Panel filterrrrrrrrrrrrrrr

[TonyS9]

I don't get all this talk about flow rates with Turbo's. The air filter will not improve the flow rate at peak power, all that will happen is that the turbo will spin slower.

It may help low end torque when the turbo is not spinning or speeding up, otherwise nothing once its above 2,500.

The Turbo is a constant pressure device, what restrictions are before the turbo are irrelevant (up to a point).

I suppose there might be a small benefit from the lower exhaust restriction, but the point about turbos is that the power benefit is many time the strain on the exhaust side, so air filter benefits are going to lead to exhaust benefits many times smaller.

The better low end torque is nice to have but if you need a speedy take off in a turbo you need to rev it up anyway.

[gpl1968]

Intake restrictions do make a difference to the efficiency of the system.

You can liken the car's intake to a vacum cleaner where the suction drops as the bag fills up, thus reducing the flow of air.
The intake restrictions will ultimately limit the maximum flow of air to the turbo at high turbine speeds.

The question here is by how much.

Assuming the figures in the quoted article are correct, then the pressure drop across a standard paper filter is ~1 inch/water or 0.036psi.
The Pipercross filter is alleged to improve air flow(across the filter) by ~30% which would reduce the pressure drop to 0.025psi across the filter.

Seeing that there are greater restrictions in the system that are easier to remedy, I don't see that changing the filter is worth doung.

[Palmer]

All this is a bit technical for me...

So an OEM filter is better than a Pipercross?

Palmer

[gpl1968]

Originally Posted by Palmer

All this is a bit technical for me...

So an OEM filter is better than a Pipercross?

Palmer

In my opinion, yes.

[smithy]

i have had a 850 k/n cone on my 940 no probs at and now i have a pipercross turbo cone filter and thats good too all with 3in outlet for the 960 amm.

[CTCNetwork]

Hi,

Originally Posted by Palmer

All this is a bit technical for me...

So an OEM filter is better than a Pipercross?

Palmer

But better at what? Filtering? Probably. At letting more air through? Probably not.

Originally Posted by gpl1968

In my opinion, yes.

My emphasis. Indeed - just opinion. Each to his own.

Des. . .

[1stRaven]

Originally Posted by gpl1968

Then why bother with a filter at all then. especially an expensive foam filter that doesn't filter as well as the original and provides only a marginal increase in flow rate?

When I look in the bottom of my air-box and see the build up of dust and silt, I'm glad that I know the filter is doing it's job.

The filter stops the larger objects coming in and its true, maybe I could use a better filter but the stock airbox will not flow enough air for my engine specs.

Originally Posted by TonyS9

I don't get all this talk about flow rates with Turbo's. The air filter will not improve the flow rate at peak power, all that will happen is that the turbo will spin slower.

It may help low end torque when the turbo is not spinning or speeding up, otherwise nothing once its above 2,500.

The Turbo is a constant pressure device, what restrictions are before the turbo are irrelevant (up to a point).

I suppose there might be a small benefit from the lower exhaust restriction, but the point about turbos is that the power benefit is many time the strain on the exhaust side, so air filter benefits are going to lead to exhaust benefits many times smaller.

The better low end torque is nice to have but if you need a speedy take off in a turbo you need to rev it up anyway.

I don't think you've driven a stock car and one with a 3" exhaust. The larger exhaust and lack of back pressures means that a much larger turbo will spool at the same rpm as a standard one. Just imagine the difference it will have on a stock turbo.

As for the airbox, it is worth changing at certain points since the stock one can not flow high air for higher boost pressures. What the limit is depends on the filter you are running, and the mods done to the air box.

[Steve940estate]

There is a bit about different styles of filters in the Mini Tuning book by David Vizard. He actually flow tested a range of filters to see which ones were best and the good quality standard style paper ones came out pretty well.
K&N ones were top of the list, they filtered well when new and when full of dust.
The standard paper ones were nearly as good when new but got clogged up quickly.
So, if you bought a good quality paper filter (genuine Volvo) and changed it often it would be nearly as good as a K&N.

One thing he does say is that the size of the filter is important. Even a K&N will perform badly if it's too small for the engine.

[TonyS9]

Originally Posted by gpl1968

Intake restrictions do make a difference to the efficiency of the system.

You can liken the car's intake to a vacum cleaner where the suction drops as the bag fills up, thus reducing the flow of air.
The intake restrictions will ultimately limit the maximum flow of air to the turbo at high turbine speeds.

That only works for N/A cars. Vacuum cleaners, unlike turbos, are not pressure regulators. If you put less restriction in it will simply spin slower. It will not 'flow more', all it does is maintain the pressure in the manifold at a fixed value, the engine can consume any amount of air it likes the turbo will just keep it pressurised.

All a better air filter will do is does is create less back pressure at the exhaust because the turbo is not working as hard. I would surprised if it was more than 2 bhp.

It will only make a difference if the turbo cannot keep up the pressure, for instance if you increase the boost pressure and maybe do other mods. This can be seen by a drop in boost pressure, but is quite rare.

The same can be said for putting in a bigger turbo, the only point in doing it is if your current turbo cannot maintain the pressure you have set at top rpms, although a bigger one might last longer.

[TonyS9]

Originally Posted by 1stRaven

The filter stops the larger objects coming in and i
I don't think you've driven a stock car and one with a 3" exhaust. The larger exhaust and lack of back pressures means that a much larger turbo will spool at the same rpm as a standard one. Just imagine the difference it will have on a stock turbo.

As for the airbox, it is worth changing at certain points since the stock one can not flow high air for higher boost pressures. What the limit is depends on the filter you are running, and the mods done to the air box.

Granted if you have tons of mods and are producing 300bhp+ a better air filter may allow the turbo to maintain pressure, but if your that marginal you probably need other improvements anyway.

On a standard 940 2.3 HPT, I don't see that a 3" exhaust is going to make much difference. Removing the rear silencer is just about noticeable at low revs, but I doubt the pipe size really contributes much. In fact a larger pipe may reduce the gas speed and temps such that there is alot more mass+friction in the system.

The speed of the larger turbo is also not that relevant, it best to match it to the available power, bigger turbos and bigger exhausts do not produce more power automatically, they are supplementary improvements so that other modifications are not limited. I suspect the 3" exhaust you refer to had a straight through system and other upgrades.