Trying to modify my grill block to be more aerodynamic.
 

So I had a full lower block but even on colder days I heard my radiator fans going a lot. So I am trying to design something that will get more air to my radiator but also be very aero dynamic at the same time. I have two designs and I currently am using type one of my two designs and it seems to be doing well with the cooling, I hardly ever hear my fans going, but I am afraid that is is causing unneeded drag.

I feel like type two would work more efficiently but I wanted to get the peoples perspective on the issue first. Thanks guys!

P.S. I know my car is super dirty and the paint is kinda ****ty, but I love this little fuel sipper regardless :)

perspective
 

What sucks about any 'fixed' design,is that the car is always operating in a transient environment:freezing/cold/warm/hot................... and that could be on the same day!
The automakers have hedged their bets by going to the hidden shutter system which takes it's cue from an array of sensors,which help to optimize its performance.
Some members have articulated 'doors' on their blocks,and with a thermocouple and temp display,can alter the cooling capacity of the car as they drive.OR,with a sensor pack,servo motor, and MPGuino-based logic,have an automatic system which does the same thing as the big dogs.
You might keep an assortment of block panels with you in the webbed storage behind the seats and change them around as weather conditions dictate.
Like the Insight!

Thanks for all the info, I will take your advice and have different sized blocks in the car. What style of block do you think would be more aerodynamic? Type 1 or type 2?

style
 

I'd be inclined to go low and keep the inlet right at the stagnation point
http://i1271.photobucket.com/albums/...itled-14_2.jpg
http://i1271.photobucket.com/albums/...titled-5_1.jpg
http://i1271.photobucket.com/albums/...ntitled-19.jpg
http://i1271.photobucket.com/albums/...titled8_22.jpg
http://i1271.photobucket.com/albums/...itled24_10.jpg
http://i1271.photobucket.com/albums/...itled14_11.jpg
http://i1271.photobucket.com/albums/...ead2/205-1.jpg

So from my reading I just did the stagnation point will be in the middle of the vehicle probably centered in the grill?

Also, if it were to be centered would type 1 or type two be better. Would an abrupt entrance be best or would a sloped entrance be best for an inlet? I seen both on the vehicles that are posted. Thanks!

The stagnation point is where air that lower goes under the car and air higher goes over. It depends on the overall shape of the nose.

Likewise the inlet depends on the path the air will take from there to the radiator, which should be in a sealed duct. Is you diagram looking from the top down or from the side? And which way is the radiator?

Top down, with the nose facing up in all the drawings

The drawing in the frame that is rotated left 90°? I confuse easily. :confused:

Let's try this: Is the radiator centered or offset left or right? The inlet duct should be longer than the height of the radiator and the opening should be 1/6th the area. A centered duct into a centered radiator is a very direct path. If the radiator is offset to the left (for instance) and the inlet is on the right, then a longer path is available. Then all you need is to make the duct evenly divergent ...maybe turning vanes in the corners.

So the photo is sideways. So based on the photo as it is shown the front is to the right. all are drawn from top down.

The opening should be 1/6th the area of the area of the radiator? Awesome, that makes things pretty easy. I can remake this as many times as needed as Coroplast is pretty cheap in bulk.

http://ecomodder.com/forum/member-fr...1215138521.jpg

This is where that comes from. There exists a version that wasn't photographed off a monitor.

That is really helpful, thanks! Ill try to get it as airtight as possible :)

point
 

By definition,at the forward stagnation point,the air actually comes to rest.It's just impacting the body,with full dynamic pressure.
If you mixed carbon black (lamp black) and kerosene and dribbled it on the nose of the car,then immediately drove fast,the stagnation point(s) (forward) would be revealed by any dots which failed to smear off in some direction.
And this would be the best place to site the cooling inlet.

entrance
 

The inlet opening should be perpendicular to the flow all around ingesting the blue pressure spike
http://i1271.photobucket.com/albums/...ead2/12-19.jpg
And the inlet itself should not have squared edges of the flow will be choked off with what is referred to as a vena-contracta
http://i1271.photobucket.com/albums/...Untitled32.jpg
The inlet and airtight ductwork should be like the venturi inside a carburetor
http://i1271.photobucket.com/albums/...titled3351.jpg

Hi sort of off topic and maybe covered elsewhere but I saw your pressure map a couple posts up and I am just curious if running your outside vent (fresh air) fan in the car, assuming the air scavenges from beneath the hood at the wipers, would pull enough air from the high pressure zone at the bottom front of the windshield to improve drag more than energy consumed by running the fan?

Thanks!

Probably not. Tuft testing would tell if there is a positive effect, but won't quantify it.

My guess is that attaching a leaf blower to the vent might. The blue area reaches halfway up the windshield and out onto the hood. There's a lot of air moving through the high pressure zone with maybe a little bale of rotating air right at the base. The air an inch or so off the surface is being flattened by the onrushing volume of air.

scavenging
 

The entire front of the car,right up to the windshield header,over the roof,and door sides (depending on the vehicle) is attacking the air and the air is held against the body up to the region where the body reaches it's maximum cross-section.Flow attachment here isn't really an issue.
The horsepower available from the ventilation fan wouldn't even register in comparison to the power of the airstream.Also,you'd want as much air moving outside the car as possible,as internally,it's a torture chamber.
A 'blown',or 'suctioned' slot would do more good at the back of the car,where it could energize an otherwise feeble boundary layer which is at risk of triggering separation

A case on point: 1500 cubic feet per minute of engine cooling air (not the exhaust) into a ring-shaped slot at the rear of a boat tail. This might have some effect.

http://ecomodder.com/forum/member-fr...ed-stinger.png

The one on the left. This is called a Coanda nozzle.

(aerohead — I'm going to take some Aluma-panel upriver after it thaws and fashion a boat tail for the '58 Baja.)