standard air filter
18 June 2008, 06:27 PM
#1
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standard air filter
I'm thinking of changing my green cotton panel filter on my MY99 back to a standard air filter as I'm worried about the MAF failing on the car.
Am I likely to notice any difference in performance?
Am I likely to notice any difference in performance?
18 June 2008, 07:38 PM
#2
I would say no. You will notice a little less induction noise, which can make you think its less sporty, but as for actual power loss its only really negligible. I also have a MY99 and I have been running a KN filter for years with no problems, I have changed the MAF after a remap, but this was as a precaution not because of a failure.
18 June 2008, 09:16 PM
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ok thanks. I am thinking of going back to a standard OEM filter as I though maybe it will prolong the life of my MAF a bit longer as I heard they're really fragile.
I'm interested to hear that your K&N panel filter hasn't caused it any problems though!
I'm interested to hear that your K&N panel filter hasn't caused it any problems though!
19 June 2008, 02:42 AM
#6
There will be no perceptable performance difference. It may even perform better, marginally on the Subaru O/E filter.
I tested four pannel filters on two consecutive days and the spread from "best" to "worst" was 2bhp.
The O/E filter performed well.
The "best" filter trapped particles less well and the "worst" filter trapped the smallest of particles and was the best fit.
The reason the test was done the second time on the next day was that results were contrary to what I expected but they were the same both times.
Claims that a particular filter on its own adds 5 bhp or more are lies.
I tested four pannel filters on two consecutive days and the spread from "best" to "worst" was 2bhp.
The O/E filter performed well.
The "best" filter trapped particles less well and the "worst" filter trapped the smallest of particles and was the best fit.
The reason the test was done the second time on the next day was that results were contrary to what I expected but they were the same both times.
Claims that a particular filter on its own adds 5 bhp or more are lies.
19 June 2008, 10:45 AM
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There will be no perceptable performance difference. It may even perform better, marginally on the Subaru O/E filter.
I tested four pannel filters on two consecutive days and the spread from "best" to "worst" was 2bhp.
The O/E filter performed well.
The "best" filter trapped particles less well and the "worst" filter trapped the smallest of particles and was the best fit.
The reason the test was done the second time on the next day was that results were contrary to what I expected but they were the same both times.
Claims that a particular filter on its own adds 5 bhp or more are lies.
I tested four pannel filters on two consecutive days and the spread from "best" to "worst" was 2bhp.
The O/E filter performed well.
The "best" filter trapped particles less well and the "worst" filter trapped the smallest of particles and was the best fit.
The reason the test was done the second time on the next day was that results were contrary to what I expected but they were the same both times.
Claims that a particular filter on its own adds 5 bhp or more are lies.
My MAF isn't failing but I've heard they're very fragile and I don't want to risk damaging it. Also the Green panel filter looks as if it's been there for a while so it'd be good to change it for a new fresh one.
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19 June 2008, 01:00 PM
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Does this remain true if you have the car remapped? I mean to say if you have the car remapped should you really invest in an aftermarket panel filter at this point? Or just regularly change the std type one?
19 June 2008, 06:28 PM
#9
Andy Forrest recommends a KN panel filter on his stage 1-2a upgrades. I am sure there is a reason for this. To be honest he will know more about impreza's than most of us put together. So the answer must be yes before you remap pop an uprated filter in.
20 June 2008, 08:04 AM
#10
If I am keeping a car I will use a K+N pannel simply because it is reusable but it does not produce or flow more air than the O/E Subaru. That is a fact so remapping will make no difference between a K+N or an O/E Subaru.
So Andy, if you are keeping the car you can fit a K+N and with a cleaning kit you can clean it every 3000 miles or so or just fit the Subaru item and dispose of it less regularly but if it is some time since you had a filter change it is certainly worth trying to improve the air flow prior to mapping.
Skooby53 : I don't quite follow your logic. I went to the trouble of conducting well controlled tests on four pannel filters on the Dyno Dynamics rollers at TEG Sport with Steve Simpson. The results were not what was expected and therefore we repeated the experiment the next day with every care taken to get the best results we could. The outcome was a repeat of the previous day. There was less than a 2 bhp spread, the O/E and K+N gave virtually identical results, the filter that flowed best was the HKS Green sponge (Re-usable) and the filter that came "last" was the STi but that is a replacement ie not re-usable.
In subsequent tests I found that the filtration ability of the HKS was rather poor and it would let quite big grains of sand/dirt through. The O/E and K+N were very good in filtration terms and the K+N was re-usable but more expensive. The STi had the best filtration of all four, the least power over the HKS by 1.8 bhp from memory and it was disposable.
"Best" and "Worst" are not really good terms as the spread was under 2 bhp and I certainly don't want large particles going through the filter, shot blasting the MAF sensor and travelling through my engines.
I also removed the inner wing snorkle as this is a performance mod in "Scooby mythology" That resulted in a drop of, again from memory, 7 bhp+ Nothing else was done. Just the snorkle removed and nothing done to smooth the air flow to the MAF Sensor.
I don't know what the result would have been with a remap but the car in question was an STi 3 Wagon (335 bhp/333 ft.lbs) with standard ECU which was not mappable. At that time also standard turbo, top mount and injectors. If efforts were made to smooth out the air flow arriving at the MAF sensor and the engine was carefully remapped for the new conditions then the results may have been different but that was not the purpose of the experiment.
These results were published on S/Net and a couple of other forums and some "experts" then came on and rubbished them. After some time Mike Wood of Prodrive kindly came posted and said that my results were in line with Prodrive's findings. I was already confident of my findings and it was nice to have the backing from Mike Wood and Prodrive. As I expect you know Prodrive are probably the top Subaru rally tuning company in Europe if not the world as well as being involved in Aston Martin, Alfa Romeo, F1 etc. etc.
One of the problems with Scoobynet and similar forums is that there is so much disinformation and too few recommendations are backed up by solid measured personal experience. For instance, I am yet to see a BOV that improves the acceleration or power from a car but certain vendors and manufacturers of BOVs make dishonest claims about acceleration and power none of which are backed up by actual figures. Similarly with air filters some dishonest vendors claim 8, 12 or even 15 bhp and similarly there are exaggerated claims regards certain exhaust systems.
Also remember that some vendors will promote their own products because that is what they sell regardless of whether it gives the best performance benefit. They sell it to make a profit so they portray the product as the best thing since Red Bull because they want your hard earned money. Just think about that. Food for thought. Just because something is in vogue does not mean it is the best performing piece of kit. It may have more to do with the marketing, glossy advertising and fan club following.
No doubt someone will find one of the original air filter posts and Mike Wood's comments.
So Andy, if you are keeping the car you can fit a K+N and with a cleaning kit you can clean it every 3000 miles or so or just fit the Subaru item and dispose of it less regularly but if it is some time since you had a filter change it is certainly worth trying to improve the air flow prior to mapping.
Skooby53 : I don't quite follow your logic. I went to the trouble of conducting well controlled tests on four pannel filters on the Dyno Dynamics rollers at TEG Sport with Steve Simpson. The results were not what was expected and therefore we repeated the experiment the next day with every care taken to get the best results we could. The outcome was a repeat of the previous day. There was less than a 2 bhp spread, the O/E and K+N gave virtually identical results, the filter that flowed best was the HKS Green sponge (Re-usable) and the filter that came "last" was the STi but that is a replacement ie not re-usable.
In subsequent tests I found that the filtration ability of the HKS was rather poor and it would let quite big grains of sand/dirt through. The O/E and K+N were very good in filtration terms and the K+N was re-usable but more expensive. The STi had the best filtration of all four, the least power over the HKS by 1.8 bhp from memory and it was disposable.
"Best" and "Worst" are not really good terms as the spread was under 2 bhp and I certainly don't want large particles going through the filter, shot blasting the MAF sensor and travelling through my engines.
I also removed the inner wing snorkle as this is a performance mod in "Scooby mythology" That resulted in a drop of, again from memory, 7 bhp+ Nothing else was done. Just the snorkle removed and nothing done to smooth the air flow to the MAF Sensor.
I don't know what the result would have been with a remap but the car in question was an STi 3 Wagon (335 bhp/333 ft.lbs) with standard ECU which was not mappable. At that time also standard turbo, top mount and injectors. If efforts were made to smooth out the air flow arriving at the MAF sensor and the engine was carefully remapped for the new conditions then the results may have been different but that was not the purpose of the experiment.
These results were published on S/Net and a couple of other forums and some "experts" then came on and rubbished them. After some time Mike Wood of Prodrive kindly came posted and said that my results were in line with Prodrive's findings. I was already confident of my findings and it was nice to have the backing from Mike Wood and Prodrive. As I expect you know Prodrive are probably the top Subaru rally tuning company in Europe if not the world as well as being involved in Aston Martin, Alfa Romeo, F1 etc. etc.
One of the problems with Scoobynet and similar forums is that there is so much disinformation and too few recommendations are backed up by solid measured personal experience. For instance, I am yet to see a BOV that improves the acceleration or power from a car but certain vendors and manufacturers of BOVs make dishonest claims about acceleration and power none of which are backed up by actual figures. Similarly with air filters some dishonest vendors claim 8, 12 or even 15 bhp and similarly there are exaggerated claims regards certain exhaust systems.
Also remember that some vendors will promote their own products because that is what they sell regardless of whether it gives the best performance benefit. They sell it to make a profit so they portray the product as the best thing since Red Bull because they want your hard earned money. Just think about that. Food for thought. Just because something is in vogue does not mean it is the best performing piece of kit. It may have more to do with the marketing, glossy advertising and fan club following.
No doubt someone will find one of the original air filter posts and Mike Wood's comments.
20 June 2008, 01:08 PM
#11
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Thanks for the info Harvey, it's answered doubts in my head over supposed increases from aftermarket panel filters. I'm going to go ahead and fit an OEM one on the next service.
By the way, what was meant by the "removing of the snorkel on the inner wing". Does this actually increase bhp or is it not worth doing?
Thanks
By the way, what was meant by the "removing of the snorkel on the inner wing". Does this actually increase bhp or is it not worth doing?
Thanks
22 June 2008, 01:50 AM
#12
The Subarus have a snorkle or bladder located in the inner wing on the driver side. air enters the ducting behind the driver side headlight. The ducting leads the induction air to the snorkle which is made from smooth black plastic. The air leaves the snorkle in another duct that leads to the MAF Sensor and then along the inlet tract to the turbo.
Does removing the snorkle add power?
Please re-read what I said above. I am not sure there is much I can add to that.
Does removing the snorkle add power?
Please re-read what I said above. I am not sure there is much I can add to that.
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