Blocking Grill - safe operating tems

This is with all blocked but the bottom most lower slat.

Interesting huh?

Icarus

 

Davide Beale Writes: "First, in general, best MPG or most efficient operation is at the highest temp the engine will run without damage. It's a heat engine. They work best at the highest temps they can reliably operate at. I haven't calculated the temp at which the "stock" coolant boils, but it should be around 130C. I would start to worry at 115C. With both grills blocked I have seen 110C at 20C ambient on the highway (worst case). In the city at 20C ambient the coolant was running around 95C."

I agree with you with this caveat: The most efficient operating temp MAYNOT be the one that assures long term reliability. Metallurgy being what it is, what most engines don't like is temp spikes up or down. Running ~255f maybe under the boiling point of the coolant, but what effect does it have on other engine parts? Seals, gaskets, etc. I don't have a clue. I think that running around 200f would be fine all day.

I also agree that there has to be tons of head room. If the coolant is ~105, the t-stat is open and the fans are going, it certainly is time to uncover a bit. On the other hand, I have run 210f, and the radiator is almost cold to touch. Remember, the coolant loop in the engine (pre t-stat) may be hot enough to need some cooling, but the reserve coolant in the radiator may cool, or (in the event of very cold ambient) very cold. In other words the engine strives to keep itself ~190, dumping a bit of hot when it needs to , adding in a bit of cool (or cold) Between the fans and the reserve in the radiator gives LOTS of head room, even if you are +220f.

What is really required is getting a sense of how things run. Everytime you stop, check the temp on the scan gauge, then feel the radiator. You figure out when you need to do what.

Icarus

 

yes
kind off disapionting

 

I live in So. Cal. It has been "cold" here for the past few months. Around 50-75f. Should I block my grill or not.

It would be trick to develop a grill blocking mechanism that you can operate from the driver's seat.

 

ok i 'll give specifics

1) 190, 150

2)210, 215

for reasons, look at the threads provided. fyi, the numbers i state above are my guidelines only.

obtw, i block 100% of the grill as long as temps are in the 40's

 

It sounds like there is a possible trade-off between fuel efficiency and engine wear. I was telling someone yesterday that my 2008 Prius should last a long time because the electrical motor is very solid and the otto-cycle engine should have less wear due to lower operating temps and stresses. Higher temps shouldn't anneal the metal of the engine block but it could have adverse effects on other parts of the engine in the long run.

 

atkinson engine not otto

and if you keep it in normal operating temp. then i dont think the other parts are in trouble!

 

ok. i can not edit my previous post for some reason so i will add this

ok... i have been doing this for a quite awhile in pretty mild conditions... winters generally not that cold, spring is mild, (albeit, generally only slightly warmer than winter) i removed one slat in spring only last year around the end of april because had several days in the 60's... remove all on june 1st...
i think the highest temp i have ever seen has been 208...iow, couldnt even make tea with it.

 

Heh, I'll try to crack the scangauge code to get the inverter temp in my next project.

 

Inverter Temp. code for Scanguage would be very much appreciated!

Cheers,

Geoff

 

I've kept the top grill blocked all year. My "fully blocked" bottom grill leaves the middle row open. I have yet to hear the fan turn on even with the OAT at 70F so I'm keeping the bottom blocked until I do hear the fan.

So far this winter I am keeping my lifetime average.