The CVT

Dyno testing a car with an automatic transmission is always a bit more complex than testing a manual transmission. The ability to shift the gears manually makes it a bit easier to set up a manual transmission on the dyno. With automatic shifting, however, finding an appropriate final gear ratio is not a simple task.

A continuously variable transmission (CVT), has a continuous range of effective gear ratios. The gear changes are more seamless than in a conventional mechanical transmission, which has a limited number of gear ratios. With a CVT design, the angular velocity stays constant, putting power to the wheels at a range of different speeds and with a higher efficiency than a mechanical transmission.

Because of the continuous change in gear ratios, we needed to adjust and reset our dyno to compensate for these 2016 Honda Civic parts. We opted to record our runs within the 3,700 – 5,800 rpm range and within a gear ratio difference of 1.0. These settings allowed for the most accuracy possible in comparable and repeatable runs with this CVT design.

The MAF housing

Generally, when designing the housing for the mass airflow (MAF) sensor, the inlet diameter should be as close as possible to the stock diameter. This allows the sensor to accurately read the increase of airflow while staying within an acceptable air-fuel ratio (AFR) that’s safe to run on a stock tune. This isn’t applicable to all vehicles; in some more sensitive engine ECUs, this increased airflow can result in a limp mode with self-adjusted ignition timing, fuel trims and throttle position. This situation destroys any potential for a power increase, so the MAF housing was important in the design of these prototype 2016 Honda Civic parts.

Due to the proximity of the turbo and the radiator, we knew that the front section of the 2016 Civic intake pipe we planned to replace would need a precise design. Replacing this section with steel-reinforced silicone seemed like a great solution to help keep intake temperatures cool. We 3D printed the gray seen in the image above so we could get started with testing.

To find the most effective size for the MAF housing, we 3D printed multiple MAF housings of slightly different sizes. We first tried a MAF housing that was the same size as stock, but that yielded a loss in power. We then reduced the size to one millimeter smaller, and that put us back at stock power output.

This told us that reducing the size of the MAF housing might yield some power gains. So we reduced the MAF housing to two millimeters smaller than stock, and this is where we began to get some favorable results! Check out our graph below.

Our results were taken from an overall average of the runs we did on the dyno. We never use any single highest or lowest run, because that can wildly skew the results. As you can see in the figure above, we made some good power gains; the power increase was 9.38 hp and 9.67 ft-lbs of torque. We did lose about 1.5 ft-lbs of torque for about 150 rpm, but we suspect that this minor loss in peak gains resulted from the way the CVT behaved on the dyno rather than an actual power loss. Also, the gains in torque everywhere else along the power-band more than makes up for that minor loss! After the 4,500 rpm mark, we were able to keep the power above stock all the way to the end of the run, which is good for a smooth, consistent power gain for this 2016 Civic intake.

How about our AFRs? Check out our graph below.

This 2016 Civic intake will stay safe to run on a stock tune. We did lean the results out a bit, but this is to be expected, as more air is a sign that more power will be made.

How about a quick clip of what our intake sounds like on the dyno!

The tone has improved with a more throaty and aggressive sound under induction. We know that this is an important feature for this car, so we took time to make sure the intake sound was up to good standards.

What’s Next?

Now that we have some awesome testing results, we are ready to kick off our production process! Before we begin the stage of market production, we need to get a production sample of this intake to ensure perfect fitment. Once those pieces arrive at our facility, we’ll have an awesome update for everyone.

As we discussed in the last post, we wanted to utilize the stock air inlet as much as possible, which is why we kept an opening at the top of the airbox. The remainder of the filter enclosure is protected within the physical box, to help keep out heat. The opening on the box where the mass airflow (MAF) sensor housing sits will be lined with weather stripping not only to prevent debris from getting inside, but also to secure the housing in place and absorb any flex resulting from engine torque.

The MAF housing looks really sharp! The cuts and edges on this piece are super clean, even though this is just a prototype unit. The MAF sensor will plug right into this unit. Check it out below!

Prototype MAF housing for the 2016 Civic intake

This prototype isn’t painted yet; the final version will be powder-coated black. Painted or not, this piece looks really great. Some nice features stand out on this simple piece, including the laser-engraved “AIR FILTER” at the top and the ever-so-slight venturi-style air inlet. A venturi-style inlet is a common feature on intake manifolds and throttle bodies. It simply means that the small, tapered opening at the entrance where air gets sucked in helps to increase velocity.

These awesome silicone hoses are reinforced with steel wire to prevent misshaping under induction. The silicone construction is beneficial when it comes to preventing heat-soak whereas an aluminum piece would pick up a bit more heat due to its proximity to the turbo and radiator.

Let’s check out more cool shots of the kit!

That just about does it for the majority of the R&D on this intake. The last thing we need to do before officially kicking off production is to confirm fitment on our 2016 1.5L T Civic loaner. Below is a shot of the entire kit, including mounting hardware and brackets.

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The silicone intake hose will not only come in red. Just like our Mishimoto Civic 1.5 L T Catch Can, we will offer the color options of red, blue and black. Also remember the MAF housing will come powder-coated black instead of the polished pictured above. Once we make sure everything fits perfectly, we can move forward!

The newest Si sets itself apart from the standard EX-T. The aggressive new styling, 18” alloys, and sporty interior let everyone know that you’re not driving just a Civic. The improvements don’t stop there. Along with the enhanced styling, the Si also gets a helical limited slip differential to evenly distribute the extra 25 horses and added torque to the front wheels. Under the hood, however, one might take note that the L15B7 powering the updated Si is the same powerplant that can be found throughout the Civic line, which begs the question, why does it need its own intake?

Honda has traditionally equipped the Si with the same engines from the standard Civics, but with a few extra tweaks to give it that enhanced driving experience. The same is true for the 10^th generation. Under the hood throughout the turbocharged Civic line, excluding the Type R of course, the engine bays are more or less identical, including the intake systems. Given this, most of the legwork for our Si performance intake was already finished.

The only components that changed in the intake system were a different MAF sensor and a slightly different housing. Given our engineering team’s familiarity with how this Civic’s ECU behaves, we made quick work of adjusting our current design to play nicely with the Si’s sensor. With the new housing sorted, it was time to see how our intake performed on the Si.

First up was the road testing. If you look back at the testing procedure during the development of the Type R’s intake system, you’ll notice road testing is a critical step in the process. No matter the power figures an intake system puts out, it’s important to determine if installing the new components are going to illuminate any unwanted lights on your dash. Our benchmark is at least 1000 miles per test. This is ample time for the ECU to learn and determine if the air to fuel ratios are still in a good standing with the adjusted MAF. Since this particular Si was on loan to us, we had its owner do the testing and report back, at which point we pulled the data. We can confidently disclose that our new, Si-specific housing kept the CEL at bay.

There is also a secondary benefit to conducting this road test. In order to achieve the most accurate numbers on the dyno, the adjusted long-term fuel trim has to “settle in.” Once the long-term fuel trim plateaus, and fully compensates for the increased airflow into the intake, we can find the most precise figures of what you’ll experience on your Si on a daily basis. If we ran this car on the dyno right after installation, we would have recorded much larger power gains, but those augmented numbers would have been fleeting. Instead, this is what we recorded.

In addition to turning up the volume on your 1.5T soundtrack, your Si gets a 4.2 whp and 4.3 wtq boost in power on the stock tune. While this might not sound like much of a bump in power, one thing to consider is that the Si’s ECU is already a tuned version of the EX-T and Sport variants. Installing our intake on your Si increases the potential for even more power once you tune the ECU further. The cooler, and increased airflow combined with the improved flow characteristics help with the increased boost you’ll see with a more aggressive tune.

The increase in flow is essential for effectively cranking up the boost on your 1.5T Si and enhancing your driving experience even further. More boost and aggressive tunes are the go-to for any turbocharged vehicle, but let’s not forget the effect that has on your intercooler system. Make sure you head over to our 1.5T  intercooler post to see just how we’re planning on keeping your L15B7 in your Si cool under increased pressure.