Engine insulation for hybrids to improve fuel economy

[hayden55]

I'm about to just throw a piece of R16 or whatever in there. full fluff is 3.5" and is single digit dollars. I have a full upper and lower grill block on my prius and it still doesn't maintain temps, but it does do pretty well, it doesn't get those 50 degree swings like normal priuses. I think the insulation would be the last push it needed to be as good as it can get.

[Phase]

https://www.dynamat.com/products/hoodliner/

anyone know how this does for heat?

[hayden55]

Damn boys i put R13 or whatever on the prius since i have a roll for my garage door i'm doing. Slapped it on and heat retention is massively improved. with a upper and lower grill block and a header air intake i'm basically back up to summer gas mileage around town with the automatic heat on as well.
i used a piece of 3.5" thick by 48" long and i think 18 or 24" thick. so like 4$ worth

[freebeard]

Originally Posted by Phase

anyone know how this does for heat?

I'm going to get some next time I roll past Graffiti Alley on River Road. I think they had a competitive knock-off product as well.

[hayden55]

I've always been told if you can see the heat source use that shiny stuff, and if you can't to depend on the air gap. So think like an infrared light and metal objects. Instead of absorbing the infrared it'll bounce off more. But with that said i would just go with airgap on this one. Toyota oem engine bay insulation is just yellow fiberglass, albeit more compressed since its more for sound and not for heat retention.
I'll have to add a pic of my engine bay.
$20 warm air intake tube, $2 in foam, and $4 in insulation later and i have a car that can do 60mpgs in the winter with the heat on. I never have to worry about dropping below like 170s and the car won't go over 202, even the inverter temps are good.
Its seems so good when temps get above 60s again i will leave the insulation and just unplug the grills in order of what i need to maintain good inverter temps and what the cooling system for the engine can handle.

[hayden55]

Talos you win bud. never in my life would i have ever thought to do this, but this is why i love the internet.

Not even lying I think this is like the most effective mod ive done personally. I may redo it and cover the whole hood area and leave a gap around the inverter.

[ps2fixer]

I knew about this mod, but haven't actually insulated the hood. I've sealed the hood seams through with truck topper foam, works ok but the hood can be a challenge to pop sometimes since snow melts and freezes in the crack.

I've been thinking about doing something like this on my prius since as you say, warmup time is 3-4 miles with a grill block and lately my trips are both cold and short trips so should be a massive improvement.

I haven't seen any info on this idea before, but another concept I've had that's similar to this is oil pan and transmission heaters that run only when the engine is cold assuming you don't have an easy to access outlet to pre-heat the vehicle. The theory is to warm the engine up quicker to get it to operate more efficiently, but the extra load while code might offset any benefits. It could be possible to use the prius logic and run the heaters off a spare battery then once the engine is warm, recharge the battery back up off the engine, or take it inside to charge off the grid/battery bank for the house.

Anyway, sounds like I need to throw some fiberglass insulation over my engine and see how much of an effect it has short term to I work out a better long term version =).

[Piotrsko]

You all using bagged insulation or typical house one sided?

The bagged stuff comes foil covered both sides or not, but the bag used to be semi puncture /rip proof

[ps2fixer]

Originally Posted by Piotrsko

You all using bagged insulation or typical house one sided?

The bagged stuff comes foil covered both sides or not, but the bag used to be semi puncture /rip proof

I planned to use just normal house fiberglass insulation for now just for testing. Remove the paper and there's no fire hazard. I know several people that have used the same process to build their own insulated wood stove pipe and it works quite well. I'm sure there's better products to use, but the top of the engine doesn't exactly get that hot, I mean as the OP post says, there's plastic on the hood, so it's not going to get over ~125C as most plastics don't go hotter than that. PVC is roughly 80C which is common cheap wire insulation. Higher grade engine bay wire is 105-125C rated and intended to be used right on the engine, like the injector harness.

I figured that's the easiest thing I have around that's basically fire proof and insulates.

[hayden55]

the paper is fine. just put insulation side down. As said it doesn't get that hot in the engine bay. around the front and top of the engine you may get up to 150F air if you're lucky. Engine metal temps a bit higher but not a big deal. The big problem is water though, but my engine bay stays dry up top so figure it on your personal vehicle. Just don't touch the headers lol