Intercooler Sizing
 

I have a small IC.

Attachment 207707

I'm currently running 8 PSI.

I logged a 5th gear pull the other day. It was 1*F outside. I pulled from 1600 rpm to 6000. 27 seconds straight in boost. IAT went from 1* to 50* in 27 seconds. The first 43* went pretty quick - 16 seconds. Then it stabilized and crept only 7 more degrees in the next 11 seconds. Granted, it was 1* out and I was pushing a lot of air through it. I can't imagine that a 50* delta will hold when it gets warm out.

That said, is the IC undersized for 8 PSI? Undersized for 10 PSI?

What is the normal acceptable delta from ambient temp, through the turbo and then cooled by the IC?

What is the highest IAT that you want to see going into the TB?

I have an invisible IC.

Attachment 207705


There are no clear cut answers to any of those questions. What's acceptable depends on your goals and budget.

The IC has a length. The longer it is, the cooler the air will be.

And it has an area, which is it's height times its thickness. Like my IC is 18" wide, 12" tall, 3" thick. So the area where the end tanks hooks to is 12x3 = 36^2 in. But only say 40% of that area actually has opening for the air to flow though. So maybe 14^2 in of actual opening for air to flow through. More area is better as you have less resistance and less pressure drop across the IC.

That said, I have ~1PSI pressure drop across my IC at 7K RPMs. But it's a relatively large IC. Oh yeah, and and I see a 2-6*F increase in temps when in full boost. ;)

49*F ambient
Attachment 207706

You receive "maximum" cooling benefit from an IC who's runners are around 18-21" long.

how long are yours? I'm assuming 8.5". The problem with the vertical runner design is that the charge has not been fully cooled before it reaches the end of the runner. An IC with only three 21" longs runners would more than likely be much more efficient than an IC with twenty-one 3" runners. Even though there's the same amount of volume the charge is being passed through.


22° Δ with a 18x12x3" core on a 75°F day on a dyno with no airflow: http://i46.photobucket.com/albums/f1...s/dynopull.jpg

I don't typically see more than 7-10°F Δ under the same conditions on the street.

IC runners are about 10" long, about 12" high, not counting endtanks.

is it a BEGi IC? my (uninstalled) BEGi IC of the same design has only 8.5" runners:

http://www.boostedmiata.com/random/t...eats%20(3).JPG

No it isn't that one. It might be 8.5x10. It's taller than wide but narrow than yours and closer to square. I may have guesstimated high in both directions.

I think 8.5x10 is pretty close the more I think about it. I'll throw a tape on it tonight when I am working on the car.

I know that a 27 second pull is extreme. I'll check some real world logs when it is running well and no zero out. Tomorrow it's supposed to be 50*.

Also you could work on ducting for your IC, that would help it a ton. You have to force air to go through it for it to reject heat.

Sounds like someone got bit by the boost bug. :)

Brain-how do you type the greek symbol delta?

All along I planned on 10 PSI max with this turbo. Just enough to get over WG to run an EBC as much to improve spool as a bit more power. That's it. When the 550's are here and cleaned and installed and running well, I will do the EBC. I might only get 9 with this IC. If that is all I can do safely, so be it.

If this S2000 comes through like I'm planning, I may just leave it on stock injectors, 8 PSI and WG and hack that thing for a toy.

charmap.bat or copy & paste.

hahah . . .that's my deal. I bougt a new S2000 two years ago. the miata became more of just a toy than it was before. so the boost and silly mods have gotten a little out of control, but it is fun and that's what a toy is all about right?

My IC is a fairly cheap tube-n-fit unit purchased from some fly-by-nite ebay seller, of the long & thin variety. I know that the core depth is 2.5", not sure about length & height, but here's a shot of it in situ. Don't mind the interheater mounted in front of it, that's long gone.

https://www.miataturbo.net/forum/att...498757-ic3.jpg


Now, here's a log snapshot of a nice boosted pull off the line from a standstill. This was taken on a fairly warm day. As you can see, IAT is 92°F at the onset, drops a few degrees as the car starts moving, and peaks at 112°F as I let off at just over 7,000 RPM in third. MAP is steady in the 185-190 kPa range, which is about 12.5 to 13 PSI of boost. The turbo in question is a TD04H-15G, so it was working pretty hard at this point. Note that while I do have water injection, my IAT probe is before the injector nozzle.

http://img01.picoodle.com/img/img01/...tm_d52b95b.gif

Ambient temp during my drive in today was 54*. Cruising on the highway my temps stayed right around 56*. After a quick run to 100 mph my temp went up to 62* and as soon as I came out of boost it quickly went back town to around 56*. IC is a CXRaxing 29x9x3.
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