After market air filters

[Deleted]

I know this has probably been asked thousands of times before but here it goes,

I'm thinking off fitting a K&N air filter into my 1.6 injection Astra (fitting it into the original air box, not an induction kit) and then drilling the air box and fitting a Vectra air intake (Lets more air in)

I'm not really doing it for 'mad power gainzzz' but to make it a bit more rev-happy at lower speeds and for a nicer engine noise

I was just wondering if this will affect MPG in any way? Basically I'm going to be spending the summer darting between London and the Lake district and don't want the car to be drinking up petrol or this will cost me a fortune!

[scruff]

Might do, most intakes are tuned by the manufacturer for minimal noise and minimal losses at cruise to get maximum cruise mpg.

A filter like that will make it noisier certainly.

The 924 N/A has a odd shaped plastic horn on the front of the airbox and one guy (Albertog) removed this and replaced it with a smooth wide open intake with back to back power runs within a few mins. He gained 1 bhp at near the red line but lost about the same mid-range.

Basically made no appreciable difference.

[stealthstylz]

It'll use more fuel because you'll put your foot down more so you can hear it.

[Deleted]

How will it affect the car if I don't drill the air box and instead just have a K&N filter in the air box? will there still be a noticeable sound?

[cobblers]

It'll make no noticeable difference to performance, sound or MPG I'm afraid.

[Copey]

Apr 30, 2012 16:55:46 GMT stealthstylz said:

It'll use more fuel because you'll put your foot down more so you can hear it.

this is true! stuck a cone filter on my Saph (just for the noise) and now i cant stop puttin my foot down! good job its still got a quiet exhaust haha

[bornretro]

whatever type of filter or intake system you fit, on its own it won't make any noticable difference, even the specially designed ones.. after all, the throttle venturi, valves, exhaust manifold, exhaust system, fuelling Etc will still be the same...its a carefull amalgamation of several of these factors together that makes better power/torque figures.... its like the youngster that tells you his 4 inch bore back box on its own gives 10 more Bhp, he had better not sit down or nobody will hear him ;-)

[bl1300]

Will make no appreciable difference other than it may confuse the ecu a little due to the above normal mass air flow

[bortaf]

May 1, 2012 8:29:33 GMT bl1300 said:

Will make no appreciable difference other than it may confuse the ecu a little due to the above normal mass air flow

Why would it ? the ecus job is too adapt to differant throttle positions and air flow combinations to maintain the mixture, surely, it will just add the right amount of fuel for the air thats entering the system ?

[popuptoaster]

Some cars benefit from improved airflow and some do not, it depends how bad the stock set up is, take my 940 for instance.

The stock panel filter is the same as is used on the 240bhp T5, so thats going to flow enough air easily for my current power levels.

However, mine was a low pressure turbo version and they only have a 50mm air inlet into the air box, the high pressure version has more air inlets into the air box so while the filter is fine Volvo decided the higher power version needed more air through it.

The ECUs are identical between both cars, its capable of running either at the stock 3psi, the HPTs 7psi or as i currently have it set, around 11psi.

So some research is needed before this kind of mod, it CAN make a difference, but not on every car.

[bornretro]

There was a side by side test a (very) long time ago with an XR2 and a EFi XR3...first they were dyno'ed stock, the XR2 was around 95hp and the XR3 around 106hp...first, they changed just the air filter for a pipercross item then re-dyno, the XR3 went up to 108 with near zero change to torque/power curve, the Xr2 on the other hand stayed as was (95) but developed a "flat spot" around 3900-4200 rpm....then a janspeed full system was fitted to each, the Xr3 again pushed up to 115hp but the poor old XR2 lost power down to 92 hp but torque stayed the same but also the flat spot was worse!... after much fiddling with the xr2 they did manage 106hp but at the cost of a flat spot at 4000 rpm.... I love retro cars (new cars suck..) but although I too believe in making them better plus 27 years as an engineer, building things from a rear drive V8 Golf (!) to a 840bhp Camaro, there is still a bit of me that thinks that with a multi-million pound development budget and a team of proper engineers behinfd them, do I really know better than the guys who built it??? I think not.... Pride can be Hazard lights on the hard shoulder!!

[Copey]

May 2, 2012 16:02:59 GMT bornretro said:

there is still a bit of me that thinks that with a multi-million pound development budget and a team of proper engineers behinfd them, do I really know better than the guys who built it??? I think not.... Pride can be Hazard lights on the hard shoulder!!

i have often thought the same thing, but everyday manufacturers build cars at a compromise, they don't get at much power as possible from an engine because they want reliability, they don't fit freeflowing exhaust because they want the cars to be quiet, they don't fit freeflow air filters for the same reason, plus more air means more fuel to add to the mix so would hurt MPGs

and its the same story with internals, cams are profiled for MPG as much as power, valves aren't made massive for MPG reasons, compression isnt as high as it could be to save the head gasket and make the car more reliable

so you do get companies who build tuning parts and do headwork, valves, headskims etc etc which will give more power but will lessen MPG and could prove less reliable (not everytime)

as a rule i have found that changing exhausts and filter on their own is ultimately a waste of money if you are hunting for power, but if you start swapping out cams, fitting curse word valves and having the head machined, fitting bigger carbs/injectors then exhausts and filters can make a difference, if they are actually well designed and the manufacturer has thought about things like backpressure and flow when designing them, sometimes bigger isnt better

anyway, enough rambling

[popuptoaster]