dyno tuning - exhaust manifold heat management

hey guys, been on the forums for some time, and ive finally started doing some dyno tuning at a mates shop.

i had a bit of a question regarding the exhaust manifold, and the method that is taught within the course.

so when andre is tuning, he shows the he single cell tunes ( for majority) up to around 4500rpm. while monitoring all criticals. and when the iat / ect gets to hot will let the car rest until its back to an acceptable temperature.

so i was doing tuning an evo ( which already had a map in it and knew it was a good safe map) using this method and was closely monitoring coolant / iat etc and they were all at a normal operating temp, and i was starting to get higher in the rpm and my mate who owns the dyno said i had to stop immediately due to the exhaust manifold being pretty much see through.

the timing in the map wasnt by any means retarded, as it was already pretty well tuned we were just doing an e85 map and winding it up.

my mechanical side of me does worry about this, as itll be hurting the manifold, and possibly the valves. but i havnt heard andre in any of the videos say anything about this, and during the lessons, it does run a way more retarded ign map then i would of been.

is it just a matter of when you start getting into these parts of the map to give the car a break, let it cool down, start it back up and start skipping a few cells and interpolating, and trying not to spend time in the higher rpm cells for very long? as i can imagine andre would be substancially faster then me at making the changes in these cells, for both fuel and ign.

what is the the procedure i should be doing as a beginner

It is common for the exhaust manifolds and turbine housing to get to what seems to be extremely high temperatures - this will look a lot worse if the room/area is on the darker side. It's not that unusual to have NA engines with manifolds that seem to be 'transparent' too.

It 'shouldn't' be an issue if everything else is fine, but the most critical part will normally be the turbine blades - this is why it's normal practice to monitor the EGT as different manufacturers may use different materials with different maximum ratings.

It's a timely reminder to make sure the heat shielding is up to the mark and there's nothing that could be damaged left unprotected.

You may find this useful for re-assurance, as an average max' for the turbines tend to fall into the 1400-1500f range - but you should check with your turbo' manufacturer's recommendations and, remember, the external manifold temp' will be a little lower than the internal gas temp'.

Depending on the dyno room, cell you're using, fans, etc. this changes quite a bit. If the room has awesome flow for the room's volume, you won't need as much cool down time, but most dyno rooms have fans that do not keep up with the heat being generated. Lots of time to cool down is often required. Also keep in mind without sufficient flow under the car, the exhaust may cook things on a dyno which wouldn't happen on the road.

In terms of EGT, monitoring it and using that data along with dyno measured torque, knock readings, help make more informed ignition timing decisions.

good responses, appreciated!

most cars i would be tuning initially are unlikely to have EGT, so i guess just a bit of common sense, and monitoring the sensors i do have are the crucial elements. as long as the fans are on and the cars critical sensors are in check, in theory i should be fine, and maybe once i get into the higher rpm areas, to just let it cool down a little?

at the higher rpm im going to assume most people wouldnt be spending time in each cell either, more likely to skip a couple to not labour the engine? is this accurate?

I think the simplest way I can put it is my ratio of steady state time to cool down time reduces progressively, bordering on exponentially, with RPM and load.

When working with a vehicle that has decent cooling systems, a decent dyno cell, you may be able to spend a minute, perhaps even more than a minute tuning low RPM, light load, but by the time you get to for example 6000 RPM, you might only get a 3-5 seconds at moderate to high load before something overheats.

Just keep in mind there are things that can overheat which you don't have sensors for, and airflow in the dyno room you're using is likely massively reduced compared to driving on the street. I've had people tell me they lit the underside of their car on fire, etc. on the dyno just because they forgot about the lack of airflow blowing over various parts of the vehicle.

Also make sure you're giving the room time to cool back down and clear out, otherwise you can end up tuning the vehicle for a condition where it's ingesting dirty hot air.