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IAT Heat Soak hell

Old 06-22-2008, 03:59 PM
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Default IAT Heat Soak hell

I'm having issues with my IATs getting really high. on a 80 degree day, like today, I was seeing as high as 147, with cruise temps between 127-130.

My car is naturally aspirated, with MSPNP, using the no-MAF kit from DIY autotune, a cone filter, a Monster flow intake with a heat shield and another heatshield on the header along with a vented headlight lid. If I put my hand on the "no maf kit" tube, its ridiculously hot to the touch, the intake tube is hot, and the intake manifold is a bit cooler (phenolic spacer). I think heat from the radiator is soaking into the air intake system.

would an extraction hood help? or would I be better off trying a BEGI or DIY cold air box. Just looking for advice from those who have dealt with this before.
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Old 06-22-2008, 04:06 PM
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Those temps are normal but most of it is IAT sensor heatsoak. Are you using an open or closed element sensor? There is a reason the OEM IAT sensors are all plastic bodies instead of brass like the GM ones. If I was you I would relocate the IAT sensor so that its not seeing air as it passes through the radiator. You should cover the IAT hole with tape and put the sensor right near the cone filter, if it's the open element sensor it will still react well to different ambient air temps without issue.

I bet your idle gets really really bad when you come to a stop light. How much correction are you using for IAT based density?
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Old 06-22-2008, 04:24 PM
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Here is what the setup looks like. The IAT is right behind the Air filter, in the black tube, it is pointing straight down. Since the pic was taken, I rotated the sensor closer to vertical and added another heatshield on. That has been good for 10 degrees.



The sensor is open element. The car idles pretty good, but sometimes it stalls right after a hot restart especially with the A/C on. Not sure what I'm using for IAT correction... not sure where to find that in MT.
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Old 06-22-2008, 04:41 PM
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Try rotating it so that it's as far away from the exhaust manifold as possible..

or maybe move it to just before TB.
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Old 06-22-2008, 05:13 PM
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why don't you go ahead and source air from the cold side of the motor? no reason to have the retarded around the world tube anymore.
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Buy an MSPNP Pro, you'll feel better.
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Old 06-22-2008, 05:32 PM
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Originally Posted by Ben View Post
why don't you go ahead and source air from the cold side of the motor? no reason to have the retarded around the world tube anymore.
I'm thinking that will be the solution. Get a 180 degree silicone u bend and a pipe... until I do that there is probably nothing I can do to keep the tube from heat soaking off the radiator. I just have to relocate the A/C relays. No headlights would make things much easier.
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Old 06-22-2008, 07:13 PM
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When I removed the MP62 with IC, I hung a pipe and air filter in the same location. Watching the IATs showed that the air intake temps were much higher than when I was running the IC in the intake tract. When the blower was on, I put the air filter right behind the driver headlight, and made a heat shield to shield the side facing the engine. I think the temp difference between just hanging the cone filter like you did and running it the way I had before was a difference of at least 20*C. Even in boost, the IATs didn't go any higher than the temps I see now driving around town. Get the air filter tucked behind the headlight and shield it from engine heat, or go to the coldside, but you'll still have to shield it from hot air through the radiator.
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Old 06-22-2008, 07:48 PM
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I'd just stick the filter directly on the throttle-body and mount the IAT sensor in the coupler... then a NACA duct for the passenger headlight FTW.
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Old 06-22-2008, 08:15 PM
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Originally Posted by samnavy View Post
I'd just stick the filter directly on the throttle-body and mount the IAT sensor in the coupler... then a NACA duct for the passenger headlight FTW.
Not enough room for that. Radiator hose and A/C relays get in the way. Massive heat would get sucked from behind the radiator too.

I Might just make a better heat shield just to see what happens. That at least wont require any rewiring. The area between the headlight and the throttle body is tight. a 180 that tight might be a restriction.
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Old 06-22-2008, 08:34 PM
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As long as you're moving the AIT sensor away from the exhaust manifold, it's nothing but a good thing.
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Old 06-22-2008, 08:45 PM
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Originally Posted by GTS MIATA
With my DIY (bought everything from lowes) over the radiator intake, mine is pretty much at ambient as long as the car is moving... The temp sensor is about 6" away from the throttle body.
As witnessed by me, his typical cruise AITs were 2X atmo during cruise before the above pictured air cleaner relocation.

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Old 06-22-2008, 08:50 PM
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thats kick ***. I assume the filter hangs down in the mouth?
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Old 06-22-2008, 08:53 PM
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yeah--I thought that would be kind of obvious. Scott's car is turbo now, maybe he kept that intake
He's in Athens.
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Old 06-22-2008, 10:47 PM
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I was battling some nasty heatsoak...but I noticed with the higres code, the AIT corrections work much better than before. Where I used to get a lumpy idle after sitting at a light and seeing +120*F temps, its now solid and i dont have to overcorrect it and run rich to smooth things out.
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Old 07-10-2008, 10:54 AM
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I did something similar to scott on our 99- using a narrowed radiator. Another option might be moving the washer bottle and canister, then building a cold air box in that space. Air could be provided via some 1" holes drilled under the headlight assembly. That area is quite isolated on the underside. I'm thinking of the same approach (driver side) for the turbo inlet. The extractor did drop my temp (filter mounted behind-ish the driver headlight)- but I'm still 6-7*f over ambient at cruise in the summer heat with everything thoroughly heat soaked. That temp rises another 15*f @16-17psi from 3-7k rpm. IMO it's missed opportunity not "get" ambient air from somewhere.
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Old 07-10-2008, 12:57 PM
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Originally Posted by Braineack View Post
I was battling some nasty heatsoak...but I noticed with the higres code, the AIT corrections work much better than before. Where I used to get a lumpy idle after sitting at a light and seeing +120*F temps, its now solid and i dont have to overcorrect it and run rich to smooth things out.
Probably the most noticeable change after I installed Hi res. I had to redo all my AIT corrections.
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