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-   -   Measuring heatsoak vs actual AIT? (https://www.miataturbo.net/race-prep-75/measuring-heatsoak-vs-actual-ait-88180/)

Braineack 03-17-2016 07:13 AM


Originally Posted by Savington (Post 1316405)
Can you quantify how much heat is transferred to the intake charge through that pipe (let's say it's a 2.5"x.080"x24" pipe) in that period of time?

BEGi claimed they measured a 20°F temp drop between the turbo outlet and intercooler inlet with their aluminum pipes at 6psi on a 95°F day measured at a constant for 25sec done 12 times in a row.

If one eats a gallon of ice cream, then installs a silicone IC outlet pipe or SS or insulates his, he will barf and then never worry about heating the charge back up -- but the reheating couldn't be as much as the heat losses, since the outlet temps of the IC are much closer to the underhood temps.

90civichhb 03-17-2016 07:49 AM


Originally Posted by Braineack (Post 1316425)
do they?


I'd say it's like 10% and those are just NB owners and people who still put the AIT behind the radiator.

I know I get lean on hot starts and there are a few threads dedicated to finding out the reason why this happens. NB owners seem to think it's the returnless fuel system while others credit bad AIT placement. I've got my AIT sensor in the IC endtank and see high 15 to low 17 AFRs on restart on my 1.6L car. It settles itself down if I let it idle for a bit or run it up to 2k rpms. I digress.

Great thread, quality information and knowledge expressed in here. :likecat:

Braineack 03-17-2016 08:43 AM


Originally Posted by 90civichhb (Post 1316432)
I've got my AIT sensor in the IC endtank and see high 15 to low 17 AFRs on restart on my 1.6L car.

did you attempt to tune your MAT corrections table or leave the default values?

90civichhb 03-17-2016 08:56 AM


Originally Posted by Braineack (Post 1316440)
did you attempt to tune your MAT corrections table or leave the default values?

I've played with it a bit but I am still taking data so that I can more accurately address the percentage correction. I don't want to derail this thread but I used a lot of the information in this thread for help. It may be a bit dated now though.

18psi 03-17-2016 09:07 AM


Originally Posted by Braineack (Post 1316425)
do they?


I'd say it's like 10% and those are just NB owners and people who still put the AIT behind the radiator.

95% of the 10% is what I meant :giggle:

Braineack 03-17-2016 09:08 AM

my advice is to zero out corrections from table completely and tune it last.

a quick look at datalogs can tell you a lot.

example, lets say you start the car and idle and your injector pw is 1.8ms at idle and you're lean. then after 60sec of idle, youre now sotich. did the pw change? did the ait change? what changed? stuff like that.

90civichhb 03-17-2016 09:16 AM


Originally Posted by Braineack (Post 1316447)
my advice is to zero out corrections from table completely and tune it last.

a quick look at datalogs can tell you a lot.

example, lets say you start the car and idle and your injector pw is 1.8ms at idle and you're lean. then after 60sec of idle, youre now sotich. did the pw change? did the ait change? what changed? stuff like that.

I'll give that a try. Thanks.

18psi 03-17-2016 09:20 AM


Originally Posted by Braineack (Post 1316447)
my advice is to zero out corrections from table completely and tune it last.

a quick look at datalogs can tell you a lot.

example, lets say you start the car and idle and your injector pw is 1.8ms at idle and you're lean. then after 60sec of idle, youre now sotich. did the pw change? did the ait change? what changed? stuff like that.

for returnless nb's: the fuel temp changed. so the AIT readings aren't really useful to log, however you artificially manipulate ASE corr and taper to get rid of the issue.

but anyways, back on topic lol

nitrodann 03-17-2016 09:22 AM

have kitty brain.

aidandj 03-19-2016 09:35 PM


Engine running. Same result

nitrodann 03-20-2016 12:12 AM

Thankyou.

So you gotta get the sensor in direct cooling airlfow like the front of the IC.

Braineack 03-20-2016 08:49 AM

this is why we say to get it away from the radiator.

and if youre running MS, zero out your AIT corrections. The default curve from B&G if youre not using a basemap is based on the Ideal Gas Law, problem is it doesnt take in account for things like shown in the video above. So it pulls fuel based on an AIT reading that isnt accurate.

Tune that curve based on what you actually need when you're actually driving the car.



what would happen if you did that same test, but held the throttle open at like 2-3K?

shuiend 03-20-2016 08:49 AM


Originally Posted by aidandj (Post 1317004)
Heatsoak test Pt. 2 - YouTube

Engine running. Same result

Have you been approached to help film the next Cloverfield movie? You got the shakey camera action down.

Also you might have an issue with oil temp readings if your gauge only goes between -1 and 1.

aidandj 03-20-2016 08:56 AM

Oil Temp: See the latest video in my thread.

Brain: I'm running some updated table I found. To cancel out what they do.

I can do idle test mode and get ul around 2k. I'll try that again today.

Braineack 03-20-2016 09:12 AM

1 Attachment(s)

Originally Posted by aidandj (Post 1317031)
Oil Temp: See the latest video in my thread.

Brain: I'm running some updated table I found. To cancel out what they do.

I can do idle test mode and get ul around 2k. I'll try that again today.


aren't you on ms3? 100% across would cancel it out.


this is what I start with:


https://www.miataturbo.net/attachmen...ine=1458479554

aidandj 03-20-2016 09:18 AM

Yep. That's the exact one I'm using.

sixshooter 03-20-2016 11:34 AM


Originally Posted by aidandj (Post 1317004)

Engine running. Same result

Thank you. I already believed, but thank you.

What I really have to determine is if the WI nozzle will skew the results more if it is before or after the IAT sensor. The injection will obviously cool the charge and that should be measured, but the water or meth will probably damage the sensor and cause in an inaccurate reading. How do people do this?

Braineack 03-20-2016 11:59 AM

it should be atomized by that point and not even be an issue. the GM sensor element can be submerged in water and not fail.

meth/water can drastically reduce intake temps and you really want to know, as close as possible, temps you're actually ingesting.

sonofthehill 03-20-2016 01:03 PM

In my opinion the IAT sensor is meant to be a point of reference only, since obviously you can't read the charge swirling in the combustion chamber. I always have the same argument with one of my good engineer friends. I think that depending where between your IC and TB you mount it your VE table will look slightly different. Just as long as you don't mount it behind your radiator.
And hot starts are part of the reason there are so many start up features.
:2cents:

90civichhb 03-20-2016 03:24 PM

So to further a bit on the water/meth injection idea. Would you want to place the nozzle before the AIT sensor? For instance would placing it in the "hot side" of the intercooler endtank be a good place for it? I know some cars come OEM with intercooler sprayers like the EVO and some Japanese spec STIs but that is external and I've not seen people run it like I mentioned before. Usually it is always near the throttle body.


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