Small K&N cone filters: How well do they flow?

[futurevr4man]

Your question is really not worded correctly at all. What an inlet restriction would do is hinder your compressor's ability to compress the air effectively. I'm sure that the filters each have a corresponding air flow rating, but the efficiency (and general size) of your turbo has a lot more to do with horsepower output than anything. That's not to say the filters don't make a difference... even a significant one.

There was thread on 3si that I read once, where Trevor (I think?) put filters directly on his turbos, did a dyno pull. Then put on pre-turbo intake pipes and did another pull.

Huge difference. Like 40 horsepower or something.

The flow being more guided and laminar really changed how well the fluid (air) was compressed. The filter would also have an impact similar.

[RealMcCoy]

There is also the very direct pressure differential to consider. All being equal, same airflow, same temp ect, pull 2 inches of vacuum on the compressor side, you are losing 1lb of boost..

[Toni]

I like simple questions and simple answers but understand that it's not always that simple.

If there was a huge intake restriction and I reduce said restriction (no or bigger filters) then I might actually end up running higher boost numbers because my boost controller is set and doesn't have any feedback.

Generally, would my gains be from more airflow into the engine at the same boost or the fact I can run a bit more boost before hitting the knock threshold due to increased efficiency?

[DocWalt]

Both of the above, Toni. You'd see slightly improved efficiency which lets you push a bit more air for the same boost level.

[futurevr4man]

More airflow from the same boost pressure is where you will see most of your gains. The efficiency thing... you are pushing hot air efficiently, or really hot air inefficiently... either way, you find that knock threshold fairly quick.

But a lot of that comes into play with the head castings, carbon buildup on valves, yadda yadda yadda. So yeah, they both have an effect, but quantitatively I would say that the more air per lb boost is the biggest impact.

[Chris@Rvengeperformance]

An intake restriction will also require more driving energy from the exhaust, so got more power that way. Its like installing a bigger compressor wheel.

[RealMcCoy]

An intake restriction will also require more driving energy from the exhaust, so got more power that way. Its like installing a bigger compressor wheel.

Exactly... people often look at their gauge pressure and say 15lbs, is 15lbs... But if you have a 2 inch vacuum on the inlet, that turbo is having to make 16lbs to show you that 15 on the gauge.

[CoopKill]

Would love it if someone could do a dyno run (virtual, or real) with the filters, and without. Get an idea of what gains are to be seen. (rpm/spool, hp/rpm, power curve)

[futurevr4man]

I half-ass looked for the thread I was referring to. No dice. I am still pretty sure it was trevor who did it though. Back before his single turbo build.

[AdamVR4]

You're thinking of snakeskinner dynoing his 8 sec car. I miss Trevor