Experimenting with Intake Air Temp. Request for comments.

SouthArk370Z

I added two pics of how the insulating is going (Nissan 370Z Forum - SouthArk370Z's Album: Air Duct), but my camera died before I could get a shot of the front of the filter box.

Still trying to find a 4-6 channel thermometer at a reasonable price. If anybody runs across one for less than $200, please let me know.

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juld0zer

your air boxes are looking like mine. i used 1.5 x 10m rolls of the foil insulation tape to do both completely. All wrapped up til the rubber post-MAF hoses. At the time i was too lazy to take the bumper off so i didnt wrap the pre-airbox duct but i might do that next time i have the bumper off.

The stock IAT sensor on the bank 1 MAF module suffers from heat soak, no doubt about that. Once you're stuck at one light and IAT rises, it will never go back to what it was prior to the red light. Could be due to a slow reacting sensor but from memory it's an exposed thermistor & that's as good as they get.

Before wrapping my airboxes and MAF housing tubes, the surfaces would be very hot to touch, almost dangerous to touch. After wrapping, the interior surfaces are warm to touch but not scalding like before so they make a difference, even if the effect on power is slight.

I've wrapped my MAF tubes in heat resistant mitt neoprene style material (buy an oven mitt made of this material & cut it up). This insulates against radiant heat, esp on the alternator side of the engine where that very hot coolant pipe is. With the finger parts of the mitt, i cut an opening in each and slipped it over the MAF connectors. Lots of zip ties ensured a snug fit around the cables and sensors. This helped delay heat soak but idling on a very hot day (35*c+) but it still suffered. Problem with this sort of insulation is that it also keeps the heat from escaping but i'd say its protection from radiant heat is worth this downside.

Biggest (and cheapest) improvement was relocating the IAT sensor by way of a separate thermister mounted in the pre-airbox duct. I can get IAT within 1*c while cruising at 60kmh on a 22*c night. While there might be some discrepancy between the actual air temp and the output of this sensor, i havent measured it & i'm not too fussed. It cant be that far off. Both the sensors have the same resistance at 20*c

SouthArk370Z

Thanks for the input.

I'm wrapping mine with 1-1/2" wide Thermo-Tec Thermo-Shield (thin layer of insulation on a foil cover) and then covering that with DEI Reflect-A-Cool (no insulation to speak of, just a reflective barrier). Only reason I chose those particular products is because that's all I could find locally.

I was able to spend about a hour doing more insulating last night. I have the short filter inlet duct finished and most of the filter box/MAF tube is done. Now I just have to buy more insulation so I can do the other side. I like you idea of using a mitt - I'll probably use that on the flex tube.

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Sh0velMan

Cheap header wrap + Reflect-a-cool/gold works too. That's what I've got mine wrapped in.

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juld0zer

Yeah that's the same width tape i used. Stanley knife blade to cut it and trim it to fit over all those ridges.
I'll get some photos of the airboxes soon!

For the flex tube (i assume you mean the accordion tube) i am just going to replace it with a silicone one. Silicone should be more resistant to heat and insulate better, plus it smoothens out the airway for some slight gains. Only problem is they're much more expensive than oven mitts! and for me i'll have to wait about 2 weeks for them to arrive from the US.

I would advise against more than 1 layer of the foil reflective tape. Some parts of the airbox are quite close to nearby components so you don't want any rubbing or fitment issues if you make the airbox too fat

JARblue

So I subscribed to this thread pretty much immediately for results, but I am now also wondering what kind of temperature difference you're hoping for and/or expecting, SouthArk.

I have R2C black nickel intakes, so unfortunately, there's no way I would consider any of the exterior wrap options. After I purchasing the intakes, I borrowed a friend's scangauge to monitor the IATs. They certainly get heat soak (I would guess worse than stock), but now I am wishing I had recorded my endeavor as I cannot remember exact numbers. I just remember that the results weren't too concerning after all my forum research. Do you know at what temps the ECU will interfere? Is the ECU using the same IAT reading I get from the scangauge?

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SouthArk370Z

I'm not looking for a big drop, 4-5°F would make me happy. I'd also like to get temps back to normal a lot quicker after sitting in traffic.

IIRC, the ECM starts pulling timing advance when IAT gets above 95°F.

Yes. The ECM uses the temp sensor in the bank 1 (right side) MAF and that is what you see on the ScanGauge. I wouldn't be too surprised to find out the sensor data is massaged a bit before being reported, but it should be close to what the sensor is seeing.

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SouthArk370Z

I did a visual check and didn't see any spots that would be problematic, but some places are impossible to see. I guess I'll find out when I go to do the install.
I tried to keep the overlap on the tape to a minimum and don't have a lot of overlap on the foil.

I used the last of the tape and foil earlier today and will have to make time to go to the auto parts store to get more.

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JARblue

95 eh... That's less than ambient for about 6 months out of the year here in TX So I guess my timing is retarded in the summer

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SouthArk370Z

Due to roof, plumbing, and bathroom repairs, this project is on hold for a few weeks.

I'm still looking for a multi-channel thermometer.

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JARblue

Sorry to hear. Hope you get everything taken care properly and in a timely manner

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SouthArk370Z

Insurance is paying for most of the roof. Only very minor damage from the plumbing problem (it was out in the garage, so most of the water drained quickly). Been wanting to get bathroom fixed up for several years now and figured this was a good time to do it. All-in-all nothing earthshaking, just time-consuming and a bit on the expensive side. And noisy - construction crew is tearing out the old tile as I type.

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juld0zer

Where did you get the 95*F figure? I'm very interested in reading more about this topic as over here in Australia, we experience ambients over 30 degrees celsius for half the year. But from general driving experience this summer i think you're on the mark. It could be even lower like 30*C/86*F as that's when i start feeling the bog on take off.

What i can say is relocating the IAT sensor by way of a separate IAT sensor (think of the GM HSRK sort of thing, except a ghetto version) was the best thing i've done to address the heatsoaked sensor issues. My IAT sensor (a thermister type) is installed inside the bank 2 air intake duct (the barrell between the airbox and the fascia).

I chose bank 2 because firstly i was misinformed on a thread somewhere. But in the end it seems that the radiator piping around bank 1 airbox/duct radiates a lot of heat so if i was to do it again, i'd stick with bank 2 and put up with running the extra wire.

It's mounted about 2.5" from the mouth as that's the closest i could get a flat surface to mount it with a grommet. IATs are within 2*C while cruising on a cool day/night. On a hot day you can't avoid hot air wafting upwards from the radiator and being drawn in while the car is stationary but within a few seconds from take off, i'm within 5-8*C of ambient (based on the outside temp onboard sensor).

As for the foil wrap, mine overlaps a few mm over each section of tape and that's the way it should be. The places i wouldnt do extra layers on is the side which faces the front of the car as that's where mine looks quite snug. Every other side you have sufficient room to go nuts

SouthArk370Z

I wish I could remember where I saw it. I think it was on this site but a Q&D search didn't turn up anything.

Thanks for the input.
The front of the filter box was fairly easy to do and I ended up with no overlap for most of that area. It looks like covering the bottom of the filter box is going to be a PITA. I plan on looking online for a blanket-type insulation for the tubes between the MAFs and TBs.


I may have found a thermometer.
4-channel temp logger on eBay. Comes with two sensors. Extra sensors can be had for $2-5.

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juld0zer

I actually found the bottom and the front-most side the most annoying the do. These were the sections i used the smallest and most pieces of tape. The ribbed areas you can either make an incision and split it over each side of the rib or just tape over the rib and press it down on the centre (looks neater).

For the post MAF tubes, i'd probably recommend the neoprene heat resistant mitt material i used on the tubing where the MAF sensors are mounted. Cant seem to find a source to buy this stuff in bulk (or as sheets) though I think i'm still keen on getting silicone replacements for the post MAF accordions.

I'll upload some pics of my airboxes (they look like charcoal chickens wrapped in foil!)