993 turbo - any benefit from a K&N element?
Discussion
Performance wise... you'd be lucky to get an extra 1bhp with a K&N on a normally aspirated car, even with a remap. On a car with forced induction, air flow into the engine is less critical, n'est ce pas?!
Sound... you can certainly hear the induction engine noise more on normally aspirated 993s. Sounds quite nice. On a turbo it would probably be drowned out. Not sure.
Engine wear... dogsharks will gladly tell you about the evils of aftermarket filters. Basically, anything which flows better tends to allow more dirt into the engine, which can be detrimental to an engine in the long run.
All in all, there ain't much wrong with paper filters - honestly!
Sound... you can certainly hear the induction engine noise more on normally aspirated 993s. Sounds quite nice. On a turbo it would probably be drowned out. Not sure.
Engine wear... dogsharks will gladly tell you about the evils of aftermarket filters. Basically, anything which flows better tends to allow more dirt into the engine, which can be detrimental to an engine in the long run.
All in all, there ain't much wrong with paper filters - honestly!
It will most definitely have an effect. Whether it is the effect you require is a different matter. As a rule, turbos will make more power than N/A with an increase in air flow, but it's forced induction so no surprises there. What is probably more interesting and more expensive/difficult to workout, is the correct length and diameter of the induction tubing.
Buy and read G. Bells, book on forced induction tuning if you want to get into the details. An excellent book.
Buy and read G. Bells, book on forced induction tuning if you want to get into the details. An excellent book.
Thanks - fair comments. I've always enjoyed the increased induction roar from K&Ns on my previous cars, but no doubt you're right that I won't be able to hear a difference on the turbo.
In theory a better flowing filter should make a difference even in a forced induction engine because there will be less depression downstream of the filter when the throttle is fully open, hence more flow. Modern control systems with hot-film air flow meters and all the gubbins would then detect the extra airflow and fuel up accordingly, so I don't see that it should necessarily need remapping of the ECU to get some benefit.
Am surprised to hear that these aftermarket filters aren't well considered for their filtration capabilities, i.e. they let more crap through! I thought that that aspect of their performance was acceptable. Anyway, if there is a possibility of increased engine wear then maybe I should reconsider.
In theory a better flowing filter should make a difference even in a forced induction engine because there will be less depression downstream of the filter when the throttle is fully open, hence more flow. Modern control systems with hot-film air flow meters and all the gubbins would then detect the extra airflow and fuel up accordingly, so I don't see that it should necessarily need remapping of the ECU to get some benefit.
Am surprised to hear that these aftermarket filters aren't well considered for their filtration capabilities, i.e. they let more crap through! I thought that that aspect of their performance was acceptable. Anyway, if there is a possibility of increased engine wear then maybe I should reconsider.
There's a K&N filter on my car and the induction sounds are sooooooo much better. Not really a direct comparison for two reasons though as the filter is part of a ZucZ PowerFlow induction kit and the car's a 965 Turbo 2 not a 993 Turbo 4.
Regarding engine wear, if it was bad enough to worry about then K&N would be out of business. If filtering was done with a single layer of material where bigger holes = more flow = lots more crap gets through = lots more wear, then it'd be crazy to fit aftermarket kits but filter design is more complex and you can get more flow without compromising your oily bits.
One point to bear in mind, intake temperature. If your filter is grabbing more hotter air then it's possible for output to decrease. I had my induction kit fitted around the same time as a GT2 rear wing to get cool air to the filter from the right side intake (and a GT2 type front splitter for balance and aesthetics), as well as a B&B triflo sports exhaust and 1 bar boost.
For the price we're talking about, why not give it a try and see if you like the sound better or not, and if the car drives better or not. There was some controversy over the ZucZ kits in 'Excellence' magazine a few years back but I'm not complaining.
Again not strictly like-for-like but see what Boxster and 964 owners found from their ZucZ PowerFlow kits
[url]www.alexia-media.com/boxster/mod.html[/url]
[url]www.9mracing.co.uk/html/generated/articles/Article20.html[/url]
If you're interested enough ZucZ do a kit for the 993 but I haven't heard much from them for a while.
Regarding engine wear, if it was bad enough to worry about then K&N would be out of business. If filtering was done with a single layer of material where bigger holes = more flow = lots more crap gets through = lots more wear, then it'd be crazy to fit aftermarket kits but filter design is more complex and you can get more flow without compromising your oily bits.
One point to bear in mind, intake temperature. If your filter is grabbing more hotter air then it's possible for output to decrease. I had my induction kit fitted around the same time as a GT2 rear wing to get cool air to the filter from the right side intake (and a GT2 type front splitter for balance and aesthetics), as well as a B&B triflo sports exhaust and 1 bar boost.
For the price we're talking about, why not give it a try and see if you like the sound better or not, and if the car drives better or not. There was some controversy over the ZucZ kits in 'Excellence' magazine a few years back but I'm not complaining.
Again not strictly like-for-like but see what Boxster and 964 owners found from their ZucZ PowerFlow kits
[url]www.alexia-media.com/boxster/mod.html[/url]
[url]www.9mracing.co.uk/html/generated/articles/Article20.html[/url]
If you're interested enough ZucZ do a kit for the 993 but I haven't heard much from them for a while.
You guys may be right. UV knows more about these things than I do; most of my experience is with normally aspirated pork. I can tell you that aftermarket filters made sod all difference to my Lotus Carlton though. Couldn't hear them either ;-)
A traditional remap, increasing boost/fuel etc. will get you bigger gains. I think the exhaust is an area of more concern than the filter. From what I've seen, the paper ones simply aren't that restrictive. I have never been concerned with engine wear when I've fitted foam filters or KN - it may happen but not in my ownership
- but there is some evidence out there to suggest they may be inferior to paper. Cue dogsharks...
A traditional remap, increasing boost/fuel etc. will get you bigger gains. I think the exhaust is an area of more concern than the filter. From what I've seen, the paper ones simply aren't that restrictive. I have never been concerned with engine wear when I've fitted foam filters or KN - it may happen but not in my ownership
- but there is some evidence out there to suggest they may be inferior to paper. Cue dogsharks...nel,
I've got before and after graphs for my "K&N style" filter for my 996 turbo (which I guess should be fairly similar application). The peak power was only up by 5bhp but there are gains of upto 12bhp in the mid-range. The main thing it did was fill in one or two small holes in the power / torque curves. There will obviusly be an issue with filtering i.e. if it lets more air through it WILL let more dirt through. For me, it's not a major issue, I don't live in Saudi or do a million miles a year and don't plan to keep the car forever.
Steve, 996TT
I've got before and after graphs for my "K&N style" filter for my 996 turbo (which I guess should be fairly similar application). The peak power was only up by 5bhp but there are gains of upto 12bhp in the mid-range. The main thing it did was fill in one or two small holes in the power / torque curves. There will obviusly be an issue with filtering i.e. if it lets more air through it WILL let more dirt through. For me, it's not a major issue, I don't live in Saudi or do a million miles a year and don't plan to keep the car forever.
Steve, 996TT
aceparts_com said:
Save your money for a genuine 450BHP upgrade kit from carnewal for about £3,500! That's new K24 turbos, ECU & oil cooler.
I'm still in the throws of talking myself out of it. Maybe we could do a group buy?
My car's already had a Porsche upgrade to 450 bhp, though exactly what that entails I confess I don't know, other than the visible bits such as the oil cooler and exhaust system. I know that the operation cost the owner £10k back in 2000. So don't talk yourself out of it - the carnewal business sounds like a bargain!!
996 turbo said:
nel,
I've got before and after graphs for my "K&N style" filter for my 996 turbo (which I guess should be fairly similar application). The peak power was only up by 5bhp but there are gains of upto 12bhp in the mid-range. The main thing it did was fill in one or two small holes in the power / torque curves. There will obviusly be an issue with filtering i.e. if it lets more air through it WILL let more dirt through. For me, it's not a major issue, I don't live in Saudi or do a million miles a year and don't plan to keep the car forever.
Steve, 996TT
That's very interesting Steve and has just about convinced me to give it a try with mine! Was there any ECU re-mapping done when the K&N was fitted, or did the beast just notice a bit more fresh air coming in and adjust itself accordingly?
Nel, it is an obvious mod to do in many cases. Don't you think that it would have been done with the 450bhp upgrade if it was necessary? For the sake of 70 quid, I'm sure they would have fitted it if the result was 455+bhp not 450.
With respect, I am not sure anybody notices an extra 5bhp in a 450bhp car anyway. You will go a lot faster from A-B by spending the 70 GBP on a Goldtrack evening session and learning how to drive the car quicker.
With respect, I am not sure anybody notices an extra 5bhp in a 450bhp car anyway. You will go a lot faster from A-B by spending the 70 GBP on a Goldtrack evening session and learning how to drive the car quicker.
domster said:
Nel, it is an obvious mod to do in many cases. Don't you think that it would have been done with the 450bhp upgrade if it was necessary? For the sake of 70 quid, I'm sure they would have fitted it if the result was 455+bhp not 450.
With respect, I am not sure anybody notices an extra 5bhp in a 450bhp car anyway. You will go a lot faster from A-B by spending the 70 GBP on a Goldtrack evening session and learning how to drive the car quicker.
All true, and yes, putting a 5 bhp gain into the context of the existing power it does seem rather laughable! I asked the question because I noticed that she's still running the paper filter and I've K&Ned every car I've had for years now. To be honest the main gain on previous cars has been the increased induction roar and hence the impression that one's going faster!
Given Steve's comments above relating to his 996tt I reckon I'll give it a go, then drive around with all windows and sunroof open trying to hear the induction roar!
The limitation on getting from A to B faster with this car is fear of losing my licence rather than driver competence, though I have no doubt that the latter would be improved immeasurably by some professional training off the public road.
UV's book sounds interesting.
If you want some K&N lambasting, just for interest (as I have had K&N/foam filters on many of my cars, simply because of the psychological advantage of feeling my car should go quicker ) then check out dogsharks' profile. Search members, or just search the Porsche forum for 'K&N' and see what comes up. He found a load of stuff, technically based, which showed that paper filters weren't actually that bad for flow - and that the advantages of K&N may have been 'marketed up' over the years. He did concede that they seemed to offer gains on racing engines, but then wear isn't a factor.
Anyway, jury's out. I may well have one again, but it's no longer a must have for me.
Let us know how you get on, anyway.
If you want some K&N lambasting, just for interest (as I have had K&N/foam filters on many of my cars, simply because of the psychological advantage of feeling my car should go quicker
) then check out dogsharks' profile. Search members, or just search the Porsche forum for 'K&N' and see what comes up. He found a load of stuff, technically based, which showed that paper filters weren't actually that bad for flow - and that the advantages of K&N may have been 'marketed up' over the years. He did concede that they seemed to offer gains on racing engines, but then wear isn't a factor. Anyway, jury's out. I may well have one again, but it's no longer a must have for me.
Let us know how you get on, anyway.
OK - have just read the thread that you were thinking about Domster - www.pistonheads.com/gassing/topic.asp?t=94546&f=48&h=0&hw=K%26N
The K&N subject makes depressing reading on that US forum! While it's important to stay cynical so some of it might not be innocent debunking, there were some telling comments on Porsche design of the intake and exhaust systems (for a 944). Porsche engineers tend to be conservative and designed the systems with an overcapacity relative to the absolute demands of the engine. Hence reducing the pressure drop across the filter is of very limited benefit.
On the 993tt there is no convoluted air box with hose arrangement - it just sucks fresh, ambient air, dust and shite through a hole in the intercooler straight into the filter chamber. OK bollox then, given that I may just hang onto this car I'll stick with OEM filters and not risk it. The VW Golf runabout can keep its K&N on the other hand - its death would just be an excuse to buy a faster runabout!
Thanks for your responses everyone - a handy source of info!
>> Edited by nel on Monday 16th August 16:18
The K&N subject makes depressing reading on that US forum! While it's important to stay cynical so some of it might not be innocent debunking, there were some telling comments on Porsche design of the intake and exhaust systems (for a 944). Porsche engineers tend to be conservative and designed the systems with an overcapacity relative to the absolute demands of the engine. Hence reducing the pressure drop across the filter is of very limited benefit.
On the 993tt there is no convoluted air box with hose arrangement - it just sucks fresh, ambient air, dust and shite through a hole in the intercooler straight into the filter chamber. OK bollox then, given that I may just hang onto this car I'll stick with OEM filters and not risk it. The VW Golf runabout can keep its K&N on the other hand - its death would just be an excuse to buy a faster runabout!
Thanks for your responses everyone - a handy source of info!
>> Edited by nel on Monday 16th August 16:18
Jeez Dogs, it's taken you 26 hours to reply to a K&N thread 
You're slipping
I have to admit your links to the K&N information have been the deciding factor why I resisted the urge to change to a K&N. A few more BHP is just not worth the risk to wear and tear inside my engine. I simply change my £4 paper filter more often than recommended so it's not too dirty.
You're slipping
I have to admit your links to the K&N information have been the deciding factor why I resisted the urge to change to a K&N. A few more BHP is just not worth the risk to wear and tear inside my engine. I simply change my £4 paper filter more often than recommended so it's not too dirty.
aceparts_com said:
Save your money for a genuine 450BHP upgrade kit from carnewal for about £3,500! That's new K24 turbos, ECU & oil cooler.
I'm still in the throws of talking myself out of it. Maybe we could do a group buy?
I could be talked into this if you think you could get a group discount from Carnewal
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