Apexi air filter performance

[J-GTi-R]

Ok, test have proven this is the best flowing and filtering air filter on the market, so we all know it's not down to the filter performance, but having had mine on for a few days I have to say, on standard boost, putting it on has actually made my car slower....

When it's night and the ambient air temp is low the car flies, but during the day, when I've been sitting in traffic or driving sensibly for a bit it feels flat and lifeless. I know the Scoobies have this problem, where under-bonnet temps mean you're getting much warmer and less dense air going in than if you had the standard air box, but it appears the same is true for the 'R.

When the boost goes up, I'm pretty sure the standard box will become restrictive, but it's something to keep in mind if you're swapping out the standard air box and only running small amounts of boost.

...and no, my standard air box isn't for sale...

 

[wizgti]

Good point but was wondering when you have your 'fog lights' on do you think there's an improvement? Cos when I recently went on the rolling road I found I got an increase of 1BHP over the standard air box! But you also have to take into account that some people buy it for the noise as well as a slight increase in performance.

Ta
Andrew

 

[J-GTi-R]

I've no idea with the fog light, as they both went on at the same time (the 0.9 does make a big difference either way).

I know people do put them on for the noise, but I just hate mods that make the performance go backwards. I'm pretty sure the standard box will give the same sort out results as you got, because it will become restrictive as the boost goes up. Interestingly, for a long time people with standard boost cars have always gone on about how fast mine was for standard. Recurring detail is they always had performance air filters on...

I'm going to make up a cold air feed to start with, then try and build or adapt a big airbox like Skiddus's to get around the problem, as I'm trying to go faster, not slower... :?

 

[turblio]

Defo agree the Apexi on mine lost me some low down power, but gained more mid to top end
Frank

 

[GTI-R Kid]

Frank is yours just sitting in the engine bay too or do you have it fitted in some type of box?

Maybe all it needs is for the filter to be slightly isolated from the warm under-bonnet air. The original has its protection from the box, but an aftermarket cone is left exposed to heat and a less dense charge of air. Once moving the air coming in from the front can counter this problem which would explain why an improvement is noticed in mid to high rev range.

I reckon you're going the right route anyway J in trying to crate a box similar to that which Skiddus is using. Let us know how you get on and if you notice an improvement when you try it?

 

[nickg123]

Definitely need some sort of heat shield around it - but it's not easy to do without relocating the battery.......

I'm almost tempted to get another vent cut in the bonnet by the filter - like a mini Scooby scoop, or something, that'd make loads of difference!

An Astra GSI style scoop turned round to face forwards would be good.......

 

[GTI-R Kid]

I'm almost tempted to get another vent cut in the bonnet by the filter - like a mini Scooby scoop, or something, that'd make loads of difference!

Caleb has one of them fitted to his GTI-R (pics in the gallery section of the main site). Looks like a universal NACA type scoop that directs air straight to the cone filter.

It will help a little - but there'll still be the problem of warm air when in traffic or just at slow speeds.

 

[turblio]

No Rob mine needs to be in some kind of cold air box really, like you say
in this sort of weather its not too bad but summer is a prob
Frank

 

[turblio]

Theres a couple of peeps on here that have put the massive evo k&n on
just wondered wether they noticed any improvement over the apexi?
Frank

 

[GTI-R Kid]

I think i have one of those fitted to mine (EVO VI K&N) - just about squeezes in behind the battery.

Can't make any comparison though as it was on the car when i bought it so i've nothing else to compare it against.

 

[turblio]

shame we're not nearer could have done a bit of swop and see! :lol:
Farnk

 

[GTI-R Kid]

Who's Farnk? :lol:

Maybe if i take a good run before i throw and release it might reach you? (well if i manage to land it on a flight bound for Heathrow anyway) :lol:

 

[turblio]

Ha! MusT Lurn tO spel :lol:
Frank (I think)

 

[J-GTi-R]

I'll first try a direct cold-air feed as temporary solution while I make up the box, then try the box (or possibly heat shield) once that's built, see what differences it makes and report back.

Like Nick said, the ideal thing would be to relocate the battery to the boot to free up some space, but I'd still need a box or shield of some kind. I've thought about the NACA duct as well, but again you'd still need to seperate the filter from the rest of the egine bay.

I'll let you all know how I get on...

 

[skiddusmarkus]

In the short term-get hold ogf some foam such as is used in sofas etc.I got mine from a firm on an industrial estate and it cost me about £1 for loads(offcuts).The just trim this and plug any gaps where air can get through from the hot side of the bay-anything to the left of the filter.Foam is good for this(not builders funny feckers)as it will squeeze into gaps and block them up,plus it's a good insulator.It looks crap but does the job.
The main problem is the fans blow air straight onto the filter and when you're in traffic it gets very hot.

 

[turblio]

The main problem is the fans blow air straight onto the filter and when you're in traffic it gets very hot.[/quote]

Good point Skid never thought about the fans
Frank

 

[Davey]

not to sure what the standard airbox is meant to look like, but when i got my car, it had the entire bottom of the box cut out, so the filter was sitting on top of the hole in the engine bay, isloating the filter from the hot air, but also (maybe?) reducing the restriction of the satnard box,must have helped a bit, i'd have thought :?:
BTW, i replaced it with a K+N, didnt notice any difference either way, but me and mikey are hoping to make up a heat shield/box, just waiting for some ally plate, eh Ben?