Desnorkel vs Cold Air Intake
 

Hey y'all....
I've searched, and while there is plenty of discussion in both topics, I haven't found anyone who has compared the sound of a desnorkeled car to one with a CAI.
Can anyone comment? I'm interested only in the sound, for now. I've desnorkeled, but if a CAI is noticeably throatier, I'll do that.



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The stock 986 already has a cold air intake, but it definitely sounds better without the snorkel.
If you're referring to a K&N type setup with a cone filter (or other) inside the engine bay, not only will that muffle sound, but it will become a hot air intake.

Thanks, yes I saw the disambiguation on other threads as well, so i could've been more clear.
I would not simply remove the airbox and ad a cone filter, letting it breathe hot air. There are any number of CAI kits on the market that include a panel and gasket to isolate the cone type filter from the engine bay. (I guess an important part of this discussion then, could be how effective this isolation is? )

Here's the thing: I test drove an '02 S before I bought my '03 S. The 02 seemed to have a much more pronounced 'snort' from the air intake than my desnorkeled '03. That sound was part of my decision to buy a 986. I'd like to find it.

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the difference then is panel filter vs cone filter (either is in a plastic box on the side of the engine bay). not sure there is much difference soundwise.

most of the cold air kits come with the pipe from intake to throttlebody, as such they do-away with the helmholz chamber on the oem intake pipe - try removing that (plug the opening) and see what happens.

Ok.... that's a new word for me.... I gotta go look it up.... haha.

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it's that weird warty thing on the intake pipe - designed to muffle the intake sound to meet noise regs (and perhaps provide a tiny bit of low end power. perhaps).

I went from a desnorkeled intake to cone / barrier setup. It is significantly louder under load.

http://i.imgur.com/f72Nejyl.jpg

Nice first - hand - response! Thanks! Which cone / barrier did you get? Any down - side? (Seems some have postulated there COULD be a slight loss of low-end torque. Interesting that radiumking suggests the same could be true of removing the hemorrhoid box) (COULD be, he says. And there's the rub: most of us never follow these mods with a dyno run, haha)

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Thanks RK! I'll take a loom at it this weekend!

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uhm...how about desnorkel + race filter (BMC or K&N)?
A little bit more power and way more intake sound.
That way you won't have all the hassle with the cone cold air intakes, because it is all easy fit plug'n'play.

I would wager that removing the factory cold air intake and replacing it with a warm/hot intake would result in a loss of HP on a dyno.................

Just rip all that stuff out and put a K&N in there. The engineers at Porsche don't know how to make a car sound good. Right? :cool:
...or is there physics involved? I read about this stuff once and had a basic understanding, maybe you can too.
Pressure waves, harmonics, volume, length, clean flow vs disturbed, ... Way too much engineering involved for me to think I could make it better with a little sheet metal, some PVC, and a generic filter system.
Simple:
https://itstillruns.com/air-intake-resonator-do-12156112.html
For the engineers:
FLUID DYNAMIC STUDY OF INTAKE MANIFOLDS OF INTERNAL COMBUSTION ENGINES IN PRESENCE OF ACOUSTIC RESONATORS

Thanks bran, hadn't considered this.... probably should.

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Jfp of course your theory is sound, the question remains: How effective is the "shroud" at blocking the heat? As far as insulating qualities of the materials, clearly the thin abs used by the factory for the intake tube and airbox is not an efficient insulator. But it is somewhat sealed from the warm air of the engine bay. So how effective are the panel and gasket in comparison?



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If you look on Pedro’s website, he shows a cost effective method to remove the hemholz box and make it a straight pipe from the MAF to the throttle body. Nice thing is if you don’t like it you’re only out ~$30 and some time.

Wow.... what an incredibly snide and condescending response. But I'll play along.
To suggest that somehow the engineers at Porsche read my mind and designed this system to meet MY specific needs or desires is preposterous. I'm sure the amount of noise I'm looking for would be considered unacceptable by many, or most, and CERTAINLY by most DOT standards. And if you think that the system installed by Porsche can't be improved upon, you're sorely mistaken.
As to the physics: while this is my first Porsche, I've built plenty PLENTY race motors, both superbike, muscle car and even a little fiat 1.8L that'd wind to almost 9k: the way "the physics" say something should work is not always the way it works, because your basic calculations don't take into consideration all of the other variables. So you go ahead and sit on your unmodified car (because Porsche clearly optimized everything on this car, so why would you change ANYTHING, and for that matter why would Porsche ever build another car if they got it right this time?) While you convince yourself that the wave modulation of the hyfendufenator serves to counter the harmonics of the filter bearings.....
Me? I'ma go ahead and tear out all KINDS of useless crap that Porsche designed and installed because they were required to compromise, like every other automotive engineer and manufacturer.

How'd I do? Did I accurately match the tone of your post? ;-)

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Thanks! I'll take a look.

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The air in the engine compartment on these cars is hot, that is why they put a fan in there to aid cooling. Hot air does not make as much power as cold air, period. That is why Porsche put the factory cold air system in in the first place.

Yes and no. I have never made a 1.8 Fiat engine that could wind to 9k nor do I aspire to. From your original post it seemed that you may not have known much about the design of the intake. To me, making significant changes to the intake, just to make a better sound without consideration to the purpose of the design could be a mistake. I wanted to make it clear that there is a purpose for the "weird warty thing" you didn't know about - pass on some of what I have learned.

http://986forum.com/forums/uploads02...1522419318.jpg

In answer to your original question:
My snide response for the day - How about an Android app and some good speakers?

https://www.roadandtrack.com/new-cars/car-technology/news/a21724/how-to-make-your-prius-sound-like-it-has-a-v-8-33857/
http://986forum.com/forums/uploads02...1522418538.jpg

agreed.. but ignores the question: how effective is the shroud/gasket? The air travels the same path whether into the factory system or another filter, IF that filter is effectively blocked from drawing air from another source. Perhaps I'm missing something obvious, JFP, and that's why I keep coming back to the same question, and you keep giving me the same answer, haha. My knowledge on this car is so far only about surface-deep. I haven't had any time to even crawl under it yet.

lol...holy shnike, guys...is there a full moon coming? :rolleyes:
If it is about sound...rip out the snorkel and replace the paper filter with "race" BMC (or whatever) filter (it is a 1:1 filter replacement with higher AIRFLOW and LESS filtering, NOT a cone filter system)...That was the Task, this is the answer.
Question: Isn't higher pressure and faster/better airflow at least equalizing air temperature?
Now go at each other if you must, but behave like gentlemen! :cheers:

HAPPY EASTER :D

the aftermarket cold air intakes tend to be open-topped, designed to seal against the engine cover. this seal is very imperfect. as a result some hot engine compartment air gets injested and lowers power.

other factors are heat sink - cheaper aftermarket cold air intakes are metal and will heat soak. benefits of the cone are more filter area, as well as less perimeter in contact with with other intake elements so as to reduce heat soak. unfortunately, all aftermarket cone filters i am aware of are resuseable and as such require oiling which can cause issues with mass airflow sensors downstream. this is why most folks that are into tinkering go with the 987 airbox - oem disposable paper cone filter in a a cold air intake with better airflow than the 986 unit.

while you specifically stated that you didn't care about power, other folks seem to care about that for you so ... hot air will kill power at all levels - low load torque, wide open throttle horsepower. other things you do to 'improve' airflow in the intake (remove the helmholz chamber, reduce restrictions, increase diameters to improve airflow) will detract from the tuning of the intake system envisioned by porsche. this tuning was intended to accelerate airflow at lower rpms, facilitate cylinder fill, and improve torque at low rpm. this same tuning introduces restrctions at higher rpm that impacts hp numbers. so, you have to ask what you want - torque or hp. and ultimately we are talking a few, under 5 for sure, '# or hp. again, the hot air is a big killer at all rpm levels.

but ultimately, the only real data point you have is alm - he put in a cold air intake with a cone filter and sound improved. ask, however, did he do this in conjunction with desnorkling - how much of his sound improvement was a result of the snorkle being removed?

My point is that you have to have a sealed air path from the outside to the throttle body; some of the posted photos show open filters, which are going to suck in hot air with out that seal, losing HP. Most of the jury rigged attempts at this we have see leaked air like a sieve......

Hahaha...I just bought the app for iOS 11, damn it is not working (screen freeze), not sure if it is a scam :D
But yeah, it would be a helluva fun to run my Boxster, with a Prius, Fiat Cinquecento or VW 1300 Sound. Gotta get in contact with the dev. Thanks for the great find. :D

y'al are awesome. Thanks for all the replies. ALL of them!
So here's where I should clarify some things:
It's not that I'm not interested in power... I am. This is why I'm interested in any REAL power losses that have been experienced. JFP's reasoning is very sound, but the practical application of theory is not always noticeable. That's why I was looking for something quantifiable, or even an "I installed xyz and felt a noticeable seat-of-the-pants drop...." sort of anecdotal evidence.

What I'm finding is that y'all don't seem to trust the ability of the aftermarket setups to insulate / isolate the warm air from the intake. It makes sense, of course. Though I have a setup like it on another vehicle which is actually QUITE effective, and seals tightly against the hood. But that's a front-engine V8.... very differnt situation. If the setup can't keep warm air out of the intake, then it's a step backwards. If it can't insulate the engine sound from the intake sound, then it's even a step backwards in sound, (for my tastes).

But maybe the hyperbole can that JFP described in his post is a place I can start, as well as replacing the filter with a less-restrictive one.

I am not a newcomer to making power, or modifying vehicles, or racing them. I Am a newb when it comes to Porsches, and mid-engine cars in general. So I'm approaching this as being interested in learning what y'all know. No sense reinventing a wheel that's already going. That's much better than me coming in and acting like I know everything, right? BUT: I'd like to understand it and weigh it against the knowledge I've already got under my belt. I'm not a guy who'll ever just buy and install a product (or worse yet: leave one intact) just because somebody else says I should. That'll ALWAYS be followed-up with a "WHY?"

And to be clear: I"m a smart-ass at heart. I like it when someone sends me a reply like the on below by cb350 (or whatever) because I can put on my smart-ass hat, and not feel bad. :-) I also assume others are not mean.... so no harm where none's taken, right?

well, it seems your not sure what you want. power? sound? fluid dymanics tutorial? perhaps consider that before you call-out other forum members.

Seriously?
I swear..... communication skills are beyond those who don't wish to communicate.
I've been quite clear, I want the sound. I said so in several instances. I then clarified that I'd prefer not to sacrifice power, but I haven't seen any evidence that the one precludes the other.
And you gotta admit that I didnt call anybody out at all.... I responded in kind to a reply. Thats it.

C'mon people....

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Hyperbole? We have had the pleasure to work on a couple of the GT Cup cars over the years, and interestingly, they run the stock OEM air filters, not aftermarket air filters or cold air packages. When asked why, we were told point blank: They didn't add anything performance wise, just more intake noise. No low restriction or oiled filters, just the plain old OEM paper filters. And believe me, these guys analyze absolutely every part on the car, only use what makes it faster.

A few years back, we had the opportunity to watch a series of dyno pulls on a 986 that was trying out a bunch of things, ranging from different cold air intakes, intake modifications, and filters; to aftermarket exhaust systems. And while some of these products added more noise, none of them made any measurable or repeatable power increases. So unless you are counting the weight lost from your wallet by purchasing this stuff, there ain't much to be had.

If you are out to make the car louder, fine; just don't expect real performance jumps.

Sorry JFP, my phone changed helmholz to hyperbole. It changed it to hemorrhoid in another post, so.... Hahaha.

No, I appreciate all of your responses and help. You've obviously got a great deal of experience with these cars, and your willingness to share is fantastic. Thank you.

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Not a problem, I have the same problem with the spell checker on my phone......

Maytag, you don't know the half of it. JFP has provided more guidance and support to 986 owners here than you can imagine. He is always straight forward and honest with what he says and you can ignore his advise at your own peril. He has helped me with everything ranging from spark plugs to transaxle fluid and cooling systems, all within this forum.

and that sent me down the Craigslist rabbit hole looking for a CB 350 Four to buy or 550, or 750. I love those old 70s Honda Fours and its coming back to the season for a bike. Nothing local, but I found this on eBay:

http://986forum.com/forums/uploads02...1522441133.jpg

For you: Cut out the resonator or do the Pedro mod, and get the filter suggested by Bran. With the happy sound, you won't likely miss the HP/Torque from the resonator. Plan for a 550 SE or 987 airbox in your future with a tune and larger throttle body.
Look for stuff like this on the forum:
http://986forum.com/forums/performance-technical-chat/32074-987-v-986-air-box.html
http://986forum.com/forums/diy-project-guides/55966-intake-plenum-911-throttle-body.html
http://986forum.com/forums/show-tell-gallery/56928-bang-buck-mod.html

Lots of different personalities and communication styles on this forum. Now, go here and tell me what "maytag" is about? http://986forum.com/forums/boxster-general-discussions/70622-whats-story-behind-your-forum-name.html

absolutely. Thats the benefit of these types of forums: guys like JFP. And so many others, even those who've tried and failed, and shared what they've learned.
As I get more experience with this car, I'll hope to be able to contribute as well.... from both the "here's what I know" and the "here's what I tried and failed" perspectives.

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Hmmm..... great post. If that seal to the engine cover sucks, then it's quite clear it's a no-go. Your costs about heat soak are also important, and are things we worry less about on a front engine car where the incoming air cools the intake tract which is in front of the motor. (Though it can still be an issue, for sure)

The car isn't a rocket ship, by any means. Throwing money at it to try to find a couple hp will probably frustrate me.... So I'm not gonna. But it needs to make me smile when I drive it.... And that's so much about sound for me.

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A man after my own tastes. I spent a season racing an RD400 in vintage classes... what a nasty fun little beast. Power was insane... And the throttle was a light switch. Those old CB's were bullet proof and would do anything.

I think you're on the right path for me, for this intake sound I'm looking for. I need to put my eyes on the helmholz that JFP is talking about and device on that too.

Thanks again y'all!

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the cb's are going up in price - lots of aftermarket for them as people convert them to bobbers and cafe racers.

hp is tough to find on our cars, but there has to be more to be found. bmw gets 360 hp out of the normally-aspirated s54 3.2 litre engine right from the factory - more than 100 hp/litre. our 3.2 shares the bottom-end and important parts of the heads with the 3.4 that was put in the 996, yet the 996 makes more hp/litre (what, 78 vs 88). if internals are the same, the lost hp has to be in the intake, exhaust, and programming. i can understand when jfp says that the cup cars are fine from the factory as they are a race-bred automobile, but the 986 is a de-tuned civilian car that, if you believe the conjecture, was further de-tuned so as to not detract from 996 sales. given that, there has to be power found in intake, exhaust, and tuning improvevments. i find it hard to believe that jfp was unable to realise any gains in his testing on our cars - and i state this only to generate discussion and get his input on the matter, not to be a jerk. most of my work has been with adapting 996, 997, and 987 components to the 986 in an effort to incorporate oem porsche design improvements. in the threads previously referenced - 987 airbox, 987/996/997 throttle body, 996/997 intake plenum, 996 programming, 987 exhaust, etc. if we can get to 996 hp/displacement levels then 280 hp should be possible.

for what it is worth; i've got absolutely no dyno proof to back me up.

Yeah, so... my fear is that I could spend a FORTUNE trying to find HP in this car.... and it'll still be just a fun car.... it already is that.... there are much cheaper ways to go fast, if that's what I wanted to do. And ultimately, this 986 is the "consolation prize" that I bought when the offer I made on the car I really want was rejected. But I've still got my eye on that car, so I don't want to dump that budget into this one. haha

It's just fine being a "fun car". Cheap giggles. y'know?

Looking at this in the simplest form, the purest way to add sound and power (without adding compression psi or chilling air) is to run a straight unfiltered intake and a direct exhaust (removing the muffler). Obviously this solution would be, well stupid, but if you look at it on a prismatic scale with this option being infrared and the other end (sealed intake and exhaust...which would be the most quiet and least power) being ultraviolet, the task at hand is to try and move the needle as far infrared as possible. Now here's the crux...how? For me this is a rabbit hole that I personally didn't want to fall into, because once you do, the bottom is unreachable and the only result is going to be some sort of compromise. Let's focus on that word...compromise. And the other word of the day, trust, because without trust, no compromise will be acceptable.

So, now let's look at engineering, or to be more specific, engineering in a large corporate environment. Porsche engineers (I assume) would like to keep the needle in the far infrared range, but there are some constraints...cost, regulation, (litigation?), and also not to build an entry level car that out performs higher end models; so we end up with compromise. Now as the owner, I fully understand that compromises have been made, but I'm ok with that...because I trust that the compromises were at least true to the basic core beliefs of Porsche, and that even though they colored inside the lines, they colored to the very extent of the lines...it's possible they didn't, but I choose trust over paranoia. Could I improve on the compromises made? Sure. Would I feel like I violated trust? Maybe. But knowing who I am, if I start re-engineering in one area, I won't be really happy until I fix every compromise or perceived compromise, and before I'd know it, I'm midway down that darn rabbit hole with exponential velocity...and in the end I'd just end up with a compromise anyway.

So lets see if I got this right.

You are going to make some mods. And you don't think that Porsche engineers with multiple tries at getting it right and with a dyno at their disposal had a chance at getting better results out of their multiple tries than your single "I know better" mods?

It is your car and I wouldn't begin to tell you how your car should sound. I can, however, tell you that our ears are only designed for so many vibrations at any given set of amplitudes and your future hearing aids will probably cost you as much as all of the mods you are planning.

Be sure and dyno the before and after. Some who have mod'ed hundreds of M906 engines have.

porsche engineers designed the ims yes? i always think of that when i get the "porsche knows better' stuff used as an argument.