HKS Super Power Flow (SPF)

In this feature, Temple of VTEC - World's own comments are published in italic fonts.

HKS is one of the premier Honda tuners in Japan. The Malaysian HKS representative is Aerotech and is run by Mr Rennie Khoo, a very knowledgeable engine tuner in Malaysia. Recently, I've had the very good fortune of receiving Rennie's hospitality and we are now embarking on a special feature of tuning products that HKS specially makes for Honda. Drop by often to look out for new products covered. To contact Aerotech in Malaysia, their phone number is 60-3-7556112.

The major strength of the SPF focuses on two main areas. One is a venturi built into the mouth of the air passage. This venturi helps speed up the air after it flows in through the main filter element and into the engine. The photo of a cut-out of an SPF at the right shows the venturi structure clearly.

The other more significant design point of the HKS SPF is its foam filter element. This foam element is a dual-layer design. Rennie explains that form is superior to paper in air-flow properties but has the disadvantage of an inferior filtering ability. Filtering ability can be enhanced by having a denser foam but this will compromise the air flow ability. The SPF element overcomes this by employing a two layer design. The outer element is coarser while the inner element is denser. In normal dual foam elements, bonding of the two layers by glue will lead to air-flow hinderance. HKS overcomes this by using 'heat lamination' to bind the two foam layers together. Foam is made up of a network of many fine rubber 'legs'. Heat lamination bonds the foam elements at the individual 'legs'. This effectively means that there no obstruction to air flow at the bonding layer.

After taking care of the air-flow requirements, HKS now reinforces the filtering ability of the SPF element by developing a special oil to coat the foam element. The special oil attracts and sticks all kinds of dust and oil thus enhancing the filtering ability of the SPF element while allowing it to maintain its superior air-flow properties.

Finally, the metal cover of the HKS SPF is of a honeycomb design, an evolution over the square design of the older HKS Power Flow filter. HKS says that this honeycomb design gives superior air-flow properties.

1. What is HKS' comments with regards to 'cold-air' type of air-filters, eg ICEMAN or the original stock filter which takes air from behind the front bumper (or fender) while HKS SPF takes air from inside the engine bay which is hot and less conducive to high power output from the engine

HKS acknowledges this effect. For standing starts, putting an open element filter in the engine bay does have a detrimental effect. However this effect is rapidly neutralized once the car starts moving as airflow into the engine bay will quickly bring the internal temperature down to almost the same as the outside air. HKS feels that at speed, the advantages of the cold-air type of filter is very minimal.

Checking the Honda Performance List archives however, I found some interesting information. At idle, engine bay temperatures can often exceed 120 degree F! However, this will drop drastically once the car gets moving. In one post by Theron Ross who used a Radio Shack digital temperature probe, he measured a difference of 7 to 13 degree F between engine bay air and outside air temperature. This is confirmed by Chris Heerschap who measured the air temperature at the mouth of the throttle body, also with a digital temperature probe and found a difference of about 10 degree F between open element and when he fed the filter some outside air via a hose.

2. How often the filter element needs to be changed for optimum results. At this point, note that when you purchase a new replacement element, the instructions on the cover tells you to replace the element once per 3000-5000km. This can get quite expensive !

Rennie rightly points out that the actual replacement interval should depend on usage conditions. Assuming normal city use, he estimates that a 10,000km replacement cycle to be a good interval.

3. Lastly, TOV-W asked Rennie to confirm that the HKS SPF is indeed non-washable and needs to be replaced.

The older HKS PowerFlow's foam element can be washed. The SPF element however cannot be washed because of the special oil that HKS uses to treat the foam. This oil cannot be substituted using WD40 or other types of oil (ie. the type that K&N uses).

©1998 Temple of VTEC
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