Lexus4321

Is there any design function of the engine cover cap? Like does it help direct airflow or something?

Also wondering if anyone has ever added some sort of separator plate alongside the battery to deflect all the heat that hits the side of the battery due to the radiator fan.

Grumpa

I don't know about the GX but on my JK it's only purpose was to cut engine noise. I removed it and eliminated some overheating i was getting at high altitude crawls. Sounded better to me too. Interesting comment about the battery. Warm air from the radiator is not likely to be an issue IMO but radiative heat from the engine may be worth considering if your in a hot place.

chiph9

It might prevent the hood paint from baking.

I had a turbo in the 90s that turned the paint orange from the heat coming off it.

Chip H.

Lexus4321

As far as I can tell, just a dressing and perhaps a tad of sound diversion. I leave mine off to allow heat to move more freely up away from the engine. The engine itself does not get that hot, and with hood insulator in place there should be no worry about too hot on the hood. The cover does not stop heat from going around it, and, the cover covers mostly the coolest part, the intake.

About 2yrs ago I thought about installing louver vents into the embossed rectangle areas of the cover to allow more heat flow, but decided to not bother and just leave the cover off.

Turbo's (hot side) need to be wrapped. Wrapped from exhaust ports to turbine, and then 1-3ft aft the turbine.