Scientific approach to air filter setup

[RomanV]

Here's a quick timeline of automotive 'facts' regarding air intakes, as best I can recall.

1. pod filters arent good anymore, they stopped giving you power in about 2001. Up until this point, noticable power gains could be felt and seen with a short ram pod filter setup.

2. From 2001 to about 2007, the way to make the most power was to have a pod filter, but in a cold air box up the front.

3. From 2007 onwards, factory airboxes are the best option, but with a factory air filter replaced with a high flow aftermarket one.

Now either the laws of physics have been subtley changing over this period, or people have had done little to no actual scientific testing of what works best in each instance.

Well, here's an article of someones findings when actually doing some testing involving scientific method, rather than seat of the pants feel, or "I spent money, therefore I gained power"

http://autospeed.com/cms/A_2232/article ... larArticle

Interesting that an air filter isnt really a restriction at all... I guess it just 'looks' to be restrictive, because air is expected to flow through something which we cannot see through.

[Mr Revhead]

I recall seeing an article like that but in much more detail by the same guy in a magazine years and years ago

[sergei]

This article is awesome:
http://www.autospeed.com/A_110989/hDg34 ... ticle.html

[Akane]

Cheers for the links, I <3 autospeed

[Loudtoy]

So apparently 1 and 2 might actually do something but possibly not, to figure out if it's worth while doing you nedd to 1st buy a gauge and put it somewhere you can see it. Interesting to note that they never tried doing the test with no airbox at all. After saying "if we were paid to imagine things" and then what he said he goes on to day that it's likely that the restriction is probably in the airbox itself re-word that to day we didn't actually test it but we imagine that ....

And to all you people who have ever said the best gains over standard would be to put an aftermarket filter in the factory airbox. Ram air to get good gains and that aint factory cept on bikes

[pc]

I think dyno testing would be more scientific... more expensive yes, but the goal isn't to reduce the negative air pressure in the intake, it's to get more torque/power... so why measure air pressure?
Did they prove in previous testing that varience in air pressure in the intake & torque over the entire rev range on dyno results correlate exactly?

[Loudtoy]

Actually something good for mythbusters, i got 2.5kw out of mine when i changed it but i changed everything and didn't just bung a pod on the end of the airflow meter, that was back to back and if it wasn't so long ago i would still have the dyno sheets

[Adamal]

This thread is worthless without a RomanV trademark graph.

[matt dunn]

I know that the 2JZGTE levin went away from pod filters to panel filters and got good dyno gains,

It now runs 3 JZA80 TRD panel filters in a custom cold air box feeding into the turbo's,
instead of two massive pod filters in the similar place.

[Mr Revhead]

When was the last time you saw a pod filter on anything professional? ie F1, GT Touring Car etc etc

[RomanV]

So apparently 1 and 2 might actually do something but possibly not, to figure out if it's worth while doing you nedd to 1st buy a gauge and put it somewhere you can see it.

Yep... Just the basic application of scientific method, as per 5th form science. I dont understand why people arent more interested in verification of a modifications worth.

Back in the day I had a bunch of people tell me a bunch of different things about the best way to set up an air intake... Dynoed a bunch of different setups (Back in the days of torque performance dyno days, RIP ) and found that there was margin of error difference between top of the line apexi pod filter setup, and factory airbox with repco panel filter.

Perhaps if you're trying to suck 500hp through a panel filter is when you need to improve flow or something, but I'd wager in most cases mild modifications to motors still keep them well within the capabilities of normal panel filters.

And to all you people who have ever said the best gains over standard would be to put an aftermarket filter in the factory airbox.

Another regurgitated internet fact that no one seems to have any proof of, for good or bad. Wouldnt be half surprised if these 'facts' first came from people with financial interests in selling after market filters.

I think dyno testing would be more scientific... more expensive yes, but the goal isn't to reduce the negative air pressure in the intake, it's to get more torque/power... so why measure air pressure?

Because more pressure drop = more resistance to getting air in the motor, which = less power.

Did they prove in previous testing that varience in air pressure in the intake & torque over the entire rev range on dyno results correlate exactly?

A dyno shows how a car can make power when it's sitting still. When a car is travelling there are other forces in play, engine bay cooling or heating, air pressure increase at the front of the car, etc.

As said in another of their articles, putting the air filter intake pipe in a high pressure zone at the front of the car can lead to a higher than atmospheric pressure *after* the air filter element.

But obviously, this only works when the vehicle is driving at speed.

It's entirely possible that one intake setup could show better results on a dyno, (with the bonnet open) but less power by comparison in a real life scenario.

This thread is worthless without a RomanV trademark graph.

Topic unrelated:

[THA SHZ]

i like your graph , and the details in it , pics please

[solidog]

I think dyno testing would be more scientific... more expensive yes, but the goal isn't to reduce the negative air pressure in the intake, it's to get more torque/power... so why measure air pressure?

Because more pressure drop = more resistance to getting air in the motor, which = less power.


Just curious, isn't negative air pressure in the intake going to try and 'equalise' with the atmosphere, acting as a vacuum through the filter setup?

Peak powers at full load with WOT so doesnt that mean the negative (low) pressure is trying to equalise with atmosphereic pressure (high) btw allmotor!

[fivebob]

Pressure drop is a useful measurement but higher pressure drop doesn't always equate to less flow. e.g if you measured the pressure in a venturi compared to atmospheric pressure;)

[85AW20v]

So I actually did something right when I put the bit of 80mm wastepipe into the standard airbox with a highflow aftermarket filter on the MR2 I only did it because the origial pickup point was causing the filter to block at gravel events.

[Flannelman]

On Sunday the local FPV/Tickford club had a dyno day. Very interesting as on 4 models AU Fairmont straight 6, V8, T3 TS50, and a BA XR8 preformed a comparison of "with airbox" and "without airbox" dyno runs.
ALL had an improvement. THey were
AU Fairmont 4.0L VCT single cam 6, 134kW to 137kW
AU Fairmont, 5.0LWinsor V8, 143kW to 154kW
FTE T3 TS50, 5.6L stroked Winsor V8, 162kW to 173kW
BA XR8, 5.4L BOSS V8, 230kw to 244kW

The BOSS didnt get a bottom end torque increase as the others did but benifited most at the top end as the twin cam head breathed much deeper than the others.

Apon investigation it was found that the air entry into ALL airboxes were not up to the task of suppying air for the engine. The holes for the airbox were smaller than the main induction pipe to the plenum and had nasty bends and kinks not helping airflow at all. The air cleaners themselves where in good condition, yet probably didnt help the situation either.

When designing an airbox, be sure that it isnt being a restriction and you will be rewared with induction noise, exta power/torque and fuel economy.

[Mr Revhead]

induction noise, theres there key when talking about factory new cars

[Lith]

Fwiw I've played around with or been there for the playing around with various intake setups. Back in around 2001 a mate of mine with an otherwise standard Integra Type-R bought a short ram intake to put on it, he first booked some dyno time and put the car on the dyno with the stock airbox - bonnet closed for the run.

He then popped the bonnet, changed to the short ram setup, dropped the bonnet again and ran it up on the dyno again. From memory, the average power loss from going stock airbox to a short ram with no shielding was around 3kw @ wheels with the bonnet down. After shielding the filter from memory it ended up gaining 3kw over having stock airbox, or 6kw from having an unshielded filter.

The exact numbers will be fuzzy, but that should give the general impression of it all. With my Prelude (big lardy cruisy thing with heaps of stuff to shut the intake up so it isn't noisey) I pulled all the resonators and such forth out and replaced it with a 3" pipe from the throttle body to the guard and put a K&N filter on the end. Versus a short ram intake this was worth around 9kw @ wheels!

All my intake dyno comparisons are done with the bonnet down as running with the bonnet up using a short ram make it look a lot better than it would really be.

[Dell'Orto]

On Sunday the local FPV/Tickford club had a dyno day. Very interesting as on 4 models AU Fairmont straight 6, V8, T3 TS50, and a BA XR8 preformed a comparison of "with airbox" and "without airbox" dyno runs.
ALL had an improvement. THey were
AU Fairmont 4.0L VCT single cam 6, 134kW to 137kW
AU Fairmont, 5.0LWinsor V8, 143kW to 154kW
FTE T3 TS50, 5.6L stroked Winsor V8, 162kW to 173kW
BA XR8, 5.4L BOSS V8, 230kw to 244kW

The BOSS didnt get a bottom end torque increase as the others did but benifited most at the top end as the twin cam head breathed much deeper than the others.

Apon investigation it was found that the air entry into ALL airboxes were not up to the task of suppying air for the engine. The holes for the airbox were smaller than the main induction pipe to the plenum and had nasty bends and kinks not helping airflow at all. The air cleaners themselves where in good condition, yet probably didnt help the situation either.

When designing an airbox, be sure that it isnt being a restriction and you will be rewared with induction noise, exta power/torque and fuel economy.

Interestingly, those power gains are similar to what SS Inductions claim their high flow induction systems will make...which effectively all they do is remove the nasty kinks in the intake pipe.

[ChaosAD]

One thing to take into account is if the car uses a MAF sensor.

The ecu will be calibrated for the MAF sensor with the factory intake setup.
If the setup changes this will alter the calibration of the maf sensor.

The altezza is an example of this.