Years ago we used to use cardboard(or thin blueboard) in front of the radiator to produce more heat. Any reason that won't work with a Prius?? Not as visible as packing the grill full of pipe insulation.
That could work... Or foam tubing in between the spaces in the grill work is the most popular way. But key is that you want to monitor the water temp. so you'll need to install a scan-gauge or Pri-Dash or the Torque app to do that. Important point is that this only improves MPG cause your car will warm up quicker on cold days. Once your car is warmed up it won't improve MPG to raise the temp. higher and you could damage your engine if you unknowingly let it get too high.
The cardboard would be a temporary solution at best, and as suggested above may work a little too well. I'd be worried about the cardboard getting water-logged and turning into pasta. Most of the grill blockers out there that I've read about do so more permanently - especially with the lower grill. Good Luck!
Pipe insulation is much much easier to install than a piece of cardboard or coroplast which would have to be mounted from behind the bumper. If you are going to go through the effort of installing a solid block like that then make sure it is waterproof! As always, make sure you have a monitoring device to watch temps. The small gain in mpg is not worth premature parts failure...
I popped the plastic top radiator shield off(5 push pulls) cut the 1/4" insulation to fit ( 2 pieces) and slipped them in. Took 10 min. and I don't have to look at the pipe insulation or have people ask me about it.
Just a reminder: I recommend not to block the lower quarter of the radiator. That is where the inverter radiator is on the gen II Prius.
via another thread I discovered this Prius User Guide which includes a section on Grille Blocking wherein the following is stated Does anyone do this? Is 15.5℃ a reasonable temperature? Are there any warranty implications? When you take the car in for service do you have to remove whatever you've installed for blocking? Is the comment about blocking the lower quarter of the radiator valid?
Catgic's recommendations of "hybrid driving," contains this which appears to answer my question, at least for my 2013 Prius v
Hi Thymara, sorry about the late reply. For your car, the comment about blocking the lower quarter of the radiator is not valid, because your car is a gen 3 Prius, and this comment applies to the gen 2 Prius. For the gen 3 Prius, I recommend not to block the upper quarter of the radiator. That is where the inverter radiator is on the gen 3 Prius. It's difficult to make a grill blocking recommendation without knowing the driving conditions. It can take up to an hour for the engine and transmission to reach maximum temperature. The same amount of grill blocking that is perfectly safe for short, low speed trips on level ground may cause overheating on long, high speed trips in mountainous terrain. To be on the safe side, one should employ some form of temperature monitoring when grill blocking. .
