The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support Fuel Injector Clinic
Please Support Fuel Injector Clinic

Hood-mount intercooler


DSM Wiseman
Feb 15, 2006
Los Alamos, New_Mexico
I'm guessing this has been tried or atleast considered...has anyone tried mounting a large intercooler under a custom cowl built into the hood? I have a lame Paint image of what I mean:

You must be logged in to view this image or video.

If an intercooler with inlet/outlet on the passenger side was used (end tanks toward front and back of car), one could be right above the compressor, and the other could be right above the throttle body. Obviously, the intercooler would be mounted not to the hood but to brackets in the engine bay. And changing the oil would require you (maybe) to remove the intercooler, but...

And would this be a "HMIC"?

Just an idea.


15+ Year Contributor
Nov 6, 2003
Livonia, Michigan
It kinda reminds me of the mazdaspeed 6. The unit works pretty good, except when multiple runs are done back to back, they tend to heat soak. A few of them have water to air IC's positioned there however. I was also linked to a thread from the MS6 guys, to the suby forums where an Sti swapped from top mount intercooler to a FMIC and actually lost power. Ill dig up the thread if you like, I dont have time right now. Im not saying that TMIC is better than FMIC, it seemed to work better for that specific application. I still believe that FMIC with an efficient radiator, or a v-mount set-up is the best solution from a performance standpoint. At least someone is thinking outside the box:dsm:

edit: I just actually understood exactly what you drew now. I like it! with a nice heat barrier under the hood to resist heat transfer from the bottom, and those directed louvers it should be pretty efficient. Especially because you arent blocking the radiator now, you can run a little cooler which is ideal. The only problem would be not making it look ugly and protecting it from destructive objects.


15+ Year Contributor
Jun 28, 2003
Portland, Maine
You mean like the WRX's and rally cars?
1)I think the only benefit to doing that, is it protects the intercooler from rocks and debris when they're racing on dirt roads.
2)The hood is in a low pressure zone. You would need a big cowl - think STI huge
3)I've always thought the V-mounts they run on RX7's are cool, but they have a lot more room from front to back because of how small the rotary package is.


Supporting VIP
Jul 20, 2007
Omaha, Nebraska
HMIC haha. Porsche uses above engine mounted intercoolers on some of their cars but I have also seen a lot of road race porsches that use FMIC probably better for keeping off heat soak.


15+ Year Contributor
May 8, 2004
Palos Heights, Illinois
Read this: Browser Warning

Yes it works and spoolup is outstanding, I drive an STi with a TMIC. Bad thing is heatsoak at low speeds. On a hot day I can see the heat "wafting" up thru the I.C. hood duct when the car is parked. You don't get that with a SMIC or FMIC. Low speed operation is going to hurt you. Highway speeds I think a properly ducted TMIC could rival an equally sized FMIC as at high speed my STi pulls very hard and there is a ton of ram effect in the tall hood scoop.

Only way to stop the heat soak is to completely duct/insulate the I.C. exit and install a puller fan, just like your average FMIC setup operates.

I believe the Mazda Speed TMIC actually ducts the I.C. just like an air intake. Basically using a "flat snorkel" over the radiator to the front grill.

From what I've seen on my STi, the biggest problem isn't whether its TMIC of FMIC as far as power goes. Its the fact your limited in core size under the hood.
FMIC just lets you go nuts on core size, TMIC is extremely constraining that way. My 2 cents.


DSM Wiseman
Feb 15, 2006
Los Alamos, New_Mexico
I was trying to think of alternative IC mounting locations, then when searching around for sequential turbo info, I saw the RX-7 intercooler location and started thinking of the TMIC.

Certainly this can be rearranged quite a bit. I had thought about the low pressure stuff, and I'm now thinking of reversing the flow in the picture and turning the lower duct (now the inlet) around so that you have a ram air inlet at the front of the hood and the outlet above the IC. If the low pressure sticks around even with a raised cowl, that would actually help suck air up through the intercooler. So air would get rammed in at the front of the car, run up through the IC, and get sucked up out of the hood.

I thought the very-short-route piping was a really cool side-benefit, but nobody even mentioned it :(.

As far as core thickness, I was under the impression that if you had the choice, you'd go with a larger width and/or height before adding thickness, as the benefit of extra thickness really drops off after 2" or so (that's my vague recollection from Corky's book, anyway). And you could use a HUGE but thin core (that hood's pretty big).

Anyway, I don't have the knowledge or skill to do the fabrication of the new hood, so I'll probably never actually do this, but I figured I'd pass it on.


15+ Year Contributor
May 8, 2004
Palos Heights, Illinois
I'm toying with the idea of Water/Air intercooling using a PWR "hotdog" style core. Reduce total I.C. volume and length almost to nothing. Heard awesome improvement in spoolup. I'd toss the water heatexchanger into the FMIC position I have now.


15+ Year Contributor
May 4, 2007
NORTH HILLS, California
Well If you do spray it with water or have a water sprayer located on the Intercooler, this could possible work.

Now the only problem is money. LOL


15+ Year Contributor
Sep 16, 2004
Worcester, Massachusetts
As I have said before with regards to intercoolers (and many, many other things), the old real estate adage comes into play here: location, location, location! :)


15+ Year Contributor
Dec 20, 2004
Laurel, Maryland
I understand that spool up time would decrease since you'd have a lot less piping going on but I don't think it is justified due to the following:

1) Core size: You couldn't possibly fit as big of an intercooler on top of the engine as you could in front.
2) Heat soak: Sitting on top of the engine, there will be a lot more head radiating through that core, especially while sitting still like someone suggested.
3) Air flow: Air flow through the core will be dramatically less than through a front mount.

In my opinion, the pros wouldn't outweigh the cons in this instant. However if you're just trying to be different and going for looks, then yeah, go for it. On a performance point of view, I doubt it would be worth it for.


15+ Year Contributor
Sep 8, 2004
Reno/Sacramento, California
Almost as sweet and a side mount.

Maybe not that bad but still, have we all lost our minds on tuners? Eff a little lag, since when does cooling efficiency/hp < slightly less lag?


15+ Year Contributor
May 8, 2004
Palos Heights, Illinois
When it affects radiator efficiency. I'll hang my STi all day long on a roadcoarse before the coolant temp needle budges, no way I'm trying that with my radiator blocking FMIC on my DSM. Like I said, pros & cons.


15+ Year Contributor
Mar 11, 2007
Gresham, Oregon
There are many cars out there that have huge front mounts with turbos and boost levels that aren't really pushing the limits of an upgraded/supra SMIC. They have overheating issues, and aren't gaining a tremendous amount of cooling efficiency over a significantly less complicated intercooler setup. Is this idea worse than that? I don't feel that it is.

As with all modifications, it's what you want with your car, and weather the benefits outweigh the drawbacks. Is anyone going to try it? There's no reason it shouldn't work, might be fun to play with fiberglass too!


15+ Year Contributor
Nov 5, 2007
RIpley, West_Virginia
I've built a couple of turbo RX-7's and their TMIC works "ok" but nothing to write home about. Because they(rpary motors) are so so prone to being dead at the first onset of detonation, we always moved them up front. I've done a lot more WRX's than RX-7's and the WRX cooler works quite a bit better, but they all will heat soak really bad under low speed and back to back pulls. When going FMIC on a WRX i've seen HUGE drops in intake air temps ( 70* difference in some places when comparing logs)

It would be a nice direct path though, i personally have wanted to make one that mounts at an angle facing the ground and put it behind the radiator some where with a scoop to draw air. Similar to the setups common on 2.3l ford turbo cars (mustand and turbo coupe t-bird and even some rx-7 kits mount it in this same place and angle) But all in all there doesn't seem to be room for something like this in an eclipse.


DSM Wiseman
Jan 13, 2003
glorious Galt, California
Where you show an "outlet duct" would be an intake duct.
As for room, the lump in the hood is to clear the cam cover. You'd need another hood design to clear it, one that may not look especially attractive in the overall look of a coupe. It's one thing on a WRX where they're starting with a clunky box, but DSMs did have some intended style.
Otherwise, an intercooler doesn't care where it is. You're better-off with a shorter intake run so you have less volume to pressurize, and in that regard an air-to-liquid IC would be best, but then you have the parasitic crap to cool it.
A front mount is probably the best compromise. Airflow through a topmount would be problematic without the shape of a sedan, and probably ugly.


15+ Year Contributor
Jul 26, 2006
South Bend, Indiana
Somewhat on the same topic, but look at the intecooler and engine for the new 2009 corvette. - 2009 Corvette ZR1 LS9 Supercharged Engine Pics
That would be your idea design, but room is a big issue on a dsm. If this were done, you would be left with 6+ inches above the hood, and I would think that would be a big visial problem for the driver and the car itself.

I would still like to see it done at some point.


Apr 5, 2003
Coloma, Michigan
Where you show an "outlet duct" would be an intake duct.
I agree.

The area I circled will be tricky feat. The high pressure (across the top of the hood) will want to "escape" to the low pressure area through what is labeled the "outlet duct". This will negate the airflow through the intercooler's core.

It is possible to set it up correctly, but it would take some crafty design to make it function well.

I imagine under-hood heat could play a large role as well. Logically thinking, it would be safe to assume that it would have a higher propensity to heat soak as apposed to a front-mounted design.


  • Hood-mount-intercooler2.bmp
    437.4 KB · Views: 741
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds