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Old 05-07-2011, 12:36 PM   #1
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Default intercooler size limits

what size intercoolers can be fit in the front of the little guy.. got a 95 and working up to about 200+ hp and wondering what size to go with for best cooling and not to limit air flow to the rad... also doing over the rad piping if that accounts for anything
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Old 05-07-2011, 12:41 PM   #2
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Well you probably want to go with a IC that has the same width as the track dog. I havent gotten a chance to drive it in that hot (90+) weather however so far i've had no overheating issues. The main thing of how track dog does is their IC is crooked so the top of the rad is getting blasted with cold unaffected air.

I dont think you'll be able to put a bigger ic in there unless you find a way to get middle outputs or weld some crazy piping to the ic to get the piping to the right position. Now you do have NA model so you might be able to use the holes already in there but you'll have to slash the underside support of the hood a bit.

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Old 05-07-2011, 01:34 PM   #3
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thats what im aiming for there.. how wide is your IC.. because that piping looks like it comes in very square.. same look im going for... very nice looking set up there
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Old 05-07-2011, 02:10 PM   #4
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what core is that triple88a? look great

edit...nevermidn it's in your sig!

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Old 05-07-2011, 06:38 PM   #5
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12X18X3" here. You can go bigger, but would require more severe changes including mounting the radiator at an angle. You can go with something smaller, but I would rather have some headroom and run 200 whp through an intercooler that can support a 300whp setup than run at the limits of a smaller IC. The bigest drawback people claim for larger IC's is the pressure drop due to increased volume after the turbo, before the throttle body. This is solved by supplying your wastegate vacuum signal off of a point on the intake manifold instead of the turbo. The wastegate will then "see" the pressure your motor is seeing, and compensate for the pressure drop by allowing the turbo to spin a bit more at high rpms.

Going smaller in IC size to avoid "blocking" more of the radiator is a myth IMO - even with a small IC, you're positioning it right behind the mouth of the bumper - thus blocking the radiator's air source just the same.

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Old 05-07-2011, 07:03 PM   #6
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Originally Posted by ThePass View Post
12X18X3" here. You can go bigger, but would require more severe changes including mounting the radiator at an angle. You can go with something smaller, but I would rather have some headroom and run 200 whp through an intercooler that can support a 300whp setup than run at the limits of a smaller IC. The bigest drawback people claim for larger IC's is the pressure drop due to increased volume after the turbo, before the throttle body. This is solved by supplying your wastegate vacuum signal off of a point on the intake manifold instead of the turbo. The wastegate will then "see" the pressure your motor is seeing, and compensate for the pressure drop by allowing the turbo to spin a bit more at high rpms.

Going smaller in IC size to avoid "blocking" more of the radiator is a myth IMO - even with a small IC, you're positioning it right behind the mouth of the bumper - thus blocking the radiator's air source just the same.

My IC is like 1/2 the size of yours and my car makes twice the power. On a 5th gear pull I see about a 10* rise in temps max. 1psi pressure drop max too.
:shrug:
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Old 05-07-2011, 07:34 PM   #7
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Quote:
Originally Posted by Faeflora View Post
My IC is like 1/2 the size of yours and my car makes twice the power. On a 5th gear pull I see about a 10* rise in temps max. 1psi pressure drop max too.
:shrug:
Ever seen the racetrack? That's where his car lives. Us track-folk don't measure temps in "pulls", we measure things in "what is the temp change after the turbo is glowing yellow for 15-minutes?"
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Old 05-07-2011, 07:51 PM   #8
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Originally Posted by hustler View Post
Ever seen the racetrack? That's where his car lives. Us track-folk don't measure temps in "pulls", we measure things in "what is the temp change after the turbo is glowing yellow for 15-minutes?"
Please explain why a glowing turbo manifold/housing will affect the AITs in any way other than by heating up the compressor housing from radiant heat and heat coming through the CHRA.

Worst case small IC scenario I can think of is that your IC will heatsoak if your turbo operates in an efficient spot on the map for an extended time.

Going for empirical data, what IC are you running and what temp changes do you see? Please do tell.
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Old 05-09-2011, 03:04 AM   #9
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Originally Posted by Faeflora View Post
Please explain why a glowing turbo manifold/housing will affect the AITs in any way other than by heating up the compressor housing from radiant heat and heat coming through the CHRA.

Worst case small IC scenario I can think of is that your IC will heatsoak if your turbo operates in an efficient spot on the map for an extended time.

Going for empirical data, what IC are you running and what temp changes do you see? Please do tell.
You can do ten runs back to back on the freeway and you're still not going to come close to simulating all the radiated heat and heat soaking that you would see on the track.
-turbo glowing for 15 minutes = engine bay air temps astronomically hotter than under usual street or dyno conditions. Even with heat shields and ducting this is unavoidable. It's like doing dyno pulls in the middle of Death Valley. Over and over and over again.
-Yes, your compressor housing will be stupid hot
-Yes, your intercooler will get heat soaked

I would not feel comfortable with a smaller intercooler on the track. Look at Savington - he's at your power level. He's not using a tiny IC . You can only get away with stuff like that on the street.
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Old 05-09-2011, 04:56 AM   #10
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^ That's what I've been worried about, entering a roadrace and having to deal with a perpetually heatsoaked IC and all around engine bay... I'll upgrade my IC before the events take place, but it's a constant concern..
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Old 05-09-2011, 11:02 AM   #11
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Quote:
Originally Posted by ThePass View Post
You can do ten runs back to back on the freeway and you're still not going to come close to simulating all the radiated heat and heat soaking that you would see on the track.
-turbo glowing for 15 minutes = engine bay air temps astronomically hotter than under usual street or dyno conditions. Even with heat shields and ducting this is unavoidable. It's like doing dyno pulls in the middle of Death Valley. Over and over and over again.
-Yes, your compressor housing will be stupid hot
-Yes, your intercooler will get heat soaked

I would not feel comfortable with a smaller intercooler on the track. Look at Savington - he's at your power level. He's not using a tiny IC . You can only get away with stuff like that on the street.
Ok, thanks for the info. I didn't know that radiant heat and heatsoak was that bad. Why don't more track people run water injection to help?
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Old 05-09-2011, 11:21 AM   #12
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Faeflora and Hustler, what intercoolers are you guys running? If I'm remembering right you both bastardized Bell kits right? Is it still the original intercooler that came with that kit and which option was it? I'm still on the small one that came with my old S3 kit and haven't seen any reason to upgrade, although my car pretty much just stays on the street.
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Old 05-09-2011, 03:19 PM   #13
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Quote:
Originally Posted by Faeflora View Post
Ok, thanks for the info. I didn't know that radiant heat and heatsoak was that bad. Why don't more track people run water injection to help?
This question prompted me to do some searching to supplement what I know off of the top of me head.

Some do. Savington did. I don't know if he does now, but he's switched over to E85, which solves the detonation issue partially or fully in its own way. Many are moving away from it now, having used it in the past. It's great for street use, even as a complete substitute for an IC, but at the track, relying too heavily on water injection seems to be very risky. Trackdayhookey lost 2 motors to "water injection snafus".

For a car like mine, using an IC with headroom, a "300-350 rated" intercooler (ballpark/arbitrary estimate by mfg of the IC) on a <250 hp car is a good recipe for enough cooling ability to handle these effects. There aren't a ton of guys who are over that power level who are regularily on the track, you can probably count them all on two hands for the Western half of the country. A lot of boosted track cars, even at 250 hp or less do a lot of work to deal with all this, v-mounts etc, E85 conversion...

Sav (350+ whp turbo) is using E85 + big intercooler
Hustler (275 whp? turbo) is using magical unicorn urine injection?
Bellwilliam (240 whp supercharged) E85 + intercooler of some size
Trackdayhookey (350+ whp supercharged) same size IC as mine, exclusively uses 100+ octane race gas

Superchargers tend to cause much less radiant heat, so I suspect that's why trackdayhookey's setup works out.

Then again, there's bbundy who appears to scoff at the notion of IATs.. He's using (according to his cardomain) a 22x9x3.25 intercooler, which is almost exactly the same volume as mine, with no mention of E85, water injection, etc. but pushing a reliable track used 350 whp??

For someone in the low 200's or less, I'd recommend copying my setup. Oversized intercooler, aluminum radiator, oil cooler, shrouding. Can rock 91 octane on the track with no issues, and in a 20 minute session the water and oil won't budge past 210* F.

Last edited by ThePass; 05-09-2011 at 03:29 PM.
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Old 05-09-2011, 03:31 PM   #14
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Wouldn't a larger intercooler only help cool more than a smaller IC if it has airflow across the full surface?

Otherwise, I'd think that the parts that are not exposed to airflow would just get hot and decrease the overall effectiveness of the IC.
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Old 05-09-2011, 03:36 PM   #15
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2 words, Surface area.

The more surface area an object has, the more efficiently it can exchange heat. The other side of this equation does infact have to do with airflow, but the only reason that airflow is needed is so that there is a temperature differential between the intercooler, and the air around it.

An example of surface area, take two different ice cubes. One cube with the dimple in it, and one without. which will melt faster? the one with the dimple.

Now if you put a hair dryer infront of both cubes, they are both going to melt really really fast. but the cube with the dimple will still melt faster.
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Old 05-09-2011, 03:43 PM   #16
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Originally Posted by Gryff View Post
2 words, Surface area.

The more surface area an object has, the more efficiently it can exchange heat. The other side of this equation does infact have to do with airflow, but the only reason that airflow is needed is so that there is a temperature differential between the intercooler, and the air around it.

An example of surface area, take two different ice cubes. One cube with the dimple in it, and one without. which will melt faster? the one with the dimple.

Now if you put a hair dryer infront of both cubes, they are both going to melt really really fast. but the cube with the dimple will still melt faster.
Yah but I'm talking about radiant heatsoak.

if you have a 500* engine bay the parts of the big IC with no airflow on it will soak up the heat from the bay.

This is all conjecture on my part though, I'd like to hear more details about what is proven to work. The "how to make your miata trackworthy" sticky has none of this stuff in it.
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Old 05-09-2011, 03:45 PM   #17
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Hence why ducting is important.
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Old 05-09-2011, 04:04 PM   #18
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^ This.

Ducting prevents the air from having any alternative route around the intercooler. Heat exchangers like IC's create a substantial amount of resistance to air going through them. So, you've got a mouth opening that's (arbitrarily) 18x6", and an IC that's 18x12". Without ducting, air comes in, hits the IC, some of it passes through the portion of the IC it hit and a lot of it passes around the IC. In this example the parts of the IC which do not see direct airflow do little to nothing.
Add ducting. Now, the air comes in and hits the exposed portion of the IC. Some goes through it there. The remaining portion of air has no around the intercooler option, and therefore spreads out over the surface of the intercooler and passes through the whole thing.
This is why cooling effectiveness for the radiator drops significantly when you remove the plastic undertray that boxes in the bottom half of it. It's also why the radiator in the car can be more than twice the frontal size of the opening in the mouth, and that works.

Race data done both in the big leagues and done by some here (Sav and Bellwilliam come to mind) show that the sweet ratio for mouth opening to intercooler/radiator surface is ~1:3. IOW, a given bumper opening can supply enough air at speed for ~3 times as large of a surface area of a heat exchanger. Both of those guys have actually closed off their bumper openings partially to make the opening smaller in order to reach this ratio. More air entering just = more drag, because it all piles up trying to get through the heat exchangers since there is no alternative route for the air to go.
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Old 05-15-2011, 04:41 PM   #19
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Didn't think this thread would get so in depth, but its really helpful info. Thanks guys!
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Old 05-15-2011, 04:54 PM   #20
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Didn't think this thread would get so in depth, but its really helpful info. Thanks guys!
this is what happens when newbs have ligit questions.
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