lower grille block questions

[philip1]

I tried an 80% block on my lower grille and had the cooling fans cycling while on the freeway. I reduced it to about 70% and no change so I pulled it all off. I am wondering how much can I get away with? Should I just start at like 10% and creep up till the fans come on and then back off a touch?

I also have some aero questions:
Hard bellypan vs screen
lip spoiler vs kamback

[DRW]

Take a look at the coolant hoses where they go in/out of the radiator. If they're offset to one side you could try blocking the side oposide of the inlet/outlet. The majority of the hot water flow will stay close to the hoses, so the other side won't contribute as much to cooling. Block that side.

If the hoses are centered along the top/bottom of the radiator, try blocking a portion of the sides and see if the fans come on or not.

How are you monitoring the fans on the freeway?

[philip1]

I have a volt meter hooked up and when the fans come on it takes a big dip.

[charlesB]

I also have some aero questions:
Hard bellypan vs screen
lip spoiler vs kamback


On a wagon, you definelty want to go the Kamback route. The lip spoiler is doing you no favors. In fact, I'd bet that its increasing the size of your wake. Lip spoilers are for 3 box vehicles that need help straighting the airflow that becomes turbulant behind the rear window. With a wagon, you already have attached flow, and your goal should be extending that flow past your vehcile.

The best OEM example of this I have seen is on Toyotas hydrogen Highlander. Check out the kammback, and note this vehicle also has a faux upper grille.

http://images.worldcarfans.com/articles/2006/6/21/6060621.002/6060621.002.Mini3L.jpg

And are you blocking both the upper and lower grilles, or just the lower? I would suggest blocking the upper grille over the lower grille. Reason being is the air that would enter the upper grille is directed up and over the vehcile. The lower grille block often directs more air under and/or around the sides of the vehicle, both of which are bad.

Good luck

[brucepick]

Hard bellypan vs screen?

I think it has to be a judgment call based on what you find underneath your car and what your fabricating skills are.

In my case, I built a flat panel undertray that goes from the bottom of air dam back to behind the radiator - where it joins the existing belly pan that goes as far as the front axles, which is about another 20". That was reasonably easy to do. A sheet of thin plywood cut to match the curves of air dam, some angle brackets and screws + 1x2 wood strips to stiffen the thin sheet.

For the area behind the front axles I plan to use screening. The car is rear-drive and an '89 so there's a ton of stuff on the underside. I think for this car using stiff sheet material would be a real challenge. So I'll stretch some aluminum screening and prime it with latex primer made for aluminum (brush on). It's white. Then black over that.

Look under your car and see what you think. Since it's a lot newer than mine maybe it would be reasonable to fasten in some flat sheeting. People have used sheet plastic (Home Depot/Lowe's) and coroplast and also aluminum. I like 2.7 mm. lauan plywood. Also comes in 5.4 mm. Holds up very well without any primer due to lots of drying airflow. I used house paint oil primer on my front panel (see avatar here) due to the air battering it gets. Primer is holding up super through winter.

[Hateful]

[QUOTE]The lower grille block often directs more air under and/or around the sides of the vehicle, both of which are bad.[QUOTE] http://www.gassavers.org/garage_images/0jfjc7ltkztw8slvzeq7.jpg]
Now you tell me?

[charlesB]

sorry, I guess I should say "less ideal", not "bad". Any grille block is going to help. However, most cars have very turbulant underbodies and wheel wells. It looks like you have addressed these issues, so the extra air going there shouldnt cause you any problems. :)

[Hateful]

BTW; original window screen underside still holding well.:).. My main reason for screen is heat from exhaust pipe or cat convertor melting any plastic materials. Oil change only needed a hole to stick arm into( then zip tied back closed)/ oil drained right through screen into drain pan; detaching a hard belly pan would take some time.

[Greybrick]

BTW; original window screen underside still holding well.:).. My main reason for screen is heat from exhaust pipe or cat convertor melting any plastic materials. Oil change only needed a hole to stick arm into( then zip tied back closed)/ oil drained right through screen into drain pan; detaching a hard belly pan would take some time.

I guess you looked at various types and meshes of screens before installing, which material did you go with? Do you have any photos of some of the underside and did you bring the screen all the way to the edge of the rocker panels. From the photo it appears that your tires are fairly narrow,...are these a stock width or something less. Thanks.

[Hateful]

http://www.gassavers.org/garage_images/cht7zzemfj2k33tmb9n2.jpg older pic; I added some spray paint toward the middle and back. It goes from just before the oil pan( foam board covered in duck tape from there to front) to the back bumper. It's aluminum; I just happened to walk by it at Wal_mart. It's covered all the way to the inside of the wheel wells and attached to pinch weld on sides and to bumper in the back. The tires are just regular stock 195 70R14's. Hub caps are stock with black duck tape blocking holes and painted black.

[Greybrick]

Definitely need a kamback for one of these;

http://www.automedia.com/NewCarBuyersGuide/photos/2005/Nissan/Pathfinder/SUV/2005_Nissan_Pathfinder_ext_1.jpg

[Greybrick]

http://www.gassavers.org/garage_images/cht7zzemfj2k33tmb9n2.jpg

Cool, thanks.

[philip1]

looks familiar to what I have done
http://www.gassavers.org/garage_images/l23czc4muk69u594xups.jpg
the front is coated below the grille opening to encourage the air to go through the radiator. I have an air dam to take care of the drips
http://www.gassavers.org/garage_images/99a9gq1zcpxt5o0elqso.jpg
I'm wondering if a hard belly would be better for aero and I think the spoiler is going to go bye bye. Even though I like how it looks.

[Hateful]

http://www.gassavers.org/garage_images/jhtvz14dgd3c1v4md1sb.jpgspoilers do look sporty, but if you're not doing 130mph around turn two, it's really useless.As you can see,I've given up on good looks.
http://www.gassavers.org/garage_images/6vw3hfdv540gr6uce15o.jpg I like the screen better than a solid pan. it would be hard to find or make a pan with the sloped front you have.

[philip1]

I've taken the spoiler off so we'll see if that makes a measurable difference. I think it will... While it was on the wake would suck leaves off the ground and toss them up to 6-8 feet in the air. if the wake no longer does that it should mean a reduction in cd.