scoobynewbie1

Howdy guys & gals,

been doing the usual searches through this forum to try and find a definative answer but have failed miserably.

I have a MY05 WRX 300, which for those that don't know, is a standard WRX fitted with PPP (as standard) and some nice cosmetic bits.

My question is: will fitting a "better" panel air filter (K&N.?) actually make a difference...?

From what i've read already, it seems that this will definitely improve the airflow through the filter as you would expect, and deliver a greater volume of air. But, the question of whether the Prodrive ECU would be able to interprete this into generating greater power seems not to have been conclusively answered.!!

Will the ECU see more air and think, hmmm don't need to "boost" so hard, and end up with the same power but maybe better fuel economy. Or will it see more air and give the same "boost", meaning more power..?

Wadda we all think..?

Please excuse me if I have missed the one post amongst a thousand that really did answer this, so if I have be gentle and point me in the right direction

I'll see if I can get an aswer from Scooby HQ or Prodrive as well.

cheers all

Rich

Nick Read

The ECU will respond to what you want. If you're pootling around town it looks for fuel economy. If you've got your toe buried in the carpet and you're heading for the horizon like your **** is on fire, then it does what it can to give you maximum output at the expense of fuel economy.

A higher flowing panel filter will make life easier for the turbo and give the potential for more power, bearing in mind that an engine is basically an air pump, the quicker you can get the charge in and out, the better. All ECUs can adjust their timing and fuelling for variations in the inlet charge - because cars are driven on hot days, cold days, damp days, dry days, at the tops of mountains and at sea level. These all affect the inlet charge and the density of oxygen it carries.

So in other words, put a better flowing filter in and the ECU will compensate by adding more fuel as well, up to the limit of the injectors, which I would expect to be nowhere near a 100% duty cycle yet (i.e. open all the time). This will result in better performance but worse fuel economy, if that's what you ask for by putting your right foot down.

scoobynewbie1

cheers Nick.

So, basically you think that the PPP map has enough margin on heavy throttle (in UK atmospheric conditions) to allow extra fuel to be added to the mix when it is presented with a higher quantity of air..?

Please excuse my ignorance if I'm misinterpreting what you say as my total knowledge on the turbocharged engine has been gained from this site (thanks scoobyNet and everyone) in 2 weeks ! Previous car was a Merc S320 - different kind of beast all together

scoobynewbie1

anyone else got any comments also...?

Has anyone actually done it...?

cheers

Robocop

Put one in my MY04STi PPP last week. To be honest I can't compare the difference as I haven't used it too much and the days are getting colder so that may bias the results.

Bartop

If you're feeling particularly bored you might want to have a read of this

http://bbs.scoobynet.co.uk/showthread.php?t=462807

GrollySTI

The only thing I remember reading ( I think posted by Andy F a while ago) was that if the filter can flow more air,then on a very cold, high pressure day there could be a possibility of overwhelming the limits of the map/injectors and therefore could run lean.But I'm certainly no expert.

scoobynewbie1

thanks Bartop - yeah read that many a time and dream of oneday being able to have the ***** to void the warranty on a new car and achieve something fantastic. !!

The reason I posted despite reading the Newage Mod article was that it didn't seem to refer to the PPP remap, so I wondered if the same results could be inferred....?

corradoboy

I run a JR Racing filter and noticed a slight improvement in throttle response throughout the rev range after fitting. I have since removed the ram-air scoop and resonator, isolating the air supply to the inner wing to get a plentiful supply of cold air along with the free-er flowing filter. This improved things even more, as well as making the spool-up marginally earlier and audible it also made the OE recirc dump valve audible which was a bonus (people pay hundreds for silly VTA's to do that). I've never done the RR thing to be able to give any true figures so all I say is purely my point of view, possibly distorted by placebo, but I like the way mine works and will be leaving it that way.

Nick Read

Well I have no knowledge really about PPP but I'm just explaining general engine tuning principles particularly when turbocharged. But the principles apply to every turbocharged car equally.

I would certainly be POSSIBLE to map a car so close to the edge, for absolute maximum output, that the combination of changing to a higher-flowing filter and a very cold day could cause a leaning out of the mix as the pump and fuel injectors would be running at 100%, unable to supply any more fuel to maintain the correct ratio. But anyone who mapped a car that edgy would be a bit thick. If there is even the slightest chance of getting near 100% injector duty, it means the injectors need changing for 'bigger' ones. Any mapper or tuner who doesn't know that has no business working on cars. I've personally never known an air filter change to put increase the air flow so much that the injectors can't keep up. If that's the case, the car's been mapped really badly and there isn't even enough safety margin for normal running with a standard air filter.

I am 100% certain that a different air filter with the PPP ECU is fine. If you want to learn a bit about the subject,and turbocharging in general, an excellent starting point is 'Forced Induction Performance Tuning' by A. Graham Bell. Replaces any amount of pub talk with hard engineering and design facts.