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Old 04-17-2011, 11:24 PM   #1
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Default Is upgrading my FMIC a good idea?

I have the old FM intercooler and my IATs get up to 130-140 degrees on an 75 degree day during a quick 25psi pull.

Even cruising around town my IAT will be 96-105 on a 75 to 80 degree day. I haven't relocated the IAT sensor to the IC exit, but it's not right up in front of the TB either. Does it look like an IC is in order, or do you think the IAT sensor location is the main issue? $100 bucks for a new intercooler seems pretty reasonable if it will keep the temps down so that I don't have to rely on large MAT corrections.



This is the IC I am looking at.

http://cgi.ebay.com/ebaymotors/Unive...Q5fAccessories
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Old 04-17-2011, 11:27 PM   #2
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i say get some alcohol/water injection!
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Old 04-17-2011, 11:44 PM   #3
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Where is your IC located? It might be worth while moving it to a new spot. But at the same time, a new intercooler wouldn't hurt.
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Old 04-18-2011, 12:08 AM   #4
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I was using the old FM intercooler too, and just recently installed the new style one with side tanks, not top and bottom. I'm still waiting on some eBay couplings to show up, but I ordered the **** almost 2 weeks ago. How long does it take to ship some silicone couplings?
I too am curious to see where my IAT's will be.
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Old 04-18-2011, 12:09 AM   #5
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Give us some pics of your IC and it's location please. Along with AIT location.
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Old 04-18-2011, 12:38 AM   #6
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Quote:
I was using the old FM intercooler too, and just recently installed the new style one with side tanks, not top and bottom. I'm still waiting on some eBay couplings to show up, but I ordered the **** almost 2 weeks ago. How long does it take to ship some silicone couplings?
I too am curious to see where my IAT's will be.
Please post soem before and after IAT numbers.

Quote:
Give us some pics of your IC and it's location please. Along with AIT location.
IC is mounted front and center. I came across this thread. https://www.miataturbo.net/diy-turbo-discussion-14/ebay-intercooler-would-you-buy-31074/ My IAT sensor is located about 2/3 of the way down the straight length of pipe that conects the elbow to the TB and the pipe that curves around to the IC. The bung is welded to the back side if the pipe. Overall distance I would say it is half way between the IC and TB. almost level with bottom of radiator. Levnubin said he was getting better IATs with the busted *** looking FM one like I currently have. MAybe it's not worth it, IDK.

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Old 04-18-2011, 01:08 AM   #7
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I have a relatively small begi "#3" intercooler. It's worked fine for me up to 400hp with no rises in AITs on 21psi pulls.

My AIT sensor does indeed heatsoak though- located about 10 inches from TB inlet.

Huge intercoolers aren't neccesary. I say move your sensor first and then log. It's easier.

BTW how much power are you putting down @ 25psi with that china 2870? 3...40?
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Old 04-18-2011, 08:29 AM   #8
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Quote:
Originally Posted by Faeflora View Post
I have a relatively small begi "#3" intercooler. It's worked fine for me up to 400hp with no rises in AITs on 21psi pulls.

My AIT sensor does indeed heatsoak though- located about 10 inches from TB inlet.

Huge intercoolers aren't neccesary. I say move your sensor first and then log. It's easier.

BTW how much power are you putting down @ 25psi with that china 2870? 3...40?
I guess moving the sensor is the cheapest step to take. I'm not sure what I'm putting down. There really isn't a good way to estimate with the china stuff. I'm trying to get a few small things sorted so I can go put it on the dyno.
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Old 04-18-2011, 09:26 AM   #9
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It appears you're only making a delta of 35F at 25psi.

Assuming the turbo dumps out 10* per psi (i think it's closer to 15-20), that means it's 86% efficient.

granted you didn't hit redline... the lowest you logged was 98*F, I assume your sensor heatsoaks if you were saying it was a 75*F day out?


You want an IC with at least 18" runners...your current has what 7-9'?
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Old 04-18-2011, 09:42 AM   #10
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begi #3 intercooler, high to mid 60's, on a racetrack, 3rd gear.

This is before I worked on the ducting.

I think that no matter what turbo car I own, it will always have a BEGi intercooler. I like it because the tubes and and fins are thicker than most. Some of my past intercoolers have probably lost efficiency due to bugs and rocks, this one looks relatively unaffected by them.
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Old 04-18-2011, 10:36 AM   #11
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Brain: It sounds like you suggest that the IC is fine, but then say it's length is inadequate. Are you suggesting an upgrade or not? It sounds to me like you think the efficiency is higher than 86% if you feel that 10* per psi is conservative. If it can maintain 135-140* to redline do you suggest keep it or upgrade?

Hustler: What was ambient temp that day?

Just out of curiosity, if your using the diy GM IAT sensor, what are your resistor values?
I can't remember if I'm using the suggested values for IAT and slightly modified values for CLT.

I don't want to waste time moving the IAT sensor if the IC is inadequate form the beginning. If everyone thinks there will be a marginal gain from a new IC, then I'll just move the sensor and be happy. I'll probably move the sensor anyway. I bet it will only take an hour to drill and tap the IC. Anyone happen to know the thread type for IAT? I have some NPT taps.
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Old 04-18-2011, 10:50 AM   #12
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Quote:
Originally Posted by djp0623 View Post
Brain: It sounds like you suggest that the IC is fine, but then say it's length is inadequate. Are you suggesting an upgrade or not? It sounds to me like you think the efficiency is higher than 86% if you feel that 10* per psi is conservative. If it can maintain 135-140* to redline do you suggest keep it or upgrade?
Yeah but your log also shows a min of 98* and it was probably sitting closer to 110*F before you went WOT. On a 75 day, my AIT sensor shows 76-77F. That makes me think the sensor was not reporting the correct temps prior to the pull, and the delta was more like 55.

Regardless, those temps are getting into the range of wanting something longer. Do a pull from 2-3-4-5 all to redline and see what the temps get to.

FYI. The longer the runner the better, obviously. 18-21" long tube reaches the point of diminishing returns. Those short runner IC simply don't cool the charge by the time the air reaches the endtank...not long enough.


Quote:
Just out of curiosity, if your using the diy GM IAT sensor, what are your resistor values?
the "GM" selection under thermistor calibration.

Quote:
I don't want to waste time moving the IAT sensor if the IC is inadequate form the beginning. If everyone thinks there will be a marginal gain from a new IC, then I'll just move the sensor and be happy. I'll probably move the sensor anyway. I bet it will only take an hour to drill and tap the IC. Anyone happen to know the thread type for IAT? I have some NPT taps.
The benefit of moving the sensor is getting more accurate temps reported. Before I moved mine I used to see my AITs drop in boost because all the extra airflow would actually cool off the sensor. I typically see 5*F above ambient when I'm cruising around.
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Old 04-18-2011, 10:56 AM   #13
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Any new data on the bar and plate vs the tube and fin? The one I'm looking at (link in first post) is a tube and fin design.
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Old 04-18-2011, 10:59 AM   #14
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tube and fin is lighter and more efficient, however they dont flow as well.
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