Grille Blocking For Better Mpg Anyone?

[mfs1011]

I recalled advice from John1701a's Guide to the Prius II available from his website and thought I'd seek other views before proceeding...

http://john1701a.com/prius/prius-userguide_iconic.htm

John suggests blocking the grille in cold winter temperatures to preserve engine heat and hence the need for the engine to run solely to remain warm. This should reduce fuel consumption??

Here is what he says in the guide:

"

Grille Blocking

Efficiency & Emissions are both dependent upon warmth. During the winter, colder temperatures require the engine to run more to provide that. By blocking the grilles, warmth can be retained longer. With less cold air hitting the radiator and passing through to the engine compartment (along with an accompanying aerodynamic improvement), the overall amount of fuel consumed can be reduced.

Discreet Look

Unless you're specifically looking for it, you may not even notice the upper-grille is blocked entirely and the lower-grille partially.

Blocking Method

There are a variety of different methods available for grille blocking, some more cosmetically appealing than others. Squeezing half-inch foam pipe insolation between each grille slot is a quick and inexpensive method that works surprisingly well. The only tool you need is a knife to cut notches in a few places to allow the foam to insert flat. The tight fit holds the foam in place.

Partial Blocking

Once the daytime high temperature in your area drops below 50 F degrees (10 C), it is safe to block the upper-grille entirely and the lower-grille partially.

Full Blocking

For those experiencing in harsh climates, such as Minnesota, there can be a benefit from blocking the lower-griller entirely. You'll want to monitor temperature of the coolant though. Also, note that outside temperature won't be displayed correctly, since that will inhibit the sensor.

Temperature

Use an aftermarket add-on device, like ScanGaugeII, to monitor the engine coolant temperature. The normal operating range of 186 F to 194 F degrees (85.5 C to 90 C) is what to expect. At about 204 F degrees (95.5 C) the radiator fan will turn on. Above that is when you should be concerned. The heater will trigger the engine to restart at 145 F degrees (62.8 C)."

So given that we are faced with prolonged sub zero temperatures it seems, should we follow the advice of this Minnesota resident? Or is this just geekery taken to excess? Has anyone tried this? Is there a cost/benefit gain?

[GreenJuice]

So given that we are faced with prolonged sub zero temperatures it seems, should we follow the advice of this Minnesota resident? Or is this just geekery taken to excess? Has anyone tried this? Is there a cost/benefit gain?

I tested out his technique last year and am doing it again this year. I monitor engine temperatures using ScanGauge II.

His information is correct & slightly conservative - when outside temperatures are 10C or below, you can do a full grill block and never get near the 95C temperature that triggers the radiator fan!

The radiator fan only came on once last year for me when external temperatures were about 15 C and I was on a 1 hour run around the M25.

The car definitely warms up more quickly and keeps warm more consistently - particularly noticeable with current subzero temperatures. I do a lot of pulse & glide, trying to minimise petrol burn, and can see how quickly the engine cools on long glides without grill blocking (I was a bit lazy this year and only got round to doing it 2 weeks ago). I guess you can trade the benefits off for either improved cabin temperatures & comfort or for fuel economy (or a combination of both!). I like pushing my fuel-e limits, so I wrap up warm & keep as much as possible switched off - but only when the missus and her mother are not in the car! There are many other factors that may have a greater influence on fuel-e though, tyre pressures at these low temperatures being an important and easily fixed one.

As most of my driving is urban, short trips and many stops, I use a full grill block through the winter months. I also have one easiliy removable lower part of one segment which I take out when I'm anticipating a long motorway run.

The idea is not really anything that special. Many London cabbies do this, but I think the benefits are greater with a hybrid, because the engine is off for significant amounts of time. The pipe insulation cost me about £3.50 from a DIY shop last year and about 20 mins to install. I managed to keep my mpg in the 50s throughout last winter.

[mfs1011]

So given that we are faced with prolonged sub zero temperatures it seems, should we follow the advice of this Minnesota resident? Or is this just geekery taken to excess? Has anyone tried this? Is there a cost/benefit gain?

I tested out his technique last year and am doing it again this year. I monitor engine temperatures using ScanGauge II.

His information is correct & slightly conservative - when outside temperatures are 10C or below, you can do a full grill block and never get near the 95C temperature that triggers the radiator fan!

The radiator fan only came on once last year for me when external temperatures were about 15 C and I was on a 1 hour run around the M25.

The car definitely warms up more quickly and keeps warm more consistently - particularly noticeable with current subzero temperatures. I do a lot of pulse & glide, trying to minimise petrol burn, and can see how quickly the engine cools on long glides without grill blocking (I was a bit lazy this year and only got round to doing it 2 weeks ago). I guess you can trade the benefits off for either improved cabin temperatures & comfort or for fuel economy (or a combination of both!). I like pushing my fuel-e limits, so I wrap up warm & keep as much as possible switched off - but only when the missus and her mother are not in the car! There are many other factors that may have a greater influence on fuel-e though, tyre pressures at these low temperatures being an important and easily fixed one.

As most of my driving is urban, short trips and many stops, I use a full grill block through the winter months. I also have one easiliy removable lower part of one segment which I take out when I'm anticipating a long motorway run.

The idea is not really anything that special. Many London cabbies do this, but I think the benefits are greater with a hybrid, because the engine is off for significant amounts of time. The pipe insulation cost me about £3.50 from a DIY shop last year and about 20 mins to install. I managed to keep my mpg in the 50s throughout last winter.

WOW :o

That's settled it for me then - alas, the local DIY shop has sold out of pipe insulation. Wonder why :)

Any other insulating techniques or ideas?

[phil4]

I thought long and hard about this, and then suddenly twigged that as I don't have a Scanguage, I'd be putting my car at risk. No temp guages inside, mean that wihthout the scanguage, I could quite easily push the engine far further than I'd intended. Perhaps once that's sorted, I'll have another think (and with the post service frozen, that could be another year)

[timberwolf]

Is foam pipe insulation meant for 15mm diameter pipes too large to fit in the grill? The foam I've got looks a lot bulkier than the stuff in the pictures.

Does grill blocking cause the Outside Air Temperature sensor to read higher than it should?

[Fujisan]

I thought long and hard about this, and then suddenly twigged that as I don't have a Scanguage, I'd be putting my car at risk. No temp guages inside, mean that wihthout the scanguage, I could quite easily push the engine far further than I'd intended. Perhaps once that's sorted, I'll have another think (and with the post service frozen, that could be another year)

I'm with you on this Phil.

I searched all the grille blocking threads on Priuschat, sometime well before Christmas and came to the same conclusion, that you are seriously putting your engine at risk if you do not have an engine temperature monitoring device, like a scanguage.

I'm not sure how much a scanguage is (and personally from the photo's I've seen I don't particularly like the look of it sat on top of the dash) but I will be saving up any spare cash with a view to getting some winter wheels and tyres in time for next winter.

[timberwolf]

I searched all the grille blocking threads on Priuschat, sometime well before Christmas and came to the same conclusion, that you are seriously putting your engine at risk if you do not have an engine temperature monitoring device, like a scanguage.

Could you provide some links to posts where grille blocking has caused damage to the engine or cooling system? - I've not come across any when I've looked in the past and the top of the search list just now was the following link

http://www.cleanmpg.com/forums/showthread.php?t=16071

which was not what I had in mind :)

EDIT: I found a thread on PC http://priuschat.com/forums/gen-ii-prius-m...ng-caution.html

I haven't read all the way through yet, so I am not sure that anyone has suffered an actual failure rather than guessing at what may happen and BTW I agree with being cautious.

[cootuk]

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[cootuk]

I think the only warning sign of overheating is the cooling fan comes on which could indicate temperatures are getting a bit warm.

It would have been nice for the MFD to have customisable fake gauges for canbus readings like inverter/coolant temps etc - would have been quite easy to access through the info screens as an extra menu.

Even blocking the upper grille (only for GenII as the inverter cooler is low down, but the GenIII is higher up?) seems to have a positive effect.

Engine block heaters might be a cheap idea for those of us with short runs - though 400W seems a lot of power - maybe a few quid a months if run for a couple of hours each morning

[Yaumeister]

Would somebody confirm which measurement on scangauge is for engine temp. Is it WT?

[timberwolf]

It would have been nice for the MFD to have customisable fake gauges for canbus readings like inverter/coolant temps etc - would have been quite easy to access through the info screens as an extra menu.

Even blocking the upper grille (only for GenII as the inverter cooler is low down, but the GenIII is higher up?) seems to have a positive effect.

There was a third party product called CANview that could be wired into the MFD, but it didn't work on the later Gen2s.

The Scangauge2 (and similar products) can be a bit of double edged sword, yes they provide more information but they can also be a source of worry or puzzlement when the Prius doesn't do what you expect.

[timberwolf]

Would somebody confirm which measurement on scangauge is for engine temp. Is it WT?

Yes, it is one of the of built-in gauges and displays the engine coolant temperature, either cWT or fWT depending on whether you have the units measurement set to Celsius or Fahrenheit.

For the Gen 2 Prius, there have also been a number of user programmable X-Gauges published, including one for engine temperature.

[mfs1011]

I searched all the grille blocking threads on Priuschat, sometime well before Christmas and came to the same conclusion, that you are seriously putting your engine at risk if you do not have an engine temperature monitoring device, like a scanguage.

Could you provide some links to posts where grille blocking has caused damage to the engine or cooling system? - I've not come across any when I've looked in the past and the top of the search list just now was the following link

http://www.cleanmpg.com/forums/showthread.php?t=16071

which was not what I had in mind :)

EDIT: I found a thread on PC http://priuschat.com/forums/gen-ii-prius-m...ng-caution.html

I haven't read all the way through yet, so I am not sure that anyone has suffered an actual failure rather than guessing at what may happen and BTW I agree with being cautious.

So the key lesson here is to pay heed to outside air temp and partially unblock when temperature go above freezing, then completely unblock when we get above say 15c?

[Fujisan]

Could you provide some links to posts where grille blocking has caused damage to the engine or cooling system?

No, but I'm very cautious with mods like this.

My own opinion, yes block the grille if you have a scanguage to monitor the temperatures. But don't gamble and risk causing espensive damage, just on gut feeling and 'it'll be all right' hopes.

I doubt Toyota would pay out any warranty claims if you cooked something.

Also remember, the guys over in the States and Canada who do block their grilles will have very much lower ambient temperatures than here. On a long motorway run or up and down hills in this country, things could get warm.

- I've not come across any when I've looked in the past and the top of the search list just now was the following link

http://www.cleanmpg.com/forums/showthread.php?t=16071

which was not what I had in mind :)

Ouch! :o That must have hurt!

EDIT: I found a thread on PC http://priuschat.com/forums/gen-ii-prius-m...ng-caution.html

I haven't read all the way through yet, so I am not sure that anyone has suffered an actual failure rather than guessing at what may happen and BTW I agree with being cautious.

Has I said if you monitor temps, OK do it. But without a scanguage, it is a hell of chance to take in this country.

So the key lesson here is to pay heed to outside air temp and partially unblock when temperature go above freezing, then completely unblock when we get above say 15c?

No - actively monitor the engine temps. Different runs,ie motorway compared to short trip to the shops, will have different effects on engine temps.

Don't make guessed-i-mations that might prove very costly.

Has a final thought, I wonder why Toyota did not fit active aerodynamic cooling flaps with the Gen3. BMW have been doing it for a while now, to only allow cooling air into the engine bay when it is needed.

[wooski]

Has a final thought, I wonder why Toyota did not fit active aerodynamic cooling flaps with the Gen3. BMW have been doing it for a while now, to only allow cooling air into the engine bay when it is needed.

Yes, I'm surprised by this. With such a hi-tech car you would have thought Toyota would have done this. The first car I know to have this feature was the Porsche 928S4 which came out in 1986. But then that car had loads of features still not on most cars - like tyre pressure sensors etc. Maybe on the G4 due in 4 years time!

[phil4]

Has a final thought, I wonder why Toyota did not fit active aerodynamic cooling flaps with the Gen3. BMW have been doing it for a while now, to only allow cooling air into the engine bay when it is needed.

Yes, I'm surprised by this. With such a hi-tech car you would have thought Toyota would have done this. The first car I know to have this feature was the Porsche 928S4 which came out in 1986. But then that car had loads of features still not on most cars - like tyre pressure sensors etc. Maybe on the G4 due in 4 years time!

I've always thought these great little ideas aren't carried over due to patent and licensing reasons... a few things on my BMW I thought would have been handy:

* Dipping of left hand wing mirror when reversing (yes, can turn off).

* lazy lane change signalling (again, could be turned off if not to taste).

* parking sensor beep from front or rear Speakers according to which being triggered.

Just to name a few.... and as some of them are a doddle (dipping lef hand wing mirror for example), I can only see it as a license/patent issue.

[Sagitar]

I can only see it as a license/patent issue.

I doubt it. Some Toyota built vehicles already have those features.

Several cars that I drove in the 1950s had radiator blinds. They were common before the advent of electric fans with thermostatic controls. I agree that it would appear to be a useful feature on the Prius.

I wonder to what extent weight is an issue? A feature that improves consumption through temperature control for a couple of cold months, but makes it worse for twelve months through increased mass may not be a good deal overall. A few lengths of tubular foam, manually applied, will weigh very little and will be there only when you want it to be. But a set of vanes in a structure stiff enough to resist the pressure of air at high speed, with actuators powerful enough to turn them against that same air pressure, together wtih the appropriate thermostatic controls will weigh a significant amount and be a permanent part of the vehicle.

[tore]

Hi from freezing Norway.

Living in Norway, we have experienced very cold weather during the last 3 weeks. Temperatures as low as -20 to -25 degrees ( C) has been normal in my area ( Oslo). So, based upon what you are suggesting in this thread, we should absolutely block the front part of the vehicle...

However, a fact that most of you seem to overlook, is the computer controlled water pump for gen 3 Prius.

As the temp. becomes very low, the cooling water pump will operate with a reduced water flow for engine cooling, and so the ICE will subsequently warm up quickly and remain warm even if the ambient temperature is very low.

As a matter of fact, I have not noticed any big difference in engine watertemp commuting to my work during the current cold weather compared to my earlier autumn commuting, even if the ambient temp then was maybe 30 degrees warmer( +5 to 10 degrees) In addition, the colling water will not start circulating in the radiator until the thermostat opens. ( warmer than 80 degrees ( C ) The cabin heater will produce warm air in 4-5 minutes after starting from my home, similar to my experience in the autumn. I use the Scan Gauge II connected to the OBD II connector under instrument panel for accurate engine Wt indication.( and rpm, voltage,average fuel consumption,engine hp,battery charging etc. )

So, I cannot see any good reason for closing the openings in the front of the car, based upon my experiences so far this winter. Having the SG II fitted just behind the steeriing wheel, I can all time check various engine parameters while driving.

To day, I have reprogrammed the awful seat belt warning signal to terminate, and monitoring of the charging/discharging amperes of the hybrid Battery as well, by using my SG II. The codes for the programming I found on the Prius Chat Forum.

[Sagitar]

However, a fact that most of you seem to overlook, is the computer controlled water pump for gen 3 Prius.

As the temp. becomes very low, the cooling water pump will operate with a reduced water flow for engine cooling, and so the ICE will subsequently warm up quickly and remain warm even if the ambient temperature is very low.

Thanks Tore - very helpful - I hadn't spotted that.

[Car Enthusiast]

However, a fact that most of you seem to overlook, is the computer controlled water pump for gen 3 Prius.

As the temp. becomes very low, the cooling water pump will operate with a reduced water flow for engine cooling, and so the ICE will subsequently warm up quickly and remain warm even if the ambient temperature is very low.

Thanks Tore - very helpful - I hadn't spotted that.

[mfs1011]

[so, I cannot see any good reason for closing the openings in the front of the car, based upon my experiences so far this winter. Having the SG II fitted just behind the steeriing wheel, I can all time check various engine parameters while driving]

That is the Gen3 - I assume that the same does not happen in the Gen2. Good info though.