Intake System Upgrade
Intake System- Quick Access:
Intake Upgrade Description
Much like the exhaust system, the intake system has been an ongoing,
multi-stage upgrade process. To date, the Supra has seen 5 air filter setups:
#1 Stock airbox & filter
#2 HKS Super Power Flow filter, with Air Flow Meter [AFM] adapter
#3 K&N 6" Universal filter, using the HKS AFM adapter
#4 Same as #3, but a Home Depot-sourced shield was implemented
#5 K&N 9" Universal filter, not shielded, & using a modified HKS Vein Pressure Converter [VPC] adapter
The original, enclosed stock air filter-box was designed to provide not only air filtration, but to reduce the large
amounts of noise that an intake system can produce. I suppose if the car remained stock, the setup is perfectly fine,
but remaining stock has never been an option. Although better flowing filter elements for the stock box are available,
the restrictions inherent to the box design, remain. Swapping to an open filter element is the only way to go, if
realizing maximum gains are to be seen; not only in performance, but increased efficiency in terms of gas mileage as well.
This is one of those rare mods that offer a winning situation in both of these areas.
The first intake upgrade was an HKS Super Power Flow filter, done way back in 1994, & it was my 1st engine upgrade on
the Supra! The 2nd intake upgrade was done only after it was realized the reusable HKS filter was simply not filtering up
to expectation. Despite its 2-stage foam elements, I would find dirt that had made its way into the intake piping. I am
one of those who can verify the nickname "Dirt-Flow" for the HKS product. It's filtration was simply very poor.
The 2nd intake upgrade, done in 1998, entailed the removal of the HKS "Dirt-Flow", & the installation
of a K&N 6" universal filter. Since the HKS kit had already provided an AFM adapter, the filter was a plug 'n play
proposition, requiring only a few minutes to complete the swap. The improvement to air filtration was incredible, &
not only that, but there was a very noticeable gain in engine response and overall driveability. I nearly kicked myself
for not having done the swap much sooner.
The 3rd intake upgrade was a creative modification to the then existing K&N setup, adding a heat shield to the filter to help
ward off the radiant heat encountered in the engine compartment- a common issue in turbocharged engines. A quick trip to
the local Home Depot provided the perfect galvanized steel sheet metal ducting I was looking for. By wrapping the outer
edge of the filter's base with rubber foam strips, the ducting fit around the filter almost perfectly. As the duct was
also conical in shape, it even conformed to the cone-shape of the K&N. Initially, the entire duct was used. Not too
long after having done the mod, longtime Supra-friend Dean Marcum, made me aware that I had created a great shield, but
at the expense of the filter's flow capability; basicly a gnarly restriction. Dean was kind enough to cut out one side
of the shield for me, exposing roughly 1/2 of the filter on the side facing the fender, away from the radiant heat.
Woohoo!
This setup was on the car when the engine dyno'd 354rwhp.
The 4th, & current intake upgrade, involved a swap-out of the 6" K&N + shield to an unshielded, 9" version of the
same universal style K&N. During more than one dyno session, I'd recieved comments from respected modders that upper
RPM horsepower could probably be further enhanced by going larger on the filter element. Since I'm at the point where
every little bit counts, I decided to take the advice. The mod is done, but is so new that I haven't even had the chance
to go for a drive yet, much less dyno! I'll be heading out for a cruise in a little while, & will post an update from the
Seat-of-the-pants meter [SOTP]. And shielding? Well, like I said, the new filter just went in, so a new shield will
definitely come, but at some point in the future.
The air filter is not alone when it comes to modifying the intake system for more power & efficiency. Another very
worthwhile mod that I put on the Supra is the Cold Air Induction [CAI] mod. Quite simple in both concept &
implementation, the CAI mod basicly routes ambient air into the engine compartment in close proximity to the air filter.
This is another Home Depot mod, consisting of 4" aluminum-covered flexible dryer hose, a couple of 4" duct
joints, aluminum tape, & some cable-ties. More info can be found in the Stage One
tech tip. At any rate, the induction of cooler ambient air helps reduce intake air charge temps, besides the obvious
benefit of reducing overall underhood temps as well. Selection of materials decides the mod's longevity, since I'm
currently on version 3.0, due to the materials' breakdown in the automotive environment. That's OK, since I'm a firm
believer that this mod is worth the effort, & minor expense [~$15].
Here is the HKS SuperPowerFlow air filter.
If you look closely, the outlet for the Cold Air Induction Mod
can be seen directly in front of the filter.
K&N air filter before shielding. This pic gives you a good idea of air filter fit/location,
if you have the stock AFM & decide to use the K&N with the HKS AFM adapter...
the Filter Injection Performance Kit [FIPK] alternative.
Scroll down to see a standalone pic below.
Here is the shielded air filter/intake tube assembly. The exposed surfaces were further
insulated from radiant heat with aluminum-backed pipe insulation foam.
On the left, front view of the shielded 6" K&N. The outer ring was retained to provide
support.
On the right, a shot of the 'Poor Man's FIPK' now offered in kit form by
SupraSport.com.
This shows the 6" & 9" K&N filters side by side.
More surface area equals more flow.
The 1st 2 small cuts allowed the 6" filter to fit better in the cramped space.
The 3rd large cut, was the chunk taken out to accomodate the big 9 incher.
The big piece on the left is what remains of the original VPC tube.
Doing it once, & doing it right is a nice thought, but
refinement is oftentimes a product of retrospect.
This shows the new 9" K&N filter installed.
I guess I should take the wrapper off :-)
K&N filter installed, #2.
K&N filter installed, #3.
CAI example, as offered by SupraSport.com
CAI hose inlet in lower left grille area.
CAI hose outlet behind the passenger side headlight.