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True value of grille blocking?

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by bilbo04096, Jan 27, 2014.

  1. bilbo04096

    bilbo04096 Member

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    Ok, I got the pipe insulation in place shortly after I brought home the new PiP in December, and amazingly, it hasn't blown away on the interstate yet.:LOL: :LOL: I blocked only the lower grille, but it is interesting to read of cold state northerners also now blocking part of the upper grille too. It's my understanding that we do this to facilitate faster gas engine warmup in order to get faster cabin heat, but is there more to it than this? Is fuel efficiency also increased somehow? If we didn't block the radiator, but never used the heat either, would we be losing out?
     
  2. -1-

    -1- Don

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    :)I have my lower grill "taped off" versus using the pipe insulation. For me, the pipe insulation looked too sloppy for my taste. The tape I used, is almost invisible (black) from several feet await and it's holding up well. I'm having to lower my speed at least five MPH just to make it all EV on my one way commute, most of the time. I assume grill blocking works? If I make my commute in EV, does grill blocking help or if it only beneficial with the ICE running?
     
  3. El Dobro

    El Dobro A Member

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    Grill blocking is mainly for the ICE, I used to do it with the TDIs when I had them and now I do it with the Prius. It keeps the temps up higher and longer when the blocking restricts the amount of cold air blowing through the radiator.
     
  4. bisco

    bisco cookie crumbler

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    i think it's helpful in all situations to not have cold air pouring through the the engine bay, but it's mostly about less warmup time which increase mpg's and provides quicker heat. it's not a huge effect and you would probably need a scangauge to measure it. but the colder it is, the more effective it is.
     
  5. El Dobro

    El Dobro A Member

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  6. MarcSmith

    MarcSmith Active Member

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    I've done the reading... and I'd like to block the lower grille.

    no scanguage, nor do I plan on it..

    I hate the look of the foam pipe, yeah I know its cheap and easy, but looks like crap.

    I'd like to make a "plug" of sorts that fits inside the entire rectangular lower grill. sort of a "pop-in" "pop-out" using a zeus type fastener. that way its easy to do, a clean fit and looks like it belongs, no tools needed and when not in use hangs on the wall

    I'm thinking I could take the factory grill and use it to make a pattern out of something like aluminum or sheet metal that way I could bend it to fit the contour and put some sort of edge guard on it to prevent damage to the paint if it happens to rub.

    I guess I could always use the grille as a pattern and lay-up a layer of glass or carbon over the top to get a real different look... and get a better fit..

    it could be painted the body color or black...

    i thought about using a landscape "filter fabric" but it gets me in the "cheesy look" category again..
     
  7. DadofHedgehog

    DadofHedgehog Active Member

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    Marc, after I saw your grill block today I like the idea and your execution. Allowing for slight variations between models, you might be onto a neat aftermarket niche item here. The key element is an elegantly done attachment mechanism. Off I go to hunt on fastener websites...
     
  8. Vman455

    Vman455 Senior Member

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    The major benefit of grill blocking is improved aerodynamic efficiency--the reason more and more cars and trucks today are fitted with shutters that close off cooling intakes under certain conditions.

    On my old Civic, I actually used expanding foam to close off most of the front end, fiberglassed and painted over. with a 12"x4" slot for air under the license plate.

    [​IMG]

    Note that I did this only after weeks of testing with an adjustable block in the middle of summer. When blocking, use a Scangauge II or similar to keep an eye on coolant temperatures.
     
  9. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    With the Prius (standard or plug-in), don't you have to worry about the inverter temperature as well? There is also a radiator for it, and you really don't want to damage the inverter ($$$$$).
     
  10. miscrms

    miscrms Plug Envious Member

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    My experience on the Gen 2 is that the primary benefit is keeping the ICE warmer longer while its not running. Not that it gets very cold here, but I start to notice a real difference once the temps get down into the 50s. At those temps or lower, doing much gliding at all with the ICE off will cause it to cool down quickly and then have to run a longer cycle to warm back up on the next pulse. Puts a real dent in my city mileage. With the upper grill blocked (inverter rad is on the bottom on the gen 2) its pretty much back to the same as spring/fall numbers. Not a huge impact, but probably about 10% on city driving, or mid to high 40s without blocking vs low to mid 50s with. Haven't noticed any real impact on highway mpgs as the ICE is pretty much always running anyway.
     
  11. Vman455

    Vman455 Senior Member

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    The inverter radiator is above the main radiator on Gen III; I plan on leaving the upper inlets open for that reason.
     
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  12. markabele

    markabele owner of PiP, then Leaf, then Model 3

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    Good looking job!

    But curious why you'd simultaneously use grill blocking and a sun shade.
     
  13. Vman455

    Vman455 Senior Member

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    Thanks!

    This picture was taken in June. As I mentioned, the primary benefit of grill blocking is aerodynamic, not insular. The body of the car is much more streamlined than the engine compartment, and any air you divert around the car rather than through it lowers the total drag. According to Volvo, as much as 30% of a vehicle's drag is due to air passing through the cooling system. Probably less on a Prius, where the open grill area is smaller than on a typical car, but there should still be room for improvement.
     
  14. DadofHedgehog

    DadofHedgehog Active Member

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    This was a classic design problem on mid-20th century high performance piston aircraft, like radial engine fighters etc. The airflow over air-cooled engine fins was critical, and also was a major factor in aerodynamic drag.
     
  15. uropip

    uropip Member

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    Running a scangauge via obd2 connection and been paying attention to coolant temps and some other stuff since I blocked the grille.

    What's a safe max coolant temp with a blocked lower grille? I saw 190ish yesterday
    Air temp was in the 20's at the time and I was driving about 65-70mph
    Galaxy S4 ?
     
  16. markabele

    markabele owner of PiP, then Leaf, then Model 3

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    Perfect. As long as you don't routinely see temps in the 200's.

    30's or 40's at that speed may be a different story. Especially up big/long hills.
     
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  17. john1701a

    john1701a Prius Guru

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    I have never seen a temp higher than 198°F with the lower grille 100% blocked and the upper left open.
     
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  18. Lourun

    Lourun Member

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    Same here, when my OBD 2 is working.
     
  19. markabele

    markabele owner of PiP, then Leaf, then Model 3

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    Up to what ambient temps?
     
  20. john1701a

    john1701a Prius Guru

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    Daytime temps no higher than 50°F.