Can an intercooler be too small?

[Malykaii]

I've been trying to figure out a better way to mount an intercooler for my turbo Montero for a year now. Just when I was about to buy some ebay pipe kit and make a front mount by the radiator, I find this pic.

 

http://i37.photobucket.com/albums/e82/silverquest/Quest%20Pics/mm-swap1.jpg

 

It's smaller than stock, so can there be any issues?

[Malykaii]

Oh, so it's all stock now. I'm switching to a 52mm throttle body and 16g turbo. I'm still deciding if boost will be set to 7psi or 10psi. Nothing wild here.

[ucw458]

This is my take on the issue. May not be a perfect interpretation but this is how I understand the physics involved.

 

The short answer, yes an intercooler can be too small.

 

 

The long answer, any intercooler is better than none. The problem is prolonged cooling. The IC needs to be able to reject heat as fast or faster than the heat is produced. When it can't you get heat soak. Basically if the too small IC can't handle the heat then intake temps will rise until you take your foot off the gas and let the system cool down. A top mount like you posted came on many cars. But they heat soak quickly so they don't help much during prolonged wot periods. What most people do when modding is take the top mount off and add a much larger front mount. Or replace the air to air top mount with an air to water top mount. But the air to water system is either going to have a front mount radiator (street) or a trunk mount ice box (drag race). Either way, water to air ICs are mostly used when space is tight or you want ice water or NO2 blown through it for maximum cooling in a drag race.

 

 

Simple answer, any IC is better than none but stick with a stock SQ size or preferably bigger IC for best results.

 

 

 

 

For example, stock SQ IC.

http://i463.photobucket.com/albums/qq352/ucw458/MPI/PIC_1070.jpg

 

 

 

When I switched to MPI I upgraded my IC to an Izuzu NPR diesel truck IC. Wider, taller and thicker with 2.5" in/out.

http://i463.photobucket.com/albums/qq352/ucw458/MPI/PIC_1077.jpg

[scott87star]

I'd guess you're thinking in terms of physical size when you should be thinking in engineering terms of volume, pressure drop, % efficiency. Stock Starquest intercooler has a pressure drop of 2 psi at full boost (7.5 psi in the intake) and is 70% efficient. I never measured the volume. If you can find something physically smaller that can meet or better those numbers then it isn't too small, if you find something physically bigger than still can't match those numbers than in engineering terms its too small. Good luck getting engineering numbers from an ebay intercooler vendor.

 

You will find better numbers in an air to water intercooler because they have different heat transfer properties, they are much more efficient. Air to air units need to slow down the air to get heat to transfer, hence the presssure drop, air to water units do not so there is virtually no pressure drop. Back to the stock Starquest, with 7.5 psi boost in the intake there is a 1.5 psi pressure drop across the throttle body, add that to the 2 psi pressure drop in the intercooler you are actually making 11 psi boost at the compressor. Swapping to an air to water intercooler and you'd only need to get to 9 psi to see 7.5 psi boost in the intake. It happens faster meaning faster spool. I have an air to water on my MPI car, the disadvantage is of course the pump and plumbing required.

[Malykaii]

Ok, so the biggest issue is that at wot and high boost I risk heat soak. Since it's a lifted SUV, and I drive it as such, I'll be fine.

Only time I hit wot is emergency situations such as passing. Like you said, 15 seconds and then plenty of time to cool off.

 

Scott, I agree that getting ebay intercooler specs wont happen, so I'll guess that the little oem mazda ic will do better than a slightly bigger ebay ic. I'll try to find some specs on the mazda one, as I was only looking at physical size.

[creakyjoints]

For your use I would say its about perfect.

[Turbo Cary]

I dig using the Turbo II intercooler.

[Malykaii]

I finally gave up. I even tried to measure a way to make the stock intercooler work on top.

 

So I ordered the Mazda top mount. All I got to loose is $60 and a hole in my hood.

 

How would I know if there is a problem? Like are there symptoms of heat soak that I can look out for?

[ucw458]

You just lose a little power when you heat soak. Kinda like driving a non IC car. They are noticeably quicker when the engine is cold.

[Malykaii]

Interesting... When I install it and find myself a place where I can, I'll try a hard pull at night with the engine cool and compare on a hot day fully warmed up.

 

Thanks.

[Malykaii]

Ahhh! After a thorough read on that intercooler, only problem I found is it blocks the oil cap! intercooler comes off to add oil lol.

[mstieg]

So long as the upper mount doesn't soak up heat from the engine at a rate it prevents the IC fins from cooling the air that passes through.

 

Also, I'm sure you're not bottlenecking with a smaller diameter in/out for the IC than the pipes to TB right? 2" or bigger should be good for your application.

 

Too BIG of an IC can be problematic. Some guys have a huge IC with tiny turbo that can't push all that air, then wonder why it won't spool until 4500rpms. Some guys are running 3" IC pipes for some odd reason. Worse yet when their TB's are smaller than that, thus creating a bottleneck at the TB. Some also then run a TB much too big even though their intake won't flow that much. SMH at lost spool time pushing all that extra volume air without it being able to flow - ends up going out the blowoff valve or worse, back against the turbo. (Tangent rant over)

[Fuze]

The T2 cooler is efficient for 80's tech, is neat and tidy, and will do the job with a hood vent. Still, it's not a bar and plate cooler so it's inherently not going to be as efficient as one that is, ebay or no. (Less internal surface area to dissipate heat.) Should do the trick it's not like you're boosting a lot or beating on it.