john banks

The filter on the APS induction kit for MY99/00 cars is diminutive. For various reasons I want to stick with this but still run 450 BHP and 400 lbft with a 2.4 stroker engine and 690 (or larger ) CFM turbo.

APS said they are doing some work on this with some testing but no results yet, and that G-Force have done some work also, but I can't get a reply on the topic from G-Force.

Anyone make any suggestions re a larger K&N filter that can be used and still fit in the inner wing?

P20SPD

iTrader: (1)

John

Whats the diameter of the mouth of the cast pipe in the inner wing where the filter connects to it?

john banks

Sorry Stephen, don't know with the car being away. Were there some suggestions you know of with certain sizes? Any links with pictures/sizes?

P20SPD

iTrader: (1)

I cant remember the link, but if you look on the k&n site, you should see the universal filters available there. The give all the dimensions length width height (for odd shaped ones) and the size of the neck of the filter.

Alternatively, measure what space you have available and then go to a Halfords with a Ripspeed section and they will show you the measurements from their catalogue of filters.

Why do you want to keep it in the wing? Why not change like Harevy did and build a box? Just a thought.

Steven

P20SPD

iTrader: (1)

i was hoping this pictue would show my filter, but it doesnt.



the filter fits under the aps pipe work, and touchs the strut turret just below the selonoids. Although i dont use the MAF sensor.

I have a sheet of heat reflective material that i was going to make a cool air box out of, but that can wait now, as i dont want to waste the material.

Steven

Jolly Green Monster

iTrader: (4)

Happen to have a mag in front of me with the K&N universal filters in..

dunno if any use to you but they list them with BHP..

So for 400bhp you can have a :
152mm long 178mm diameter 76mm neck and it is tapered round..
going to running beyond its capacity.

625bhp :
254mm long, 127-191mm diameter, 152mm neck and it is tapered round..
going to running beyond its capacity.

I would assume the APS must be around 80mm internal diameter as you are suppose to fit standard maf etc and standard maf housing it 80mm from 99..
So you might be lucky with the 400bhp one fitting but you need more!!! )

Simon

The Fixer

John, I have the APS cold air intake with a large BMC filter fitted to it in the inner wing(fitted by G-force at my request instead of the APS small one). I don't have the car at the moment, its at Scooby Mania but I'm sure Mike would measure it for you, give him a call.

Regards

Conrad

David_Wallis

john, Im sure harvey said the aps filter kit was cr@p..

I would simply either make your own.. (prone to collapse if its all samco..) or just get a spun cone as I use..

I know mark does them as do roger clarke

David

P20SPD

iTrader: (1)

the kit that Chrome will be using on his car, when the rest of his bits arrive.



Steven

RB5SCOTT

The internal size of the APS kit is 80mm where it joins the filter!

Scott

john banks

Thanks guys, the BMC one sounds good if it also fits the classic APS induction kit.

The pipe diameter of the elbow into the wing appears to be similar to the rest of the inlet tract at least, plus I don't want to spend any more money than just a filter on it as I want to see some returns from the car first I am not a natural fabrication or oversteering god like T-uk/Andy F I am afraid.

Bob Rawle

John you will probably find that the filter as supplied is virtually as big in dia as you can get in, Conrad has an STi7/8 iirc. A K & N 57i kit suitably shortened in rubber pipe length fits perfectly and seems to be good for about 500 bhp.

cheers

bob

AlanG

Interesting, cause the std 57i air filter supplied for most '99's isn't much bigger physically than the APS filter, but the APS has the advantage of a more consistant air temp feeding it.

Alan

Fatman

I've got an APS kit here waiting to be fitted to my car. Are there any particular dimensions you need?

john banks

The inside diameter of the neck where it goes onto the pipe, the length of the exposed pink filter, the circumference at each end of the pink filter area.

Bob Rawle

The 57i filter is shorter and larger in diameter, it has an offset built into it that allows it to fit under the aps fmic pipework.
Oh and if under the wing don't forget to scrape the mud off it regularly !!! The liners won't stop it.

bob

[Edited by Bob Rawle - 10/18/2003 8:08:48 PM]

harvey

iTrader: (48)

David : I did not say it was "Krap" but what I did say was it had its problems. When I fitted the APS cold air kit I picked up number 2 piston in the bore because I did not realise the dramatic effect the CAK would have on AFRS while relying on the MAF. I used the APS CAK successfully for many thousand miles after Bob installed the Link ECU which does not rely on the MAF.
I would not have an APS CAK on any car still utilising the MAF although some technical wizards claim to have the problem solved with some off-set values on the MAF output.

The APS CAK is OK up to around 400bhp and I concluded there was not enough space in my inner wing for a bigger K+N cone or parallel filter. My solution was to fit a larger filter and shield it in a cold air box which Tristan Pye made for me. At the time this showed surprising power gains.

john banks

Can you quantify the gains Harvey?

harvey

iTrader: (48)

417 bhp on G-Force rollers. Ten days later 434 bhp with some other minor work done and a few days after that 450 bhp as a result of an intensive mapping session with Bob Rawle at Bruntingthorpe.

harvey

iTrader: (48)

From 417 bhp to 434 bhp for £30 odd inc. VAT. Pretty good bangs per buck. All figures @ G-Force.

john banks

Thanks Harvey.

Fatman

inside diameter of the neck where it goes onto the pipe = 9cm
length of the exposed pink filter = 14.5cm
circumference at each end of the pink filter area = 29cm top & 37cm bottom

john banks

Thanks, most appreciated

aus73

John,

Appologies for the delayed response - we've been having some email problems here, so I will post my email reply here (as it will probably save you waiting another day or two).

Our experience with the MAF based APS intake pipe suggests the pipe diameter is too small for more than 420/425bhp. We have a similar problem with 993 Turbo Porsches, which supply both turbos through a single MAF sensor - though these run into problems at around 620bhp. The only way we have been able to get around the problem is to run a larger intake pipe and rescale the engine management to suit.

We have only done this on one car - as the original MAF based load had to be maintained to comply with the rules he was running to. This was supposed to keep costs down - but ended up costing around the same money as simply changing to a MAP based ecu system.

On applications intending to run more than 420bhp on the Subarus we are going to run the rotated mount turbo system with a larger intake pipe. I don't think there is provision for a MAF sensor - but I won't know the final details until I have on in my hand after SEMA. I'm sure this pipe will be 80mm direct to the turbo inlet - which happens to be 5mm dia smaller than the inlet pipe we ran on the 993 Turbo mentioned earlier - that car topped out at 810bhp.

The filters themselves are a bit small - I agree. We run BMC filters, as used on 996 Porsche Cup cars (380bhp standard) and baby GT3-R GT Porsches (410bhp standard) as I am happier about the amount of air that can get in - and more importantly, the filter structure is a lot stronger so there is less chance of the filter collapsing under high negative pressure - which you'll get with 400bhp +.

When Harvey had his car on the dyno here and changed filters we did see a large increase - though in percentage terms the initial gains were small. From memory his car ran around 420bhp initially. He changed the filter system and the power rose to 434 I think - an improvement of around 3%. You would probably see this sort of improvement in changing from a dirty K&N filter to a clean performance filter - as I said I prefer BMC, though Pipercross isn't bad either. The intake pipe on Harvey's car was changed, and remapped to give 450bhp at that stage - again I'm not surprised as the pipe diameter is becoming too small to work efficiently at those bhp levels. (assuming it is on pump gas).

The problem with the pipe diameter size is that as the airspeed increases inside the tube, the attached boundary layer becomes larger and larger. There is a maximum air speed achievable inside the pipe - which corresponds to a maximum airflow. As more air is being sucked through the pipe (by a turbo for example) the frictional losses become greater and greater as the boundary layer expands, until the pipe will no longer supply the turbo with the air it requires. There is some maths to go with it so you can size the inlet system correctly, but you also get into wave frequency calculations and it gets a bit complex - as the longer/shorter the pipe the more/less impact it has on airflow. these principles are the core of inlet system and header system tuning on racecars - particularly naturally aspirated. The turbo application is a little more straight forward - but still a little tricky.

How did you work out the turbo cfm flow rate? Turbos should be sized in ib/min airflow - not CFM. Turbo airflow is temperature dependent, so they flow air mass - not air volume. If you take a nimonal temperature and convert to CFM you have o ensure the figure is truly representative of turbo inlet temps on the road - or you'll end up with a filter which is too small anyway.

To be honest, sadly I think you will struggle to get the performance you need from a MAF based system without using a larger pipe and re-scaling the system. Its the only way we got around it on the Porsche, and we change to MAP based load on the higher BHP Subarus aswell. There are other reasons for changing the system on the Subarus, but changing the load input is a major advantage.

Hope this helps.

Chris Davies
Technical Manager

dowser

Thanks Chris.

But Harvey is still using the APS CAK pipe with just a different filter, no? He doesn't have the restriction inline caused by the MAF, but the pipe's physical diameter is still flowing enough air into the turbo for 500+ If the restriction, or friction, were too high his turbo would need to do too much work to produce this sort of power level reliably, no? I've been wrong before

I will rescale the MAF on mine (it will be a lot of laborious work though....anyone want to send me a rom file for a MAF pipe with +30% flow? ). I'm still undecided where the filter will be on mine, but pipe work from it to MAF will not be any narrower than my new MAF pipe, and may well be much larger (considering fitting the bell close to MAF).

Richard

Richard

john banks

Thanks Chris. The manufacturer publishes the compressor maps in CFM at a standardised (realistic) temperature.

Richard I think that Harvey is not using the APS cast elbow any more.

I might contact you Chris for a BMC filter to go on my induction kit and see how I go with that.

The Fixer

Harvey, no longer uses the APS CAI kit.

The Fixer

John, are you on new age? I have removed mine, you could borrow it to try if you like? Bear in mind that its from a new age. Drop me an email if youre interested.

Conrad

john banks

It is a MY00 UK turbo. Is it compatible?

dowser

Ah, OK..

Richard