[Coupes33]

I have been reading an American book "TURBO Real World High-Performance Turbocharger Systems" on Intake Air. In this section, it has formulas for calculating the square inches of filter required based on the size of engine, boost and rpm that max power is created. The formula is supplied by K&N for their style of filters. I did a couple of calculations with interesting results.

The first calculation was using the standard oem filter box with a K&N panel filter. The dimensions for this filter is 10" x 9" = 90 square inches. So using the formula in reverse to work out the suitable boost, it came to 10.4psi. A 3.0L engine is 183 cubic inches and my max power is created at 6,200rpm.

In the second calculation, I used my boost at 26psi and the filter size required was 150 cubic inches. I run the OEM filter box with a K&N panel filter and an additional pod filter. By these calculations, my engine requires more filter area and is probably choking somewhat at the top of the rpm range.

There is also a formula for working out the height of a circular filter or the length of cone shape filters. I measured up the filters on my spare AFE DCI and did a reverse calculation which resulted in these filters only good for 15.5psi boost. These filters are 5.5" long but for my application would need to be 7.7" long.

Something for me to look further into and see what options or better filter system I can design and build.

[Socket]

Interesting..... maybe best thing to avoid restricting airflow is to run without filters

[Brule]

The rear turbo position is an issue for sure. A big filter would be good but theres no room.

When Vargas first released stage 2 turbos he tested them and showed dyno of turbos with no filters. ( undisclosed at the time) and he was making most power on twins at the time, I cant remember exactly but around 540 or 570 when everyone else was making 525hp max before inlet days.

Obviously not worth wrecking turbos in possibly a few runs but worth looking at a rear filter thats not going through the rear inlet piping.

[Coupes33]

Originally Posted by Brule

The rear turbo position is an issue for sure. A big filter would be good but theres no room.

When Vargas first released stage 2 turbos he tested them and showed dyno of turbos with no filters. ( undisclosed at the time) and he was making most power on twins at the time, I cant remember exactly but around 540 or 570 when everyone else was making 525hp max before inlet days.

Obviously not worth wrecking turbos in possibly a few runs but worth looking at a rear filter thats not going through the rear inlet piping.

I agree Brule. There is very little room around these engines to do anything. I was contemplating installing a small fan on the intake of the OEM filter housing that would force air through the filter and reduce the resistance of the filter and inlets on the turbos. This should also allow the turbos to spool quicker at low rpm.

[Socket]

Originally Posted by Coupes33

I agree Brule. There is very little room around these engines to do anything. I was contemplating installing a small fan on the intake of the OEM filter housing that would force air through the filter and reduce the resistance of the filter and inlets on the turbos. This should also allow the turbos to spool quicker at low rpm.

How about running a snorkel down into the front bumper in front of an air duct Coupes (like the dinan air intake without the filter on the end)

Should get much better air velocity then a fan would generate

[Coupes33]

Originally Posted by Socket

How about running a snorkel down into the front bumper in front of an air duct Coupes (like the dinan air intake without the filter on the end)

Should get much better air velocity then a fan would generate

Yeah Socks. I already have something similar but not as smick as the Dinan unit. One thing I will do is replace the SAAS filter with a longer version like the Dinan. A 100mm long filter will give me the 150 square inches that I am after.

[Socket]

Originally Posted by Coupes33

Yeah Socks. I already have something similar but not as smick as the Dinan unit. One thing I will do is replace the SAAS filter with a longer version like the Dinan. A 100mm long filter will give me the 150 square inches that I am after.

Attachment 1965181

Attachment 1965182

I see you already thought of this..... Always said you were a genius Coupes

[Coupes33]

Originally Posted by Socket

I see you already thought of this..... Always said you were a genius Coupes

I am far from that Socks. If I was a genius, I would be a millionaire and be driving around in a 488 Ferrari.

[Coupes33]

Today, I did a test to determine whether the air filters were causing a restriction. I disconnected the front DV from the front inlet and in its place, I inserted a bung with a vacuum gauge attached. I then took the car for a drive and gave it a full power run to see if any negative pressure was indicated in the inlet. Nothing was shown on the gauge. This indicates to me that the air filter configuration that I am running is ok. If the air filters were restrictive, negative pressure should have been indicated on the gauge.

[Aus335iguy]

Originally Posted by Coupes33

Today, I did a test to determine whether the air filters were causing a restriction. I disconnected the front DV from the front inlet and in its place, I inserted a bung with a vacuum gauge attached. I then took the car for a drive and gave it a full power run to see if any negative pressure was indicated in the inlet. Nothing was shown on the gauge. This indicates to me that the air filter configuration that I am running is ok. If the air filters were restrictive, negative pressure should have been indicated on the gauge.

Back in the day Julian Edgar wrote a book about turbo charging and im pretty sure but dont quote me he said that you cant measure the pressure in absolute terms, you have to measure in relative terms.
In other words in order to find out if your filter is restrictive you measure in front of and behind and the difference in pressure is caused by restriction.
Also does the area calculation take into account the pleats in the filter?
The way i understand it the depth of pleats can vary a bit and that's how some filters flow more whilst occupying the same space and being made of the same material..

[Coupes33]

Originally Posted by Aus335iguy

Back in the day Julian Edgar wrote a book about turbo charging and im pretty sure but dont quote me he said that you cant measure the pressure in absolute terms, you have to measure in relative terms.
In other words in order to find out if your filter is restrictive you measure in front of and behind and the difference in pressure is caused by restriction.
Also does the area calculation take into account the pleats in the filter?
The way i understand it the depth of pleats can vary a bit and that's how some filters flow more whilst occupying the same space and being made of the same material..

Yes, I agree that measuring the differential pressure across the filter will indicate any restriction. The use of a 'U' tube where you have atmospheric pressure on one side and the suction pressure from the turbo on the other side could be used. If there is no restriction, there should be no difference in the pressures. As far as the depth of pleats go, the formula in the book is based on areas of K&N style filters.

[juld0zer]

Originally Posted by Coupes33

Yeah Socks. I already have something similar but not as smick as the Dinan unit. One thing I will do is replace the SAAS filter with a longer version like the Dinan. A 100mm long filter will give me the 150 square inches that I am after.

Attachment 1965181

Attachment 1965182

Not worried about water ingestion?

[Coupes33]

Originally Posted by juld0zer

Not worried about water ingestion?

There is an aluminium duct under the air filter that will direct any water past the filter to a drain that I installed into the wheel arch. Also, I don't drive through water that is deep enough to be above this level.