Hi Guys,

I have picked up a HKS Intercooler for my FC3S RX7.

It is a direct Top Mount replacement intercooler, which is my preference.

Now, I have just measured up the stock intercooler and the HKS intercooler and really would like someone who has some technical knowledge on flow, surface areas etc to comment on whether the small incremental increases in size listed below will actually make any difference?

Would it improve flow?
Would it improve cooling?

Here are the numbers...

STOCK INTERCOOLER
WIDTH:300mm
LENGTH: 170mm

THICKNESS: 65mm

INLET PIPE: 41mm internal diameter
OUTLET PIPE: 50mm internal diameter

HKS INTERCOOLER
WIDTH:260mm
LENGTH: 260m

THICKNESS: 65mm

INLET PIPE: 46mm internal diameter (5mm bigger ID)
OUTLET PIPE: 55mm internal diameter (5mm bigger ID)

 

How will that inter-cooler work? The air outlet pipe is facing the wrong direction isn't it?

And would cooling capability be reduced by not having a heat-shield on the HKS unit?

 

The stock outlet pipe goes into a 90* hose stock, it appears the HKS unit would use a shorter straight coupler to attach to the inlet on the TB.

HA. That little metal piece has NOTHING to do with cooling, its there to channel rain water away from the various electrical connections and lines underneath the IC. I just drilled the rivets out of mine and removed it so I could install an FPR and parallel fuel system. I took before and after logs of AFM/Intake/coolant temps, and it makes no difference whether the sheild is there or not , top mounts suck bad unless you are moving 40+ mph. Period. If I came to a stop the TMIC would actually raise intake temps from the afm (which is sucking in hot air from the engine bay to begin with) by anywere from 10-20*.

There was a test done a while back that compared various stock IC and it actually found the FC TMIC to be one of the best (did I mention this was a while back? ) Also, they rated the S5 jspec IC higher than the S4 due to increased flow as a result of slightly larger inlet/outlets (somewhere in the neighborhood of 4mm larger) That said the HKS unit should definitely improve flow, since it is larger, has larger openings and seems to promote smoother airflow. As far as how much.....you got me there.

 

I've seen some improvements by using bolt-on TMIC upgrades on Subarus. There isn't a lot of information available on the intercooler in question here because they were discontinued a long time ago.

 

area is LxWxH

stock is 3,315,000mm3

hks is 4,394,000mm3

hks has 30% more area.... bigger piping, a nicer cold side end tank.

 

And here I was think that was volume...

 

what would u measure that in mm^3?

 

Yes, that would be cubic millimeters.

The HKS does have a bigger top area, . There's only so much room for improvement there though, as the stock IC duct is only so big - around 13" x 9", or 330mm x 228mm, for an area of 75240 sq. mm. The HKS has a top area of 67600 sq. mm vs 51000 sq. mm for the stock IC. So, it theoretically fills more of the duct, except the duct is only 228 in one direction, leaving the HKS 30 mm blocked by the hood on one side.

Of course, this is a horrible way to compare intercoolers. What matters is bottom line numbers such as intake temps, pressure loss and the tradeoffs that make one better than the other.

 

Heat exchanger efficiency is almost impossible to estimate based on size alone. Without a flow bench and some other equipment, there won't be any way to tell for sure until you try it out.

Larger piping will help with flow, and I agree that the cold side tank looks better, but that's based only on external views. That dent in the side has me a little confused though.

 

lmao! i'm not an engineer, and this is why

 

You can't really use volume as the end all for intercoolers though...for example... a

20" widex 10" tall x 3" deep intercooler will cool a **** of a lot better than a

10" wide 3" tall 20" deep intercooler even though they have the same area.

A better equation would be the front surface area times a third of the thickness.

That, of course, does nothing different here, as the two intercoolers are the same thickness.

I'm done rambling now.

 

Wait a minute, are you suggesting bigger is not better??

 

Its more important that you know how to use it right.

 

i have the same IC. polish that baby up. Do you also have the hotpipe for it?

 

That is also there on the stock one too, it is to clear the alternator.

Definitely plan on giving it a good clean and polish.

When you say "Do you also have the hotpipe for it?" ....what do you mean?

It came with a silicone joiner for the TB and an extension tube and silicone joiner for the hot side, is that what you mean?

 

heres an old pic pre-touch up polish job. I dont have the manifold to intercooler bracket btw, so had to rig something up.


Hotpipe - from turbo to intercooler.

I bought my car with it so i couldnt tell you the benefits over stock since i never drove stock. JTP put a blow off flange on the hotpipe and has it recirculating to a custom intake. My car doesnt have the intercooler insulation on the hood.. .and I know at one point, he had that mazdaspeed larger snorkel scoop , so i dunno if that improves air flow or not.

I think this is the same one. Looks really good polished





give you some ideas on polishing it
http://minkara.carview.co.jp/userid/422759/blog/p9/

 

While we're discussing this top mount HKS, where did you manage to find this thing? As far as I know, they are quite hard to find.

 

Here's one...

http://page6.auctions.yahoo.co.jp/jp/auction/f88007336

 

It looks Great polished