2010 Prius Grill Blocking strategy

I know this is a long discussed thread, but winter is on the way and I have questions:
It seems to me the whole idea of grille blocking is just covering up a more fundamental issue. That is, the thermostat. If the thermostat worked perfectly, then no/little liquid would circulate in the radiator until the ICE reached operating temp. Seems to me, Prius uses the same old wax capsule thermostats that have been used forever. Yes, tried and true, but isn't what we really want is a better thermostat? One that stays completely closed while "cold". I know some BMW's have electric thermostats, but don't know their characteristics.
Wouldn't a better thermostat alleviate all of this air flow blocking?

First post here after lurking a long time,
Thanks,
...bill

 

Hi Bill
What is your idea on how a thermostat should behave differently? Are you suggesting that the thermostat should take ambient temperature into account, etc.?

 

The idea is to reduce the airflow so the ICE doesn't cool down needlessly. No thermostat can do that. What is needed is active shutters, though those might fail. Pipe insulation is cheap.

 

Thanks for the responses.
Maybe I've misunderstood what the grille block is suppose to do. I assumed this was to help the ICE get to high operating temp quickly at startup AND maintain an efficient temp. Seems to me a good closed loop coolant temp control system can do this. The simple case, a thermostat that switches abruptly from no (radiator) flow to fully flowing at the proper temp could achieve this. As this is a real control loop, I understand it's not quite that simple.
What I'm gathering from these responses is the ICE block looses so much heat from engine compartment airflow, the ICE temp can only be raised by blocking the grille.
If that's the theory, I understand. But I'd argue the thermostat never runs closed with a warmed up ICE even at 0F. Therefore, better management of coolant diversion into the radiator should be able to achieve any ICE you'd like at any ambient without blocking airflow.

Please correct me if I'm not getting it,
...bill

 

Hi Bill
While raising the coolant temperature is part of it, maintaining coolant temperature is just as important. Consider the differences in the operation of the Prius engine compared to conventional cars, such as:

1. The Prius engine spends a reasonable amount of time switched off while the car is moving swiftly through cold air.
2. In the Gen III even when the engine is switched off the heater, a/c compressor and water pump could be running as they are not belt-driven.

Both of these factors are removing heat from the engine when no heat is being generated by it. The engine gets up to temperature fairly quickly if it is running continuously (without ceasing) but it will lose heat when running continually (on and off).

Speaking of coolant diversion, the US-spec GenII had an insulated bottle to store 3 litres of warm coolant for up to 3 days and this was delivered back upon startup. In praise of the lowly block heater - MetroMPG.com

 

Hi Bill!
I think you are definitely getting it, but perhaps you haven't considered a couple other points yet.

Not only does grill blocking increase and help maintain coolant temperature; it also increases engine intake air temperature and thus efficiency under certain conditions, and reduces aerodynamic drag significantly at higher speeds.

A similar or better result can also be achieved by using intelligent thermostats and/or automatic grill louvers as some other car makers and modders do. At first glance, it may seem that Toyota is behind in this area, but in fact, with the gen3 Prius, true to the Prius philosophy, they have gone ahead to an even more effective method of thermal management: The exhaust gas to coolant heat exchanger.

Nevertheless, I wouldn't be surprised to see intelligent thermostats and/or automatic grill louvers on future Prius generations or on presently modded Prii for that extra little bit of efficiency. As fuel prices rise, and as intelligent thermostats and automatic grill louvers become more widespread, standardized, and cheaper, there may well come the point where it pays off.

So why do so many Prius modders do grill blocking?
It is fast and easy to install.
It is fast and easy to adjust.
It is fast and easy to remove without a trace.
For mileage mods, after tire pressure, it is perhaps the cheapest, and gives the biggest bang for the buck.

The disadvantage is that it is not automatic. One must think about it, monitor temperature, and, if necessary, manually adjust. But some of us tinkerers actually enjoy doing that.
.

 

Thanks folks... I "get it" a bit better.
If I understand, the solution in the limit, would be to make the entire engine compartment a thermally sealed container.
This container can be maintained at optimum temperature with controllable ducts/vents to the ambient as necessary.
What I failed to realize was the impact of thermal extraction when the ICE was not running (heater, whatever, ambient loss).

However empirically discovered, the wisdom is:
- Grille blocking improves MPG (for probably a multitude of physical reasons)
- It's cheap and easy to do with foam pipe insulation. There's no reason not to do this
- Downside is to implement only when solidly in the "cold" season.

Thanks for the replies. I will do this. BTW, I already run my tires at higher pressure since day 1.
...bill

 

I agree that aerodynamic improvement also plays a major role in the effectiveness of grille blocking. That is why EVs have completely blocked grilles or mostly blocked grilles like the Volt.

 

Traitor.

 

I blocked the grille in my PIP too. haha

 

Good to see you around here. Don't be a stranger.

 

Ah, a fellow northern CA PIP owner! Though the MPG advantages may be minimal compared to snow zones, am I correct that even with mild avg. winter temps. of 40 deg. F/ 55 deg.f (dec, jan), that 100% blocking the lower grill is safe. It just seems that there is no down side to letting the engine compartment maintain a warmer (interior) ambient temp. around the ICE for efficiency and getting cabin heat sooner for the wife on these cold mornings. I am about 30 mins due west of Stockton. This morning I started the car (lives in closed garage that is mostly insulated) and the ICE started as I backed out into the drive way (to galk at the green HOV stickers I had put on last night late. ). Not sure where the PIP's cabin inside temp control was set, but I do not think the cabin heating fan was on. Garage air temp was between 50-55 deg. F. (might be reason 13C-4b that ICE came on )

Anyway, any reason not to block the PIP's lower grill? At least until April when avg temps get to 48F/71F. (I can't stop fiddlin' with this thing! )

 

Should be safe blocking the PiP, too. I would take it out though if you have many uphills at higher speeds on a particular route.

 

I agree 100 % .... Grill blocking works !! We all proved it !! But Toyota should have a Computer Operated Shutter System Kit retrofitted for all Prius hybrids. I would LOVE to have it.

 

There was a Japaneses company working on a unit but it hadn't gone to production last I heard (year or two ago). Tried to find it but no go.

edit - found the thread where it was discussed.

 

My wife's commute takes her over some small hills (50-55 mph). One steep grade (no longer than 2-3 minutes at most) and 2-3 mild grades. At least a few minutes of downhills/flats between grades.

 

Might be good use of your time to run her commute and really watch Torque on the steep uphill to see what temps are getting to.

 

Perfect excuse to keep the car home one day! I love it Mark.
The harder thing will be to convince her to leave her Android cell phone with me for the day so I could run this test. She uses it for work so not sure. (slows self down... )
Oh, and I'd need to buy a (known good) OBD II Bluetooth adapter.

Before investing $80 to $100?? for adapter, what data is most commonly watched and most useful data with users of Torque? I actually have a regular OBD II reader, so if/when any trouble codes develop, I should be able to pull the same DTC code info Torque would provide, right? Or does Torque have superior DTC code reading ability. I think the only codes my OBD II does not read are ones Air Bag related.

So I can see if I can rationalize the adapter cost, what is the consensus on a good BT reader that does not have intermitent (or permanent?) issues like the $20 ish models? Brand and model and best place to purchase would be helpful. I think some had thought the one usbseawolf2000 has is pretty trustworthy. I think that was an $80+ one, but do not recall which one it was.

 

I just bought another cheap one. The last cheap one I bought got me through over a year's worth of use. I could buy 5-7 of the cheap ones for the price of the expensive one. And they do the same thing.

 

Do you have a link to a cheap one that works well?