Turbo setup on 8th gen Civic Si - k20 engines

When I decided to go the FI (forced induction) way, I have to admit I knew NOTHING about it. A lot of reading and researching solved that problem. Well, at least made me understand better how everything works - by no means I'm an expert!
So here is the first tip ... read a lot about the subject you are interested in, before starting to build anything!

Also, unless you are a guru in turbo set-ups or have a lot of experience turbo-charging a car, I would personally recommend NOT to adventure by yourself in this task. There are way too many things that can get wrong and you just won't know what went wrong or where is the problem.

I took my car to a local shop who has a lot of experience with turbo-charged cars but they never installed a turbo on an 8th generation Civic Si. They loved the challenge and they enjoyed working on the car.

Super-charged or turbo-charged!?

Originally I wanted to go the SC (super-charged) way because I kind of got scared by all the horror stories I was reading / hearing with blow up engines and all the problems the TC (turbo-charged) way it brings ... Plus, SC way sounded more cheaper and less complicated to install.

After more reading, I realized that while SC sounded simpler to install, the power gains were not that great. Plus, with SC in order to make power, you have to use power.
Confusing!? Well, it was (for me at least); but there is an explanation as to why ...

In very simple and very lame terms, SC and TC are basically the same things - a compressor that compresses (duh :)) air and force it into the engine. And while this is happening, the ECU is trying to compensate the flow of the fuel to maintain the proper air-fuel mixture.
The only distinctive difference (again in very simple and lame terms) is this:

No matter what set-up you choose however, you will still need a serious tune!

In the end, since I never liked the easy way (and a little more POWEEEEERRRRRR!!! never hurts :)), the final decision was to build a TC set-up.

What do you need for a turbo-charged set-up

Well, first of all, there is no such thing as a good cheap, set-up.
Brand new, the "cheapest", reliable kit you can buy out there is over $3000 + shipping + taxes (if you buy locally). And even then, you still need a few extra parts.

The "arguably" cheaper way will be to piece one together. You have to hunt for parts, make sure they are good quality and still in working condition (or rebuild them if you can and if they are not in a good shape).

Since I usually enjoy working on the car and looking to try and save some money, I decided to start putting this kit together myself. Did a list with what I needed and started to pay attention to the sale threads and hunting parts wherever I could get some.
In the end, the total cost of parts and installation was around $6000 (not including the tune). If you can get cheaper than that ... more power to you :).

Please keep in mind that getting the parts/kit doesn't mean the job is done.
Now you have to take in consideration the cost of installing the kit and building any additional custom parts that you might need/want, plus tuning the engine (and this is a must if you want to have your car for a while longer :)).

This is pretty much what you will need for a simple, basic set-up:

Strongly recommended, but not really required:

Turbo, exhaust manifold and down-pipe

I've ended up getting the Greddy's T517z turbo (the smallest turbo Greddy builds), exhaust manifold and down-pipe. The turbo was used and the other two seemed to be new, unused parts.
The turbo unit came with an internal waste-gate so I didn't had to worry about an external one (external waste-gates are usually "arguably" better and more manageable than internal waste-gates - something to keep in mind if you are looking for better gains).

Internal waste-gates are not bad at all... actually to be honest I prefer them to external ones especially when you are limited by the space you have in the engine bay.
You can get better performance out of them by replacing the actuator with a more manageable one or getting an adjustable one (allows for replacing the springs).

Now here is another tip...
If you buy your turbo as a used part, and you don't have much knowledge about them, when purchasing the part, make sure you have someone with you that actually knows how a turbo is working or else you might be fooled into buying something bad ... :( ... just like I was.

Later on, I realized that the turbo had major problems so I've end up replacing all the internal parts. I even had to change the turbo's center housing. The feeding oil line mounts were broken off and there was no way you would be able to install a feeding line in.
So, basically the only good thing about my turbo was the Turbine wheel and housing, the shaft and the compressor wheel and housing. Talking about a good deal ... :| ...
The up side is that I learned in the process how to take a turbo apart and how to rebuilt it :).

If you are looking to get more gain out of your set-up, is a good practice to have the exhaust manifold and down-pipe custom built - might be a little more costly than the kit parts, but if you are really looking for high gains, this is the best way to go. The log manifold that usually comes with the kits are not the most efficient ones.
Personally I was happy with the power gains that the Greddy parts give. I never really thought about going over 300whp to begin with.

Another good tip, especially on the 8th gen Si is to wrap the down-pipe with heat-wrap to reduce the amount of heat you get inside your engine bay. Keep in mind that everything is very tight inside the engine bay and where the turbo sits (between the engine and firewall) is very little space that allows for ventilation.
Also, while you are at it, put a heat-blanket on the turbo as well.
When it comes to wrapping, you will get a lot of different opinions on if its good or not. Some say that the wrap will trap moisture and cause the downpipe/turbo to start rusting. I honestly hardly believe that ... with the high temperatures that goes trough these parts, I doubt any water will get to stay for long in there. Plus, the silicon will help preventing this; no matter how slightly the chances are.
And in the end, even if is true, I would prefer to change these parts every 2-3 years rather then set my car on fire - no matter how small the chances are. In the end the decision is yours :).

Installing these parts are quite straight forward.
Remove your stock or after-market exhaust manifold (sell it or put it aside for rainy days), install the turbo manifold, the turbo on top of it and then the down-pipe to the turbo.
Now don't be fooled. This sounds easy enough, but remember that the working space is pretty tight so be patient. Best way to work on this is to have your car up on a hoist.

Connecting the down-pipe to your cat-back will require some extra piping and welding. The shop where you took the car to do the installation should be able to help out with this without a problem.

Oil feeding and returning lines

These lines are very important if you are using an oil-cooled turbo.
The feeding line is usually running from the oil pressure sensor to the turbo and the returning line from the turbo to the oil pan.

The most complicated part will be to remove the oil pan, drill a hole and weld a fitting that will allow you to connect the return line. This hole must be done as high as possible on the oil pan. The logic here is that you want the oil to flow freely back into the oil pan. Having this return line at the bottom of the pan will cause the oil to back-up into the turbo and this is not a good thing. The turbo will not cool down properly and you will blow the turbo's seals very fast.
Look at the pictures to get a better understanding of where to tap the oil pan.
Btw, do yourself a favour and DO NOT consider other options for the return line - there is NO other reliable way. Be warned!

Boost controller...

A boost controller is something that you can use if you want to increase the PSI without changing the actuator for the waste-gate. They come in 2 flavours: manual or electronic.

What is the actuator you ask!?
Well, the actuator is what actually opens the waste-gate once you reach at a certain PSI number - depends on what the actuator is set-up for.
You can consider it as a safety item because in essence is having the same function as a blow-off valve.
The actuator opens the waste-gate, forcing some of the exhaust to by-pass the turbine wheel (on the exhaust side... duhhh :)). This will prevent your car from over-boosting while the throttle-body is opened. Once throttle-body closes, blow-off valve kicks in... :|.

If you have an after-market actuator, that is adjustable you don't necessarily need a boost controller.
An adjustable waste-gate comes in 2 flavours...
One will allow you to change the tension of the spring inside the actuator - this will mean that you need more PSI to open it.
The other one will allow you to change the spring inside with a stiffer spring that will compress at higher PSIs.

The boost controller is installed before the actuator and it will allow you to control at what PSI the actuator will open.
Is usually a good idea to never set your boost controller to hold the boost more than double the PSI of your actuator's set-up.

A manual boost controller usually has 2 ports and is a very, very simple device - you can even build one yourself if want to (search for DIY manual boost controller - tons of of them).
One of the ports is connected to a pressure source and the other one is connected to the actuator. You adjust it by turning the knob/screw to increase the tension in the spring inside.

If you decide to go with a manual boost controller, I would personally recommend you to purchase one. A very good one is usually between $50-$100 and will be decently accurate (almost rivalling the electronic boost controllers).
Not that the one you would built is not good enough... but it won't be as accurate, made of similar good quality materials and especially as good looking :).

An electronic boost controller, also called solenoid, by some, is the ultimate choice and is installed in a similar fashion as the manual controller.
The only difference is that you will adjust it electronically via software - in my case, FlashPro from Hondata.
Yes, the unit will need to be connected to your ECU and Hondata has a good diagram on how to install one.

If you purchased a MAC or Hondata electronic boost controller... (honestly they are basically the same unit with a different stamp...) and depending on what kind of waste-gate you have (internal or external), there are different set-ups for the port connections, so make sure you read the instructions that comes with them.
If there are no instructions, you can find them on-line with a simple search.

Intercooler, charge pipes and blow-off valve

Now this is the most trickiest part of the set-up.
If you buy the TC kit, it usually comes with the pipes and intercooler already set-up for your car. All you have to do is "plug it". However, if you piece the kit yourself, you will have to do custom pipes.

If you have to build custom piping, I would strongly recommend to start with the Intercooler. Take measurements and plan the route of your pipes.
Usually, the best place for the intercooler is way in the front of the engine and as low as possible. I would also recommend to have an intercooler with both inlets on the same side (driver side) - this will save you a little bit on the quantity of pipes you need.
You will also have to take the decision if you really need the AC.

If you decide to keep the AC, you will be hit with two problems:

I do not recommend to remove the re-bar. Believe it or not, it is an important piece on your car especially when involved in an unfortunate accident. It also offers a small "structural stiffness" to the body of the car.

In my case, for a better cooling and fitment, I decided to remove the AC completely.
This actually give me more room for routing the pipes and removed some of the weight. True, is not much and in the end might not make a big difference, but at least this improved the air flow/cooling a little.

If you remove the AC, you MUST get a new belt. K-tuned has a great kit for our k20 engines and is not that expensive either. The kit includes a new belt and a replacement for the top pulley. This kit will also allow you to adjust the tension on the belt. Pretty neat - I got it and I love it!
If you do not want to buy this kit, you will have to find a belt that will fit. Since I got the K-tuned kit, I am not sure exactly of the measure you will need. There isn't a specific belt that Honda makes for us if you removed the AC (I've actually went to one of the Honda dealers and asked about the belt ... they looked at me very, very confused :| ... ).

To have more space in the engine bay, I've also moved the battery in the trunk. HUGE space saver!
Battery is sitting nicely in the spot where the spare tire used to be :).
"But dude, what if you need the spare tire!?" - Shshh you insolent prick - bite your tongue and hope for best :). Real men don't need spare tires :D.
Seriously though, if you need a spare tire you can always just leave it in the trunk ... above the carpet.

My pipes are starting from the front of the engine bay with a dry HKS filter, then a pipe that steps down from 3" to 2.5" and is connected to the compressor's inlet with a hose that steps down from 2.5" to 2.0".
From the compressor's outlet, there is a new 2.5" pipe that goes down behind the engine and then under the engine (hugging the engine - there is a distance between the pipe and the engine though) and goes to the front, trough the wheel well, around the frame and connects to the bottom inlet of the intercooler (the pipe is pretty far away from the wheel so there is no danger of touching or rubbing - the wheel well plastics were removed as well).
Now, from the outlet of the intercooler, a new pipe starts climbing between the car's frame and the radiator towards the throttle body. We had to cut a small portion from the car's frame where the pipe goes because there was not enough space. This part was reinforced to make sure the frame will not be weakened.

On the last piece of pipe that goes to your throttle body, somewhere as close as possible to the throttle body, you should install your blow-off valve. The shorter the vacuum line from the blow-off valve to the throttle body, the better the response of the blow-off valve!

The role of the blow-off valve is to remove the pressurized air to the atmosphere when the throttle body is closing - very important part of any turbo set-up.
You do not want your turbo to keep on building boost while throttle is closed. The air will try and escape somehow so it will either blow your pipes if they are weak or go back into the turbo creating what is called a surge. Surge is bad for turbos - in time the turbo will get damaged beyond repair; so make sure your blow-off valve works properly!
Personally, I end up getting the TiAL blow-off valve after a few cheap and bad experiences - read this as: "Don't cheap out, get the good stuff". Trust me ... been there, done that!

And that's pretty much about the pipes and intercooler.
This part requires a lot of careful planning. It is a very important step because if your pipes are not set-up properly or weak at any point, you will not be able to build boost at all.
Make sure you securely mount the pipes in key points so it doesn't move around. Do not just leave it hanging. Weld your pipes and don't use too many hose connectors; but do use a few to have some flexibility in the pipes while engine is moving/vibrating.

Injectors, fuel rail and fuel pump

Injectors ... you need them :); and depending on the power you are looking to have, you will need larger injectors.
For example, I was looking to get around 300whp so a minimum size of 550cc injectors is a must. However, if you would look for more, then bigger injectors will be needed.
For my set-up, I end up getting the RC 550cc.
A lot of people just go for the biggest they can get (1000cc or so) and stick with them.

If you do not want more than 300whp, the fuel rail and fuel pump are not really required, but if you plan to upgrade later on, and your budget allows you to do so ... is never a bad idea to have them already :). Plus, they will help with the fuel flow a little and any after-market fuel rail looks better than the stock one ... so why not :)?

I choose to go with the Skunk2 fuel rail and Walbro 255 fuel pump.
The Skunk2 is not as bad as some people might tell you. Just make sure you do not over-tighten your bolts since everything is pretty much brass and it will be easy to strip. Oh, and replace the top washer with a brass one. That's where the problems usually are :) - see pics (not sure how to call that specific part).

For gains around 300whp, the 1 step colder spark plugs (iridium) are more than enough. For 400whp, I would recommend to go with 2 step colder spark plugs.

Installing these components are pretty much plug-and-play. Unfortunately I don't have any pics of the installation of the fuel pump :(.

Boost controller, Hondata 4bar MAP sensor and Hondata FlashPro

The boost controller will allow you to increase your boost over the boost limit of your internal/external waste-gate.
The Hondata or MAC boost controller (also called solenoid) will both do the job very well. Is up to you which one you choose. Both are controlled and installed in the same way.
Hondata, in their FlashPro help menu, has a nice diagram on how to install and set-up this component.

The MAP sensor will be required if you are going to boost more then 10psi. The Hondata 4bar MAP sensor is good up to 40psi (more than you will ever need).
If possible, you can also use the RDX 2.8bar MAP sensor (which is good up to 26psi).
After you install your new MAP sensor, your car won't be running as smooth anymore. Actually, when I've put the 4bar MAP the car will start and immediately shut off if I would not rave up the engine. Even so it was running quite bad.
Updating the ECU with an upgraded turbo base MAP got the car going again. I will explain later how to set-up this via FlashPro - please remember though this will be a temporary tune! It will get your car going so you can drive it to the dyno for a serious tune.

FlashPro is basically just an ECU editor or a sort of a fuel management system that allows you to change almost ANY settings on your ECU.
Very useful and very recommended. Even if you buy a TC kit that already have some sort of fuel management system in it, I strongly recommend not to use it. Sell it and instead upgrade to FlashPro.


There are at least 2 gauges that you really want to have. Boost gauge and wide-band gauge (with the sensor - all the "good" companies sell their gauge with the Bosh sensor)
The two gauges are nothing but visual aids that will tell you how the engine is running.

The boost gauge will help you monitor your boost so you can make sure you are not overboosting and risk damaging your engine.

The wide-band gauge will let you know what are your air-fuel ratios.
A slightly rich mixture is not a problem; however, a lean running engine is a problem. Check those number from time to time and make sure they stay around the soft spot ...

Everything else can be monitored via FlashPro trough data logging.

To make sure your readings are as accurate as possible, go for the good stuff, not the cheap eBay products.
Stick with at least names like AEM or AutoMeter. I end up with the AutoMeter brand because it has a more stock look.

Oil cooler

The oil cooler is not a must but it is something that I would strongly recommend. If your turbo is oil cooled then a lot of extra heat will be added into the engine. Having a way to try and cool it down sure sounds like a good idea to me. And the good part is that you do not have to buy the expensive stuff either :).
I mean if you are into it, you can buy a very good kit from Greddy for around $700 - $800 (if I remember correctly).

The most important piece of this set-up is the mash/adapter plate.
What I end up doing was to get the Greddy mash/adapter plate with the thermostat built in. The good thing about the thermostat option is that the oil cooler set-up will be used only when the oil is getting to a specific temperature (honestly I cannot remember at what temperature is opening :|). This piece was the most expensive part (a bit over $200 including shipping)
The braided hoses, fittings and oil cooler radiator were bought from eBay as no-name parts and they work beautifully. You will not have any leaking problems as long as you use Teflon tape. And everything was about $100 - $150 including shipping. Doing this give me a nice saving.

The installation again is very simple but like everything else, requires some patience and planning.
You have to drain your old oil and remove the old oil filter. Before installing the new filter, you have to install the mash/adapter plate and then connect the new filter to the mash/adapter plate.
Now, find a place where you want to install the oil rad and make sure your hoses will reach there :). Usually is good to install it somewhere in the front of the car or under the car where air flows nicely but the rad is not exposed to stones and other stuff.

When putting the new oil in, put the normal quantity of oil that you usually put, then let the car running until it warms up properly so that the thermostat opens and lets the oil go trough the oil rad. You will have to add more oil - remember that now, you have more space where the oil travels trough so you will need more oil than what you usually use.

Uploading a base tune with FlashPro

Once everything is connected, before getting the car running, is a good idea to update a base map from Hondata via FlashPro. This will get your car going until you reach the dyno where you plan to do the final tune. If you are just planning to tow the car there, then just skip this.

First of all, make sure you follow the Hondata's instructions on how to install, lock and connect the FlashPro unit to your car.
Once that part is done, have your FlashPro unit connected to your car's ECU and laptop. Put the key in the ignition and turn it on - as in lights on the dashboard are on but the engine is off :).

Start your FlashPro Manager, click on "New Calibration..." and select your car model.
From the "Calibration type", select "Speed/density (MAP) calibration" and then click on filters. From the "Injectors" drop-down, select your injectors; or if not present, select the ones that are the closest to the size you have (the smaller ones).
Now, under "Calibrations" you should have only one map - double click it to select it.

After the new map is loaded, select the "Calibration" window and then click on "Sensors". From the options, select the MAP sensor you have installed on your car.
Select the "Closed Loop" and deselect the "Secondary oxygen enabled" option.

Now, update the map to your ECU and make sure you don't touch anything while the map is being updated to your ECU. Follow Hondata's instructions on how to update a map.


This map is just a TEMPORARY map!
DO NOT push your car at the limits - you will blow it up ... eventually :).

This is just to let you drive the car to the dyno under normal conditions - stay out of boost! There are no "caps" or cut-offs enabled for over-boosting.
Now, if you do know what to do and how to use FlashPro to tune the engine by yourself, then more power to you :).

Next stop for the car ... dyno shop :)!

K-Tuned dyno tuning

I have tuned my car at the K-Tuned shop and they did a great job. Based on my set-up I am very satisfied with the results - I highly recommend them!
I got exactly what I wanted and expected from my set-up - 304whp and 207wtq - Mustang dyno.

And no, I am not getting paid to advertise them ... I am genuinely one happy customer! And just to clarify (since some believe this), they DO NOT e-tune the cars. Is a proper dyno tune.

What now!?

If you reached this far and your car survived everything :), then you sir are DONE (until you decide you want more) - congrats!
All that is left now is to go out at the track and test the car. I would recommend to push the car slowly and keep your eyes on gauges. Also make sure to datalog your runs and look for any anomalies.
You can even send your datalogs to the shop where you've tuned the car and asked them to have a look at them and see if they have anything to say/adjust/recommend.

Other then that, I really hope you found this "sort of DIY" helpful and put it to good use.
If you have anything to add or ask me, feel free to contact me (link in the menu at the bottom) or leave a comment on this page.


I am NOT a professional mechanic. Everything I do I gathered from my experience and from other car enthusiasts.
While what I advise and recommend is one way of doing things, please understand that you take your own chances following my DIYs and I cannot be held responsible if you damage your car or hurt yourself by not following the "proper procedures".