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ASP Medium Intercooler Kit

I have had this intercooler for a while and I have never had any regrets about purchasing it. All the parts are high quality and it has excellent performance without a lot of compromises. This product is available from Mostly Mazda for approximately $1500.

The kit includes:

  • Assembled intercooler core and end tanks
  • (4) 2.75" silicone hose connectors
  • (8) constant-torque hose clamps
  • (2) 2.75" semi-polished, mandrel-bent aluminum pipes
  • Fiberglass duct with black gelcoat and rubber seal
  • Duct extension scoop

Things you will need to install:

  • GReddy intake elbow
  • Four feet of 3/4" self-adhesive Velcro or a few inches of angle aluminum to keep the core in place

The virtues of the ASP Medium kit are many. Here is a list of the most important ones:

  • Large core provides excellent cooling and low pressure drop
  • The one-piece duct is air-tight and well-sealed
  • Piping is low-volume (reduced lag) and low-restriction (reduced pressure drop and better flow) while being more attractive and reliable than the stock pieces
  • Silicone hose connectors offer increased reliability
  • Constant-torque hose clamps stay tight through heat-cycling
  • Does not cause overheating like front-mount intercoolers
  • You can keep the battery and air pump (but the stock intake has to go)

Go directly to: [ Core | Pipes | Duct | GReddy Elbow ]


Here are the specs on the core as compared to the stock intercooler:

  Stock ASP Medium ASP / Stock
Volume (in3) 11.5" x 4.5" x 2.5" = 129 11.5" x 12" x 3.5" = 483 3.7
Internal flow area (in2) 11.5" x 2.5" = 28.75 11.5" x 3.5" = 40.25 1.4
External flow area (in2) 11.5" x 4.5" = 51.75 11.5" x 12" = 138 2.7

The core is 11.5" x 12" x 3.5"

core.jpg (16596 bytes)

The inlet and outlet (shown here) connections are 2.75"

outlet.jpg (7792 bytes)

Pipes & Hardware

The pipes come lightly polished, but you probably will want to finish the job for best appearance. I had both pipes and the end tanks polished for $150 at a local shop. I should have also gotten the top of the intercooler core polished.

Both pipes with a ruler

pipes.jpg (12591 bytes)

The outlet to throttle body pipe with two (of four) hose connectors

spipe_conn.jpg (10723 bytes)

The turbo y-pipe to intercooler inlet pipe with two (of eight) hose clamps

jpipe_ruler.jpg (9246 bytes)

A blurry shot showing the pipes to be 2.75" in diameter

pipe_diameter.jpg (9979 bytes)


The duct is a single piece made out of fiberglass with a black gel coat on the outside.

A side view of the duct

duct.jpg (6629 bytes)

The duct inlet

duct_inlet.jpg (11555 bytes)

The duct outlet with rubber seal (shown upside-down here)

duct_outlet.jpg (15460 bytes)

The duct with the included extension scoop, that can be optionally installed

duct_ext.jpg (10479 bytes)

GReddy Elbow

You need to buy the GReddy intake elbow separately, which is available from M2, SR Motorsports or another supplier for $150-$200 (more with injector bosses). You need only the single elbow piece as you will have no use for the other pipes that are available in the GReddy piping kits. The elbow is available with or without a pair of injector bosses. It comes nicely polished. Here is a picture of the elbow:

greddy_elbow.jpg (8080 bytes)

One thing you will notice with the GReddy elbow is that there is no nipple for the AWS hose on the outside of the elbow bend. You have several options for how to plumb the hose with the GReddy elbow installed. I wrote a long post to the RX-7 Mailing List and I have provided it for your information below. Since writing this, I have not replumbed the hose. If you live in a warm climate, the stalling problem is not that frequent is occurrence and it is easiest to simply plug it. Another note is that the little rubber plugs I mention both failed when used for the AST removal, but the AWS plug has held up nicely.

I recently installed a new intercooler and a GReddy intake elbow. The
GReddy elbow does not have the large nipple on the outside of the elbow
bend that is required to hook up the AWS (Accelerated Warm-up System)
That leaves you with three options for the AWS: vent it to atmosphere,
plug it up, or reconnect it to the intake plumbing. Here are my
thoughts, opinions, and experiences with each of these options. 
After consulting the list, I decided to vent it. Because intake air is
drawn in to the engine through this hose, it clearly needs to be
filtered. I bought a small K&N filter from Elite Motorsports
( for this purpose. It is a tight fit,
but I installed the filter directly on the metal pipe that comes out of
the manifold. This was a nice clean installation and I was initially
very happy with it. 
My first time using the car was a few short test runs on a Thursday
night, and then Friday I drove down to Summit Point for MADS (a 500 mile
trip). Everything was working fine. Then I was on the track on Sunday,
and after the first session I found oil all over the middle of the
firewall and the surrounding area. Yuk! It was coming from the AWS vent
Why would the AWS solenoid be open on the track? I thought it was only
supposed to open for cold starts? Well, I think that it opens due to
only having the boost pressure on one side of it, where when it was
plumbed to the intake before it has the same pressure on both sides.
It's just a theory, but I think it is opening under boost. 
I spoke to another vented AWS guy at MADS and he said that he gets some
oil leakage that he just cleans up periodically, and that it was not a
big deal. A contributing factor to the huge amount of oil that leaked on
my car is that my first turbo is near death and must be dumping a lot of
oil into the intake. Needless to say, I don't want this thing vented
The AWS is commonly described as being a system with the single purpose
of warming up the pre-cat by making the idle quite high (3000 RPM or so
when it is really cold). Running the engine at 3000 RPM right after it
starts seems like a bad idea in terms of wear and longevity, and I don't
have a pre-cat, so disabling this system seemed like a no-brainer. 
Yesterday, I plugged the AWS. I removed the filter, and found that it
was much easier to get off than it was to get on. I think that it had
stretched to its new dimensions, but it was not damaged and was still
suitable for the task. The worm gear hose clamp that I had installed had
loosened quite a bit, also to my surprise. 
I installed a heater hose plug (5/8" I think) that I bought at the auto
parts store. It was one of those HELP! products that I have been growing
surprisingly fond of (check valves, AST removal plugs, etc.). The cap
fit reasonably snugly and I put a new hose clamp on it. 
It is still on there and I haven't seen any more oil, so I am reasonably
pleased with the result. However, the car stalled this morning right
after I started it (which it has never done before, and it was not even
cold out), so I am left to question whether the AWS may be present for
more than just emissions purposes. Also, I read a post in the last day
or two about what RPM the engine would idle at with the AWS plugged. The
report included mention of the engine stalling after the first start. 
So, now I want to replumb the AWS. A local friend of mine has an HKS
piping kit (which is also missing the nipple for the AWS) and he had a
shop add a nipple onto the pipe. I think it cost <$50, so it is not a
very expensive modification. 
It seems like this is the best solution. I don't want oil leaks or
stalling, so this is the solution for me. If anything else happens that
is weird, I'll report back (with info on how and why you should add a
tiny AWS turbocharger ;-), otherwise you can assume I am happy with my
replumbed AWS.

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