Engine/exhaust thermal management

[fanamingo]

So what concerns are there in restricting airflow through the engine compartment and around exhaust components? There's the obvious issue of the engine overheating if air is restricted too much. What if the engine stays at normal temps but the rest of the engine bay heats up. Will this have adverse effects on the battery, exhaust, catalytic converter, etc?

Over on CleanMPG, drimportracing had the idea of insulating his Metro's hood Geo Metro Insulated Hood "how to". This seems like a good idea, but combined with a partial or full grill block and underbody tray, could you start to run into issues with not exhausting enough hot air?

I'm wondering about using drimportracing's idea to insulate my hood and the part of a future underbody tray that would be close to the exhaust pipe. Most of the engine bay would be sealed off with one inlet in a partially blocked grill and one outlet flowing around (and through) the exhaust pipe and finally exiting in the tailpipe area. Benefits would include:
* great warmup times
* less heat from a block heater lost to surroundings
* the engine should retain heat longer, thus benefitting fuel economy when running multiple short trips back to back.

Thoughts?

[FastPlastic]

I've seen several production cars that have it stock. I think over the winter it's probably fine. It would keep all the components in the engine bay warmer. Probably better for your battery(mine has an insulation wrap). Summer time you would probably want to watch the temps if you have a grill block already. One place that sells it says it will protect your paint from getting too hot as well.

[RH77]

It depends on the driving conditions and cooling efficiency of the model in question. I have to block nearly all airflow over the radiator in Winter temps, or suffer transmission consequences (delayed shifts). IATs should be examined as well, but again, it varies by model.

One test should not preclude a decision -- if it is Scientifically valid to reproduce, it should be -- but unfortunately, the results apply to that specific model only.

RH77

[orange4boy]

There are ways to mitigate excessive heat in the engine compartment like an insulating header wrap in which you wrap your exhaust manifold and/or header in woven refractory.http://www.heatshieldproducts.com/lava_wrap.php

Ditto on the battery, warm is better.

You could install some flaps/vents in the belly pan to allow some convection with only a small loss in aero. I have left a small opening in my grille block to allow some cool air in.

The best would be to monitor the temp. and mitigate if necessary. Next question is how hot is too hot? I'd like to know this too.

[nascarnation]

Really high underhood temps will tend to "bake" plastics over time. This includes wiring insulation, connectors, and various electronic sensors. So, common sense is the best course here. May need to tailor the engine compartment airflow to the ambient temp.

[Daox]

I agree with nascarnation. Most plastics in the engine bay are probably alright, but prolonged exposure to high temps will tend to degrade them faster. Do your mods and throw a temperature monitor in the engine bay. If it gets too warm, put some vents in. I'm sure you can block a ton of area off before you start seeing real high temps.