I added sound proofing foam under my bonnet. I don't really think it helps in term of soundproofing. But I thing it does helps with heat insulation. However, since I am living in a country that is warm all year long, I am wondering if this can cause adverse effects of engine overheating. Since the heat get bounced back to the engine, it cause engine and especially the inverter runs hotter? So I am wondering if I should keep it or remove it?
Since the foam doesn't do what you wanted it to do (eg, sound insulation), and you live in a very warm climate, why keep it? Seems self-evident to me....it certainly cannot HELP in terms of engine cooling.
I'm guilty of one under-the-bonnet (aka under-the-hood) insulation addition, leave it in year 'round in, albeit, in a more temperate climate: It's foam plumbing pipe insulation. It has a slit along it's length, I push it onto the crimped seam there. The bonnet has sealing gaskets at front and rear, but none down the sides. Besides holding the heat in I think it might reduce dust build up.
FWIW: seems like a useful addition to me, and I doubt it increases ambient heat much. I live in Utah, latter-day dust bowl....
Yeah I suspect it's more that it prevent air exiting than entering. That maybe amounts to the same thing though: if potential air exits are blocked it also reduces air incursion?
Thanks for the comments, I will monitor my engine and inverter temp a bit to see how it goes. Problem is, I don't get to drive much due to current situation. Here is a picture of what I did:
Was there something on that zone already? North American Prius has some sort of black, fibrous panel in that zone already. Believe it's: Insulator, hood part no: 53341-47020 (there are fasteners indicated too) Here: https://www.amayama.com/en/catalogs/toyota/prius/3-hatchback-right-xw30-2009-2830/3/172 Pricey though.
Looks like OP already has that part. Shown laying on top of the engine in the photo, right? I'll guess it gets reinstalled. In general, extra insulation on the hood like that should reduce temperature variation, especially after shutting down - meaning it will cool off at a slower rate. That's generally a good thing. Rapid cooling (or heating) with varying coefficients of thermal expansion will create stresses, causing popping sounds, etc. Not that it's a problem in the Prius, and my first guess would be that the Toyota engineers have this all figured out, considering other factors such as cost, weight, assembly, extra power and wear on the water pump to offset the higher temp while running, but it should help. I still remember my Granddad laying a blanket on the hood of his car every time after getting home from a drive - young enough at the time that I did not fully understand what he was doing, but I figured it out later. If the car is used around the clock as a taxi cab, I can see a definite benefit to keeping it in a constant state of being warmed up and ready to go.
View attachment 192239 Yes, that cover is laying on top of the engine. It got reinstalled. You got a really good point there on keeping the engine cool down slower. BTW, for those who are unaware, the hood is actually made of aluminum. Other parts are made of metal but not the hood. Whole piece of hood is NOT magnetic.
If you lift the hood on a Corolla (for comparison), you really notice the difference: steel hood much heavier.
