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Auris Hsd Grille Blocking

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Hi all,

I've noticed that temperatures are dropping and so are the MPGs, so I thought I would give grille blocking a go this year. I’ve read a fair bit about the subject on this site and links to other sites, but there seems to be little information specific to the Auris HSD.

I've pieced together what information I could find and have tried to apply this to my Auris and thought it may be useful to others thinking of trying it (and I may pick up other tips/advice along the way…)

So I popped down to my local DIY store and purchased a length of foam pipe insulation (£1.99 for 2m). This got cut into three pieces and zip-tied (I had some laying around, but Maplin currently sell packs of 100 for about £3) to my lower grille – I’ve not attempted to block the upper grille, I don’t have a Scangauge so am being cautious.

So far I've only done a couple of couple of journeys, so too early to tell the impact it has had on my MPG, but I’ve been logging consumption on Fuelly for a couple of years now so should be able to build a good picture over time.

I've attached a photo of the results.

Happy to receive feedback/tips/advice/criticism etc


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Come On GAV 18 get an AURIS Life.

Fannying about with attempting to improve on the Auris HSD's [or the other inferior one's] technology by using 1950's "Autocar's" tips is blatantly idiotic, [i bet the !Removed! read them too !!.]

Your comments re. the winter drop in temperatures and increase of our consumptions have been well or even over documented in the past, and accepted as status quo.

Forget the inbuilt performance data from your in car performance readout [the right clicky thing on the steering wheel], it is highly over optimistic to be absolutely irrelevant.

Hey!! Do you know were I can get some Asbestos ? or tips on de-coking an Atkinson engine? - I've just had a cunning plan.

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I am wondering how do you know if you are blocking the correct portion of the radiator? i.e. you do not want to block the part of the radiator used for the cooling of the Inverter. That information may possibly be in the Service/Repair Manual but you'd probably have to pay a subscription fee (about 4 years ago it was possible to subscribe for 1 days access - I don't know if that is still the case?) to access it online from Toyota.

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Probably any savings are cancelled by the increase in drag coefficient - also insurance implications with body modifications

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Happy to receive feedback/tips/advice/criticism etc

If you are 'boldly going' it's a good idea to have a scangauge (or similar) that can monitor engine and coolant temperatures.

Follow up Timberwolf's advice and find out where the inverter is.

Contrary to cuius's comment, grill blocking works very well on hybrids.

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I have a Scangauge2 and block my grille (as Gav has done).

The engine warms up quicker (while moving), and more importantly does not cool as quick when in motion and under EV power. This is important, as the coolant needs to hit about 40 degrees before the ICU will consider switching to EV but this temp is dependent on ambient temp and whether the heating is on in the car. Having the heating off, at 19 degrees, at 23 degrees, etc. all impact on how the ECU calculate what temp the coolant should be at, and whether to continue gliding under EV.

It DOES make a difference, I also plot my mileage (brim to brim calculations) and my back-of-a-!Removed!-packet finger-in-the-air benefit is I would say at least 3-5mpg more in this weather.

Having come from a car with a rev counter and a temp gauge, I find it useful to see what the car does under different conditions. Hope this helps :-)

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Hi I blocked 1/3rd of my bottom grill on my Prius last year and had a improvement of about 4MPH against unblocked I would however question blocking the whole grill and also find out if you are blocking the right half as the Gen 2 was round the other way (rad on top inverter on bottom) I cannot find any information reguarding the Auris rad position.

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  • 2 months later...

Hi gents ,

I have been following this topic with interest , and I went so far as to block off the lower half of my Auris HSD grille. I did it at work today and then drove home 50 miles. Cant say I really noticed any difference.Then I started to think about it and I can't think how grille blocking can possibly make any meaningful difference to economy.

My reasons are;

When the car is started from cold the thermostat valve in the cooling system prevents the cooled fluid which is in the radiator from circulating so the fluid around the engine is in a closed loop until the fluid reaches a pre-determined temperature(whatever that may be), only then does the thermostat start to allow colder fluid from the radiator to enter the system. So how can blocking the grille speed up warmup time ?

In cold conditions (like now in the UK) when you have an excess of cooling capability-, once the car reaches operating temp the thermostat again will progressively shut if the fluid temperature drops thereby preventing un-necessary heat loss from the engine. So the radiator is not in the loop so once again the grille blocking is doing nothing.

The only time that grille blocking would increase temperatures is when you do not have enough cooling capability then the thermostat will be fully open - taking cooled fluid from the radiator but if the surface area of the radiator is not enough then the temps will continue to rise- but surely that is not something any owner would try to do??

What I have just described is a very simple car cooling system - and I would expect Toyota to have refined and improved it for the hybrid-particularly since heat loss is a form of energy loss which is detrimental to economy,

So what I am missing here ? Please correct me if I am incorrect here guys ?

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