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Sym322
Monza


Joined: 25 Dec 2011
Posts: 235
Location: Greater Manchester


PostPosted: Fri Jan 15, 2016 3:48 pm    Post subject: 997.1 GT3 Air Filter Change Reply with quote

Hi guys, i have a 997 gen 1 GT3 and would like to change the stock air filter for a BMC one.

Can this be done in situ?

Thank you in advance Thumb
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Stuart
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PostPosted: Fri Jan 15, 2016 4:39 pm    Post subject: Reply with quote

You'll need to remove the air box, very easy to do. Unclip MAF, undo clamps around intake connection, undo bolt holding air box by latch, wiggle a bit and it's out...

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Sym322
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PostPosted: Fri Jan 15, 2016 5:20 pm    Post subject: Reply with quote

Thank you very much, seems very straight forward thumbsup
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Roro
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PostPosted: Fri Jan 15, 2016 7:21 pm    Post subject: Reply with quote

Very easy, exactly as described by Stu. Even I managed to do it Grin
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hopeydaze
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PostPosted: Wed Aug 08, 2018 6:54 am    Post subject: Reply with quote

I’m curious - why make the change? I have a 997.1 GT3 and I would hate to think I’m missing out on something
 
  
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Senoj
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PostPosted: Wed Aug 08, 2018 8:43 pm    Post subject: Reply with quote

hopeydaze wrote:
I’m curious - why make the change? I have a 997.1 GT3 and I would hate to think I’m missing out on something


Youre not, wont make any difference.
 
  
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Roro
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PostPosted: Wed Aug 08, 2018 9:05 pm    Post subject: Reply with quote

I can’t even remember why I made the change in the first place. I may have read somewhere about better flow or something, but don’t think there was much difference if any
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RL1989
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PostPosted: Wed Jan 02, 2019 4:59 pm    Post subject: Reply with quote

I work for an OEM designing induction systems...given the filter surface area on a 997 there will be absolutely zero real world difference in performance, however there will be a dramatic increase in dust particle size and quantity ingested into your high performance engine.

Stick with the standard filter element and replace with genuine parts on a regular basis. The difference between a clean and dirty filter element is larger than the difference between a standard and aftermarket filter.
 
  
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Phil 997
Le Mans
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Joined: 05 Dec 2015
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2009 Porsche 997 Carrera 4S

PostPosted: Wed Jan 02, 2019 5:51 pm    Post subject: Reply with quote

RL1989 wrote:
I work for an OEM designing induction systems...given the filter surface area on a 997 there will be absolutely zero real world difference in performance, however there will be a dramatic increase in dust particle size and quantity ingested into your high performance engine.

Stick with the standard filter element and replace with genuine parts on a regular basis. The difference between a clean and dirty filter element is larger than the difference between a standard and aftermarket filter.


Have you looked at a BMC filter , they actually filter to a smaller micron particle than the stock paper one , so interested to understand how it can take in more particles , seems it would be less . I am no filtration expert so keen to understand the technicalities of your post. Dont know Question re whether they actually do anything performance wise is always a great topic of discussion , personally having have them on both my gen1 and gen2 non GT cars, I am in the camp that says YES you can feel a bit more but more importantly IMO that horrific wheezy flat 6 engine sound that the stock filter gives will go and the car will sound like it breathes so much better and rev much more freely. I am always happy to debate it with those that have tried a sports filter but most of the time those against have never actually tried it. Do note that if the car has a Porsche Warranty then you cant do it. Thumb Thumb
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RL1989
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PostPosted: Thu Jan 03, 2019 10:31 am    Post subject: Reply with quote

Phil 997 wrote:
RL1989 wrote:
I work for an OEM designing induction systems...given the filter surface area on a 997 there will be absolutely zero real world difference in performance, however there will be a dramatic increase in dust particle size and quantity ingested into your high performance engine.

Stick with the standard filter element and replace with genuine parts on a regular basis. The difference between a clean and dirty filter element is larger than the difference between a standard and aftermarket filter.


Have you looked at a BMC filter , they actually filter to a smaller micron particle than the stock paper one , so interested to understand how it can take in more particles , seems it would be less . I am no filtration expert so keen to understand the technicalities of your post. Dont know Question re whether they actually do anything performance wise is always a great topic of discussion , personally having have them on both my gen1 and gen2 non GT cars, I am in the camp that says YES you can feel a bit more but more importantly IMO that horrific wheezy flat 6 engine sound that the stock filter gives will go and the car will sound like it breathes so much better and rev much more freely. I am always happy to debate it with those that have tried a sports filter but most of the time those against have never actually tried it. Do note that if the car has a Porsche Warranty then you cant do it. Thumb Thumb




Yes, i have looked at them.
BMC filter elements are filtered down to 7 microns according to their website.
Since the filter elements are constructed of cotton gauze, this level of filtration is achieved by oiling the element (Important for later)
BMC's website incorrectly states that OEM paper elements filter to 10 microns, this is not the case. Particles as small as 0.5 microns are trapped by standard OEM filter paper.

The performance of filtration can be measured with the efficiency (% dust particles removed).
Paper elements are generally >98% efficient when new, and are >99% efficient when loaded with dust.
Oiled cotton elements such as BMC and K&N ands around 90% efficient, and only ever reach around 96% efficiency.
How does this impact engine wear? Well, any particle which is larger than the underlying film thickness with cause damage and wear. This film thickness varies from 0.1 - 20 microns. The larger the particle size the greater the relative wear.
To put this into context, a gram of dust erodes 2.5 - 5 microns of cylinder lining.
The capacity of BMC / K&N filters is also lower (Due to the shorter pleat heights and number of pleats), which means they have to be cleaned more regularly compared with swapping out your OEM filter.
Once cleaned they need to be oiled again, as mentioned earlier the oiling of the filter is what provides the fine filtration.
Not enough oil and you no longer filter down to 7 microns, in fact you barely filter anything at all, Just take a look through a BMC filter looking into a bright light, you will see sizeable gaps in the gauze not found on paper elements.
Without oil the efficiency would be comparable to foam elements at around 50-60% initial efficiency,
Too much oil and you risk contamination of the MAF.


Pressure loss improvement varies, but cotton filters usually have around ~15-30% lower pressure loss, this varies hugely depending on the filter surface area vs mass flow rate (Therefore flow velocity).
However, filter elements take up a very small portion of overall induction losses. To put this into context, on one of our products the improvement measured in PS was lower than the noise of the dyno measurement, around 0.2PS.

The improvements marketed to people are based on maximum flow rate achieved for a given vacuum, the numbers are not relevant to the real world.
As mentioned in my earlier post, i would expect the flow velocity through the filter element on a 911 to be much lower than that of other mass produced hatchbacks, therefore the relative improvement would be lower.
the standard layout on a 911 is very good indeed and i would not look to make home made improvements.
Any improvements you feel is purely down to placebo.

I know for a fact several well known tuning companies fit K&N style elements not for real world impact, but because it is easier to market the kits as the customer feels they are getting more value for money.

Ask yourself, why would Porsche fit paper elements if this was a limiting factor in performance?
We are not talking about run of the mill hatchbacks with 1-2% profit margins here.

Last edited by RL1989 on Thu Jan 03, 2019 2:40 pm; edited 1 time in total
 
  
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Phil 997
Le Mans
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2009 Porsche 997 Carrera 4S

PostPosted: Thu Jan 03, 2019 10:43 am    Post subject: Reply with quote

Thats just the type of answer I like , and an excellent counter argument for the sports filters .
Thank you for explaining in detail it will certainly allow for a better understanding about filters and allow us to at least go in eyes open if we choose to do this mod.

The performance gains are at best minimal I agree, but my big win with them is the freely breathing engine. whats your thoughts on the way they rev more freely and sound less wheezy without the restrictive paper filter and with a sports filter . can this be overcome with a better solution than a sports filter or is that just the downside of having 98% filtration .
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RL1989
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Joined: 20 Mar 2016
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PostPosted: Thu Jan 03, 2019 2:12 pm    Post subject: Reply with quote

Phil 997 wrote:
Thats just the type of answer I like , and an excellent counter argument for the sports filters .
Thank you for explaining in detail it will certainly allow for a better understanding about filters and allow us to at least go in eyes open if we choose to do this mod.

The performance gains are at best minimal I agree, but my big win with them is the freely breathing engine. whats your thoughts on the way they rev more freely and sound less wheezy without the restrictive paper filter and with a sports filter . can this be overcome with a better solution than a sports filter or is that just the downside of having 98% filtration .


No problem, Smile
How the engine revs is determined by the reciprocating mass (i.e flywheel) and the available torque (Directly related to volumetric efficiency).
As mentioned the filter element is only a small portion of the overall intake losses, so a small improvement in a small portion of the overall intake losses will have very little impact on volumetric efficiency and therefore torque.
In my experience exhaust back pressure losses impact an engines volumetric efficiency more than intake losses anyway.

The data doesn't lie, the only measurable impact on how freely the engine breathes with a new filter is the improvement in pressure loss within the induction system, and we know this to be very insignificant. Anything you feel is your perception given the change you know you have made Thumb

As mentioned i would look to replace the standard element regularly if you want to keep filter losses to a minimum.
If you wanted to reduce intake losses significantly then replacing the entire air cleaner with a cone filter would improve the losses i would imagine. However this opens up a new can of worms with hot air ingestion.... warmer air reduces charge density - undoing all your good work on pressure loss. The stock system is a cold air intake, most of the aftermarket kits you see are not.
Stick with the standard system would be my advice.

Last edited by RL1989 on Thu Jan 03, 2019 3:16 pm; edited 1 time in total
 
  
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Stuart
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PostPosted: Thu Jan 03, 2019 2:36 pm    Post subject: Reply with quote

Great info, thanks 👍
 
  
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Phil 997
Le Mans
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2009 Porsche 997 Carrera 4S

PostPosted: Thu Jan 03, 2019 4:18 pm    Post subject: Reply with quote

RL1989 wrote:
Phil 997 wrote:
Thats just the type of answer I like , and an excellent counter argument for the sports filters .
Thank you for explaining in detail it will certainly allow for a better understanding about filters and allow us to at least go in eyes open if we choose to do this mod.

The performance gains are at best minimal I agree, but my big win with them is the freely breathing engine. whats your thoughts on the way they rev more freely and sound less wheezy without the restrictive paper filter and with a sports filter . can this be overcome with a better solution than a sports filter or is that just the downside of having 98% filtration .


No problem, Smile
How the engine revs is determined by the reciprocating mass (i.e flywheel) and the available torque (Directly related to volumetric efficiency).
As mentioned the filter element is only a small portion of the overall intake losses, so a small improvement in a small portion of the overall intake losses will have very little impact on volumetric efficiency and therefore torque.
In my experience exhaust back pressure losses impact an engines volumetric efficiency more than intake losses anyway.

The data doesn't lie, the only measurable impact on how freely the engine breathes with a new filter is the improvement in pressure loss within the induction system, and we know this to be very insignificant. Anything you feel is your perception given the change you know you have made Thumb

As mentioned i would look to replace the standard element regularly if you want to keep filter losses to a minimum.
If you wanted to reduce intake losses significantly then replacing the entire air cleaner with a cone filter would improve the losses i would imagine. However this opens up a new can of worms with hot air ingestion.... warmer air reduces charge density - undoing all your good work on pressure loss. The stock system is a cold air intake, most of the aftermarket kits you see are not.
Stick with the standard system would be my advice.


Thats great info and nicely leads me on to my next question , I am about to fit a fab speed performance induction kit, this consists of a twin cone filter set up feeding into a carbon Y pipe ,it is only protected from the engine bay by a carbon shield , now as you pointed out and was my concern this would draw in warm engine air , I didn't do this to my gen1 as it had a true cold air sealed airbox but on the gen2 the bottom of the airbox has big holes covered in mesh to allow water to drain out , this seems to have changed my thoughts as it cannot be true cold air with these big holes in the engine bay . So with this in mind I looked at the fab speed they had run tests showing that due to the size of the intake the air was moving so much more quickly that infact it was colder entering the throttle body that air from a stock set up. which kind of made sense which is why I brought it . but it would be interesting to hear your thoughts on that theory. Thumb Thumb
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Last edited by Phil 997 on Fri Jan 04, 2019 2:26 pm; edited 1 time in total
 
  
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RL1989
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PostPosted: Fri Jan 04, 2019 2:19 pm    Post subject: Reply with quote

Just had a look at this fabspeed system and there is certainly a possibility of drawing in hot air vs the standard system.
The intake ducts on the engine cover do almost meet the cone filters so the system has been design with the consideration of hot air ingress, however there are large gaps around the edge of the shield so it would only be partially effective - even with the fan drawing in cool air when the engine bay gets too hot.

On the subject of drain holes, whilst all air cleaners should have drain holes, the amount of hot air drawn in would be minimal, some drain holes are covered with a drain valve, basically a little upside down rubber umbrella that seals against the air cleaner under vacuum, this would prevent any hot air ingress if you were that concerned.
Even with the drain holes i would expect the charge air of the standard system to be lower than the fabspeed system.

As for flow velocity, the air velocity at the throttle body will not be travelling any faster with the fabspeed kit.
The mass flow rate of the engine is the same and the throttle body diameter is the same therefore all things (temperature and pressure) being equal the velocity will be equal.
If the fabspeed kit reduces pressure losses within the induction system then the air velocity at the throttle body would actually be lower (Since Bernoulli's equation tells us for a given mass flow rate, if the pressure is higher the velocity will be lower).
In any case, you actually want lower velocity within the air induction system as pressure losses square with velocity (As per drag on a vehicle).
The slower you can move the air for a given mass flow rate the lower your losses will be(Different scenario in inlet ports as you want velocity for inlet ramming effect at high RPM).
Remember, any increase in pressure loss degrades the engines volumetric efficiency.
Sounds to me like marketing speak from fabspeed regarding inlet velocity and temperature - especially with comments on their website such as "CAD designed for maximum air flow".

Looking at the 997.1 vs 997.2 systems the 997.2 system is an improvement. two large inlets would reduce losses into the air cleaner vs the 997.1 with the bend before the air cleaner entry.

Its hard to say how the pressure losses of the fabspeed system compare with the standard 997.2 system, but i would think that there isn't much in it.
The fabspeed is probably better but any improvements in pressure loss could be cancelled out by charge temperature if the fabspeed system does ingest more hot air.
The fabspeed kit also looks to use cotton gauze filters which i don't like as discussed earlier. The standard filters actually look a little bigger than the fabspeed filters to me, which could mean the filter losses are about the same.

The biggest difference for sure will be intake noise. You completely lose the attenuation from the large volume air cleaner acting like a large spring damper.

Overall, do i think there could be some performance improvement from the fabspeed kit? yes possibly, but probably not noticeable in the real world.
The 16 wheel HP improvement stated on their website certainly seems very very optimistic to me. Launch performance in hot temperatures is likely to suffer due to hot air ingress.
Up to you if you are willing to live with the extra dust ingestion into the engine for a possible marginal improvement in performance and more noise Cool
 
  
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Phil 997
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2009 Porsche 997 Carrera 4S

PostPosted: Fri Jan 04, 2019 2:41 pm    Post subject: Reply with quote

Thank. you again for that informative view , nice to read info from someone who business is the subject in question. rather than a speculate reply based on an assumption . Certainly given me food for thought and also will I am sure help others reading this thread and allow them to make a decision what they want do.
My personal feeling is the fab speed induction kit appears to draw more air in than the car can compensate for, meaning you really need a remap this would then give you the BHP gains that they claim , although as said clever marketing wording avoids explaining this in detail allowing them to take the full credit for the gains Grin I have got a full 200cell cargraphic performance exhaust to hopefully increase the speed of exit gas while still allowing enough back pressure to not be detrimental to the science behind induction and exhaust Thumb
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RL1989
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PostPosted: Fri Jan 04, 2019 3:33 pm    Post subject: Reply with quote

One thing to remember is that the engine as standard is probably operating at very high volumetric efficiencies - the standard system is not acting as a ceiling to the limit the volume of air the engine can ingest.
Once 100% volumetric efficiency is reached for example, the only way further air can be ingested (Excluding pulse tuning) is with forced induction.

Yes, whilst not operating at 100% volumetric efficiency there are gains to be had, however lowering intake losses will not create a surplus of air as such that can be exploited with a remap (Volume flow rate would still be the same as this is determined by Swept volume / RPM * Engine RPM), but will marginally increase the pressure of the air charge (And therefore the mass flow rate of the air / volumetric efficiency)
The only way of remapping a naturally aspirated car for more power / torque without adjusting cam timing is to increase spark advance, usually limited by pre-ignition / detonation, this goes back to charge temperature as increased charge temperature increases the likelihood of pre-ignition.


Take a look at the 997.2 GT3 RS intake, very similar to the standard set up of a 997.2 Carrera.
The main difference looks to be the larger opening cross sectional area of the air cleaner inlets vs base carrera due to the higher mass flow rate of the engine.
If the fabspeed set up was better the RS set up would have followed suit.

Again, if you can keep air charge temperature the same and reduce intake losses there are marginal gains to be had, but looking at the differences between standard and fabspeed, i would expect them to be marginal as the base system looks very nice indeed and in all likelyhood the engine is already operating at very high volumetric efficiencies Thumb

Your reduced exhaust back pressure will probably help though Bandit
 
  
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Senoj
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PostPosted: Fri Jan 04, 2019 7:51 pm    Post subject: Reply with quote

Interesting read, thanks for taking the time Question


Can I say I was right then Floor
 
  
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Phil 997
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PostPosted: Fri Jan 04, 2019 11:47 pm    Post subject: Reply with quote

That really was an interesting read , I feel considerably more knowledgable about induction now , kind of killed the theory a bit that Porsche amongst other things, use the induction and exhaust as simple ways to restrict the Carreras from getting too close to the flagship models thus killing the sales of the flagship cars.
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DucatiRob
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PostPosted: Sat Jan 05, 2019 11:19 pm    Post subject: Reply with quote

This is a really interesting thread!

Making me think about the problems I had with the twin cone filter I fitted when I had the turbo wing on. Different to the Fabspeed setup in that the filters were fully enclosed in a carbon box that mated with the seals on the deck lid! The engine just couldn't cope with this set up at all, rough idling and a huge flatspot around 2500 rpm, however it did seem to fly like a scalded cat over 5000 rpm! In the end it had to come off as I was getting CELs and all sorts of fault codes. I came to the conclusion that it was potentially turbulent air over the MAF that could have been the source of the poor running! From the excellent explanations above it would seem that it couldn't have been down to any major increase in airflow/pressure reduction that the ECU couldn't cope with Question
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