zbomb

Back in my Evo 8 days, changing an intake without a tune was something that was for look fast, not go fast. The issue was that most aftermarket intakes that retained a MAF (stock ECU, does not apply to speed density standalone ECU's) threw off the MAF readings and caused a lean condition for what was a highly strung stock motor (19PSI of boost factory). However, the leaner fueling generally lead to a power increase on the dyno but was not the safest configuration for hard use. So, if going strictly by dyno numbers, it could look like a good idea.

In the graph below, you can see the opposite, the aftermarket intake is significantly richer than the 3.8, 1 - 2 points richer is a big difference and will surely have an impact on power output, among other things. I wonder if this is due to a decrease in airflow not being corrected sufficiently by the ECU or a metering issue because some feature of the Fabspeed intake makes the MAF mad and its not metering the correct amount of air, thus not commanding the ECU to supply the correct amount of fuel.

I wonder what would happen with the power comparison if the fueling was corrected for the 2 intakes and we could assess the airflow capabilities between the intakes. Now, that would still not take into account things like heat management, but as an indication of the efficiency of the stock intake, would be cool.

Anyway, cool data and appreciate FSI putting it up on their channel, go watch it and hopefully people can weigh in with their opinions of the data.

EVOMMM

Great info but I still love my competition air intake if I track my car or I can find a carbon fiber factory airbox that fits I will make that swap
but really solid info I wish someone you do a major comparison with early cable throttle 996 to see if there is any difference

dougn

That looks very extreme to me. Something isn't right

plpete84

Cool video and that's a much bigger difference than I thought for sure. I would love to see this on a stock M96 or M97 as well to see if the difference is just as great. The dyno looks to be done on a built 4.0L Stage 2 motor which I'm sure includes some improvements that probably help with airflow.

zbomb

I think people need to not look at the power degradation solely and instead focus on WHY was there a power degradation ?

What the ECU was doing for the 2 air boxes is wildly different as clearly evidenced by the dramatically different AFR.

From how rich the run was, I think it’s not of the realm of possibility that with an apples to apples AFR and timing strategy - the results would be far more competitive and if so, then you don’t have an inherent problem with the intake itself, you have a problem of a non optimized engine calibration as a result of the air box.

Maybe ​​​​​​@Fabspeed Motorsport can chime in with the ECU tuning strategy they employ with the intake and if they recommend the ECU to be recalibrated with the addition of the intake.

TexSquirrel

Fabspeed does sell a tuning product on their website, but if tuning is also required in order to "add" a few HP, their intake now costs double.
I switched from my Fabspeed intake to the 3.8 airbox because Jake said it was better.
I just didn't realize how much better the 3.8 airbox was compared to the Fabspeed.
What would have been nice to see would be a stock 3.6 airbox.
I assume it would have been somewhere in the middle.
But without a dyno, all I have are assumptions and dreams.

GC996

For a naturally aspirated engine, I would love to see all of the intake, exhaust and software folks give us quantifiable numbers and ways to configure. But it hasn't happened yet, and I doubt it will going forward. But I hope I am proven wrong.

theprf

Since the MAF only reads a tiny fraction of the actual airflow the subtitles of getting the MAF positioned correctly and the airflow through it to be representative of the overall airflow are quite important. Without changing the ECU tune the diameter and shape of the pipe that holds the MAF ought to be exactly as the factory setup. If not the MAF will see a different amount of air in it's limited vision and mess with the AFR - as that dyno graph shows, the MAF is seeing a lot more air that isn't actually flowing and enriching the mixture.
Sometimes a simple thing like an airflow straightener can get it back to normal. If the airflow through the MAF isn't nice and linear that can also cause problems. An airflow straightener can sometimes correct those problems.
If the size/shape of the pipe the MAF is inserted in differs from stock, then for sure ECU tuning is going to be required.

911h20

Is switching to a 3.8 airbox plug and play?

996C438

I am guessing that the car will perform better with the aftermarket air intake system ............... because the owners wallet is a thousand dollars lighter 😁

GC996

FWIW,

On YuTube you will find videos on testing air intakes, exhausts, etc on a dyno using a 997 from MOTIVE. Well worth the time to watch. If I remember correctly, they did NOT make any software changes. It was plug and play.

Search Motive Myth Busting and you will find it.

EVOMMM

I also believe that airflow from a car at speed creates a type ramming effect that the fabspeed picks up maybe
I also wish there was a comparison test of all boxes
so calling all you tubers make this video and use cable 996 as well as egas cars in a comparison of the top 3 air intakes and stock 3.6 /3.8 air boxes

schroederhc1

Mine was.

EVOMMM

996c you are right aftermarket boxes are expensive but when I open my lid and see all that carbon fiber and FabSpeed’s xpipe it does give me a warm feeling
worth every penny to me if I were tracking my car I would want to squeeze every performance possibility
but for now I’m content

TexSquirrel

I've installed 2 3.8 airboxes now.
1st was my 2002 C2, and the second was on a 2004 C2.

You have to relocate the SAI.
But that's a minor issue.
I actually used a Fabspeed bracket in order to relocate it.

Also, you have to do some trimming on the 3.8 airbox.
I use a Dremel and none of the trimming shows.