FL5/DE5 Air Intake Design Blog PT.3 - Testing & Validation

Our hybrid intake for FL5/DE5 is almost through the design, testing and validation stage. We’ve pressed to find opportunities to innovate with this product like we have many other products.

If you have not seen them yet, check out the earlier blogs on development of this intake where we review the OE setup and get into prototypes and our goals.

This blog is about what we’ve learned during almost a year of product development. The FL5 is unique in that Honda did a great job optimizing this engine to maximize performance. Many of the features we’d normally add to an intake are already there for the FL5. The intake gets fresh air. The piping is fluted all the way to the turbo. The OE intake can handle the OE power levels and even modest increases in power without becoming a restriction.

But it’s not all smooth sailing….

News Flash (or not). The FL5 runs hot.

It’s not uncommon to see intake air temperatures more than 50 degrees over ambient on an OE car after the intercooler. We wanted to be very careful to make sure any intake we designed kept these temps in check and not have increased post FMIC temps more than it needed to or rather more than the baselines we established above.

We’ve thoroughly tested various intake setups while carefully controlling test conditions. The OE intake performs best with respect to IATs if you check before the intercooler, with our intake a very close second. If you check after the intercooler, it can be hard to see a difference across popular aftermarket intake setups but it’s safe to say ours ranks towards the top of the list, showing results better by a couple degrees than most. We intended to include a shroud for the filter from the start. But is it really needed? And what about just a short ram (SRI) intake. Is that ok?

First, let’s talk about what matters more than which intake you have on the car.

Do you do a lot of stop and go driving? The FL5 can heat soak by 20-30 degrees during a single stop light. Do you drive primarily on the freeway? In that case, lots of air is flowing through the FMIC and IATs are dropping. What about when it rains? Well that’s actually good for a 10-15 degree decrease in IAT after the intercooler!

When air is compressed by the turbo it heats up… a lot. If you had an IAT of say 300 degrees at the intercooler inlet you might see that temperature drop by 200 degrees exiting the intercooler. Wow! So, what if the air entering the intake is 10 degrees hotter. Well, the FMIC will usually scrub most of that. It matters, but not as much as how well your FMIC is able to do its job. And if your car is moving, it’s well on its way to being able to do that.

Before we move back to intake testing, let’s state the obvious. Improving the FMIC is a great bang for the buck mod for these cars. We say that not even currently offering a FMIC for FL5 (though we do for FK8, gotta keep it 100%.

How the FMIC is performing is going to matter more than which intake you buy for your CTR. Yeah, we said it.

Any of you interested in a misting kit for your FMIC? This could be an excellent upgrade for the CTR. Convince us we should make one by commenting on this blog below.

OK, back to intake development. The graph above shows three different intakes and what happens between the ambient air temps and charge air temps going into your manifold post FMIC (i.e. the Delta) over a period of time for each.

They are all tested on the same real world test route but on different days. It’ll give you a sense of what’s going on with your intake in a real world setting. An intake without a shroud or airbox is a true SRI. It draws in a mixture of hot engine bay air and air from the intake opening. In the example above, the car was sitting for a while before testing and air temps started pretty hot. What you’ll see with a SRI is intake air temps consistently hotter than OE once the car warms up (approx. 10 minutes) and when the car is in stop and go traffic. Again, the FMIC will scrub much of that, but that’s not ideal. Especially if you live in a hot climate. So, we’re not going down this path for dev right now.

The 27WON line shows what the addition of a well-sealed shroud does. In this particular case, the temps are lower than OE. That is not something we claim for this intake. But we will show temps are basically the same as OE in nearly all situations. Adding in a well designed shroud will get IAT back to almost the same as the OE intake. That’s not a bad place to be, especially if you now get to enjoy the awesome sounds you get to hear with an open filter intake plus all the flow from a high flow filter and larger intake piping, the cool turbo sounds, and no extra IATs. We are very close to this! To that end, this is our current direction of a “hybrid” style intake for the FL5 & DE5 that uses a well sealing shroud to keep those IATs as low as possible and even matching OE in most cases while giving you all the other elements of a high performing intake.

Here is a picture of a pre-production kit on an Integra Type-S.

And here’s another one for good measure on our FL5.

This has been a long one in the making and we are excited to share final details in our release blog for this intake later this summer with you all.

-Rich

Co-Founder
REDEFINE the Aftermarket