Has anyone done a shutter grill?

[nasphere]

I agree as well. The impeller pumps in a vacuum cleaner actually spool faster when there's no flow.

Originally Posted by 2Slow4u

It seems like you could get rid of the thermostat and the pumping losses associated with it. Then control the engine temperature through a dynamic shutter grill...

I think some of the old warbirds used this method. The radiator outlets were adjustable around the large round cowl of the air cooled planes. I would suspect the inlet metering would have a less turbulent effect.

I have been pondering closing the front grill there and using the belt/motor from an old printer to open a large hole similar to what AndrewJ did with his choke cable actuated hole on his 5th gen civic.
5th generation civic hatchback - improving aerodynamics - Page 26 - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com

[2Slow4u]

Slight MPG update on the upper grill block. I drove 60 miles today, to work, out to lunch, to the gym, then back home. Averaged 63mpg for the whole trip. 15 miles of it from work to the gym I got an insane mpg increase to 72.8mpg, but overall it seems like it is good for 1-2mpg boost. Not too bad for being next to free, I guess the tape will "stick around" for now.

[02insight]

I did the same block with tape as a test some time ago. I also noticed it felt more slippery, I got 80mpg (vs the normal 70-75mpg) on a highway trip (slow driving 55-60mph). But then again, there are too many other variables with the insight, (wind, b/g charging, SOC, 12v, temp etc...)

[samwichse]

If you want an automatically shuttered grill, try the thermostat from a an old aircooled VW bug/bus:

German Supply - Parts for Volkswagen® Cars - Thermostat Bellows Late Type 1 80-85 Degree

Expands to drive a pushrod at 80-85 degrees.

For an idea of how it works, here's the whole setup:
http://images.thesamba.com/vw/classi...ix/3511459.jpg

[3-Wheeler]

Originally Posted by 2Slow4u

It seems like you could get rid of the thermostat and the pumping losses associated with it. Then control the engine temperature through a dynamic shutter grill...

Just like most of the interest in this thread, I too have thought about the "Holy Grail" of air inlet shutter building, and for me, this will be a build for another day.

However, there are several precautions when it comes to simply removing the thermostat completely....

1) The thermostat actually maintains a higher fluid pressure in the cooling system.
2) This higher pressure increases the boiling point of the flowing liquid (anti-freeze).
3) The pressure increase is highly dependent upon coolant temperature.
4) Higher temperature fluid is less viscous, and so it flows through small passages including the thermostat more easily, which actually lowers the local pressure in the system when it's hot.
5) The higher local pressure actually helps reduce localized boiling in the engine block, especially critical around the exhaust ports.
6) Though not connected to thermostat opening, higher fluid velocity near the exhaust ports in the cylinder block, more quickly removes trapped air bubble and localized boiling.

If you live in the northern state like I do, removing the thermostat might not be a big deal. But if you're in Arizona and trapped in traffic with summer heat enveloping the engine, and with the A/C on, well removing the thermostat might not be a good idea.

I believe the location of the water pump, thermostat and engine block are all located with each other to provide higher localized pressure against fluid boiling.

Yes indeed, the water pump does indeed work harder with the thermostat in place, but I'm not sure about simply removing it without doing some more investigation into side-effects.

Jim.

[rccrashed]

A water pump is just a centrifugal pump, it only uses more power to provide more flow. If you dead head (block the outlet of) a centrifugal pump the power consumption goes way down because you are not moving any liquid it uses it most power when it is pumping the largest quantity of liquid.
In industry if you have a pump that is overloaded you choke down the discharge and the overload goes away, there are many pumps that are run all the time using this method. It covers up an improper install (or changes to a design).
Ed Mc

[2Slow4u]

Another mpg update with the taped off upper grill.

I monitor my mpg on the way to and from work everyday, the way home seems to have more downhill and I get a better run. Previously I had been getting slight increases of about 0.5mpg beating previous records and have built up to 66.5mpg as a personal best.

Yesterday, with the upper grills block, I completely smashed the previous best and returned 72.8mpg. At one point it was reading 77.5mpg getting off the freeway. Not looking to bad at all for a stock CVT with 200k miles! Looks like the tape is going to continue to stick around for now. The combined mpg for the day was 67, still higher than my previous best one way trip.

[nasphere]

Eli and I were talking about this subject and he linked me to this car. The GM Precept concept car (2000).

GM Announces Hybrid Production for 2004

GM Unveils Concept Car That Gets 80 Miles A Gallon

The most notable statement in the article is:
"Designers of the Precept took their overall design cues from the EV1 and constructed the car to be as aerodynamic as possible. Exterior door handles have been eliminated, and outside mirrors were replaced by a camera system. Because front-facing grills create wind drag, the Precept has special air openings behind the rear wheels."

[2Slow4u]

I hadn't seen that GM prototype before. I'll have to read into it later but its very interesting. They weren't very creating in their design though, Aptera did a much much much better job at a hyper aerodynamic vehicle that still looked good IMO. But I don't see that chassis hitting production anytime soon either.

[3-Wheeler]

Originally Posted by rccrashed

A water pump is just a centrifugal pump, it only uses more power to provide more flow. If you dead head (block the outlet of) a centrifugal pump the power consumption goes way down because you are not moving any liquid it uses it most power when it is pumping the largest quantity of liquid....

I had discussions through work with a GM engineer many years ago, when Chevy 350 engines were popular.

This engineer went on to mention that one engine project he was managing had a water pump that would put out 65 psi when the engine was cold and running at a fast idle (thermostat closed).

That much fluid pressure take mechanical energy from somewhere, and this energy is not free. Generating 65 psi indicates that this particular centrifugal pump does not stall at no flow conditions. If it did, the water would cavitate inside the pump and completely destroy the mechanism, similar to stainless steel boat props that need refurbishing or outright replacement from cavitation in the water.

Jim.