intake air temp sensor
 

i have been using an air temp type K thermocouple for my IAT since 2013 and really like having 4 accurate readings per second. i started looking for solution after noting that my stock sensor read 27 C throughout my entire 2000 to 9000 run on the dyno.

i am just slightly aware that others are using a "fast" thermistor. the 64 $ question is... just how fast is "fast."

an important question because if your sensor lags you are going to think your IAT is just peachy when it might be getting you close to knockville.

i have spent a bunch of time searching including calling my wonderful EGT guys at The Sensor Connection but have come up w nothing as to response data.

consequently, i am going to acquire a "fast" sensor and install it along w my thermocouple in my UIM. we will then do a match race.

BTW, i have no idea as to the outcome, i just want to see them race.

RX7Clubbers, i need your input... what is considered to be the fastest thermosensor to test?

Thanks!

Likely this:

https://racespeconline.com/collectio...11742301323307

I have this:

https://racespeconline.com/collectio...rature-sensors

An exposed thermocouple or platinum resistor with very modest ceramic shroud will likely be fastest. Something that relies on couple or metalic resistance properties. Unfortunately the fastest will tend to be more vunerable to mech damage or contamination although the resolution of automotive analog to digital converters may make that irrelevant anyway. National labs use a mix of platinum resistors and various exposed thermocouples for high accuracy measurement in the ranges we are concerned with.

One of the other great things about thermocouples (apart from being accurate and responsive) is that they're cheap. Sure the amplifiers can get expensive. But once have a 4 channel one, you can measure EGT on each exhaust runner, as well air temp before and after the intercooler.

Howard, out of interest which type K thermocouple and amplifier have you been using for air temp? I've found one from one of the recommendations go to thermocouple supplier in Australia, Auber Instruments. They offer one used for automotive and aircraft air temperature readings and it can be used with adapters to suit Mazda OEM mounting. However, the probe is 150mm long which is a bit impractical. They mention that a thermocouple for intake air temperature should have small thermal mass (which makes sense so it can shed heat quickly when intake air temp changes). See: https://www.auberins.com/index.php?m...roducts_id=589

https://cimg3.ibsrv.net/gimg/www.rx7...bd0a676ca5.jpg

From the research I did I am 99.99% sure these are the same sensor. Pretty dang quick.

https://wannaspeed.com/en/home/7-87-...mp-sensor.html

https://wannaspeed.com/en/home/8-pnp...or-93-rx7.html

Brent at Wannaspeed is very nice to deal with and the PNP harness I received looked great.

^15-20 seconds is fast??

What Howard is preaching to the masses, a "fast-acting" Triumph/GM sensor (while better than the stock version) should not be our standard/go-to sensor for IAT; rather, we need instantaneous readings.

*Interested to see what the data shows during the pending comparison testing against a K-Type thermocouple.

I guess it seems quite fast compared to the stock one. Actually, wouldn't the mass of the intercooler tend to slow down changes in temperature? Maybe they don't need to be that fast. Obviously stock isn't good enough, but a 30 degrees drop in 10 seconds seems like a fair bit. Interested to see the results. Actually, that might be an ideal sensor to compare against seeing so many people use it... and by many people I mean me! :lol:

I might try test it out with a hairdryer or something if you guys want?

K-Type thermocouples are rated for multiple readings in less than a second; compared to 5-15 seconds likely for a "fast-acting" or stock sensor. For a stock or mildly modified car, perhaps this is generally okay. But more frequent/quicker & accurate readings are better in either case.

When the comparison data comes in, you're likely to see a minimum of 20x faster readings using the K-Type thermocouple vs the current standard.

IAT dynamics happen REALLY fast. if there is any lag in your sensor you are in the dark on a very important metric.

here's a recent log proving the point.

boost went from 8.9 psi at 2:59.790 to 19.4 at 3.00.374

just over a half second!

IAT went from 77 F to 126 F according to my thermocouple.

here's 8.9 psi:

https://imagizer.imageshack.com/v2/xq90/922/dy8Zdd.png


here's the log at 3 minutes and .374 seconds:

https://imagizer.imageshack.com/v2/xq90/921/xXGbqx.png

IAT rose from 77 F to 126 F in less than three quarters of a second. note the bottom section of the log... that's my 100% methanol pressure log. AI pressure rose from 23.2 psi to 121.6 psi. i can't imagine where my IAT would be without it. i do plan to add a bit more meth to drop my IAT below ambient.

thanks to the magic of methanol my IAT trends downward to 117 F at 7722 rpm 24.9 psi boost and approx 585 hp.

https://imagizer.imageshack.com/v2/xq90/922/vUdPLc.png


my IAT data is generated by a specially engineered "air" thermocouple from The Sensor Connection. the sensor is made by them in the USA and is a product of more than 20 years of engineering to get the right balance between fast and durable. it generates four readings a second and is accurate to around one per cent.

for the record i have no idea as to the speed of other thermister type sensors. looking at the graph in post 5 isn't much help. there are 20 seconds between 140,000 and 160,000 Ms. it appears that the initial rise is about 20% of the 20 seconds so about 4 seconds... the reason we can draw no absolute speed conclusions from the data is that the engine may have taken four seconds to do it's thing. all we can conclude is that it is faster than the glacial speed OE sensor.

i will be adding a thermistor to my UIM shortly and we will have comparison data.

i have a suspicion that if we knew our actual IATs there would be a lot more re-thinking of system design.

SYSTEM DESIGN

^Holler if you need a Triumph fast-acting sensor to benchtest. I previously bought a couple of them off the forum prior to going the k-type thermocouple route myself (via Speedhut air intake temperature gauge).

I just did a crude test using the Triumph sensor, a multimeter and a hairdryer and it took roughly 4 seconds to go from 14deg to 35deg. I didn't expect that IAT would change so quickly, thanks for that data Howard. Do you have a link to the thermocouple you're using?

EGT Probe Comparison Chart

EGT-AP Series

^The Sensor Connection

Obviously there is typically a lot more air flow over the sensor than a hair dryer can provide, so I just tested using water and saw the temperature go from 15-60 degrees Celcius in 1.5 seconds. Sorry, the car is in bits so I can't test any better than that. Looking forward to seeing your results. :)

this is the correct link to the air thermocouple:

Air Intake Temperature Probe Thermocouple Blower, Supercharger

^For reference, TSC's AIT probe is the same as their EGT-AP series probe. With the smaller 1/8" probe tip, curious to know how durable this probe has been for you.

The extreme duty IP series probe is rated the fastest of the bunch (2 add'l readings each second), and the most durable; presumably, due to a 1/4" probe diameter vs. 1/8". Any consideration given to this probe?
IP series (extreme duty probe)

@mrselfdestruct1994 an equivalent thermocouple available in Australia to the one linked above is this: https://www.auberins.com/index.php?m...roducts_id=182

At A$39 it's cheaper than the Sensor Connection one and WAY better value the so called "fast" reacting thermisters.

^Closed tip thermocouples provide more longevity (& reliability) over the other k-types mentioned, but at the expense of super-fast response time; I.e., just 1 reading per second vs multiple readings per. Still faster than the fastest thermistor probe, though.

For reliability purposes, I suppose this is why the SpeedHut IAT gauges come equipped w closed tip thermocouple probes. Perhaps a happy medium for most enthusiasts (longevity/accuracy vs response time), and the ultimate route I went. But I can definitely see where a high HP engine would prefer the open tip version for instantaneous response time.

I thought my sensor was fast acting till I read this thread ...now Im not so sure. This is the common GM IAT sensor. Log is 0-15psi by 4000rpm then 15 constant to 7500 then back to zero. My thought was that the lag was only about 0.5s judging by the time it takes to peak after throttle is let off. Optimistic ?
Temp is blue line in deg. C
Rpm is red line
https://www.diyautotune.com/product/...-with-pigtail/

https://cimg3.ibsrv.net/gimg/www.rx7...8a72d78de0.png

Following up on this thread, Bosch Motorsports makes a NTC sensor with exposed tip designed for "fast response". Part number is 0 280 130 085, see https://www.bosch-motorsport-shop.co...140-deg-c~4227

I managed to dig up the specs in older catalogues and it has a "thermal time constant" of less than or equal to 5 seconds. For this particular figure it was the measured time constant for a temperature jump of –80 °C to +20 °C at an air-flow rate of ≥ 6 m · s–1. While this sounds slow, the other fast acting Bosch Motorsport NTCs suitable for air temp measure 44 seconds. It is not the same as response time. See page 50 here: Wayback Machine

Compare this to the popular fast-response GM Delphi IAT sensor, which has a time constant of less than 15 seconds, 3 times slower than the above product, see: http://pe-ltd.com/assets/air_temp.pdf

I have struggled to find published thermal time constant specs for popular K type thermocouples used in automotive. This article is the best I could find just now: https://www.omega.com/en-us/resource...-response-time

It suggests that for a grounded probe thermocouple with 0.04" diameter probe, the time constant is over 2 seconds in air. This is measured at air flow rate of 65 feet per second (~20ms-1 ie much higher air flow than Bosch test). A 3mm (0.12") diameter grounded probe suitable for use as an automotive air temp sensor is therefore likely much much higher than that figure (response slows with increased thermocouple size). An exposed tip would be much much faster.

Based on this data, it suggests the Bosch Motorsports NTC sensor is likely as fast as or faster than a grounded non-exposed tip TC, but probably not an exposed tip TC.

That's the best data I could find, although I'm sure there is more out there if I had time to dive deeper.

Howard, I'd be keen to see your testing!

the 0 280 130 085 fits a 98-2003 Audi/VW 1.8, its like $16. uses an Ev1 connector.

given the cars it comes from expect a high failure rate, but it also looks like its easy to find

interesting that a post popped up in this thread as i was just going to post here too.

i have been waiting, a couple of months for a new set of studs prior to re-installing my motor. they arrived a few days ago and i expect to have my motor back in a few days and with it do some comparative tests.

i am going to use the IAT sensor that came w my ViPEC (that i never used). it is an open air thermister.

https://imagizer.imageshack.com/v2/xq90/924/WLL7Rn.jpg

as i understand there is another faster thermister sold by wannaspeed. if i test just my thermister it will solve little as people will say why didn't you test the faster one. i am not about to spend $95 to test it and then have no further use for it. if someone has the sensor lying around please consider sending it to me. i will return it in good shape in a couple of weeks. i believe the two thermisters have differing threads so before i finish putting my UIM on i will need to know if the faster one is heading my way as i am not going to go through the process of re-removing my UIM at a later date to add a different bung. if i don't get it i will test the one i have.

^PM me your address, and I'll shoot one or two your way.

just an update... i did receive the faster IAT sensors from Topolino, thanks, and will return them when finished. it appears they have 10 1.25 M threads and i have looked around for an aluminum bung but haven't been successful. any ideas as to availability? i can always fab one. should be up and running shortly with results. BTW, i have no idea what i will find, just looking for comparative data.

Howard,
I had the same problem. No weldable M10 bungs. Buy a male -6AN weldable aluminum bung. $5 on Ebay. Hold the male AN portion in a vise so as not to ruin the finished usable portion of the bung. Tap the M10 threads through the bung and then cut off the male AN end and sand the end. It works perfectly and looks factory made.
Mike

thanks for that. i bought the proper sized drill and have a couple of nice pieces of aluminum so i have it covered. i am finishing re-assembly of my car after changing the studs to Chips and expect to have some comparative data soon.
i think IAT is a big deal.

Well I hate to jump in and step all over the post, but I purchased a Triumph motorcycle IAT sensor on ebay as some recommended. Cost I believe was $10-$15. Mounted the IAT sensor in the UIM where the stock IAT goes (I believe).

Here is a log from over the weekend on a long 3rd to 4th gear pull on 93 octane with a conservative tune.

If you look at the purple line, ss soon as I jump on the throttle, you can see the temps start to move up (starting at 111F) and near the top of 4th the IAT's peak at 152F. A second off the throttle, and IATs are dropping... So maybe a second delay...



https://cimg3.ibsrv.net/gimg/www.rx7...9cf517db5c.jpg

thanks... as always it is great to get data.

my interest is primarily IAT and i am not out to prove sensors other than my thermocouple don't work. i just want to know what the real deal is. if the less expensive way works great.

i have now finished making my bung for the fast acting sensor, i have a bung for the open air sensor that came w my ViPEC and will be logging all 3 at the same time.

since you posted some IAT data i thought i would take a look at what i have. here's a run in 3rd gear. 93 pump gas with approx 1000 cc of 100% methanol as AI. just about 25 psi, EFR 9180 making 585 rwhp.

subsets from top to bottom are:

RPM
Boost
TPS
IAT (F)
AI system pressure (PSI)

first graph shows the point where my IAT starts... at 77 F and around 9 psi. this is at 2.59.706 on the log.

https://imagizer.imageshack.com/v2/xq90/923/3WdOPF.png



the second graph shows close to the top of IAT at 126 F at 3.00.441

https://imagizer.imageshack.com/v2/xq90/923/fRHxQq.png





since the high of my IAT was 129 F, 94% of the total rise in my IAT took place in .735 of one second.

your log looks like a slow sensor trying to catch up as it looks like a linear staircase. which raises the key question:

did it ever catch up? your readings in third span 6 seconds of rising readings. the question is, were your IATs actually rising during that period or was the sensor just limited as to speed.

my data shows that IAT rise very sharply and then decline. this could be for numerous reasons such as system design and methanol.

my last graph of the run shows the last 100% TPS at 7772 RPM, 24.9 psi boost, 585 rwhp and 117 F IAT.

https://imagizer.imageshack.com/v2/xq90/922/lWp6Uo.png

i hope to have some answers soon.

Oh I see what your saying. I never thought of it that way.

Howard : are you running an IC as well or just using methanol for cooling ?

https://imagizer.imageshack.com/v2/xq90/923/ryMYrr.jpg

towards the top of a run charge air coming out of the compressor is over 300 F. since the temperature is a function of compressor slippage rather than raw flow 300+ is existent whether you are running the (godawful) OE system or a high output single setup.

gasoline autoignites at 495 F. since there is overlap between the intake and exhaust even on the stock FD ports you are sweeping some exhaust gas into the intake stroke... no oxygen, just HEAT.

it is therefore important to feed the motor with really low temperature charge air... and you are starting at the turbo above 300 F.

all of my system design is driven by heat and flow considerations. of course instrumentation is needed or your are blind.

in addition to my air thermocouple in the UIM i have an air thermocouple between the turbo and the intercooler.

https://imagizer.imageshack.com/v2/xq90/924/K0V52o.png

as mentioned, i normally see air temps out of the turbo just above 300F. a combination of my favorite intercooler, the stock location Pettit Coolcharge 3 (around $1400 BTW, call Cam) and the meth remove 200 F from my charge air!

given the exhaust speed is measured in terms of Mach by BW the intake must also be running at a similar speed, imagine the amount of heat that needs to be removed from the charge air.

so let's see, we are running a super dooper V mount that is really going to drop IAT... and we locate the air intake right in the path of all the heat we are extracting?????? yikes!
https://imagizer.imageshack.com/v2/1...923/5f5gP9.png
https://imagizer.imageshack.com/v2/1...921/rxHj26.png
https://imagizer.imageshack.com/v2/1...923/pHnRWk.png


i plan to add an additional 500 CCs of meth, bringing it up to 1500 CCs and expect my IAT to drop into the 50/60 F range. ( a number of years ago i was up to 3000 CCs but don't want that aggressive a bet these days)

in addition to detonation avoidance, the other reason to lower IATs is POWER.

Power is simply burning oxygen molecules. if you compare two volumes of air at a similar pressure the hotter volume will have less molecules as they are vibrating as they heat so each molecule takes up more space. more space, less molecules. less power. that's why your car is supersonic when the temps drop and it also leans out because of so much more oxygen at the same boost.

low IATs = less chance of detonation and more power.

"what's in your wallet?" what is your actual IAT?

for more on system design:

SYSTEM DESIGN

meet with cam a few months back and preached the same u are about intake temps. he also mentioned u.
he sends his regards
I had made a lim shield, and use a air box wrapped, inconel shields on manifold and turbo.
he nicknamed me mr.shields Ha
he is the reason I kept my pettit IC
ever check wat ur temps were like without the air diverter for ur air filter HC?
https://cimg4.ibsrv.net/gimg/www.rx7...07aec9a556.jpg
https://cimg8.ibsrv.net/gimg/www.rx7...1f56a5031b.jpg
https://cimg9.ibsrv.net/gimg/www.rx7...fac4979429.jpg
https://cimg0.ibsrv.net/gimg/www.rx7...bd7aebfe61.jpg
https://cimg1.ibsrv.net/gimg/www.rx7...ee515e10c8.jpg

just finished installing my UIM yesterday and it does include the "fast" thermistor along w my thermocouple so we should be getting the comparative data shortly.

heat management is the key to a healthy setup

heat transfer/conductivity of various materials:

aluminum 240-220
inconel 15
stainless steel (304) 14.4
titanium 24.5-19.4

mica .71, yes, that is point 71

if you visit an industrial facility where they really need to mitigate heat transfer you will find mica.
if you take a look at the space shuttle's business end you will find a substance that uses mica
or, if you look carefully, you will see a quarter inch sheet of mica on duty here...

https://imagizer.imageshack.com/v2/1...924/KWnTvH.jpg

i initially ran an 1/8 in sheet and prior to installing it used a 1300 F propane air torch to heat one side for 2 minutes. i could touch the other side within one inch of ground zero with zero problems.

McMaster Carr sells a perfect 12 X 13 inch piece (1/4). so that takes care of the LIM, the PTP turbo blanket greatly reduces under hood temps which often influence IAT. PTP uses a mica like substance in the blanket.

Howard, what was your reasoning behind the switch from 1/8" Mica to 1/4" Mica? The one downside is that you can't exactly shape the stuff to your liking. Not malleable.

I'm going to have a hell of a time with the wastegate coolant paths to notch/slot/shape things to my will. Those might have to be pass-throughs with high temperature grommets. Then at the front of the manifold, it's WAY crazier. Rear I might be able to get away with.

1/4" Thick here won't work for me. 1/8" Should be doable.

https://cimg7.ibsrv.net/gimg/www.rx7...7930b136e1.png
https://cimg2.ibsrv.net/gimg/www.rx7...5525a5e8dc.png
https://cimg9.ibsrv.net/gimg/www.rx7...f8ddea3a94.png
https://cimg2.ibsrv.net/gimg/www.rx7...9e60c7fde2.png

initially i was given a sheet of 1/8 inch mica by a friend who oversees a large metal/industrial operation and told to run it. when this guy talks i listen.

i did the propane torch experiment w the 1/8 inch sheet and really did heat it for 2 minutes and i could have literally touched the exact spot on the backside but sort of chickened out. i did have my finger an inch from it and it was barely warm..

after running it for a few years i was looking at the McMaster Carr catalog and noticed they had 1/4 inch so since i (just) had the room i made the trade up.

given the location of your hotside i would say you absolutely need mica. while you may not be able to slide a flat plate of it in you could work the material a bit and probably get most of your lim protected. the material is easy to saw and drill and 1/8 will absolutely get it done.

i believe the PNs are: 85165K81 1/8, 85165K82 is 1/4

https://imagizer.imageshack.com/v2/1...922/gmDccM.jpg

Wow, I’m pretty impressed with that mica stuff, is it easy to work with?

for example, to make a air box out of, is it heavy?
on the website they also have a flexible mica sheet, I’m thinking this would be easy to shape and layer up with a few layers thick and then set it with a type of resin to make it hold its shape for complicated area’s????

i also found another type of mica sheet where when you wet it it becomes mouldable but after its heated a few times it will hold its shape, but i cant find which site it was on 😩

I’m looking at ways to really keep my IAT temps down, to make everything as efficient as possible, such as ceramic coating my exh housing and manifold aswell as turbo blanket and heat wrap, heat shields around my LIM, cold air box etc,
also preturbo water/meth injection (pumpless system).
im also on the hunt for IAT sensor, so i really look forward to the results of this test, I’m heading towards the t/c as i will be running 2 for my egt and the t/c amp box for haltech has 4 inputs so may as well make use of them all

krem

https://cimg1.ibsrv.net/gimg/www.rx7...4b3a3718b3.jpg
https://cimg3.ibsrv.net/gimg/www.rx7...cd8ed02b24.jpg
Now that my car is running. I trying to do what Howard did with mica when I saw his post long time ago. My LIM and and turbine housing are hight temp ceramic coated, but they are very close and the 1/4 " plate wont fit.. i was thinking a inconel sheet to go around that spot.
You can see the thickness of the mica and the little room between LIM and turbine housing.
Thank you Howard for this I bet it works great.

The Mica sheet is a really good, cost effective solution, as long as you can make it fit. An inconel shield like is used on a previous post, will likely be what you need. Whatever your solution try to get at least a small air gap between the turbine housing and shield. This will allow the reflective properties of the shield to keep the radiant heat away, and prevent the heat from being directly conducted.
By fitting it that close, you've made your work harder. But I'm sure you can overcome this engineering hurdle.

Yea, I am sure an inconel sheet will do. :rofl:

I now have a line on an ECONOMICAL fast acting M10x1.25 air intake sensors with EV1 connectors. YES! They take some time to get here, but quality is amazing and it's direct bolt-in for FD Upper Intake Manifolds!

Howard - What ever came of your comparison? Assuming the K type thermocouple produces the fastest responding and most frequent reading delivery, what would a solution be for a stock UIM setup using the stock IAT sensor port. Stock port being 10mm x 1.25 pitch. Without having to modify the UIM, is it possible to use a thread adapter to prevent tapping the intake. There seems to be several options on the market that are fast reacting that you can plug and play. It's just, if $50 separates me from having the fastest reacting and most frequent type of intake temp reading from a fast(er) than stock sensor, then its worth my time and engines time to make that small leap up. Can the pig tail of the K type sensor and the stock sensor wires be re pinned with a different connector?

I went ahead and fitted the same thermocouple to my intake. Unfortunately I didn't see any rise in IAT during a pull with the Triumph sensor and still see nothing with the thermocouple, so I can't say whether it made much difference. I'm running 20psi on stock twins with a 21" x 12" x 4" Plazmaman front mount intercooler.

FYI I fitted mine into the stock port using an adapter, no issues.

That's a healthy sized intercooler for the twins, NICE! It sounds as if the sensors are not operating correctly. Did the stock sensor spit out readings before switching? May be a calibration issue or wired incorrectly.

Yeah all three sensors I've tried work correctly, no odd behaviour. I suspect if I did repeated back to back pulls the temperature would increase but I'm not getting the kind of rapid change in temperature that Howard is seeing so unfortunately I can't compare the response time between them.

https://imagizer.imageshack.com/v2/1...922/1PFOvV.jpg

i remain as interested as ever re IAT. making power and not breaking motors is all about density and any uptick helps greatly. IAT thermocouples are the ruler.

2020 featured a move from Wisconsin to Georgia which is very exciting to me as no more being parked for almost 6 months a year. following getting situated (around November) a succession of events ocurred that left me mostly on the sidelines. for instance my wonderful ViPEC V88 decided to retire... something about the motherboard. i now have the most recent iteration of my V88... a Link G4X Extreme and it is amazing. it took the better part of a month to transfer my map to the Extreme and i discovered Evans Performance Academy in the process. what an awesome and affordable resource. almost every ECU is totally dissected. there are over 60 (!) 30/45 minute tutorials on my specific ECU. it is totally crazy what my new ECU can do.

whipping my instrumentation into shape presented another challenge. i run 4 thermocouples.... two EGTs, one air thermocouple just after the turbo before the IC and one in the stock location under the UIM. a year or so ago i discovered the Innovate TC4 Plus thermocouple amp. since it had 4 channels i swapped it in. it never produced 4 temps. i switched back to what i had previously run which is two dual channel amps from EGT Technologies as well as a set of four new thermocouples from "The Sensor Conection." i finally now have all four temps going as well as my "fast" acting thermistor located in the UIM. you can also see the fitting for my thermocouple in the stock location..

since i am breaking in a new ECU and map i am in the process of adding boost. i did a tip toe to around 15 psi just for a brief period to get a handle on my AFRs. here's a snippet. steady state TPS (24.7%) zero boost/vacuum air out of the turbo is 134 F, IAT at OE location from the thermocouple is 87 F and at thermistor under the UIM is 78. the thermistor is the almost flat line.

at 15.7 boost, 33.8% TPS, 4879, air out of the turbo is 188.2, IAT at the OE location thru the thermocouple is 88.5 and 77.7 at the thermistor. none of this is surprising and doesn't mean much until we get into much higher TPS settings and rpm but i am happy to just being able to generate some data.

now if it will just stop raining.

here's the log:

https://imagizer.imageshack.com/v2/1...922/Ek3hJx.png

i will be adding an additional pressure sensor at the IC outlet as well as another thermocouple in the same place. the addition of these sensors will allow me to isolate the IC and get data as to pressure drop and thermal efficiency. the primary reason for this is it will allow me to generate comparative data when i swap in something possibly quite special. stay tuned.

I figured you guys would find these logs interesting, similar to what HC is doing.. I installed temp and pressure sensors in several spots, measuring ambient, pre-turbo, pre-intercooler and manifold. you can calculate air density from temp and pressure (assuming constant humidity). the air temp sensors I am using are the haltech 1/8npt open air sensors. my setup is EFR7670 on a stockport rew, pump gas, vmount intercooled only, makes about 350whp

in the log
aat = ambient air temp
aap = ambient air pressure
tcit = turbo charger inlet temp (turbo inlet)
tcip = turbo charger inlet pressure
cacit = charge air cooler inlet temp (turbo outlet)
mat = manifold air temp (intercooler outlet)
emap = turbo manifold pressure
column M = ambient density
N = turbo inlet density
O = turbo outlet
P = intercooler outlet (manifold) density

looks like the haltech sensors go from 145F to 200F in 2 seconds, about 25deg/sec. Cool to see how much density is increased by the turbo vs intercooler. and the slight drop pre-turbo due to filter restriction

https://cimg9.ibsrv.net/gimg/www.rx7...7b2bc5c144.jpg

Excellent info! Got a question, is that info based on a single gear pull? Would love to see the same info on a 3 gear pull.

"is that info based on a single gear pull? Would love to see the same info on a 3 gear pull."

this is very close to the ultimate question re our cars and IAT.

IC heat soak, or lack thereof, may be the KEY.

for example i know of a dyno test with an NSX comparing different IC cores.

a high quality bar and plate IC lost 50 rwhp on the third pull. all due to heat soak. another IC core was immediately swapped in and had virtually no power loss after 3 runs. of course airflow thru the IC on the dyno is somewhat limited and i don't know where the IC was situated but i do know there was almost no power loss after 3 runs w the different core. i have that core fixtured for my FD and will be testing it soon.

meanwhile for most of us, especially on a road course IC heat soak is a serious dynamic challenge which calls out for proper instrumentation and eventual help.

i dont have any recent logs with longer pulls, but here is one from last year when i was running just off the wastegate spring 3rd - 5th. i was also running a more restrictive filter back then, you can see the density drop in the turbo inlet.

it does seem that the traditional open air temp sensors heat up fast, but take a while to cool back down. yea the question is, is that just because the throttle is closed and less airflow to dissipate heat soak in the sensor or IC heat soaking

https://cimg5.ibsrv.net/gimg/www.rx7...8eb10786e5.jpg

gauge pressure

https://cimg4.ibsrv.net/gimg/www.rx7...e8e2a11499.jpg

density

https://cimg5.ibsrv.net/gimg/www.rx7...3717c82686.jpg