K&N filter and Top speed

bax

Torque Junkie
Points
157
Location
Mars
Car
Rexton 270xdi 2005
People used to tell me how better the K&N drop in filters are compared to the stock filters we have on our cars , now i know this is a subject that starts debates when speaking about cars in stock conditions .
over the past 3 years ive made a number of upgrades to my Vehicle which include an Ecu Remap that took me all the way up from 165Hp 340Nm to 220Hp 460Nm and Custom bigger aluminum intercooler pipes with a custom Intercooler made entirely of aluminum , and finally a Drop in K&N filter i got from Ebay ..

these mods improved my Vehicles 0-190 acceleration times by 20 Seconds which is awesome , needless to mention the improvement in responsivness and the elemination of lags but heres the Catch back in stock condition my Vehicle managed a top speed of 193Kmh (5 Years ago ) and now with all those mentioned upgrades my Top speed stands at 190Kmh , not only did it not improve it actually dropped ..

Im still unable to explain this , when it comes to the condition of the engine and other components all should be in great condition (assumed because my acceleration times are better than similar vehicles with similar Mods) and the only weight i added to it was a 6Kg belly armor and if you must know i gained 10Kgs since then haha , the front of the car is even lower than it used to due to worn out Springs (no change was made to Rims or tyre size) ..
i can only suspect the K&N filter due to what people say about them , its either that or the Intake isnt balanced with the Emissions system and ill need a bigger downpipe with a bigger exhaust line ..

what do you guys think ? any ideas ?
 

Guybo

Torque Junkie
Points
52
Location
Tampa, FL, USA
Car
13 GenCoupe 2.0T
Any aero changes will affect the top speed. I cant see the intake causing this. The drooping front end is most likely the culprit. You may have added 16 KG that you know of, but also the bigger IC and other additions may have added even more weight.
 

bax

Torque Junkie
Points
157
Location
Mars
Car
Rexton 270xdi 2005
The custom IC i added is actually lighter than the original , its almost the same size but its made of aluminum even the tips , unlike the original with the Plastic parts ..

however you might be on to something , i did install a shark fin and a spoiler to the back which can cause extra resistance to air at high speeds .

but still with the same mods and same condition with a map of 185Hp i got same top speed for same mods but with the current 220hp map ... i dont expect much gain from 35Hp but the Top speed should be affected slightely , yet it freezes at 190Kmh as if theres some sort of limiter which cant be the case because i went past that speed while in stock condition

so youre saying theres no way the intake or the Exhaust is responsible for the drop in Top speed ? the intake being too restrictive or the exhaust not being big enough to allow free flow with the Tuned map
 

old-git

Moderator
Points
647
Location
Essex
Car
Elan & Robin Hood
Put a standard filter back in and retest :)

3kph is not a lot and this could be caused by many factors:

Variations in barometric pressure and air humidity (probably the most likely cause)

Other variables:

Tyre pressures
Weight changes
Changes in air resistance due to intercooler/radiator mods.
Ride height
 

bax

Torque Junkie
Points
157
Location
Mars
Car
Rexton 270xdi 2005
The tuner who remapped my Ecu said the original cant handle the new map and will get sucked in and damaged which is why i went for the K&N , next week im trying out the Open pod (cone filter i think ? )

i still go with the same tyre pressure like i used to
weight increased slightely (~15Kg)
the intercooler i fitted is the same size and sits in the same place as the original - nothing has been done to the Radiator ...Yet hehe
ride height dropped at the front due to worn out springs (Rear 35Cm from center of wing to ground ...front 28Cm from center of wing to ground)

i added 55hp and 120Nm to the stock stats , a drop in top speed no matter how little makes no sense to me .. i expected to be atleast able to hit 200Kmh with that much gain considering that i got 193Kmh in stock condition

Humidity makes the most sense to me right now , but i did try several runs on different times of the year and times of the day .. same result
 

Guybo

Torque Junkie
Points
52
Location
Tampa, FL, USA
Car
13 GenCoupe 2.0T
ride height dropped at the front due to worn out springs (Rear 35Cm from center of wing to ground ...front 28Cm from center of wing to ground)
+the spoiler

Need look no further. The extra power will help you get there quicker but you are limited by the extra aero, the unmodified gearbox and the compromised suspension and ride height/rake change

I am not a fan of oiled filters
Oiled filters are only a problem if you have a MAF sensor that can get fouled by the oil. This car seems to have a MAF sensor (I googled it quickly but didn't look into it too much) and maybe that is what's happening? Try cleaning off the MAF sensor and see if there's any change.
 

old-git

Moderator
Points
647
Location
Essex
Car
Elan & Robin Hood
Didn't see the mention of a spoiler. Case closed.

If the spoiler is easily removable, take it off and try again. I wouldn't be surprised if you gained more than 3kph.

If you want the spoiler for looks then put it back on. If not then list it on eBay as it will be doing nothing for the performance of your car (other than reduce it) unless it has been specifically designed for your car by someone conversant with vehicle aerodynamics and then properly positioned and set up.
 

bax

Torque Junkie
Points
157
Location
Mars
Car
Rexton 270xdi 2005
ermmm oiled filters ? i never applied oil to the filter i have ... its just one of those Drop in filters that look exactly like the original only made from that Red material instead of paper , youre probably talking about my next upgrade which is the Open pod (cone filter) ?

i spoke to my tuner he said top speed shouldve increased to 200+ kmh (tested on similar cars with an even weaker map) so that cant be the case either

correct there is a MAF sensor and it is still in its original housing (tried fitting it into an aluminum pipe a year ago and it caused lots of black smoke and a drop in top speed so i put the original housing back ... if something indeed was bothering the MAF i believe it would also affect acceleration and responsivness , but its worth cleaning ill give it a shot

the spoiler is in no way made by an expert , it was installed for the sole purpose of looks , it does stick up several Centimeters and probably does get in the way of aerodynamics .. it is however easy to Uninstall and i will be doing a test run without it as soon as possible
 

HDi fun

TC ModFather
Points
637
Location
Buckinghamshire UK
Car
Passat 2.0 TDi
+the spoiler

Need look no further. The extra power will help you get there quicker but you are limited by the extra aero, the unmodified gearbox and the compromised suspension and ride height/rake change


Oiled filters are only a problem if you have a MAF sensor that can get fouled by the oil. This car seems to have a MAF sensor (I googled it quickly but didn't look into it too much) and maybe that is what's happening? Try cleaning off the MAF sensor and see if there's any change.

I don't believe they flow much better than a standard pleated paper filter. A dirty oiled filter is claimed to be better than a dirty paper one but when a paper one is about £5 it's not worth the bother, just replace the paper one, which takes about 30 seconds.

I also subscribe to the better flow of air equates to better flow of dirt. Have a look here:

http://autohifidiszkont.hu/bmw-tuning.hu/aemszuroteszt.pdf

and

here:

http://www.nicoclub.com/archives/kn-vs-oem-filter.html
 

bax

Torque Junkie
Points
157
Location
Mars
Car
Rexton 270xdi 2005
question is >> ist really that bad ? i mean if we were to put aside gains due to better air flow the open pod grants that awesome breathing and whistling sound , i understand its a silly thing to want from an engine but i found the extra sound effects astonishing and they give that sporty aggressive feel when driving ... after all isnt everything we tune and upgrade on our cars in order to make driving them more enjoyable ?
 

SLEEPER

Pro Tuner
Points
562
how are you measuring 193kph ?
assuming the answer is sensible then it could of course be the first top speed that is wrong not the later ones,

And just a following wind could easily make that difference when you are going at that speed.
 

Guybo

Torque Junkie
Points
52
Location
Tampa, FL, USA
Car
13 GenCoupe 2.0T
Yeah good point. Are you running the same size rims still? More tread wear can even affect your speedo with the changed tire diameter
 

bax

Torque Junkie
Points
157
Location
Mars
Car
Rexton 270xdi 2005
i didnt use any special equipment to measure .. its the speedometers reading
yes same rims and same tyre size (AT 255/65/16) , back when 186Hp same tyres aswell so the new tyres with the better threads didnt change much ..

its possible that wind had something to do with it but it wasnt a single occasion in which i went past 190Kmh ..

there is however one fact that i held back due to the fact that im ashamed to admit but back then when i reached those top speeds i had 3 passengers with me unlike the runs from the past two years after the tuning (i know , i shouldnt be risking others when going at such speeds , im not as young and reckless as i was back then) ... not sure this can actually be connected to the matter but if i recall correctly once at higher speeds the weight and the momentum of the car will keep pushing it past its limits >> can it be possible that the Extra weight caused the increase in top speed or possible lead to a false reading by the Speedometer ?
Extra weight would mean less ground clearance due to the load and it would also mean more strain on the tyres where 34Psi may not be enough for a propper speed run
 

bax

Torque Junkie
Points
157
Location
Mars
Car
Rexton 270xdi 2005
I see , then ill replace shocks / springs and uninstall the spoiler
 

HDi fun

TC ModFather
Points
637
Location
Buckinghamshire UK
Car
Passat 2.0 TDi
Agree (shock, horror!), the increase in rolling resistance due to the extra weight will have a slight effect.

Agreed too (more tabloid horror and shock !!). Car makers suggest higher tyre pressures for full load operation. I keep mine at the higher settings all the time, the slightly firmer ride is small loss compared to better tyre life and steering response.
 

old-git

Moderator
Points
647
Location
Essex
Car
Elan & Robin Hood
I am interested why you get better tyre life with tyres that are overinflated for their use.
 

HDi fun

TC ModFather
Points
637
Location
Buckinghamshire UK
Car
Passat 2.0 TDi
I am interested why you get better tyre life with tyres that are overinflated for their use.

OK, interesting point. I suppose it depends upon many factors, I used to believe that the standard pressures were best for standard use (eg. empty car except for full tank and driver's body mass). Radial tyres all have the same general type of construction of course. But sidewall stiffness will vary widely between different tyres evn of the same width, profile and fitting diameter. Some have softer sidewalls than others.

I don't overinflate, I use the car makers suggested pressures for high speed full load usage. This is different from using the sidewalls maximum pressure setting.

I experimented heavily with my BMW 528i, which, was very very tyre fussy. I found that Uniroyal Rainsport 2 on the front were very noisy at anything above 'standard pressure'. At standard pressure the soft sidewalls made the steering feel mushy and the car understeery.

Vredestein Wintrac Xtreme all round were fitted in Dec 2013. These felt far better on the high settings, yielding more grip and better steering. Vredestein Apollo suggested using the high settings permanently. So I followed........

When refitting the Michelin Primacy HP tyres in March 14 I did the same thing. Bring them all up to about 40 PSI. The car was definitely a little less comfortable (but a 5 series is not exactly uncomfortable) but the handing and roadholding we both sweeter and stronger. A 5 series is not the worst handling car on the road either.

The reason for better life is less flexing and thus less heat build up within the carcass and tread.

I am surprised to find that you think I over inflate tyres.
 

old-git

Moderator
Points
647
Location
Essex
Car
Elan & Robin Hood
By over inflate I meant over inflate compared to the car manufacturers recommendation for specific use. EG, if standard is 35 and heavy load is 40, using 40 as standard is, technically, overinflating for the intended use. The recommended figures are really a guide to be used by the common or garden driver and that there is a safe range either side of these figures.

When I start racing we will decide on what presures to use based on the temperatures generated across the tread.

Do you still get even wear, or more central wear due to the 'overinflation'? :)
 

HDi fun

TC ModFather
Points
637
Location
Buckinghamshire UK
Car
Passat 2.0 TDi
By over inflate I meant over inflate compared to the car manufacturers recommendation for specific use. EG, if standard is 35 and heavy load is 40, using 40 as standard is, technically, overinflating for the intended use. The recommended figures are really a guide to be used by the common or garden driver and that there is a safe range either side of these figures.

When I start racing we will decide on what presures to use based on the temperatures generated across the tread.

Do you still get even wear, or more central wear due to the 'overinflation'? :)

No, the wear is totally even (and I do have a full geometry check/set every 5000 miles or so) so there's no feathering etc. anywhere across the width of the tyres.

I think wearing down in the middle of the tread is unlikely given the circumferential steel belt(s) which span the entire width of the tread of the tyre. There's simply not enough flex in the tread of a steel belted radial for this to occur.

And I do NOT over inflate.
 

Guybo

Torque Junkie
Points
52
Location
Tampa, FL, USA
Car
13 GenCoupe 2.0T
over inflation will cause the center of the tread to wear more quickly even with radials. I see it all the time. But that's with people using the max pressure that is written on the side of the tire which is 44 psi usually with passenger cars. That extra 4 lbs over what HDi fun is doing makes a world fo difference. Plus most people don't rotate or even pay attention to their tires at all. I am starting to pick up on my car's handling more and more now that I had it a few months and I feel the tires squirm too much when I am doing hard cornering. I'm going to try 40 front, 35 rear to even out the tail-happy nature of my car, effectively stiffening up the suspension a little and take the squirm out.
 

old-git

Moderator
Points
647
Location
Essex
Car
Elan & Robin Hood
I know that you don't over inflate but you are inflating the tyres above the car manufacturer's recommended pressure for their intended use :)

Isn't lexical semantics fun :)
 

HDi fun

TC ModFather
Points
637
Location
Buckinghamshire UK
Car
Passat 2.0 TDi
I know that you don't over inflate but you are inflating the tyres above the car manufacturer's recommended pressure for their intended use :)

Isn't lexical semantics fun :)[/QUOTNo

The manufacturer recommended pressure(s) are simply that. Recommended pressure(s). Probably based upon the OEM tyre fitments when new from the factory.

They are put there to help the masses who have no brain capacity to think for themselves.
 

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