Manifold Air temperature sensor for steady state tuning

What is a safe range i want to keep Manifold Air temperature at while doing steady state tuning?

How can i know from MAT that my FMIC is getting too hot on a evolution x what is a safe range i should keep this at?

The aim is to keep the IAT in the same sort of range that you're going to see on the street or in normal use. This can be a little challenging as simulating real world airflow on a chassis dyno bay is difficult and expensive.

The sort of IAT values you're likely to see even on the street will depend on the turbocharger efficiency, boost level, ambient temperature and the intercooler size/efficiency. In general I would like to see the IAT in the range of 20-25 degrees above ambient temps as a maximum. Temps higher than this can still be managed but you may need to start pulling timing to prevent knock, particularly if you're on pump gas.

On the dyno I often spray water onto the intercooler between pulls to help stabilise the IAT and provide consistency run to run. It can also help to run the engine at low rpm and off boost for a minute or so to allow the temps to stabilise before another full power run.

Thanks yea that's what i do now when temperature hovering over 90s , I dont have much problem keeping temperature 20 25 on FMIC

but with Subaru that's giving me a headache without a powerful fan aiming from top it's heat soaking badly when i have anything bigger than a stock turbo.

The Subaru TMIC is a pain in the ass on a chassis dyno without a specific fan to blow air into it. I keep a large bottle of water in the dyno bay and will liberally soak the TMIC core before a full boost ramp run. This still isn't perfect but it's about the best you can really achieve without some more specific fan configurations. It's all about understanding what you're dealing with and how parameters like IAT can affect your tuning. If you know what the likely implications are then you can account for them on the dyno. It's also always nice to check the performance on the road and see how it matches up to the IAT you saw on the dyno.

With a Subaru I'm usually cautious with IAT anyway as around town and in start stop traffic you find the TMIC acts like a chimney and heat soaks badly. This usually means that when you first go back to full throttle acceleration the IAT may be quite high until it stabilises. This can result in knock if your tune is on the edge. An IAT ignition trim under high load will help stop this.

You guys just need an proper dyno fan. And that means no axial blower fans! They are a waste of electrical power and just cool your coffee next to the car. An axial fan has no airflow in the middle, and reaches just around 80-100km/h airspeed at the biggest diameter of the fan. It produces also a turbulent flow and most likely the death zone of the fan sits just before the intercooler and more than the half is blown over the top of the hood and just cool your frontscreen and mirrors.

If you think about that, it's easy to see that it is a total waste of energy. What we need is high airflow speed through the intercooler an radiator.

So we need a high speed, mid pressure fan which produces a laminar flow just in front of the cooling openings in the frontbumper.

A bigg radial blower (which looks like a windscreen blower) does the job much, much better.

I'm using a big radialfan with a 15kW motor. It producess 175km/h air speed and a laminar flow. That thing cools soo good, I have the luxury problem that I have to pay attention that the car on the dyno don't get to cold. Also on Subarus and 30 degree Celsius ambient temperatures. And surprisingly it doesn't consume that much electricity. The full 15kW are only needed during acceleration to working speed.

Beside the dyno room should change the whole air in the room at least 6 times a minute and you also should have a big exhaust fume extraction system. I use there an 6500m^3/h fan and a big 35cm diameter piping system.

I agree @Adrian with regard to type of fan selection.

The problem with a Subaru is normally getting the air from the fan to the actual intercooler opening on the bonnet/hood. Most dyno fans do a great job of directing the airflow into the front bumper opening to cool the radiator or a FMIC, but very little makes its way over the bonnet. It's incredibly difficult without an OE or F1 style budget to truly replicate airflow of 150 + kmh through the entire dyno bay - Parts of perhaps, but not the entire room. Many dyno shops that specialise in Subaru tuning will have a second fan specifically routed to the bonnet scoop to cool the intercooler.