Best Honda 1.5T Upgrades - 1.5 Turbo Tunes, Intakes, & More Mods
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The 5 Best Honda Civic 1.5T Performance Upgrades

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Honda 1.5T engines are also known as the 1.5 Turbo and L15 VTEC or VTC. The 1.5L inline-4 engine delivers up to 205 horsepower and 192 lb-ft in the Honda Civic Si. It’s solid performance for such a small engine. However, the 1.5T leaves a lot of room on the table for extra power. Turbo designs allow for excellent power gains with a few simple mods.

With just some tuning and basic bolt-on upgrades like an intake, downpipe, and intercooler you can add up to 70whp to the Civic 1.5T. In this guide we’re going to teach you how to do this for less than $1,500 – digging into each upgrade, discussing its purpose and performance benefits.

Best Honda 1.5T Upgrades - 1.5 Turbo Tunes, Intakes, & More Mods

All of these engines share the same base design and 1.5L displacement. Honda uses so many engine codes, so it can seem a little overwhelming. However, the differences between the engines is pretty minor.

For additional info, check out our Honda 1.5T common engine problems guide.

Honda 1.5T Performance Mods

  • ECU Tuning
  • Cold Air Intake
  • Downpipe (exhaust)
  • Front-Mount Intercooler
  • Fueling & Methanol Injection

1) ECU Tuning

Looking for only one mod for your Civic 1.5T? If so, a tune is without question the best starting point. Not only do tunes offer massive horsepower gains, but they’re also the foundation for building more power. A tune is necessary to maximize performance gains from other mods like an intake, downpipe, etc.

Benefits

  • 20-40+whp gains
  • 20-40+wtq gains
  • Better fuel economy
  • Data-logging and monitoring

There are tons of awesome features and benefits that come along with the right tune. Gains of 20-40 horsepower and torque to the wheels is already impressive enough. With the right tuning and driving you may notice better fuel economy. However, that’s likely not the case if you’re using the new-found power.

Otherwise, some tunes offer data-logging and monitoring capability. It’s nice to see and know what’s going on with the engine. You can easily read and clear codes, and the list could go on.

2) Cold Air Intakes

This list is in no particular order, but an intake is our second favorite mod. No, an intake upgrade isn’t as capable as the other Civic 1.5T upgrades on the list. However, it’s a great mod to combine with a tune since it’s also easy to install and cheap. As you increase power and boost it’s also important to improve air-flow into the engine. That’s where a 1.5 turbo intake system comes into play.

Intake Benefits

  • 3-7whp
  • Similar torque
  • Awesome turbo sounds
  • Better response / turbo spool

Again, the gains from an intake aren’t overly impressive. It’s still a great upgrade for many reasons, though. Honda Civic 1.5T intake mods free up a lot of awesome turbo and induction sounds. We think it’s really addicting and would recommend an intake for the sounds alone. Intakes can also improve engine response and turbo spool. Just a few extra benefits to what’s already a great mod for the power gains and sounds.

Performance intakes have so many different names. Intake system upgrade, cone intakes, air-box upgrades, cold air intakes, etc. There’s one primary thing to consider in our eyes – open vs closed intakes.

3) Turbo Downpipe

A downpipe (DP) is likely the second best bolt-on mod from a horsepower and torque perspective. They’re without question one of our favorite mods on any turbo engine. That also applies to the Honda Civic 1.5 Turbo engine. The downpipe bolts directly to the turbo making it the most important piece of the exhaust post-turbo.

Stock Civic downpipes are great for emissions, but hurt performance a lot. The restrictive cat creates a lot of back-pressure, which slows turbo spool and limits max performance. Reducing back-pressure with Honda 1.5T upgraded downpipes offers a lot of benefits:

  • 5-15whp
  • 5-15wtq
  • Better turbo spool
  • Awesome sounds
  • Lower EGT’s
  • Reducing back-pressure is healthy for engines

It’s a long list. Not only does a downpipe offer significant power and torque gains, but quicker turbo spool is another major upside. This means a lot more low-end torque. You can also feel more of the push back in your seat feeling.

Combine that with a more aggressive exhaust note that isn’t overly intrusive. DP sounds are mostly noticeable with cold starts or heavy throttle inputs. Otherwise, less back-pressure helps reduce temps and is healthy for the engine and turbo overall.

Catless vs High-Flow

All of these benefits have to come with a serious downside, right? Unfortunately, that is the case with Honda 1.5T upgrades to the downpipe. The goal is to reduce back-pressure as much as possible. Doing so means eliminating the catalytic converter, which is not street legal. Passing emissions can become an issue.

Enter high-flow downpipes. These Civic 1.5 Turbo downpipes retain a high-flowing catalytic converter. They may still be considered illegal, but it’s more likely to pass emissions. Power gains aren’t quite as impressive as with a catless downpipe, and cats are expensive. It’s still an excellent mod, though.

4) Front-Mount Intercooler

The intercooler is an extremely important part of any forced induction engine. Turbos run off hot exhaust gases for one. Air also heats up as it’s compressed. Combine the two and the charge air exiting the turbo is hot. Obviously, that is not good for performance or engine safety. That’s why an intercooler is standard equipment.

The Honda 1.5 Turbo factory FMIC holds up fine on stock boost. Although, it’s quickly overwhelmed when you start adding more power and boost.

Benefits of upgrading the intercooler include:

  • 5-10whp
  • 5-10wtq
  • Cooler IAT’s
  • Consistent performance
  • Safer for engine

FMIC upgrades aren’t really a big power mod. They might pick up about 5whp on most setups, but more power is possible. However, an intercooler mod goes a long way in ensuring consistent performance. Ever noticed the car feels a bit sluggish after punching it a few times? That’s heat soak at work. It causes the engine to pull timing, boost, and overall power. As such, an FMIC upgrade may prevent the engine from losing 10-20whp.

Reducing IAT’s help the L15 1.5L engine maintain performance even after multiple back-to-back pulls. Cooler air also reduces the chance of engine pre-detonation events, which is a big cause of blown motors. All in all, don’t expect tons of peak performance gains but it’s still a very worthwhile mod.

5) Fueling & WMI

Fueling upgrades and water-methanol injection are lengthy topics and 1.5T upgrades. We will definitely address this in an individual post in the future. However, high octane and high-quality fueling is important when increasing performance. E85 blends are a great option, and some tunes allow for 30% E85 mixes with no other mods.

E85 benefits are endless. It helps the engine run cooler internally, reduces the risk of detonation, and has a rating of 108 octane. Power gains can be massive even on small blends of E85. The downside is that E85 is less fuel efficient and puts higher demand on the fuel system.

WMI offers similar benefits, but actually reduces demand on the fuel system. It also lowers intake temps significantly. These mods are a bit more advanced, so we don’t recommend jumping right in on E85 or WMI. Stick with the basic Civic 1.5T upgrades to start, and work up to more serious mods like fueling and water-methanol injection.

Price: E85 is the same price as lower grade fuels. WMI is generally $300-500+ for the full kit.

HP Per $: E85 blends – unlimited ($25-50 for WMI)

Honda 1.5T Supporting Mods

  • Turbo upgrades
  • Fueling upgrades

You may also want to take into account any supporting mods. More power means more heat. It also means you should consider traction, braking, suspension, and more. The major topic is with the CVT transmissions.

Honda CVT Transmission Upgrades

Some CVT trans begin running into issues in the 220-240 wtq ballpark. It’s not a perfect science as to when the transmission start having issues with more torque. However, it’s something to consider addressing. There are CVT cooler upgrades that may go a long way in supporting the extra power and torque.

All Of These Upgrades Will Net +50-70whp

The Honda Civic 1.5 Turbo offers great performance for its size. It’s also an efficient engine that offers solid reliability. However, some are always looking for more power and performance. The use of a turbocharger means there is plenty of power on the table. A few simple bolt-on upgrades can take the engine to the next level.

Tuning is usually the best single mod and starting point for the Civic Turbo. It’s the best bang for your buck, and also maximizes power gains from other mods. An intake is a good mod to couple with a tune. If you still want more power it’s time to move onto downpipe and FMIC upgrades. Fueling mods offer even more power, but it’s generally something to work your way up to last.

Combine these simple bolt-on mods and the Honda L15 Turbo engines can pick up as much as 50-70whp. That’s really impressive for a small engine. One major concern is the CVT trans, so be cautious with torque or consider upgrades for the transmission. Ultimately, mod away and have some fun!

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One Comment

  1. Disagree with a few of your choices, namely using a SRI style intake and a fairly low quality chinese made PLM downpipe. The PRL Cobra CAI has consistently shown itself to give the most horsepower gains, a quite useable 14+ with tune. The PRL downpipe also can give a 20+ horsepower gain. A lot of 1.5T owners are using the Phearable 1.5R tune with a K-Tuner. Running FBO, my 2017 Civic puts out close to 270hp, and has been reliable. I did have to do a clutch upgrade once I went above 250 hp.

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