heldihub

I own a Turbo MY98 and I would like to own which air filter is most suitable in terms of performance and sound of the engine.
I heard that RamAir are the best ones.
Can anybody help?

John Phillips

I changed out mine for a Ramair replacement panel filter and a scoobysport back box. I noticed an immediate improvement in pick-up. I cannot comment on other makes but the Ramair certainly is good, without huge sucking sounds from under the bonnet.

Steve Wilson

Be aware that replacing the airbox with a foam filter will significantly increase induction noise. This may not be what you want if you are travelling long distances.

On the subject of panel replacements I tried to use a Ramair filter in my STi 4 but it kept being sucked into the intake pipe above the throttle body. Basically it was not rigid enough to take the pressure exerted. I now run a K&N panel which is rigid and should be at least comparable in efficacy and resistance to foam filters.

malique

Interesting. Panel filters I mean.

When one installs a conical air filter it sucks air hot air around the engine bay and thus reducing the engine efficiency and reducing power. Whereas installing a panel filter one utilises the existing filter housing. No?

How much gain or difference is there in absolute terms between a performance panel filter and an open conical air filter induction kit?

tel

I have been told Ramair are going to be dropped by Subaru/Prodrive and replaced by Pipercross, because Ramair went out of business. Pipercross however are used by the works rally team and they have developed an induction kit which has been dyno'd to give an additional 8-10bhp. the kit as around £100

tel

The pipercross cone filter uses the duct that pipes in the cool air. So I am lead to believe.

Mike Tuckwood

I test drove a car with a HKS cone filter and whoosh valve, sounded VERY dramatic, picked up slightly quicker than my car which has a HKS panel filter in the standard air box.

Sound value = 10/10 but I would not have been able to live with the very noticeable sucking and blowing for longer than five minutes maximum.

RobAnderson

Just while you're on the subject of HKS,I've got the "Super Powerflow" induction kit and the"Sequential Blow-off valve" fitted and while admittedly there is a fair bit more noise,I just find it adds to the character(I've had them fitted for over two years and my ears aren't bleeding yet).The build and fit quality are first class and they are a doddle to fit(paradoxically, the japanese only instructions are incredibly straightforward).However I don't think the set-up provides quite as much power as the Pipercross induction kit(5BHP compared with 8BHP) if its simply power you're after.

Pete Croney

A couple of things...

Firstly, mushroom filters are not induction systems.

Induction systems are gas flowed (normally carbon fibre) pipes that ensure the intake gets into the turbo with the minimum turbulence and the maximum speed. To fit one to an Impreza, you need to removed the power steering pump. Mushroom filters are as Malique correctly said... just conical filters. They do suck in warm engine bay air, unless you partition off that part of the engine bay and provide a means of venting the area.

Secondly, if you get 99.90% efficiency from a good foam panel filter, why would you spend over 3 times as much to get 99.91% from a filter which was noisy and could not use the car's standard cool air supply (only an issue in traffic, but still an issue)?

RobAnderson

A couple more points about the HKS system.It is not simply a mushroom filter.An aluminium pipe(admittedly not carbon-fibre!)which sits after the air meter is also part of the kit(doing away with the plastic air [sound deadening] boxes that do severly hamper air flow) and the idea is to simplify and thus smooth and speed the air-flow through.This, together with the actual filter( based on a velocity stack to increase air flow, on the principle that air tends to move towards surface areas thus creating more air-flow around the edge rather than the centre of the inlet)results in smoother and more rapid air induction. Ergo, is this an induction kit or what?

Mark McE

Rob,

Who sells & how much if you don't mind....

ta

RobAnderson

Mark, All the HKS tuning gear is available from TORQUE DEVELOPMENTS in Essex (Tel.0181 591 0442).They do have a pretty much comprehensive list of bits and pieces for the scooby (right up to a full 350BHP engine conversion for a cool £15K-ouch) ,though as the majority of the stuff is Japanese imported the prices are sometimes a bit silly.Anyway the price for the 'MegaFlow' system is £155+VAT (there has recently been a price cut on HKS gear- I paid around £250 two years ago).The other thing perhaps worth mentioning is that my U.K. spec Impreza is a '95 model and thus while, as I mentioned earlier the system was a breeze to fit(no removal of p.steering pumps,etc?)I appreciate that the intake system is re-sited on post '97 models and as such fitting might be significantly different nonetheless there is a system for pre'97,post'97 and WRX models.Hope this is of some use.

Mark McE

thankyou kindly.

yee_har

HKS? - check out:

http://www.checkerflag.co.jp/overseas/checkerflag.html

for HKS and more.

No Credit Card purchase possible so you have to wire them money but my stuff turned up within 10 days and was packed in, well, Japanese style.

TDI in my experience are very expensive.

David K

I have recently been told by a guy from Pipercross that the Subaru Rally Team do indeed now use Pipercross air filters instead of Ramair.
If it's good enough for them...and all that!

P.S. Scoobysport: Ramair panel filter £56.40,Amber Performance: Ramair panel filter £37.50.

Pete Croney

Rob

It would be an induction system if once it had gone through the flange that holds the filter on, it didn't then have to negotiate the Subaru pipe that works it way to the turbo. Any gas flowing done at the end of the earlier induction systems is lost by the time the air gets to the turbo. 97 and later cars have the turbo re-aligned, so that this pipe is straight (you need a stable, non turbulent flow to get the maximum air density into the turbo) and don't have the plenum box that was fitted to earlier cars. The higher the speed of a gas, the lower its pressure. Increasing the speed of air through a carburetor (by restricting its flow) is what causes the fuel to be drawn into the flow... this high speed/low pressure is what is known as the venturi effect. I wasn't having a dig, I just don't see the point of improving air flow, only to have the benefit lost later down the pipe.

David K

Pipercross, K&N and Ramair are all great filters. There is very little between the three, except that the Ramair is a Subaru UK approved part. This may be important to owners of recent UK spec cars.

I wish we could buy our Ramair's for £37.50. May be time to hang our supplier out of the window and renegotiate our supply contract!!

RobAnderson

Pete,
I take your point about the restrictions in air-flow prior to the actual turbo but it has to be said that there must be improved flow for the significantly increased power figures (5-8 BHP,not massive I grant you) that the after-market 'induction-systems'are shown to achieve in comparison with a simple after-market panel-filter(2-3 BHP?) and thus the benefits gained initially through the removal of the air box cannot be completely lost.I agree we are not talking Group A nor indeed WRC 'induction-systems' here but I think there is still something to be said for the 'pseudo' induction systems.
By the way, I haven't investigated it yet, but I understand that REGAL have a Turbo Radius Pipe -based on the Gp.A rally systems that together with the 'induction-kit' (I'm getting a bit fed up with that word now) produces an extra 20 BHP, and thus if that's true bears out your point about the restrictiveness of the intake system prior to the turbo. Does that settle our argument?(Apart from the semantics of 'induction')

Dobbo

I've got a K+N element fitted which seems to breath and perform well. Have fitted, run for 2 days and ripped out Pipercross kit (replaces box, aluminium piped etc) as it was just too bloody noisy for every day use though sounded mean. I have it on good authority (see 'events', 'donnington park 14 Feb') that my current set up filter and Magnex back box give me a sound none too different to a Harrier on re-burn!

Down to personal preference I feel as they're all much of a muchness and generally come as part and parcel of an exhaust or chip upgrade.