Airbox Modification Tests

[Twistm4]

CTS intake is on the way to test. I am going to turn it into an MST using 1/4" sheet metal and gold reflect-heat tape with auto trim etc. Turbos are so loud already after going straight piped/ catless I can't even imagine after these are on the car. However if data points to performance similar to the Injens we'll know that the integrated velocity stacks and square box design of BMW is the superior intake system (I am skeptical that is the case.)

[Twistm4]

Testing so far is interesting....

Almost immediately short term fuel trims jumped quite a bit indicating more air (or skewed air mass readings) however it could be the car was on too much ignite. I noticed cutting out in third gear then put more 93 in and it stopped. However the original percentage was one I ran a lot on the stock intakes without issues.

The car seems to have lost a hint of torque and response, for exchange of any top end power? Doesn't feel like it.

I need to do more dragy tests. I have an abundance of 60-130s from before to compare to.

Ironically lately it has been pulling boost down in 5th gear back to stock levels for some reason (STFT too high?). It is not related to IATS. It did this before with the injen intakes but didn't seem to happen on the oem intakes which I find very interesting. This could be coincidence of too much E content but I will try to find out.

I built heat shields around the intakes and retained lower airboxes to help combat heat. IATS really aren't that bad at all. Cruising in boost it is 13-17* over ambient and idling and sitting in city traffic is 20-30* over. However turning the car off hot then starting back up and driving iats jump a bit more than stock did, but come down after some driving.

[Whyte_Diamonds]

Originally Posted by Twistm4

Testing so far is interesting....

Almost immediately short term fuel trims jumped quite a bit indicating more air (or skewed air mass readings) however it could be the car was on too much ignite. I noticed cutting out in third gear then put more 93 in and it stopped. However the original percentage was one I ran a lot on the stock intakes without issues.

The car seems to have lost a hint of torque and response, for exchange of any top end power? Doesn't feel like it.

I need to do more dragy tests. I have an abundance of 60-130s from before to compare to.

Ironically lately it has been pulling boost down in 5th gear back to stock levels for some reason (STFT too high?). It is not related to IATS. It did this before with the injen intakes but didn't seem to happen on the oem intakes which I find very interesting. This could be coincidence of too much E content but I will try to find out.

I built heat shields around the intakes and retained lower airboxes to help combat heat. IATS really aren't that bad at all. Cruising in boost it is 13-17* over ambient and idling and sitting in city traffic is 20-30* over. However turning the car off hot then starting back up and driving iats jump a bit more than stock did, but come down after some driving.

Now you have me curious what an intake like DINAN which utilizes the stock placement with carbon fiber tubing would do in a similar situation. Good stuff bro.

[Twistm4]

Originally Posted by Whyte_Diamonds

Now you have me curious what an intake like DINAN which utilizes the stock placement with carbon fiber tubing would do in a similar situation. Good stuff bro.

I did. I had the Injen Evolution which was a very similar style to oem. The filters were so tiny to fit inside the box I believe there was very little change. That one also threw a CEL for me one time roll racing.

So far I have had zero CEL or idle issues with the CTS. But if people had issues with BMS, I'm sure CTS is the same way.

Tonight I'm going to get 2 60-130 dragys once I verify it's not pulling boost in 5th like it was. Those results will determine whether or not I keep the intakes or resort to OEM.

[Whyte_Diamonds]

Originally Posted by Twistm4

I did. I had the Injen Evolution which was a very similar style to oem. The filters were so tiny to fit inside the box I believe there was very little change. That one also threw a CEL for me one time roll racing.

So far I have had zero CEL or idle issues with the CTS. But if people had issues with BMS, I'm sure CTS is the same way.

Tonight I'm going to get 2 60-130 dragys once I verify it's not pulling boost in 5th like it was. Those results will determine whether or not I keep the intakes or resort to OEM.

Good stuff bro,

Would love to see the results.

[Twistm4]

Ok soo 3000DA CTS intake did 7.5 and a 7.3 invalid.

Last week OEM airbox did 7.26 with less slope but it was like 500DA out... big difference so hard to compare. Tomorrow I'll try oem intake hopefully conditions are similar so it is a fair comparison.

[erik_m3g80]

Originally Posted by Twistm4

Ok soo 3000DA CTS intake did 7.5 and a 7.3 invalid.

Last week OEM airbox did 7.26 with less slope but it was like 500DA out... big difference so hard to compare. Tomorrow I'll try oem intake hopefully conditions are similar so it is a fair comparison.

Do you have some updates pictures how your system looks like now?

[Twistm4]

Originally Posted by erik-f80

Do you have some updates pictures how your system looks like now?

CTS with custom heat shields I made. IATS have been great actually lower than OEM once you get moving around.

But I swear to god, OEM intakes may actually OUTFLOW these cone filter designs somehow and I can't believe it.

The data keeps suggesting intakes mod literally slow the cars down. I think it actually has to do with the SAI plug not sealing correctly *right past the MAF) and letting in unmetered air. Those of you with aftermarket intakes have noticed some seem to run better than others or some give CEL with others dont. In theory that doesn't make sense while some would... Then I realized it's because that SAI hose is not sealing in there and that's probably why these intakes slow these cars down.

So I went to ACE and got a slightly thicker O ring to hopefully help the seal. Tonight I'm gonna go out and do one more 60-130 on CTS then swap to OEM and see what the dragy reveals.

[9M71]

The top portion of the boxes you fabbed up look real good. Would love some DIY or some pointers on how you got it done. Never played with sheet metal before.

[Twistm4]

Originally Posted by 9M71

The top portion of the boxes you fabbed up look real good. Would love some DIY or some pointers on how you got it done. Never played with sheet metal before.

Heres what it looked like first prototype. Literally just get some thin metal and start cutting and bending stuff and you'll get it figured out I promise. Just takes time.

[Twistm4]

CTS did another 7.3 in 3000DA. So averaged together it is now the top contender but JUST barely. Updating first post!

[Wanted_M]

Could you post a better picture of where you cut for the stock boxes? I may follow suit.

[Twistm4]

Originally Posted by Wanted_M

Could you post a better picture of where you cut for the stock boxes? I may follow suit.

I can next time they are out. Basically just imagine the car moving and think about where air would be hitting the boxes outside of the intended feed tunnel. Also, right under the airboxes is the liner from the wheel well. That is a very cool area going down the highway.

[TakeOne]

@Twistm4
You been putting in the wrench time! I applaud you man! This guy deserves more rep points!

[Twistm4]

I figured out possibly why so many people claim intakes lose power. It's the j pipe to inlet hose port. It is not sealed near as tight as oem and therefore pulling in un metered air. This in turn causes STFT to rise and the ecu to pull back boost slightly. I took my o ring off and went to parts store and found a viton ring in a slightly thicker size. Also made a boost leak testor out of a PVC cap and air fitting . I'm gonna try to boost leak test soon to see if my cts charge pipes are also not sealed against the turbos. However with my times and no codes I highly doubt. Always nice to check though!

[jballer123]

Good job!!!

[erik_m3g80]

Originally Posted by Twistm4

I figured out possibly why so many people claim intakes lose power. It's the j pipe to inlet hose port. It is not sealed near as tight as oem and therefore pulling in un metered air. This in turn causes STFT to rise and the ecu to pull back boost slightly. I took my o ring off and went to parts store and found a viton ring in a slightly thicker size. Also made a boost leak testor out of a PVC cap and air fitting . I'm gonna try to boost leak test soon to see if my cts charge pipes are also not sealed against the turbos. However with my times and no codes I highly doubt. Always nice to check though!

Do a smoke test. Then you are able to see exactly where you have leaks in the system.

[tomlong]

Best IATs I've achieved on OEM unmodified air intakes with K&N filters was 8F above ambient under light load. Highway cruising with rpms @2k

Best IATs I've achieved in WOT is 14F above ambient on OEM unmodified intakes. No scoops either.

Both measured during Summer. I would expect better numbers as temperatures drop with seasonality.

I think these are good results for stock air intakes. Personally, I don't need to hear the sound of my turbo spooling to remind me I drive an F8x M car from BMW.

[Twistm4]

What I find interesting is overall peak iats are lower with the cones than OEM. Also, heat shield helped a lot. Without a doubt the drivers side Intake is the one that gets blazing. One piece of aluminum made a big impact in city driving iats.

[Twistm4]

So to conclude this. Going fully catless and intakes in cool weather with air feeds does make the car faster. Averaging the final 3 dragys after those two mods car was running consistent 7.0s 60-130 on an off the shelf tune which is nuts.

It's currently getting sent to moon via ProSpoolFreaks on MHD and car is absolute monster up top. Hope to get some deep 6s soon!

[jballer123]

Great work, thanks

[jpy1980]

Ah but all this testing hasn’t answered the most important question of all. The most important factor for all of us here. The main reason why we get these intakes..........

Which one sounds the best?!!! Hahahah