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How to build a turbo Honda

Our article explains how to build a turbo Honda, Turbo Acura, or what to look for with a bolt on turbo kit. Homemade turbo kits are some of the best and least expensive ways to turbo your Honda or Acura.

We will continue to add to this article as time passes. If you have anything to add or have any questions, please reply to this thread.

The Honda engine is a perfect example of a super efficient modern day engine that is designed for superior intake and exhaust flow. Nothing takes better advantage of this than a turbo. The basics of a turbo is that it uses your exhaust gasses to spin a wheel inside a turbine. This turbine in turn spins and builds up air pressure that goes pushed into your throttle body and intake manifold, ultimately into your cylinder head. Honda engines absolutely love to breathe, but they also love a little help. Honda’s efficient motors are perfect for turbos and the redline9 team is going to take some time to help you understand how the system works, what you need to build your own turbo kit, and what to look out for when buying a prebuilt turbo kit. We will also talk about superchargers, and why we do not recommend superchargers for the 4 cylinder Honda engines (we are not going to be discussing V6 Honda engines in this article).

How does a turbo work on a Honda motor and a Honda ECU

Since a Honda from the factory is not designed to be used with a turbo, there are certain things that need to be done to prepare the car to accept boost. The Honda motors are very stout, and can take a good amount of horsepower absolutely stock. The trick is all in the tune. We absolutely recommend a good tune, and a good ECU to help regulate every system in the car. We are not going to go into any specific ECUs, piggybacks, or stand alone’s here, but we do not recommend the piggyback. The basic things that an ECU should be doing is regulate timing, and ensure you have enough fuel.

How much timing is best?

Every car and setup is going to be different. The amount of timing that you are going to start with, and end up with at peak boost, is going to depend on the size of your turbo, the type of Honda engine you have, how much boost you are running, what octane gas you have, outside temperature, and various other variables. We recommend that once your car is tuned, you have a warning system that in overboost conditions, your timing will yank. Take precautions with timing, it’s very important for longevity of your engine. Wouldn’t you rather lose a little horsepower, but have the ability to torture your engine day in and day out and not worry that it will blow up?

What kind of fuel system do I need?

Just like timing, the fuel system for a turbo Honda is really dependent on the flow characteristics of your motor, the amount of boost you are running, the size and efficiency of your turbo, and so on. We recommend a high pressure fuel pump, properly sized fuel injectors, adequate methods to ensure and control fuel pressure, and always having enough fuel to never have an instance or possibility to run lean (take into account overboost conditions).

Do I need a knock sensor?

This is a subject that can be debated all day long. I say, if your engine comes with one, use it. If not, then as long as you ensure your engine is properly tuned, you should not have any worries. But why not be safe than sorry? For hardcore enthusiasts with expensive motors, we recommend aftermarket knock sensors like the J&S knock sensor, where you can tune the sensitivity, and have it pull timing if it detects something went haywire.

No piggybacks

You’re going to spend a few thousand dollars on your turbo kit, and then you’re going to cheap out with the management? You are either itching for an engine rebuild, like to have rods fly through your block, or should just forget about turbo’s all together. If you want to be cool, get a front mount, and never pop the hood. You can also get one of those fake BOV’s so people will think you have a turbo. For those who are serious about performance AND reliability, don’t skimp on the management. Just about all piggybacks don’t do a good job of controlling timing, fuel management, and boost at the same time. And they definately don’t have a good overboost protection system in place.

Ok, I want a turbo. What’s the best engine for me?

Just about any 4 cylinder Honda engine is going to give you great performance with a turbo. We’re not non-vtec haters, but if you have the ability to run a VTEC head, why not do it? It flows more, gives you a better idle with aftermarket cams (although stock cams are typically just fine), and are really not much more expensive. In the long run, you will be glad you went VTEC. We have had great success with both the D series and B Series engines as the most popular Honda engines to turbo.

D Series Turbo (D15, D16, D17)

For all of you D Series lovers out there, we feel you. What a great little engine that can produce impressive horsepower, be cheap to replace, and overall be much easier to work with. The D16Z6 and the D16Y8 are the most popular D series engines to turbo, and 300 horsepower at the wheels on a stock engine with a good tune is very possible, and in a lightweight Civic, CRX or Del Sol, VERY fun! Build the motor, get a little more serious, and 400+ horsepower will keep you grinning all day long.

B Series Turbo (B16 B17, B18, B20)

The ultimate setup is a B Series Turbo (B18C1 GSR or B16A2 Si motor work well). The B16 is a little smaller at 1.6 liters, but can produce almost as much power for less cost over a B18. The B16 will rev higher, and produce less torque than the B18. The B18 would be our pick as the best Honda motor to turbocharge.

Which engine should I run?

It depends on your horsepower desires. For those people who want to go as inexpensive as possible, and run about 250 horsepower to 300 horsepower safely, we recommend a D Series. For those who want to run more than 300, we would recommend going with a B Series. Can you run more than 300 with a D Series? Sure. But after about 300, it just gets to be more expensive than with a B Series, and typically less reliable.

What should I look out for when buying a turbo kit?

If you are going to buy a turbo kit, we recommend one that does not come with any fuel management, as it’s just a waste of money. Unless if it’s something like Crome or Hondata or AEM EMS, then you are probably going to end up junking it anyway. Buy a turbo kit that comes with a turbo that is sized for the horsepower you want. We recommend getting a turbo that is a little bit bigger, so the turbo is always running in it’s efficient range. Research the kit, and make sure that others say the kit fits without any trimming, modification or problems. However, for a FMIC (Front Mount Intercooler), you will generally always need to trim your bumper.

What is turbo lag?

Turbo lag is when you first punch the throttle, and the amount of time it takes for your turbo to start building boost. We never recommend to give it full throttle until you are in a high RPM range, as you do not want to lug your engine. Lugging your engine can cause premature stress, wear and tear, and engine failure. If you want 300 horsepower, find a turbo that is efficient to say 350 horsepower. That way you can run 300 horsepower, and know your turbo is not overworking, not just blowing hot air, and is as efficient as possible. This will also keep your turbo lag to a minimum. For those people who run huge turbos at low boost, we just don’t understand why.

Will I pass SMOG or what do I do about CARB

GReddy turbo kits are smog legal, but they are basic, do not flow very well, and are designed to be low boosting, low power, and carb legal. On most Honda’s, the GReddy turbo kit is only smog legal without the intercooler. This already limits the amount of boost you can run, horsepower levels, and reliability. If you live in an area where you need to pass visual inspection, this might be the only turbo kit for you. Homemade turbo kits, and most other bolt on turbo kits, are not CARB or smog legal. This is strange to us, because with a good tune, they can be just as enviromentally friendly as a stock Honda. Oh well.

Do I need an intercooler?

Absolutely. We recommend an intercooler with every turbo setup, no matter how much boost you plan to run. The intercooler cools down the air from the turbo, so you can run most boost safely, or have an added margin of safety at your present boost. The cooler air also produces more horsepower at the same boost level.

What size intercooler is best?

The intercooler size completely depends on your setup, and how much boost you are running. The larger the intercooler, the more pressure loss you will have across it. Find an intercooler that fills your bumper, flows the required CFM for your setup, and is made with aluminum endtanks.

Do I get an internal or external wastegate?

A wastegate’s job is to regulate boost. When you run a certain amount of boost, the wastegate opens to release exhaust gas pressure so that you do not create more boost. If the wastegate can flow enough, then you will be able to control your boost properly. Typically, an external wastegate can outflow an internal wastegate. However, depending on the amount of boost you run, an internal wastegate might work fine. In addition, only internal wastegates are CARB and SMOG legal in CA.

What size wastegate do I run?

The size of the wastegate is also dependent on how much boost you are going to run. A 35 or 38mm wastegate is good for most cars that run under 20-25 psi of boost, and a larger wastegate might be needed if you do not get proper boost control with the smaller wastegate.

Do I need a boost controller?

Many people do not need a boost controller because they run the boost set by the wastegate spring. If you do not want to add another variable to your turbo setup, we recommend just running the wastegate spring, and if you want more boost to replace the spring.

Should I use a electronic or manual boost controller?

We have found that a manual boost controller controls boost just as well as an electronic boost controller for much less money. However, an electronic boost controller has several features that you might like, like being able to raise boost from inside of the car, being able to lower boost from inside the car, and boost scramble which allows you to run a higher level of boost for a set amount of time.

What kind of intercooler piping do I need?

We recommend aluminum piping, and do not recommend plastic, steel, or any other material. Aluminum doesn’t get as hot, and keeps the air from heating up as much, plus it’s rather light. Typically, you would need:

From the turbo to the intercooler inlet: 3 90 degree bends.
From the turbo outlet to the intake manifold: 45 degree, and a 90 degree that points into the throttle body.

You will need some straight pieces between some of these bends. We recommend 2.25″ intercooler piping for the inlet side, and 2.5″ intercooler piping for the outlet side. For higher boost levels, increase these sizes (boost more than 10psi, get a 2.5″ inlet pipe, and 2.5″ outlet pipe.)

What’s the best air filter?

We recommend an air filter that has an internal shell so that the air filter doesn’t collapse on itself due to the intense sucking of the turbo.

What’s the best type of exhaust manifold?

We recommend a manifold that is cast iron, or tubular made with thick steel so it will not crack. Make sure the manifold has a lifetime warranty.

What is the best exhaust size?

Turbo’s love to breathe. We recommend 3″ exhausts with all turbo setups. You can have a 2.5″ downpipe, a 2.5″ catalytic converter or testpipe (Off road only), and a 3″ catback for a good street combination. Get a good 3″ straight through muffler.

What parts do I need for a turbo kit?

Do I need a new MAP sensor?

Honda map sensors can handle up to about 10 or 11psi without throwing a check engine light. Over that, we recommend a GM 3 bar map sensor. You will need a converter to wire it up, but it’s rather simple.

Where is the best place to pipe the oil return line?

We recommend to pipe the oil return line in your oil pan at a place that is above the oil level in your oil pan. If you don’t do this, you can burn oil through your exhaust.

Where is the best place to pipe the oil feed line?

On the back of the block above the oil filter there is a great place to feed the oil feed line. Make sure you run a restrictor so you don’t put too much oil pressure in your turbo, which can make you leak oil between your turbo seals, or through your exhaust.

Where is the best place to tee for boost pressure readings?

We recommend to find a FREE source off the intake manifold. Do not tee it off the fuel pressure line. While this is a good place to read boost, you do not want to lower fuel pressure by teeing into this line.

What gauges do I need?

We recommend two gauges. We recommend a boost gauge, and an EGT gauge. The boost gauge, for obvious reasons. The EGT gauge, or Exhaust Gas Temperature gauges, to monitor engine conditions. A high EGT temperature means you are running lean. We recommend to keep the EGT Temperature under 900 c or 1650 F.

What does a blow off valve do?

A blow off valve releases extra pressure in your intake tract. When you are building boost, if you let go off the gas, you close the throttle plate. The pressurized air hits this plate. It needs a place to go, so during this condition, the blow off valve should open, and release the air. If your blow off valve is weak, or leaks, then you could have problems building boost, or losing boost pressure. We recommend to get a good quality blow off valve that is rated up to the amount of horsepower you are going to run. We *highly* recommend AGAINST ebay blow off valves.

Intercooler Clamps, Intercooler Pipe Blow Offs

We recommend strong t bolt intercooler clamps. Make sure your intercooler piping is beaded as well. With beaded intercooler pipes, and t bolt clamps, you should not have any problems with your intercooler piping blowing off. Because of the MAP sensor in the Honda, the car should still run fine, and can limp home, but it’s definately not fun to have an intercooler pipe blow off.

Startup Checklist

Woohoo! Ready to fire that baby up? Make sure you pressurize the system with oil before you start it. Pull your ECU plug, and crank the motor, so the oil can circulate through the engine, and fill in the turbo. Make sure everything is plugged in, all RTV has dried, and all connections are tight. Plug the ECU back in and fire it up. Do not rev the engine, let it idle, and the ECU adjust to the bigger fuel injectors, strange air characteristics, and everything else.

Your engine is going to steam, and burn off oil, fingerprints, dirt, and all kinds of gunk. It will stink for a few days. Don’t worry about it.

Enjoy your new turbo Honda!! 

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