Winter/radiator Blocking

[gen2]

Now the colds days are here my gen2 prius engine stays on for lot longer,last year I blocked the top half grill,and thinking of doing it again.dont know if it makes much difference it could be psychological that it makes you feel bit more warmer than without blocking.your opinions would be appreciated.

Thanks

[CPN]

I would suggest that this is probably a waste of time since the cooling system thermostat keeps the engine at its optimum working temperature anyway and it is just as effective at preventing overcooling (by the radiator) as it is overheating...

[IanIanIanIan]

Received wisdom is that blocking or part blocking the grill (different parts on different models) will significantly reduce warm-up times and also give fuel saving in that the thermal load on the engine is reduced because the flow of cold air through the engine compartment is reduced thus reducing uncontrolled external cooling. The internal cooling via the radiator is unchanged.

[Grumpy Cabbie]

If you live in the Canadian mountains or Montana where it's -30c regularly, then sure block your grill. But in the UK where it might hit -5c once or twice it's hardly worth bothering with. You might save 2 minutes on warm up if you're really bothered and if you fancy doing it, then fare play to you. But it's a bit overkill for the UK.

[timberwolf]

I don't do enough mileage to be sure, but looking back at my fuel usage, it didn't seem to make any difference for my, infrequent, 8 mile journeys. However, I don't have data on the weather conditions, so along with my limited fuel data, I also don't have any correlation with the ambient temperature.

As for the thermostat comment, my engine coolant doesn't even manage to reach full operating temperature during the 8 mile outward leg during the Winter, so as I understand it the thermostat would never open on those occasions. Sitting in a long traffic jam in late October one year, I had some time to observe and fret that the coolant temperature never got much above 40C as the engine duty cycled on and off just to recharge the HV a little bit.

[crofter]

One should remember that years ago that the fan began drawing cold air through the rad as soon as the engine started on most cars.

Blocking meant that cold air was not forced through all of the matrix so it did help the warming up process.

I had a mod on a Ford I had in the seventies that was like an upside down roller blind in front of the rad which was controlled from with- in the cabin so as the engine warmed up this could be lowered manually

Del

[johalareewi]

I find lower grill blocking on my gen3 does help improve my mpgs in the winter.

The improvement is small (about 2 or 3 mpg) but I do a lot of miles so it all helps.

My grill blockers are easy to put on and take off so there is zero messing about.

It is more trouble demisting the windows ;)

NOTE gen3 grill blocking is different to gen2.

If you are going to block, check and double check which bits you can block safely.

Otherwise you can fry the inverter.

[MEP's Yaris GS]

I find lower grill blocking on my gen3 does help improve my mpgs in the winter.

The improvement is small (about 2 or 3 mpg) but I do a lot of miles so it all helps.

My grill blockers are easy to put on and take off so there is zero messing about.

It is more trouble demisting the windows ;)

NOTE gen3 grill blocking is different to gen2.

If you are going to block, check and double check which bits you can block safely.

Otherwise you can fry the inverter.

So on my PiP I'd be safe blocking just the lower grill also?

[johalareewi]

So on my PiP I'd be safe blocking just the lower grill also?

Depends what is behind the various grill bits.

Have a look over on Prius chat (when it is working!).

There will be a PIP section where you should be able to find PIP grill blocking information.

[MLW2233]

I was thinking of doing this also as my mpg have dropped a bit since the cold struck.

Am I right in thinking you can block some of the top grill on GEN 2, and the bottom on GEN 3?

[ian rooke]

Hi you are right Gen 2 top Gen 3 bottom it makes about 2/3 MPG (for the past 7 years I have used the 15mm grey pipe insulation which has a split along it fits on the grill without any fixing.)

[Tbolt]

Anyone done this on mk1 Auris?

[Ten Ninety]

Anyone done this on mk1 Auris?

I have a vague recollection of reading somewhere that the radiator/inverter cooling arrangement in the Auris is not the same as the Prius, which is why I shied away from doing it on the Auris as I couldn't get clear info on what to block. I don't think the physical construction of the Auris grille lends itself to blocking as easily as the Prius either.

I ran 100% bottom block on the Prius last year from Christmas and didn't really notice any significant mpg change when blocked in Jan/Feb compared to unblocked in Nov/Dec, despite the heater appearing to warm up quicker. However, it was a mild winter and not exactly a scientific comparison. The figures above of 2-3mpg seem possible. However, all the other winter factors (especially wet roads and wind) will still hit mpg in the dark months - there's a lot more than just air temperature in play.