’re ready to put the new engine in.
NOTE: It’s a lot easier to do both the cambelt and the clutch with the engine out.... Just saying’.

Refitting is the opposite of removal.. So I won’t go through that in big detail.

You may find when you fit the engine back in you can’t fit it in with the turbo fitted because you’ll damage the radiator. And you’ll also find there isn’t much room to fit it from the top down, that’s all okay. When you have the engine all in and all the mounts done up nice and tight, all plugs back in, pipes back on and cables attached etc.. Remove the front sub frame. This will allow you to fit the turbo from bottom up, you may need to jiggle the radiator a little but it will fit. This is also the perfect opportunity to fit the VVC sub frame if you don’t have one already. If you have got a custom down pipe made up, fit that and then happy days, if not, bolt up the turbo down pipe to the turbo, and bolt up the normal down pipe to the cat section, if you’re a welder, you’ll know what to do to combine the two. If you’re not a welder, get one to do this bit..
Once that’s done, you’re almost there.

Intercooler time! Everyone loves intercoolers.
Remove the front bumper, there’s a few screws, nuts and bolts on the top under the bonnet, there’s few along the front underneath and there are 2 on each side bolting it to the wing. When you have the front bumper off, remove the plastic bumper bar and position the intercooler where you want it. There will be some drilling and stuff as you mount it up. Make sure you get it nice, central and straight. And try not to get it upside down like I’ve seen done before! Measure up all the piping, you will probably find you’re going to be hacking chunks out of your slam panel... I did! Spend a good morning with a lot of cutting discs, when we ran out, a hack saw and a file to get rid of the burrs. I can’t really offer much advice at this point as everyone will choose their own path for their piping. Some choose to go through the slam panel like me, others choose to have a really bendy route going up round and side to side and can be seen through the upper grill (quite common on the T16 conversions). If you’re lucky you’ll be able to refit the bumper bar in front of your intercooler, if not, it’s not that important anyways, you may as well remove the crash cans.

Right, so engines in, intercoolers all piped up and plumbed in, you should have plumbed all the coolant in by now too. It would be a lot easier if you just use a lower cooling thermostat and choose not to water cool your turbo, as I decided to fit a PRT and water cool the turbo, I now have over £200 worth of silicone hose and a fully bespoke coolant system..

If any of that makes sense to you, you’re doing well. It makes sense to me, but I drew it and designed it.. Hopefully you can use it and find it useful though.

Right! So as I was saying, gearbox oil, engine oil, power steering fluid and engine coolant all in, and at correct level? Turn the wheels from lock to lock both sides, and see if the power steering fluid goes down. Top up if needs be (with wheels straight obviously!)
Plug in your ZandF 1.8T ECU (or equivalent), and connect the battery! Check you have enough fuel, and turn to IGN2, let the pump prime. Then remove the fuel pump relay from under the bonnet and crank it over for a few seconds, plug the relay back in, let it prime again, and fire her up!
It will probably be pretty noisy on initial start-up, as it works oil up and around the engine. Get your head in the engine bay, and check the fuel rail for leaks, fuel leaks are baaaaaad. Also again check the power steering level and top up if necessary! Coolant leaks too. Do the lock to lock again with your steering, check the PS fluid, check for any oil leaks in and around everywhere, especially the turbo. I had a coolant leak coming out of my PRT on the ‘grey line’ on my diagram, so I had to get that sorted.
Right! So now we know it runs! Switch it off.
Now for all the things people don’t think about when doing the conversion!
Boost gauge. There are several grommets going through the dash, poke the Vacuum line through one of them, and plug it into your gauge. Put your gauge wherever you want and wire it into your ignition. I have a dash surround mounted boost gauge. The other end of the vacuum line is T’d into the vacuum line that goes from the inlet manifold to the FPR.
Boost controller. I chose a manual one. Just plugs onto a few nipples on the turbo, and then fully close it. The Turbo should be set to 8psi as standard which is correct for the engine. Turn it up after you’ve ran the engine in by all means, there is a K turbo out there running at 12psi.
Dump valve. Notice how I didn’t put this on the to buy list? The GT2052 has one built in. It’s the biggest nipple on the turbo, and it needs to be linked into the inlet manifold. I Y pieced mine in to the line just after the throttle body, on the line that goes into the little black canister at the back.
Oil Catch Can. You’ll have noticed a hole in the back of your rocker cover that used to link up to the throttle body, which is not done on the turbo. You can either just stick a filter on there, however I put an oil catch can here and then a filter on the return port of the filter.
AFPR. Even though the 3.0 bar FPR runs this engine, the turbo K series is designed to run at 3.5 bar. If you go stand alone, then you can get around this with extensive mapping, however if you’re sticking with MEMS3, you need to up the pressure else you’ll hit a wall at just over 5000RPM, where it leans out.. Leaning out will melt your engine.... It’ll also mess with your emissions and stuff too so you could have trouble passing the MOT.. Not to mention fuel economy... This is a pretty big one guys!

I think that’s it! If I remember anything else or I’ve missed anything then let me know and I’ll add it in. Just remember to fit your new bigger brakes instead of your little 262/262 vented set up. Rear disc conversion would also be a good idea while you’re at it... I chose to fit braided brake lines too as the 282 conversion is known for making the brakes feel ‘spongy’ due to the master cylinder being a little small for them.

Section Two;
Courtesy of Gareth Ring

This section is basically just covering the engine performance, as we’re constantly getting asked more and more about what it can achieve... The joys of this engine going more mainstream!
The 1.8T block;
The block itself is very similar to the 120/160 block (depending on when it was built, early engines use 120 pistons, later engines use 160 pistons, roughly the same time the 160 started using 160 specific pistons). The main difference itself is it has a hole drilled in the side of it for the turbo return. It also has a different oil filter housing bolted to it that has an oil feed for the turbo, however this is a removable item so if you’re turbo charging a NASP block (you’re weird and making life so much harder than necessary!) you only need to get a turbo filter housing for your feed, no fancy ass way of making your own jobby.
Internals;
Pistons;
As stated before, the standard pistons found in the K series turbo are the same pistons found in the 120 blocks, and the later turbo engines use pistons from the later 160 blocks. That said, they are good for about 220bhp.
Con Rods;
The con rods found in the block are 1mm shorter than NASP 1.8 engines, be it 160 or 120. They are the same rods used in the low compression engines you can find in the Mexico... Not that anyone here will be importing a K series from Mexico..... These are NOT forged items.. They are literally just normal con rods but shorter.. Also good for about 250bhp
Turbo engines run shorter rods to drop the compression, if you boost a NASP engine without doing this you’re in for a whole world of problems.. Insane detonation issues, as well as likely blowing your head out your bonnet or making your liners go POP (obviously at normal boost pressures... It IS possible to charge a NASP engine without altering the compression too much but you will be limited to VERY low boost and will have to take methods to cool the cylinder temps).
Liners;
The standard liners aren’t particularly strong, they are topped out at roughly 12psi (give or take, some liners can and will take more, and some will not even take 12)
Crank;
The crank is a normal K series crank, found in any 1.8 K series, be it turbo, MPi or VVC. All K series 1.8 cranks are supposed to be rated to around 300bhp. That said, if you decide to build a screamer of an engine, the cranks life will drastically shorten living life over 7500rpm. At the same time as your hydraulic lifters will start to fail.
` Head;
It’s a K series head guys, it is exactly the same as any head found on any MEMS3 K series... 1.4, 1.6 or 1.8. It also uses standard cams, found in any 105, 110 or 120 (NOT 115 or 135 engines).
Turbo;
The standard turbo, the GT2052 is a pretty good little turbo picks up boost pretty early and can boost a fair way round the clock, but it is fairly small so will never offer the sort of power some people are wanting to achieve. 220bhp easy... Want to go more? Look for an upgrade...
Now for the upgrade section! Ignore this bit if you’re doing a budget build or are poor, it’ll only make you sad.
Pistons;
Forged K series Pistons are not cheap, Omega do some but they raise the compression up a bit even with the shorter turbo rods, so fortunately for us, Jon at JDM Dyno has a patent on some low compression pistons which can be used with standard length rods. Expect to pay £600 + VAT for those. However Omega have agreed to make lower compression pistons for specific turbo builds (the for-mentioned ones are NASP orientated) if a minimum of 3 sets are ordered at around £550 + VAT a pop
Con Rods;
I've seen some Max Speeding rods going for about £230, these are standard length so would only be suitable with lower compression pistons. They only made two sets of shorter rods that would be ideal for use in the turbo engine.. In theory with the shorter forged rod you could then use the Omega pistons mentioned above but compression would still be slightly up over a normal K turbo which is 9:2:1.. However you could use their standard length rods and some of Jons pistons as previously mentioned... All this said, Max Speeding have said they WILL make more short rods, but it needs to be worth their while... Either numbers in the form of items to be made, or numbers in the form of £££££.
Liners;
Some people say ductile liners, some people say banded liners... We’ve heard bad stories with the banded liners still popping on here so we prefer ductile. Westwood sell some lovely ones, around 340 of your hard earned squids. They’re supposed to be very helpful when you get in touch with them and you can even haggle with the price abit! We love companies like that.
Crank;
Arrow make these, we’ve yet to see one used on a turbo build, only solid cam screamers that like to live somewhere in the clouds above 7500rpm. No one has ever really pushed one to its limits though... Mainly because when we got quoted for one it was £1800 + VAT!
Head;
It depends what you’re looking for... Treat it as you would a NASP head, clean it up, port it, and polish it etc... And uprate the cams, just know that all these mods have FAR greater impact on a NASP engine than they do an FI engine. You will see gains, but they will be smaller than you expect.
Turbo;
Most people would go for something along the lines of a GT28 if chasing numbers... These will see you to 300bhp ish.. But it all depends on what you want, and what you can afford... One of these will set you back £300... Give or take.
Injectors;
Pretty much any injectors that fit can be used to upgrade, if it’s a higher CC it’ll be an upgrade! Apparently 660cc should see 300bhp but this has yet to be confirmed.


Everything here listed is just a guide... It’s not fact. Prices of stuff will change, other companies will come into play. Wossner are also making stuff for the K series turbo engine now. Apparently their Piston/Rod combo is around the 9.2 C/R mark.
Most of this data has been collected by various K series gurus, so a big thanks to;
Ian Roberts, DJ Wilma, Rudder, Dave Andrews, Dave Walker at Emerald, John at Emerald and everyone else who has had input in here, sorry if you’ve not been named.......
Oh! And Gareth Ring who added plenty more stuff about the engine itself, as this was originally just a conversion guide, now it’s a conversion and general tuning guide!

If you see Errors in this, comment here and I will amend this.
Thanks to Luke for his permission to post this guide and check out the MG K Turbo Owners Facebook group www.facebook.com/groups/499316600163267/

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