IS20 Instalation Guide (1.8t)


Drag Racing Champion
San Francisco Bay Area
2015 Golf, e36 328i
IS20 Installation guide for USDM 1.8t gen 3 EA888 engines

This guide will walk you through swapping a turbo, and namely upgrading to an IS20, on the mk7 golf's 1.8t. When I was doing the swap I didn't take many pictures, so you'll have to work with what I've got, but it should hopefully be better than what I had when I did the swap.

Warning for people with AWD models:
If you have a 4-motion sportwagon, alltrack, or a golf R and are following this guide, the downpipe removal will not be as easy! I recomend following a guide for replacing a downpipe on a golf R such as DAP's: rather than what I have below.

Useful Resources:
I found this 5 part series useful, but there are some things he does which are unnecessary and different for our engines. I will talk about all of those differences below. Make sure to watch the entire series before you start as there is stuff in part 5 that is important for part 1 (Such as how to drain the coolant).

I believe this is a document written by Audi and given to Audi techs on how to replace the turbo on the A3, but 95% of it applies to our swap. Thanks to APR for getting a hold of it and uploading it for all of us MQB people.

Printable guide (Written by V I G I L):
Includes many useful additions and commentary, and conveniently includes all of the necisary extra documentation exactly when it is needed. Super convenient!

IS12 Comparison:
This should be pretty straight forward, bigger turbo means bigger power. There will be a bit more turbo lag than the IS12, which can be difficult with the super long gear ratios of the 5MT, but overall it has almost no performance or drivability downsides and I extremely highly recommend it. For those of you who have seen the power difference and thought to yourself "is a 40 peak hp difference really worth it", let me tell you it is another world of difference from Stage 1 or 2, similar in scale to the jump between stage 1 and stock, and this video clearly shows that:
I never imagined my car would ever be this fast from nothing more than a simple OEM turbo swap. If you have a manual transmission keep in mind that the clutch may not last forever with this, but because the torque is similar to Stage 2, you can probably assume the clutch will survive similar to people with stage 2 1.8t's, which as far as I've seen is much better than even a stage 1 GTI. My clutch lasted ~13k miles with lots of abuse and increasing the power with e30 and a downpipe. I imagine the clutch would last much longer IS20 no downpipe or e30.

If you're curious about the actual size differences of the IS20 vs IS12 these photos show that the IS20 is actually quite a bit larger:

IS12: .................................................................................IS20:

Vice grips/pliers
5mm allen wrench
6mm allen wrench
T25 bit
T30 bit
8mm tripple square
7mm wrench/socket
10mm wrench/socket
12mm wrench/socket
13mm wrench/socket
22mm wrench/O2-sensor-removal-tool/adjustable wrench if you're lazy
2 gallon bucket/drain pan

1 x Used or new IS20: You can find plenty of used IS20's in the classified section for under $400. I highly recommend picking up one of those, but if you buy a new one they're available from a few places for similar price to an IS38. If you choose to buy new you will likely need to perform this adjustment, but a used one shouldn't need it. NOTE: This adjustment is slightly different for the IS20 and should be looser than the video details. Tighten it until the wastegate is no longer loose but do not do the extra 1.5 turns, then do the tests from there. Also, at this point if you do not fail the test the first time, I would recommend tightening until you fail the VCDS test then loosen one step. If you do this please report your results to this thread so we can make these instructions more accurate.

EDIT: Cheaper kit that contains everything listed below:

1 x Turbo Gasket:
1 x Turbo Oil Feed Line O-Ring:
2 x Turbo Oil Return Line O-Ring:
2 x Turbo Coolant Feed Line O-Ring:
4 x Turbo Lock Nut:
4 x Turbo Studs (Optional, i.e. if you can figure out how to get the old studs out):

1 x Downpipe Gasket (I didn't change mine, but I'll include it here for reference anyways):

STEP 1: Drain the Coolant
The specific process for this isn't well detailed in any of the guides I found, but it is mentioned in part 5 of the video series mentioned above ( Make sure your car is completely cool before you start this process as it is very messy. Have a lot of paper towels on hand and get a bottle of distilled water for when you need to refill at the end. I put about 1/3rd of a gallon of extra distilled water in after I filled the coolant back up at the end, but I spilled more than I should have. I believe our total coolant capacity is around 8 liters, but not all of it comes out when you drain it from the radiator outlet. A 2 gallon container should be fine, I used one of these from walmart which was extremely helpful as I didn't need a funnel for refilling:

To start things off remove the lower engine bay cover. There are 8 T25 screws, 3 on one side, 4 on the other, and one in the middle. The cover should then pretty much just pop off.
To drain the coolant use some long pliers or a vice grip to hold the clamp open. This was difficult to get to for me because the clamp was rotated to a very inconvenient position. Just spend some time twisting it down and once you're able to slide it a few inches all you need to do is yank on the hose to get it off and coolant will immediately start pouring out. It might be a good idea to also remove the coolant cap up at the coolant reservoir to allow for better flow. Set the coolant aside and make sure it is covered and protected from debris, you will be adding it back to the car when you're done.

STEP 2: Remove the Downpipe
This is very straight forward and there are a lot of guides online. I used these instructions: MK7 GTI Downpipe Install Instructions.pdf and DAP's video.

The only difference I found is I don't have an axle heatshield, which is the only place that requires the 16mm socket, so that is unnecisary. Also, there is no need to remove the O2 sensor from the downpipe, which requires the 22mm socket. I just unplugged it from the connector on the firewall and left it attached to the removed downpipe. This leaves only the 13mm socket and 6mm allen wrench as the necessary tools for removal.

When sliding the downpipe through the exhaust tunnel make sure to rotate it such that the inlet for the downpipe is facing the ground, then it should come right out.

Warning: As stated above if you have an AWD model this part is not as simple and can add a significant amount of time. Refer to a Golf R downpipe replacement guide of your choice.

STEP 3: Remove the Intake Piping
If you've done anything related to the driver's side of the engine bay before, you probably know how to remove the intake. Undo the hose clamp on the turbo inlet pipe with a 7mm socket or flat head screwdriver and pull off the two hoses on the side of the airbox and yank it out. It has similar connections to the engine cover so don't be afraid when yanking. You will also need to remove the inlet pipe from the turbo which requires a T30 to remove it's bolt and then rotating the pipe clockwise 90 degrees. Set it off to the side, or if you can't figure out that hose that attaches to it just wedge it under the wiring harness after step 4. Finally, the silicone part of the charge pipe needs to come off, but you can leave the charge pipe itself still attached. Look at page 3 of the PDF guide for reference. You will need a T30 to loosen the charge pipe to allow for wiggle room and a 7mm socket again to undo the hose clamps. Completely remove the silicone connector and set aside. It should look like this when you're done:

STEP 4: Unplug the Wiring Harness
I assume you will have removed the engine cover by this point. You will need to remove the part of the wiring harness that connects to the ignition coils. To start you will need a 10mm socket or wrench if your socket isn't long enough to undo the grounding wires on the ignition coils. Contrary to the video it is unnecessary to remove the coils, so just leave them there. You may later need to rotate one to get the turbo to fit through, but that's it. You will also need to remove some clips holding wiring in two places. These clips are really annoying, but don't be afraid to yank a little with some help from a small screw driver shoved in there. They seem to be designed such that the metal part will bend back into place when you put them back on. Lastly you will need to unplug the wires going to the diverter valve on the turbo. After you've done those three things you can remove the harness by pressing in on the clips for the ignition coil plugs and pull towards the rear of the car. Then pull the harness forwards and zip tie it to somewhere near the front of the engine.

STEP 5: Remove the Hard Coolant Pipe
For this step you will be removing the hard steel pipe that runs over your turbo around your engine. For this you will need to remove 3 rubber pipes and 3 T30 screws, and will only need to set the piping to the side rather than totally removing it as in the video. Start with loosening the three screws identified on page 4 of the PDF, this will allow for better wiggle room. Next you will need to remove the hose clamps of the two center hoses and driver's side hose identified in the picture below. This is where vice grips come in handy, you can set them to be just wide enough that they open the clamps as much as possible without damaging them. Once you clamp them wiggle them at least an inch back, then use a wide screw driver or something better to pry the hoses off the pipe. Once everything is off you will need to pull a bracket out of the wiring harness near screw #3, then you can pull it back and out of the way. Zip ties are optional.

STEP 6: Remove the Turbo Heat Shield
Refer to page 5 of the PDF and use a 5mm allen wrench. It's very simple and quick. You will also notice on page 5 that they reference removing the VVT actuators, but the 1.8t does not have them which makes removing the turbo easier.

STEP 7: Remove the Turbo Bracket
Refer to page 6 of the PDF. The upper bolt of this actuator can be accessed both from the top and the bottom of the engine bay, but the lower bolt can only really be accessed from the bottom of the engine bay. Apply generous WD40 to the top bolt and remove with a 6mm allen, then loosen the bottom bolt with a 13 mm wrench or socket. The video says to rotate it out of the way, but I found it much easier to just remove it entirely. Be careful as there is a sharp edge where the lower bolt is attached.

STEP 8: Remove the Oil and Coolant Lines
This is the most tricky part of the install. The first one I removed was the oil feed line on the top of the turbo. The way I did it only the part that connects to the top of the turbo needs to be removed, the part that connects to the engine block can stay put. Just make sure to push it out of the way when lifting up the turbo. This is being held in with a 10mm hex bolt that the heat shield was also attached to and an 8mm triple square bolt off to the side. If you look on page 7 of the PDF it's #2 in the lower picture. You will need to yank this back and forth a bit to get it out, but it shouldn't be much trouble.

Next is the oil return line. This one is the biggest pain of them all just because of how difficult it is to wiggle out. You will need to detach it from the engine block side, don't try to detach it from the turbo side for more leverage, it doesn't work. It is held in with an 8mm tripple square bolt, once you remove that you should be able to rotate it a bit. Try to wiggle it back and forth to get it to slide out a bit, then if you can get a screw driver under it that helps a lot. Don't try brute force, it doesn't help. The key to this one is patience, persistence, and a lot of wiggling back and forth, and it has the potential to take up a lot of time and be a massive pain. Once that is removed you can ignore the other two lines next to it, unlike what the video says.

Next is the coolant lines. These ones are much easier than the oil lines, probably because they operate under lower pressure. To remove the rear coolant line, refer to PDF page 7, second picture, #1. The upper bolt is an 8mm triple square and the lower bolt is a T30. The lower bolt is very difficult to get to, so I found the best way was to take my T30 bit and clamp it in vice grips such that the head of the bit is pointing out perpendicular to the vice grips. Even then it's still a bit of a tight fit, it's just enough to get it out. Once the bolts are removed you just need to wiggle and push a bit and it will come right out. Keep in mind if you let this go below a certain height it will cause the residual coolant in your engine to spill out, and is where I lost most of the 1/3rd of a gallon of coolant. The best idea is probably to pull this line down and make sure it drains into your coolant container rather than all over the floor; zip tying it as the guy did in the video is an alternative, but it might get in the way a bit later.

Last is the front coolant line. This one can't easily be removed from the turbo while it's still attached to the car, so I removed the rubber hose connecting the line to the pipe on the top of the engine. Do this similarly to the coolant lines from step 5, with pliers or vice grips and a wide screw driver. Once the turbo is off the car I removed the bolt using the 8mm triple square and tapped on it with a hammer in a circular and away fasion until I could wiggle it loose.

STEP 9: Remove the Turbo!
You're finally on the home stretch! To start off with a few straggling items need to be addressed. First, the O2 sensor should be unplugged similarly to how the O2 sensor on the downpipe was removed, and left attached to the turbo. Then the wastegate actuator plug on the back of the turbo needs to be unplugged (I don't have a picture of it, but it's on the lower rear intake side of the turbo and the last electrical connector still attached to the turbo). Then you will need to remove the clips on the firewall that were used to hold the wires for the O2 sensors, this will make it much easier to remove the turbo. Next remove the stud from the 3rd ignition coil using a 10mm wrench/socket and rotate the ignition coil out of the way. Next push the oil feed line to the driver's side of the turbo so it doesn't get in the way, and finally use a 12mm socket/wrench to remove the turbo lock nuts. Once all 4 are removed you can pull the turbo straight out the top. You don't need to try and pull it out one side or the other like the video says, and doing so makes it almost impossible to remove. I believe you need to do it that way on the GTI because of the VVT actuators discussed above. Make sure to remove the gasket and dispose of it.

Hurray! You're most of the way there!

STEP 10: Swap Everything Over to the New Turbo
Now that the two turbos are sitting next to each other, move everything on the IS12 over to the IS20. There should be the oil return line, front coolant line, and O2 sensor still attached to the turbo if you followed my method exactly. When removing the O2 sensor I had to use a LOT of leverage. I ended up clamping the turbo to my work table and used a wrench with a pipe slid over it over my shoulder. I also transferred over my turbo muffler delete and had to transfer over the diverter valve because my IS20 didn't come with one, but I think most turbos will. While you are transferring the pipes over make sure to replace all of the O-rings, and if any of them got stuck in the fittings make sure to remove them. I got lucky and all of my O-rings were perfectly intact and on the lines, but I still replaced them just in case. When bolting in the lines, ideally if you plan to be able to remove your turbo eventually you should use antiseize rated to around 1000C for all of the bolts that attach to anything hot, which applies to almost all of the bolts to follow.

STEP 11: Install the New Turbo
Slide the new turbo in the same way you took the old one out, and bolt it on with the new lock nuts. Push all of the coolant lines and oil lines back into the engine block and turbo and bolt on with the 8mm triple square bolts. Re attach the turbo bracket and heat shield, then put the wiring harness back on. Make sure everything is properly re-attached and plugged in. There should be a total of 3 wired things plugged into the turbo.

Re-install all of the coolant lines and bolt the hard line back on, making sure to slip the bracket near the front of the engine back into the wiring harness bit. Re attach everything else and double check that everything is connected properly. Pour the coolant back in, filling up as much as you can and let it sit for a few minutes to settle back down. Repeat this several times until you are almost out of coolant in your bucket.

It is recommended that you turn over your engine without turning it on for around 10ish seconds to get the oil to flow into the turbo. The proper way to do this is to remove the fuel pump fuse, but I was lazy and just turned the key and turned it back before the car got the chance to actually combust fuel a few times. If you have VCDS now is a good time to test your wastegate settings. Like I said above this is likely unnecisary if you have a used turbo, but it's not a bad idea to perform this test anyways: Ignore this if you don't have VCDS and are using a used turbo.

You can now start the car!

STEP 12: Bleed the coolant
After you start your car, let it warm up and watch your coolant level with the cap off, adding coolant until it begins to level off. DO NOT drive your car around without distilled water handy. The quickest way to bleed the coolant system is to drive your car around with the heater on and the coolant cap off, but keep in mind this is VERY quick, and you will need to add more after a few hundred feet the first time. Do this until it begins to level off, making sure to let the coolant get up to temperature and cool off completely each time. For the next few drives check your coolant before you start your car and fill as necessary. Don't make trips longer than a few miles until you feel confident that the coolant has leveled off.

-If there is anything I have missed, should add, or any typos please tell me!
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Go Kart Champion
3rd rock
Thanks man! Nice work!


Autocross Champion
Would never have done this on my own, but reading this makes me want to try.

Great write up. So jealous, especially after looking at my boost logs and seeing drop to 14 psi at 6k rpms


Ready to race!
Awesome! You're going to make me attempt this and fail miserably, but awesome!

Considering you have to remove the downpipe, did you upgrade that as well? <-Scratch that. Just read that you didn't take off the O2 sensor, so I doubt you did. - Next question. WHY NOT?

Seriously though, thanks for putting together this guide. Especially with links/pdfs/videos. I'm going to attempt this in the near future, and you took most of the grunt work/research out of it.
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Ready to race!
This is a great resource. Thanks for putting this together.


Drag Racing Champion
San Francisco Bay Area
2015 Golf, e36 328i
Considering you have to remove the downpipe, did you upgrade that as well? <-Scratch that. Just read that you didn't take of the O2 sensor, so I doubt you did. - Next question. WHY NOT?

Partially because California, partially because when I do get a downpipe I want a nice catted one and that's expensive, and partially because according to George I've entered "no-man's land" IE beyond Unitronic's tune with the power I'm making and my car isn't having issues with it, so I don't actually need a downpipe to go further yet :D.

Awesome write-up! I wonder if the is20's wastegate needs to be tested/adjusted after the install, similar to the is38? See APR's video below.

I was concerned about that when I was doing the install, but when I had both of them next to each other their wastegates felt the exact same, so I figured because my IS20 is used that it was unnecessary. I haven't gotten any issues so I think my assumption was correct. If you get a new IS20 you will probably need to do that.
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Go Kart Champion
This is a very well written write up. To anyone thinking they cant do it, you can. It might take 6-8 hours of you take your time on ramps but honestly it isn't difficult, just time consuming. Get out there and wrench!


Drag Racing Champion
San Francisco Bay Area
2015 Golf, e36 328i
dude what do i do with my bags of quickrete again? where do i install them??

It's an alternative to VW coolant. Mix it with your distilled water before adding to your car.


Autocross Champion
I added some to my fuel tank. Now I use less gas at every fill up. It saves me about $7 every tank!

Lol. Money saving tip of the day