gaining HP with an air filter, is it true? Options

[tradisrad]

I was browsing the AA catalog and came across the MSDS high flow cone air filter (catalog page 28). The ad claims that one can gain upto 10 more HP using this air filter. Is this true? Has anyone else used one of these?

BTW my engine is a 2056, stock FI with Raby's 9550 cam and tuned MPS.

HPH sells a bored throttle body and claims HP gain with the TB. True?

[Katmanken]

Flows more air..... really?

Think about it..... an engine is a piston air pump.... (IMG:style_emoticons/default/idea.gif)

Depending on atmospheric air pressure, there is only so much air that can fill a cylinder when the piston goes from TDC to BDC .....

The only way that you can get less air in the cylinder is to place a large air restrictor into the intake and then the piston sucks a vacuum when the piston goes down.......

I'd be willing to bet a non-dirty air filter is designed to pass air and isn't enough of a flow restrictor to create a vaccum so large that it restricts horsepower by other than a very minimal amount......

Oil baths use bubbling and aren't subjected to dirt and flow changes as much as paper units are....

[Solo914]

For what it is worth, I have spent quite a bit of time on a dyno tuning my spec miata and there are 3-5 hp differences between a stock miata airbox and cone filter assembly. The early miata and the 1.8 914 have a similar intake because they use a airbox with a snorkel and bosch AFM. On the miata we found that the AFM is a large restriction and the box itself is a restriction but only one of those can be fixed, basically you can reduce all the restriction you want from the air filter assembly but only so much air is going to go through the AFM. So, the goal is to find a filter assembly that will flow air the best THROUGH the AFM. Someone with more time on their hands than me has done the testing with a flowbench and found that the AFM and the airbox were the restrictions in the system of the miata. I am pretty sure that no one has really done that kind of testing on a 1.8 914, I mean why would you. The fact is, if the 1.8L doesn't flow enough to max out the flow of the AFM or the air box/filter then you probably aren't leaving that much on the table. Then again, if it is maxing it out then there could potentially be some good HP being left on the table.

It also goes without saying that you should probably adjust your AFM if you are going to modify your intake filter assembly etc.

So, is it worth it for 0-5hp? Well, if it is a 5hp gain well thats like a 6-7% gain in HP at the wheels on a stock 914. I guess its up to you.


kyle