Has anyone done a shutter grill?

[2Slow4u]

I'm just curious if anyone has done a shutter grill in front of the radiator to improve aerodynamics. I've heard of people just putting cardboard there to block it off but I would like something a thats not going to overheat my engine on a hot day here.

The Chevy Cruze is the first production vehicle that I know of with this type of technology, but it doesn't seem to hard to mimic.

Also, what kind of mpg gains have people seen out of blocking their radiator with cardboard?

[freezin4]

Originally Posted by 2Slow4u

..., what kind of mpg gains have people seen out of blocking their radiator with cardboard?

I did not notice any mpg gains, but perhaps someone who is accurately tracking driving conditions, such as weather (temp, humidity, winds etc), along with route elevation etc (or constant round-trips), tire presure etc can offer empirical data.

[2Slow4u]

From what I can find it lowered the Cd on the cruze by 0.016 and considering that the insight is a highway cruising monster because of its low Cd, I can only see it being more beneficial. Maybe like a 3-5mpg increase?

[freezin4]

Yes, you are right about the shutter closing the hole in the front and helping air flow over the car thus reducing wind resistance. I am thinking that is a pretty well-established/proven theory.

I am unsure, however about the radiator block (cardboard or plastic sheet in front of radiator) helping the Insight's MPG by any perceptable measure. Some propose that it helps by reducing warm-up time. This may be true if you actually drive off in the winter and create airflow BEFORE the coolant has warmed up in the engine block.

Others have suggested that the wind resistance created by the cardboard in front of the radiator helps smooth airflow in front of the opening.

[Eli]

I have been dreaming about building something like this, but it's probably a long way off. I got excited when I saw that the Cruz has this technology. I bet I could adapt it.

Radiator blocking is more for winter time driving than to help with Cd. I think a radiator block is too far "in", you need the block to be at the grill louvers for the best Cd improvement.

The problem with trying to track MPG improvements with the Insight is that it's hyper sensitive to environmental conditions. A change in wind direction can easily mean plus or minus 5MPG.

I would be surprised if grill louvers provided that much of an improvement. They would have to be open at least a little bit with sustained highway travel in the summer. What they will help with is winter time driving, especially in areas where it is brutally cold.

[freezin4]

Originally Posted by Eli

Radiator blocking is more for winter time driving than to help with Cd. I think a radiator block is too far "in", you need the block to be at the grill louvers for the best Cd improvement.

- Agree. And a good advice is to monitor the coolant temp closely (recomend ScanGage or UltraGage or similar).

Originally Posted by Eli

The problem with trying to track MPG improvements with the Insight is that it's hyper sensitive to environmental conditions. A change in wind direction can easily mean plus or minus 5MPG.

- Agree. Let alone driving styles and traffic conditions. And I am always skeptical when people throw numbers out there about 10 MPG gains from this or that. I do recall one semi-scientific test being done on RE92 tires vs. Michelins done in TX. That seemed legit, albeit surprising results.

Originally Posted by Eli

What they will help with is winter time driving, especially in areas where it is brutally cold.

- I am just not sure how. Is the theory that it helps keeps the oil warmer in the pan during the travel? I have read most of the thread started by Insightful Tracker on this before.

[Eli]

I employed a small radiator block last winter, and it did seem to help, though I have no MPG figures.

When temps were in the teens and lower 20s, my coolant temp would get up to 120-140 degrees by the time I got to work(2 miles).

With the ~1/4 radiator block, temps would get up to 140-160. This coming winter, I want to try 3/4ths blocked.

I am guessing that the thermostat is closer to the head than the engine block and thus sees much warmer coolant, allowing it to open slightly before the rest of the coolant is up to temp?

Edit: Hmm. That doesn't make much sense though since the water pump is circulating coolant through the head and block. I guess I never thought about it much before, but it does seem to help warmup times, which is the biggest MPG killer in the winter with a short commute.

[2Slow4u]

I was thinking of taking the stock louvered grill, hacking it up and putting the fins on a pivot, connecting all of them with a rod that goes up and down to close/open the shutters, and have a servo control it.

Then tap into the coolant temperature sensor, and control how much they opened if any based on a simple PID loop regulating coolant temperature at its optimal point.

[Eli]

Originally Posted by 2Slow4u

I was thinking of taking the stock louvered grill, hacking it up and putting the fins on a pivot, connecting all of them with a rod that goes up and down to close/open the shutters, and have a servo control it.

Then tap into the coolant temperature sensor, and control how much they opened if any based on a simple PID loop regulating coolant temperature at its optimal point.

Yep, that was pretty much my thought as well. The electronics part of it all should be pretty easy. I'd just have to get my hands on a grill to see how that part would work. Like with the louvers folded down, will it completely block it off or will there still be gaps? etc.

Just for reference, the radiator fan comes on at 206ºF. So it would be optimal to keep the coolant at around 200ºF.

The car as stock keeps the coolant at 195-198ºF under most conditions it seems.

[2Slow4u]

Thanks for the reference number temperature. I'm going to be poking around there tonight and see if it looks possible with some simple hack job fabrication or maybe replacing with HVAC shutter ducts from home depot.

On the topic of poor mans mpg aero mods, I've been thinking of adding a lower front lip and side skirts using plastic garden trim. Its flexible and will blend in "ok" compared to the stock body work if done right. I could probably close that air gap by 2" or so without it looking ridiculous and being functional still.

I will probably also try the upper grill block just using some painters tape, see if its worth its weight.