2010 Prius Grill Blocking strategy

I have a different sort of question.

Keep in mind that the Gen3 has a variable speed electric water pump along with a thermostat and cooling system that allows coolant to circulate through the engine without using the radiator when cold. It seems that when the car is cold coolant will just circulate through the engine, the heater, and the exhaust heat transfer system and not use the radiator until it needs to. Then only as much coolant as need to keep the engine at operating temperature will be routed through the radiator.

If this is true will blocking part of the grill that feeds air to the radiator do any good at all? I think the engine will only use the radiator as much as is needed to keep the operating temperature where it belongs and during the warm up process it won't use it at all.

 

The engine will still keep its heat better if the engine compartment is isolated, as it also loses heat through its whole body. I confirm that it does work (at around 0°C in Montréal).

 

Thanks, I am currently running with the grill unblocked and recording some temperatures. Outside temp and temp to different points along the same route. After a week or so I'll block the lower grill and record them again. Hopefully I'll come up with something meaningful.

 

It will be nice to have these data points (blocking on / off). I am currently tracking with it on keeping as many as the varibles the same (distance, cab temp, etc). I don't really want to remove the blocking for the other set of points but may.

 

on a similar subject. Has anyone seen a bug screen for the Gen 3. I know the dealars say they can flush the radiators and wash bugs out. The radiators I have seen afterwards the fins are dammaged. I am in Florida and bug season is coming up shortly.

Thanks

Barn

 

Just for the record: I confirm that with 1/2" pipe insulation in place, nothing moves in a non touch car wash.

 

I've started compiling data on my morning commute (between 10 and 20km, ~3,5 hours of EBH, full blocking of lower grille, free upper grille). At outside temps of 0-5°C, I found a reduction of about 1L/100km (was 5L/100km, now around 4L/100km) (converter here if you want MPG). This is based on less than 10 data points though... I need to be more disciplined...

Hence, I've been saving 0,1-0,2L/trip, or $0.10 per day (including the EBH running cost)...... the pipe insulation should pay for itself in few weeks

As the temperatures have recently dropped quite low (-19°C this morning), I'll have to compare w/ w/out EBH under these temps. This morning, my FE was "catastrophic" (for a Prius ): 5,9L/100km... w/ EBH...

 

I assume the car is parked outside?

 

Yes.

 

I have done 99% grill blocking on both grills and it makes a good bit of difference on the long drives. It probably helps the short ones too, I just dont pay attention during my 10-15 min. commute.

But I worry about the converter when the temps get above 60f, so I remove one of the upper blocks.

Is there a way to get the converter temp with a Scanguage?

 

Apparently not, no one has discovered how to do it yet using the Xgauge commands for the Scan Gauge.

With my lower grill 100% blocked and the upper grill open I see an increase in engine coolant temperature at freeway speeds even with the outside temperature at 15 or 20 degrees F. My car usually runs at between 193 and 195 degrees at 70 MPH with the grills unblocked. With the lower grill blocked it runs between 195 and 198. I checked it on the same stretch of freeway for about 10 miles, same direction, at the same outside temperature so I think the readings were valid. That temperature is fine as far as the engine is concerned but I haven't checked it yet going uphill or at higher outside temperatures.

The warmest I've seen the engine run is 205 degrees, that was a warm day climbing an 8% grade for about 15 miles.

 

Hi Tumbleweed,

Its interesting that the difference is that small in temperature. So, the only advantage to the full block is going to be aerodymanics in the 3rd Generation Prius. That is probably because of the exhaust heat recovery system.

 

Or simply because the variable speed water pump adjust itself to the grille blocking and keep the engine to about the same final temp...?

 

That too !

But also forget to mention an advantage could also be keeping the transmission fluid in the efficient range. The Argonne study saw a significant advantage to keeping the transmission fluid warm in the Gen II.

 

What about the converter? Has anyone checked the temp on it since heat increases electrical resistance?

 

If the inverter coolant has a temp sensor, we will have to wait until the codes are cracked before we can monitor it with the scanguage.

 

We had a warm day today, 43 to 46 degrees F, so I drove the car up a range of hills at 70 MPH to see if it would get any hotter with the lower grill blocked than what I posted before which was 195 to 198 on fairly level terrain.

Much to my surprise it not only didn't get hotter it actually ran cooler? What I saw on the way up the hill today, lower grill 100% blocked, outside temp 45 degrees F, was temperatures between 193 and 197.

My conclusion is that Philosophe is probably correct and the variable speed water pump is doing it's job.

I haven't been running it blocked long enough or under enough temperature conditions to know if it warms up any faster or not. Any one else see any difference in warm up time? I would say that what I have seen so far indicates that with the lower grill blocked it does stay warm longer with the engine off.

 

I hope we are not hastening the death of the water pump by making it work more. But I live in Texas so if it cant handle winter weather, it wont like summer much either.

I noticed that the cabin warms a little faster than before grill blocking. And it gets hotter. Driving to work I have about a 5 block drive to the freeway, and about 8 miles on the freeway, then about 5 blocks downtown to the garage. By the time I am about a mile on the freeway, I am getting warm air out the vents, about 5 min.

 

Does the inverter pump on Gen III run at a fixed speed, always on?