Cold Air Induction Kits.

[Anonymous]

will my car benifit from this? i own a 2004 astra CD and i have been told that it can increase your power but wouldnt the AFM conflict with it?

[Turblue]

The gain is probably so minor, it becomes a waste of money.

No, it won't bugger the AFM. Unless you use a crappy filter.

Best and cheapest is to de-restrict the airbox and buy a 3 inch flex(heatproof) hose to replace the current snorkel. Leave the filter. It does the job well.

Total cost = $20

Buying a BMC-CDA is well over $300 and really a complete waste of time. A k+n filter is just over $100 and the debate rages as to whether they filter properly.

[EGG80X]

btw u can get defect for a pod filter

i reckon turblue is right
on a Nautrally aspirated car pod filter will do little power gain (1-5 KW)
i de-restricted my airbox and used larger and smoother intake piping on the box and inlet manifold hence faster air velocity will benfit NA cars



but wouldnt the AFM conflict with it?


get a air fuel ratio controller

[Anonymous]

i dont really get how to derestict the air box (noob when it comes to cars) lol

[Anonymous]

De-Restricting the Air Box Is Easy Just Follow These Instructions:
http://groups.msn.com/opelaustralia/howtos1.msnw?action=view_list&row=14&viewtype=2&sortstring=

*NOTE* Works on All Opel/Vauxhall Astras,Corsa,Zafira.

* DISCLAIMER*
OPEL AUSTRALIA Holds no resonsibilty to Damage,Void Warranty & Defective Vehicle Infringments, Modify at Own Risk.

[Anonymous]

and this works for the 04 astra? wow thanks!!!!

[gaero]

I had a look inside my airbox (1.8 ) the other week, this is what i saw from an engineering point of view .....

doing the de-restricting probably would be of benefit .... but based on the airfilter being 100% clean, no dirt/dust. I have a stock airbox and my filter is uniformly dusty (9 months worth/no dirt road driving). This uniformity is achieved by airbox structure (fins, curves, etc). When modified the air would loose most of the flow guidance, causing the flow to be concentrated onto a small section of the filter. Over time that area would become cloged with dirt quickly, loosing the benifits gained (as air takes the path of least resistance and use further out sections of the filter)

..... To test this theory would the de-restricted boys/gals have a closer/careful look at their filter to see if there is a "cloging" effect and post their findings.

This is what engineering is all about ... the theoretical and experimentation sides, ...... so my theory could be wrong

[Anonymous]

so your saying that derestricting may not only give you more power but can be good for your filter? :D i love this am so doing tomorrow

[gaero]

so your saying that derestricting may not only give you more power but can be good for your filter? :D i love this am so doing tomorrow

u been in ur black stallion haven't u ... too much speed to the brain will do that

I'm saying u might have to replace/renew ur air filter alot more often to keep up the gains

PS @|opel| want more power?, have u thought of an engine swap ??? I'm sure ur dad won't mind :twisted:

[astra_city]

Buying a BMC-CDA is well over $300 and really a complete waste of time.

I wouldn't say that...sure it's not the best value but I have definitely noticed an improvement - more than I could have hoped. Comparing it to my mums stock astra is very noticeable and it'll help when doing more mods down the track. But sure, de-restrict is easily best value obviously!

[gaero]

@astra_city
Now ur airbox is properly designed to spread airflow over the entire filter, and would expect it to perform

also the BMC has cyclones doesn't it?

[Mitch]

I'd just get K&N replacement filter and de-restrict the air box. That's what i did so far, next is to get some better piping from the grille to the air box.

[Bernard Siong]

i'm lost
so if u de-restrict the air box then the air filter gets dirty only in one area?

[Turblue]

Does with mine......

[Bernard Siong]

yeh i was thinking this afternoon
i was about to de restrict my air box
but then thought why would they go to such effort to design the box like this...
i was thinking of just adding a larger intake pipe and leaving the box as it is

[gaero]

Does with mine......

filter gets dirty in one spot ??

[gaero]

i'm lost
so if u de-restrict the air box then the air filter gets dirty only in one area?

This is what were are out to prove/disprove

[Anonymous]

you see, I once thought about all these little wonderful ways to pick up 1 magical kw.

then I stepped outside and saw the astra 1.8l wasn't a performance car. :lol:

spend the money and energy on something else.

the only noticeable effects are nothing more than a little bit of response and an overwhelming amount of placebo effect. :P

[gaero]

but then thought why would they go to such effort to design the box like this...


The box has had a bit of CFD done on it, u can see this by the "strange" profile on the base/external/dirty side of the airbox. this is called CAE, cars / a lot of things are now days designed based on putting structure where it is needed and removing it where it is not

[Bernard Siong]

haha i agree with autumn acid
the 1.8 is so not for performance

dont spend money on all little mods
just get your car lowered on nice rims

[macquered]

but then thought why would they go to such effort to design the box like this...
i was thinking of just adding a larger intake pipe and leaving the box as it is

Bingo!

Bunch of highly paid, highly trained engineers working for the worlds largest car manufacturer > Bunch of backyard engineers that think they know better.

Don't add a larger intake pipe either, it's designed that way for a reason.

[Anonymous]

ok, hot4's did a test on air induction a while back

they found that by removing the "akward plastic bits" in the engine bay, and running a straight tube, they lost power.

the air induction creates appropriate vaccuum and pressure. It was designed particularly for the AFR.

YES, you'll pick up a measly kw at the fly, and notice a bit of response, but who knows what damage you'll do in the future.

$100 or thereabouts sounds like it's better used taking a girl out for dinner and then a movie......

[gaero]

$100 or thereabouts sounds like it's better used taking a girl out for dinner and then a movie......


drive thru at macas and then to the drive-in, the astra will be much happier with that (jk AA :wink: , but if u want to fight about it ..... oh we are ..... :lol: )

[Bernard Siong]

whats better... a k&n filter panel or the original paper ones?

[astra_city]

sure the 1.8 isnt a performance car, but you don't have to do mods to make your car the quickest on the road :roll: A lot of us (including me) enjoy making changes to my car as it's a hobby and also makes your car personal. Others do this through bodykits or lowering, I do it through performance. What's the big deal?
Oh and it's true that the engineers do make things for a reason and some things are better left untouched, but a lot of the time that reason is for a compromise between noise/pollution/power output for class etc.

[Turblue]

Use the original paper filter.

It is basically true that most aftermarket filters such as K&N flow more, they do so by sacrificing the ability to filter. So you need to weigh up whether you want more flow and more dirt, or slightly less flow and less dirt.

Ahhh.... modding is such fun..!!!!

[woody]

Turblue, i agree but also i disagree... if you want to go and put an aftermarket filter on the car go ahead and do it - the paper aftermarket and the foam/fabric filters do let in slightly more particles than the standard ones - but then all filters let dust particles in. The difference between them.. well have a look at this website for an independant test:

http://www.bobistheoilguy.com/airfilter/airtest1.htm

If you really think you need a K&N Filter (and i have one and yes i believe it does make a small difference) or similar then yes Turblue you are correct you will find a slight degradation in filtering.

Really there is no right or wrong - just don't go into it thinking you're gonna get heaps of power from modding the air filter or on the flipside that you're gonan jam up your engine with crud if you do.

[Anonymous]

thanks for clearing that up woody i think i might de restrict it. i can always put the stuff back in cant i??

[woody]

How about you go get a second airbox from a scrap yard - mod the hell out of it - then if it doesn't work you can always stick your original one back in.

:D

[Anonymous]

Yeah, modification is a hobby. Just be careful you don't waste too much money, for too little gain.

My commodore was a different story. I spent $70 and got a whopping difference.

basically, I fitted a vs superhcrager CAI to my vp. Needed a bit of fabrication.

The vp, didnt have a CAI, it was being fed hot air from the bay.

I found that this solved a heating issue in summer. Performance.... ngh. :lol:

[Anonymous]

yea i might do that woody thanks :P

[Mr Cali]

Turblue, i agree but also i disagree... if you want to go and put an aftermarket filter on the car go ahead and do it - the paper aftermarket and the foam/fabric filters do let in slightly more particles than the standard ones - but then all filters let dust particles in. The difference between them.. well have a look at this website for an independant test:

http://www.bobistheoilguy.com/airfilter/airtest1.htm

If you really think you need a K&N Filter (and i have one and yes i believe it does make a small difference) or similar then yes Turblue you are correct you will find a slight degradation in filtering.

Really there is no right or wrong - just don't go into it thinking you're gonna get heaps of power from modding the air filter or on the flipside that you're gonan jam up your engine with crud if you do.


Dont forget that these aftermarket filters such as the K&N are reuseable. Imagine what happens when you start cleaning them??? you start tearing more holes into them. I would agree that a brand new one would be better but marginally, if you start cleaning and reusing it would be much worse. I would stick to the paper filters, they are damn cheap and u through them away and get a brand new one.

[woody]

Erm.. not so Mr Cali.... the cleaning process (for the K&N at least) is very simple and requires no scrubbing or any activity that would warrant tearing a hole in the fiter.

Instructions here:

http://www.knfilters.com/clningins.htm

[R3N]

apparently the oil from the k&ns would stuff up the AFM or something like that... or so i've heard

[Turblue]

R3N...

Yes, quite true. Some people over-oil the cleaned filter. This can cause a situation where the airflow will pull some excess oil off the filter onto the AFM.

Result is an AFM that can fail.

[astra_city]

I've only heard of the oil/AFM issue with open pod filters? And certain brands at that? Could be more for all I know though.

[entice]

you see, I once thought about all these little wonderful ways to pick up 1 magical kw.

then I stepped outside and saw the astra 1.8l wasn't a performance car. :lol:

spend the money and energy on something else.

the only noticeable effects are nothing more than a little bit of response and an overwhelming amount of placebo effect. :P

True, and somewhat not all true.
Yes, a lot of engineering time, effort, and money has gone into the R&D of all the bits and pieces that are fitted onto your car. And yes, the same thought can be applied t every aspect of your car. However, to illustrate my point, lets look at the exhaust on the car. How can there be otehr systems on the market that produce more power, proven? How can the GM gurus work so hard, only to be outdone by a bunch of petrolheads in a fabricating shop down the road?
Answer? Compromise.
GM or any mass produced vehicle must do things at the end of the day, to meet a bottom line. Compromise between, comfort, cost, performance must all be met. I'm sure that the airbox xould be redesigned to provide better performance, but at what production cost? how will it alter the characteristics of the car? Will it be noisier? What is the target market of the car?
Putting it simply, the snorkel bits on an airbox are not only in search of colder air, but are also there to decrease NVH levels. Would I mod the airbox if it were my car? Absolutely! What would I do? Either search for an ADR approved item, or, visit bunnings and fabricate one myself?

So what gives, how can this newbie start telling us what airboxes he can use and what they all do? Answer is Experience.
1. 1997 Subaru WRX - reonatorectomy and $10 worth of storm tube downpipes, elbows, etc, black paint, and a heat gun.
2. 1999 Mazda MX5 - BMC Airbox (larger version) - best CAI for this car as teh box sat directly on the exhaust manifold, and being carbon fibre, it still kept charge air cool
3. 2003 Subaru STi Ver8 - Tried resonatorectomy, then went for an APS CAI
4. 1975 Fiat 124 Sport - Ducted cold air to twin carbs
5. up and coming 2004 Astra Convertible - wife's car, so it will remain 100% stock!

So what have I found along the way? The change in airbox in each and every time (Apart from Fiat) has resulted in more noise (especially in blow off on the turbo models). Some may like induction noise, others may not. However, in each and every situation, it has resulted in Greater responsiveness and tractability, on and off boost. AFR's havent changed, as original AFM's (or in the case of APS CAI original AFM in a new support tube of original diameter) has been retained.

so what about "power"?

ummm...I would think there is not much of a difference in NA cars, as there is certainly one in FI cars (Dyno proven).

One parting note on tis topic tho...most people seem fixated by power peaks (Max power). Hang around dyno's and start spending money on mods and dyno time, and you'll all quickly find that its the power delivery (area under the graph) that is far more important. The Airbox significantly affects that....

[Turblue]

One parting note on this topic tho...most people seem fixated by power peaks (Max power). Hang around dyno's and start spending money on mods and dyno time, and you'll all quickly find that its the power delivery (area under the graph) that is far more important.

This is without doubt one of the most intelligent statements I have seen in a while..!!!!

[freaktown]

most cars arnt performance cars unless you make them so!

[Anonymous]

every car has the potential to be a performance car just go look at the at ford focus with a V8 on the off topic forum :P back to my point... people like to work with what they have so if they get a few hp and maybe 1 or 2 kw out of it then if it makes them feel happy we should be too :D

[Blitzkrieg]

Potential of your car is measured by a bank account.