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.
HKS Super Power Flow (SPF) air filter system replaces the stock air
filter system for Honda engines. Of the open element, mushroom type
design, the SPF physically replaces the entire air-filter box which is a
source of air-flow restriction. Installation requires the removal of this
box and the substitution of the SPF into the intake hose. HKS provides
different models of SPF according to different Honda models, differing
mainly by size.
TOV-W asked Rennie to explain the relationship between HKS' Super
Power Flow and Power Flow.
The HKS Super Power Flow is a newer and better version and a
replacement for the Power Flow. The Power Flow design is now
obsolete and no longer offered as part of the HKS suite of products. In
the rest of our look at the Super Power Flow, we will also compare it to
the Power Flow where applicable.
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
The photo of a cut-out of an SPF at the right shows the venturi
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.
TOV-W posted some questions to Rennie about the HKS SPF with regards to
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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