Technical Understanding: Intakes: Stock vs. Drop In vs. Aftermarket

[grambles423]

Its been quite a while since I've posted a Technical Understanding thread with some hard data and calculations to further feed our minds. Since most of the conceptual basis of the earlier threads were.....for the least bit.....theorhetical and quite possibly boring, I decided to do a little experimenting (with help from NS01GTI) to collaborate data to compare stock intake with drop ins and aftermarket intakes.

Test Requirements:
- APR K04 93OCT Runs (~366hp ~380tq)
- APR IC (will affect IATs but will remain consistent)
- 3rd and 4th Gear Runs (Data was collaborated in 4th gear due to sample size and output.)
- Consistent Ambient Runs (Or at least within a +/- 5*F Tolerance from our Nominal)
- Stock Intake is a CBFA Intake with no modifications
- VWR Drop in incorporated the deletion of the baffle at the bottom of the air box
- Carbonio was done in two stages: Stage 1 only and Stage 1+2 (PENDING DATA COLLECTION)
- Same stretch of roadway was used
- Variation in Starting RPM Ranged from 200-300RPM in 4th (~2200) and 200RPM in 3rd (2700).
- Redline will be assumed as the normal redline but some logs will be shown past 6600RPM due to the DSG Stage 2 flash (7100RPM Redline) that was added mid testing (DSG Tuning added Post VWR Drop in, Pre Carbonio Stage 1)

Results:
Stock Intake

3rd Gear Run:

4th Gear Run:

Thoughts

Immediately you can see that the stock box will not hold boost properly throughout the entire rev band. Sort of a "dying effect" much like the stock turbo sees.

Boost control is smooth in the midrange which correlates with the peak condition you see intially. Still, the "butt dyno" registers a loss in the system and takes away a lot of the "raw" manly feeling of the K04. You can see the discrepancy from requested and actual better in the 3rd gear log.

Some thoughts in my build thread about the construction of the stock box:

The filter is not the problem. Its a huge geometrical cluster f$%* from RAM Air vent to the MAF:

- Lets start with the ridiculous tubing that leads from the RAM air all the down, with gravity, into the bottom portion of the air box. We're already talking about almost 6" worth of frictional and flow loss.

- Then the air comes at an angle into the box that allows it to sort of bounce around inside without a clear direct path for it, causing turbulent flow into the filter and even more loss at higher RPMS.

- Then the air is pulled, against gravity, into a very restrictive particulate filter then is brick walled by the top of the intake box.

- From here the air has suffered enough, but keeps getting directed into the horizontal port where IMMEDIATELY is greeted by another wall to direct the flow a full 90* into the straight MAF portion. From there....its smooth sailing.

The point of most intakes is to eliminate almost 5-6 different directional changes in the system, where at each point, will create more and more loss as more flow is entering. An aftermarket setup will direction flow into one direction....directly into the MAF.

I stood there looking at this monstrosity as I was installing it and couldnt help but wonder WTF those engineers were thinking in terms of performance. I have a huge appreciation for other designs, but I cant help but wonder that there was an easier way of doing it. Sure, most of it is baffling to minimize sound, but you eliminate cooling factors and flow characteristics.

Takeaway: Stock box is not efficient enough to hold and maintain boost through the rev band an on into the upper RPMS. Also, stock box shows higher IATs up the RPM band even with the APR IC.

VWR Drop In Filter

4th Gear Run:

Comparison

So what does this mean? It seems that the drop ins will actually help alleviate some of the down low restriction and allow the turbo to spool quicker, but will not give any added flow up top. Since in fact that two MAF rates look IDENTICAL at redline, I would be safe to say that its simply not worth it. The boost still dies sharply after the "point" has been reached where the flow just cannot keep up with the requested pressure.

Dont mind the lower value for the Drop in filter for boost at the final point. This could be % error in between measurements on different days. The point to take away is that it did not ADD any "breathing" at higher RPM. Ipso Facto......the stock intake box is just too damn restrictive for the boost to keep matching requested values at the last 1/3 of the rev band.

Takeaway: While a drop in allows for some down low flow to spool slightly quicker, up top the car still cannot meet its requested boost. You're still choking the car at upper RPMs


Carbonio Stage 1

4th Gear Pull:

Looking over the logs, the carbonio decreases lag and onset WAY faster than the VWR drop in and Stock filter and flows more in the higher RPMs, thus allowing to hold boost easier (0.29psi discrepancy between Specified and Actual)

More analysis:
Max Variation Between Spec and Actual After Peak (Negative Denotes Higher Actual Reading than SPEC)
Stock Filter: 2.465
VWR Drop In: 2.32
Stage 1 Carbonio: 0.45

From here, we can see that the maximum variation between specified and boost are much much higher in the stock intake compared to the Carbonio. This easily can prove our theory that WITH an aftermarket intake, you can meet and hold requested boost much easier due to the optimum control strategies by the N75 valve and ECU

Variation Between Spec and Actual At Peak (Negative Denotes Higher Actual Reading than SPEC)
Stock Filter: -1.305
VWR Drop In: -1.16
Stage 1 Carbonio: -1.07

This measurement denotes the difference between Actual and Spec at the peak boost moment. Some discrepancies can be chalked up due to the date of runs and ambient temperatures etc. etc., but you can see that each can peak about the same over the specified value.

This proves you cannot boost higher with either intake. No difference in peak readings.

Average Variation Between Spec and Actual After Peak (Negative Denotes Higher Actual Reading than SPEC)
Stock Filter: 0.68
VWR Drop In: 0.38
Stage 1 Carbonio: -0.15

This measurement denotes the average variation between spec and actual across the RPM band after the peak. you can see that you're actually making a little more boost OVER the requested value with an aftermarket intake.

This proves the point of the "dying" effect in the RPM band of the stock intake.

Range of Variation Between Spec and Actual After Peak (Negative Denotes Higher Actual Reading than SPEC)
Stock Filter: 3.77
VWR Drop In: 3.48
Stage 1 Carbonio: 1.3

The measurement shows the range of variation across the rev band. The higher the rev band the harder the engine/turbo is working to meet/hold the requested boost.

The proves to yield more power across the rev band with an aftermarket intake. You're not really benefitting yourself by running the stock intake on a K04.

Peak MAF Readings
Stock Intake: 236.4
VWR Drop In: 235.8 *******Difference can be error between measurements
Carbonio Full: 258.8

Difference in Peak and Redline Hold
Stock Intake: 5.51psi
VWR Drop In: 5.61psi
Carbonio Full: 3.9psi

Difference in Requested and Actual at Redline
Stock Intake: 2.2psi
VWR Drop In: 2.03psi
Carbonio Full: 0.29psi[/QUOTE]

Takeaway: Data speaks for itself. An aftermarket intake is definitely worth while. Especially one that is sealed off from the engine bay and only pulls cold air from outside the vehicle.

Carbonio Stage 1 and 2

Take Away:
1) More MAF: ~6.2g/s higher (On a 9F hotter day)
2) More Boost Requested: Almost 1psi higher in the upper RPMs
3) Faster Request (Quicker Spool) in Lower RPMs:
4) Slightly Faster Response to Peak: 200RPM Sooner
5) Higher MAF Readings in the Mid Range Except under boost control
6) Equal Tempearture discrepancy from Start to Finish: 5-6*C

All in all the turbo is working less strenuously to boost better but the peak will come quicker asking for the Wastegate to dial it back quicker. This is mostly why people find hesitations in after market intakes besides the Stage 1 portions. However, I dont find too many driveability problems with this.

Additional Intake Comparison Data (Carbonio vs. Modshack)

Thanks to the help of NS01GTI, we were able to get an accurate depiction of the clear differances between the two common intakes seen on this forum. One for Noise control, the other for high performance. Its ultimately the end user's decision to make a choice and what they would like, but for some fun, we decided to take the same data that we did in the previous setup:

4th Gear Run Carbonio:

4th Gear Run Modshack:

Comparison Graphs:

What I immediately saw was the discrepancy in reuqested boost values and actual values again. It seems that the Modshack, while not having the restriction like the stock box, still shows upper RPM boost loss from requested. MAF vales were also very considerably different in the midrange that we couldnt just say there was "variation in the runs" Almost 50-60g/sec more.

The driver also noted the "butt dyno" difference between the two. At upper RPMs the car just felt out of breath.

A quick thought about the sound differences:

Its considerable enough to say that the spool is actually faster on the Carbonio causing a pressure differential in the actual mechanical structure within the carbon fiber. Since carbon fiber has more movement, it has the capability of better transmitting more frequencies of the incoming pressure waves, THAT is why the carbonio is so loud at lower speeds.

Takeaway:
1) Carbonio has more mid range MAF and a quicker spool time.
2) Ambient conditions were different to each run but both IATs got down to the same temperature (~33*C)
3) Modshack has an almost 2psi difference between requested and actual at a higher RPM. The Carbonio seems to hold the boost more.
4) Carbonio log was started at a lower RPM, yet spooled quicker than the Modshack which started almost 200RPM quicker. The Carbonio log was the "hotter" of the two logs in terms of IATs

Conclusion

All in all this was a very fun excersise and it really showed some similarities and differences amongst OEM design, drop ins and aftermarket competitors. While it was VERY hard to keep some variables consistent, we still managed data that can be judged as sufficient for analyzing.

Furthermore, even if the data speaks so much, it helped me (and probably others) understand more of the flow dynamics involved in our little TSI engines. Where's the performance compromise? Where's the sound compromise?

 

[danielj1]

Thread stickied.

 

[Erwan1]

Thanks for the great info!

 

[SkullV]

Thanks!

 

[zVp]

Hmm.. I do like the simplistic look of the Modshack intake, but I do want the extra omph that the Carbonio gives.

Decisions, decisions, decisions...

 

[grambles423]

And see that's where most of us cannot decide. Both have uber appealing qualities about them. It just shows that not all intakes are made the same and ultimate the USER must decide, but that is why we do these types of things is to help the person make their decision. People come on these boards every day and get immediately locked for "Which intake is better?" or "Which tune should I get?" because there is SO MUCH information out there.

I was just more surpirsed at seeing all of the data compared together when doing the logs. I like learning what our car can do and WHY it can do it.

 

[A_Bowers]

This should be the be all end all intake thread.

Noobs take note.

 

[hvltg]

SUPER!
THANKS!
:clap:

 

[grambles423]

This should be the be all end all intake thread.

Noobs take note.

I wish it could be end all. I would be more than happy to do this with EVERY intake out there...but I do not have the money to do so.

If any vendors are willing, I'll be happy to run the data and send the intake back.

 

[A_Bowers]

I wish it could be end all. I would be more than happy to do this with EVERY intake out there...but I do not have the money to do so.

If any vendors are willing, I'll be happy to run the data and send the intake back.

Me too!!!! That would work well for them and for us.

Two local people to eliminate environmental variables.



Hello vendors. I'm here to help!!!!

 

[zVp]

And see that's where most of us cannot decide. Both have uber appealing qualities about them. It just shows that not all intakes are made the same and ultimate the USER must decide, but that is why we do these types of things is to help the person make their decision. People come on these boards every day and get immediately locked for "Which intake is better?" or "Which tune should I get?" because there is SO MUCH information out there.

I was just more surpirsed at seeing all of the data compared together when doing the logs. I like learning what our car can do and WHY it can do it.

And thanks for the write-up!

Honestly, I've always thought the two intakes would be very similar in nature - but as your data shows, they are a bit different.

Before this write-up, I was going to just go with the Modshack since it's simple and I don't really need that extra noise. I thought it would be very, very similar to the Carbonio's performance.

Now looking at this, I'm pretty much stuck. LOL

Oh well - I probably won't get an intake this year since I'm done modding for this year, but this thread will always be my go-to when I decide.

 

[ns01gti]

And thanks for the write-up!

Honestly, I've always thought the two intakes would be very similar in nature - but as your data shows, they are a bit different.

Before this write-up, I was going to just go with the Modshack since it's simple and I don't really need that extra noise. I thought it would be very, very similar to the Carbonio's performance.

Now looking at this, I'm pretty much stuck. LOL

Oh well - I probably won't get an intake this year since I'm done modding for this year, but this thread will always be my go-to when I decide.

Great job compiling all the info, as well as providing analysis and conclusions on the data, Z!

For what it's worth, the volume levels between the Modshack and Carbonio are similar with the window down. The modshack makes a bit more "sucking" sound, while the Carbonio has more Darth-Vader sounds. With the windows up, you can barely hear the Modshack at all, and the Carbonio is louder in comparison. Windows up and tunes playing... Little to no intake noises are heard.

I was just more surpirsed at seeing all of the data compared together when doing the logs. I like learning what our car can do and WHY it can do it.

I agree with this, it was fun. It reminded me that I need to wind out 4th gear more often.

 

[Arin@APR]

Excellent info! Thank you for the writeup! : )

 

[Halvie]

any reason as to why the intake would cause the car to be below requested? Just caused from different conditions during the logs?

 

[grambles423]

Intakes can cause restriction up high. If the compressor is actually trying to pull as hard as it can through a "straw", for lack of a better word, it will not meet those requested values. You're limited physically in the system as opposed to what the computer THINKS it can do.

This is why a lot of track cars have completely open ended compressors.