Stock Airbox Dyno Testing - K&N Drop-In, Modded Snorkel and Silicone Intake

[GrimmSpeed]

So, truthfully, this is a copy of a post that I just made in our Intake Development Thread, but I thought that it could definitely stand on it's own as a resource for those not yet interested in spending the money for a full intake system just yet.

http://www.ft86club.com/forums/showthread.php?t=50492

Stock AirboxDyno Testing

Ok, Here we go. We'll go through these in pretty much the same order that we approached the dyno testing. As far as test procedure, we brought the car to the dyno that morning with a completely stock intake setup. The panel filter in the car has 10k miles on it. After strapping it down and finding a tach signal, we reset the ECU. We reset the ECU between every configuration to ensure consistency in testing method for comparable results. We utilized an OFT with a stock rom file, but changed the IAM (ignition advance multiplier) to start at 1.0 instead of .7, and scaled the o2 sensor's lowest reading only for datalogging purposes, otherwise no changes were made from the stock rom.

For each configuration, three pulls were made in 3rd gear and three pulls were made in 4th gear. We'll look mostly at 4th gear pulls, but we recorded both to show that there's no funny business. If you're interested in seeing a specific pull or set of pulls in 3rd gear, just ask. All pulls were back to back. After a set of pulls was completed, the car was shut down, ECU reset, intake configuration swapped, datalogs saved and then we went back to it. This kept the time between sets of pulls consistent as well (around 15min).

The dyno is a Dyno Dynamics unit and reads pretty low compared to others. We had two industrial fans feeding the radiator through the day - this is their standard setup. The dyno cell hovered around 41F, 32% humidity and 30.11 inHg all day. I'll post a handful of photos in a bit.

Results - Stock Airbox Configurations

Ok, the fun stuff. Parts not mentioned (airbox, filter, snorkel) in a given configuration are stock unless otherwise noted. Here's the list of configurations tested:

1. Stock
2. Modded Snorkel (I'll post photos in a bit)
3. K&N Drop-In
4. K&N Drop-In and Modded Snorkel
5. K&N Drop-In and Modded Snorkel and Silicone Elbow
6. K&N Drop-In and Silicone Elbow
7. Silicone Elbow

On with the charts. We'll keep our thoughts/theories and analysis for the end.

Completely Stock


Modded Snorkel


K&N Drop-In


K&N Drop-In and Modded Snorkel


K&N Drop-In and Modded Snorkel and Silicone Elbow


K&N Drop-In and Silicone Elbow


Silicone Elbow


Lastly, here's a comparison of Stock, K&N Drop-In, K&N Drop-In with modded snorkel and then the K&N Drop-In, Modded Snorkel and Silicone Elbow. The legend up top should help you identify which is which. I can clarify if needed. For each configuration, I selected the run in each set of three pulls that was closest to the average power gain.



Well, not a whole lot different than expected, right? A nice little bump in power (4-5whp), but she's looking pretty lean. The modded snorkel appears to richen things up a bit but maintain the gain. The silicone elbow doesn't appear to have much of an affect on performance (1-2whp with the stock filter and less with the K&N). All in all, the K&N drop-in and modded snorkel are not a bad gain for such a small investment, but we're not wild about the change in AFR.

At this point, our goal with the GrimmSpeed intake is still to show a solid gain, but with stock-like AFRs. This should provide a great bolt-on solution without any concerns with AFR and also be very tunable. After seeing the K&N results on the dyno, we were a bit nervous. Our design methodology was sound, but who knows!

Alright, so that wraps up our testing of the various intake setups using the stock airbox. This, we thought, provided an excellent set of baseline setups for comparison against our prototype designs.

Discuss!

Matt Beenen
Engineering

[Ranatsu]

Interesting that the AFR changed that much with just a filter in the same MAF housing.

Did you happen to get any short term fuel trim numbers with any of these changes?

[GrimmSpeed]

Originally Posted by Ranatsu

Interesting that the AFR changed that much with just a filter in the same MAF housing.

Did you happen to get any short term fuel trim numbers with any of these changes?

We're still going through the OFT logs and separating them for each pull. Will report back!

Matt Beenen
Engineering

[FrsDuke]

Originally Posted by Ranatsu

Interesting that the AFR changed that much with just a filter in the same MAF housing.

Did you happen to get any short term fuel trim numbers with any of these changes?

My thoughts exactly... Raises the question will the ECU bring the afr back to similar stock numbers and if so will it keep the power gains. I've got the modded snorkel and a K&N and I run in the high 11s at WOT, but it's been on the car a while.

[sirsol66]

Thank you for posting this, I ran a K&N drop in for my evo X and had exactly the same issue. I'm sure the FRS has a bit more margin being NA and DI, but I would still be nervous about running a drop in.

[mrk1]

Do you have pics of how you "modded" the snorkel?

[RallySport Direct]

Thank you for the info Matt.

Seems like more and more modern cars now days are calibrated from the factor to run specifically the stock filters.

Kirill
RallySportDirect.com

[FR-S Matt]

Makes me wonder how TRD came to the idea of making a larger box/filter over stock, but still maintains the snorkel. Besides the pretty TRD letters which we know add HP.

[GrimmSpeed]

Originally Posted by FrsDuke

My thoughts exactly... Raises the question will the ECU bring the afr back to similar stock numbers and if so will it keep the power gains. I've got the modded snorkel and a K&N and I run in the high 11s at WOT, but it's been on the car a while.

Are those 11s as recorded by the stock sensor?

Originally Posted by mrk1

Do you have pics of how you "modded" the snorkel?

Yep! I'll post a few photos at the end of this post.

Originally Posted by RallySport Direct

Thank you for the info Matt.

Seems like more and more modern cars now days are calibrated from the factor to run specifically the stock filters.

Kirill
RallySportDirect.com

Our pleasure! It does seem that way.







Matt Beenen
Engineering

[FrsDuke]

Originally Posted by GrimmSpeed

Are those 11s as recorded by the stock sensor?

Yup logged using OFT. This is however on the 1.34 OFT stage 1 tune so may be completely meaningless here. Still makes me wonder if the car will adjust toward richer afr over time, and if doing so would negate the power gains. Hard to do umpteen long term tests on so many configurations to find out. I think you're testing is still going to give us the best info we can hope for.

[GrimmSpeed]

Originally Posted by FrsDuke

Yup logged using OFT. This is however on the 1.34 OFT stage 1 tune so may be completely meaningless here. Still makes me wonder if the car will adjust toward richer afr over time, and if doing so would negate the power gains. Hard to do umpteen long term tests on so many configurations to find out. I think you're testing is still going to give us the best info we can hope for.

Yep. We do have some logs and pulls from the OFT stage 1 on our car in totally stock configuration, so when we get to those, it might be worth a comparison.

Like you said, it's impossible to do back to back to back testing and elminate variables if you need to put a ton of miles on the car between setups. Weather, gas, dyno conditions, driving type can all change. Obviously, we reset the ECU before doing the stock 'baseline' runs as well.

When we think we've got our design nailed down, we'll definitely put a ton of miles on it and see how she behaves.

EDIT: I just checked our charts of the stock vs stock stage 1 pulls and the OFT definitely keeps AFRs more steady through the pull, but also lower through the middle of the powerband by around a single point.

Matt Beenen
Engineering

[FrsDuke]

Originally Posted by GrimmSpeed

EDIT: I just checked our charts of the stock vs stock stage 1 pulls and the OFT definitely keeps AFRs more steady through the pull, but also lower through the middle of the powerband by around a single point.

Matt Beenen
Engineering

Reinforces MY belief that not only are Shiv's tunes more powerful than stock but safer. I am very pleased to see Grimmspeed using OFT not just for ease of use but for actual product development and testing purposes.

[JS + BRZ]

Great.

Just a day after I order K&N drop in. Good thing I ordered on Amazon. Free return, it is.

[wparsons]

^^ Why do you say that? They got 4whp from the drop in filter alone... or are you worried about the AFR's?