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Discussion Starter · #1 ·
Hello Volt community,

First as this is my first post, a big thanks to the creator of this site and to the gm-Volt community. I was able to find so many answers to my concerns before ordering my Volt (and dropping the idea of buying a Leaf).

I still fill guilty to have spent so much money in a car. I have been riding year round my ebike for my 12 miles RT for the past 7 years as I could not bare with staying in traffic more than 2 minutes. OK long story short: I just felt in love with the technology and quiet driving of the Volt so my factory order is on going.

Back to my question. I have seen a number of posts related to grille blocking on hybrids. I understand that the main purpose of this hack is to keep the temperature within a range where the efficiency of the gas engine is maxed out.

On the Volt, I would like to do something similar but for slightly different reasons:
- I plan to keep this car very long as for the other cars I owned i.e. 10-15 years so anything which could increase reliability is welcome.
- Most of the modules in the compartment engine have an aluminum housing which corrode with salt we have on roads 4-5 month a year.
-If you look at a 10 years radiator, you can see as cluttered it can be and how fins could be damaged reducing its efficiency.
- Hose cleaning the engine is not that exiting to me and I would like to keep it as clean as possible with minimum maintenance.

With that in mind, I was thinking of putting some sort of filters in the lower air intake. This could be furnace filters I could put apart to get rid of the frame and use several layers to catch salt and dirt. This approach would be flexible enough to put multiple layers in cold temperature and only one layer in summertime. The air flow can be modulated with the number of layers I put.

I do not own the expensive DashDaq which could be used to monitor the various coolant temperatures. I am particularly worry about the radiator cooling the electronic as I guess the cooler the better for those. For Engine and Battery cooling, I think that is would be better to reduce the cold air flow. As a reminder, we have 24/7 freezing temperature from December through March over here in Ontario.

Any idea on this hack and if could be beneficial at all?

Thanks,
Fredo
 

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I live in NH, and we have plenty of snow and road salt to deal with. I have found, that with regular washing (I try to hit the car wash anytime the temp gets above freezing) I have seen very little rust on late model cars. Cars today are painted all around, and most have some sort of undercoating on the bottom to help prevent rust. The Volt in addition has a number of plastic panels along the bottom of the car to help with aerodynamics. These also help to keep the salt off the bottom of the car.
I see your concerns stem more with aluminum engine components. In this regard, I really wouldn't worry too much. most of the corrosion you see on engine components is only surface corrosion. There tends to be a lot of metal on them, so it would take a VERY long time for the corrosion to bother them. I can't say I've ever seen anyone have to replace something in the engine due to corrosion...
All that being said, I don't see any reason the furnace filter would hurt anything. They are designed to not restrict air flow. You would probably have to clean/replace them often though. In the winter, you wouldn't have to worry much about overheating, but you still want plenty of airflow.
 

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The thing it might improve is heater efficiency, actually, since our heater is just a glorified block heater, which heats the outdoors too, at our expense. But that would mean blocking the intake, not just filtering it.

Early on, we had some reports here of people having a rather expensive repair because a rock flew in the intake and wrecked one of the radiators - well over $1k to fix (dealer only, and to be forgiving, it's a hard thing to get at in this car), and not warranty. For that reason alone I'd consider a hardware cloth (think thick screen door screen with about 1/4" mesh) "filter" there just to keep rocks out.
 

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Discussion Starter · #4 ·
The thing it might improve is heater efficiency, actually, since our heater is just a glorified block heater, which heats the outdoors too, at our expense. But that would mean blocking the intake, not just filtering it.
Good point! I was just reading the thread showing the heater coolant circuit:
http://gm-volt.com/wp-content/uploads/2010/12/fig4.jpg

Once the heater/ICE coolant temperature is sufficient, the two-way valve is closed. The heat in the cabin heater circuit will dissipate mainly in the cabin but the heat in the ICE radiator is just lost rapidly (after all this is the role of the radiator). Blocking or reducing the air flow at the intake would keep more heat for the next cycle once the ICE starts again to heat the cabin.

I might put a cheap thermometer on the front radiator (heat exchanger for the electronics) just to get an idea of the temperature increase when blocking/reducing air flow.
 

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Hmm, I hadn't seen that picture with the valve, the assumption I was making was the electric heat actually heated the engine block itself (or, too). If that figure is right, then I was wrong. I was thinking more about electric-only operation there at any rate. I'd assume a thermostat closes in the ICE coolant loop when the temperature starts to go down, but...some never close all the way, and I have no clue about this particular one, or how much of the total thermal mass is actually in the radiator.

My range goes from near 50 mpc in summer to around 35 in winter if I let myself freeze in the car and only run the heater a little to keep from actually having my hands get numb. That's just under the range I need for errand loop #2 that I make pretty often, so a little help there might be a pretty big deal.

I may experiment with "faked out hold mode" by popping the hood and forcing the ICE to run while not quite fully charged up this winter to save on gas and make the car more comfortable. In the mornings, being off the grid, preconditioning (incurring round trip losses in both house and car batteries) is not a real good option for me, yet it takes only about .1 gal of gas to get the car warm.
In maintenance mode, the engine will charge the batteries. I have no idea if it's smart enough to stop doing that when they are full, for certain the ICE will run in that mode, but I don't know at that point if the economy works out - if it's not putting on say, that last bar worth of charge, the gas is being burned for heat-only, and the net efficiency would be worse. Still, even at $5 gasoline, 50 cents to walk into a warm car from the get-go doesn't sound so bad.
 

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The primary purpose of a grill block is aerodynamic drag reduction, but it can help achieve lean-burn in certain cars. I have considered this for the Volt, too, but the problem is when the ICE comes on. Basically, this isn't a modification I would just do and forget about, which would be easy in the Volt considering all the time we run pure electric, because when temperatures get hot and the Volt's ICE comes on, you could easily overheat the engine.

Grill blocks seem very popular with Prius owners, and when they do a grill block, they typically block out 70-80% of the incoming air. Toyota designed the grill to take into account worst-case scenario driving (think heavy loads in Phoenix in the middle of summer), so there is room to play for most people.

In the Volt, if you know you are going to drive > 90% under electric power, you could potentially block 90-100% of the grill. Of course, you'd need to be very cautious if the ICE ever came on. Regardless, from my experience with this modification, you're going to see a huge improvement in mileage/range to the point that if you were barely dipping into gas before, you might have surplus electric range after. I'd love to see a wind tunnel assessment of this, but a grill block could lower the Volt's Cd to the low .27 range.
 

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Hmm, I hadn't seen that picture with the valve, the assumption I was making was the electric heat actually heated the engine block itself (or, too). If that figure is right, then I was wrong. I was thinking more about electric-only operation there at any rate. I'd assume a thermostat closes in the ICE coolant loop when the temperature starts to go down, but...some never close all the way, and I have no clue about this particular one, or how much of the total thermal mass is actually in the radiator.
There's a thread around here somewhere from last winter. Someone with a 2011 reported that they saw a significant increase in ECT from a remote start/preheat cycle, and so I did some testing with DashDAQ. I only saw a two or three degree increase in ECT after two full cycles in my 2012 - clearly the valve is fairly effective in keeping the cabin heat for the cabin (though it still draws a massive amount of power.)

I think the main reason it feels like it isn't doing much is that in Auto it pushes all of the warm air to windows and feet, warming indirectly instead of blowing hot air in your face. I think.
 

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I also got to my Volt via E-bikes. Congratulations on your Volt. I think your idea has merit and is worth doing. Report back on it.
 

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You ebike year-round in Ontario. Damn, that's dedication. Do you use metal-studded tires in the winter?

I would agree that corrosion in the engine compartment shouldn't be a concern.

For efficiency, I suppose it might help, but it's hard to say without any hard data. I have actually wondered why -- given all the effort that went into making the Volt as aerodynamic as possible -- GM didn't use a variable grill shutter like they have on the Cruze Eco. They may have looked into it and determined it didn't help much. Idk.
 

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A variable grill shutter would be nice. I'm wondering if it was added complication, price or weight. I can't imagine that it would be that difficult to build one... just a heat sensor with servo motor to control the shutter.
 

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FYI, any standard OBDII + torque app for android (or similar apps for iphone) should give you engine coolant temp..
I used it last winter, though I did not really consider blocking. Since restart of ERDTLT is based on coolant temp, I'll have to consider that. I did try the keep heater on comfort, but unless i turn the temp high enough (68 or so) that did not keep me from a second restart on the trip home. Maybe blocking will keep it warmer longer.
 

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Discussion Starter · #12 ·
You ebike year-round in Ontario. Damn, that's dedication. Do you use metal-studded tires in the winter?

I would agree that corrosion in the engine compartment shouldn't be a concern.

For efficiency, I suppose it might help, but it's hard to say without any hard data. I have actually wondered why -- given all the effort that went into making the Volt as aerodynamic as possible -- GM didn't use a variable grill shutter like they have on the Cruze Eco. They may have looked into it and determined it didn't help much. Idk.
Carbide studded tires are pretty much the only way to go. First year coming from a warmer country in Europe did not have them and felt off couple of times.

I find surprising that for aerodynamic optimization the Cruze has the variable shutter only on the lower grill and not the Volt. If it makes a difference on the Cruze similarly it should on the Volt as well. The fact that the upper part on the Volt is already blocked may reduce the drag as much as the Cruze with the variable shutter.

FYI, any standard OBDII + torque app for android (or similar apps for iphone) should give you engine coolant temp..
I used it last winter, though I did not really consider blocking. Since restart of ERDTLT is based on coolant temp, I'll have to consider that. I did try the keep heater on comfort, but unless i turn the temp high enough (68 or so) that did not keep me from a second restart on the trip home. Maybe blocking will keep it warmer longer.
Yes I agree. Limiting the incoming air flow should improve heat conservation.

I will get my car in 6 to 8 weeks (factory order) so I won't be able to report something anytime soon.
 
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