Nah, I chucked it. 2" would work pretty nicely so maybe I'll pick some up. Wish I had a hot knife.

Adjustable grille block design
 

Designing an adjustable grille is fairly easy if starting from scratch, but I wanted to see what could be done for retrofits. I figured that any block would need to be very thin and also be able to curve (at least in one direction). I also wanted a shape that was aerodynamically clean in any position and reasonably attractive (that one is debatable...). Here's the geometry that seemed simplest. The moveable part would be supported by the fixed one, which could also have a support grid underneath the openings. The sliding part could be made very thin so that it could negotiate a curve. This means it would need to be pulled, not pushed so a return spring would be required. It would be cleaner to have the fixed part outside, but the need to support the thin moving one takes priority. A purely decorative outer cover could be one way to address this (or possibly a grid shaped inner layer, maybe using those light diffuser grids you see at hardware stores). If space were at a premium a control cable could be used to a remote actuator. It only attains a maximum of 50% opening in theory (less in practice), but there's no reason part of the grille area couldn't be left totally unblocked to allow for various ratios of flow in higher cooling scenarios. There are a variety of ways a track could be made for the sliding part (not shown). https://www.fuelly.com/attachments/fo...ba787cf9ec.jpg

that has been discussed somewhat on here before.

the easiest way to adjust it would be a choke cable or similar type cable. remember though, you only have so much movement in a chok cable. you could put some sort of lever in place.

I was considering something like this for my car. my car is a special case. it gets about 90% of it's cooling from under the bumper. I was thinking of closing off that opening with something like that. I was going to use plexi-glass (plastic sheeting from lowes) to do it and just cut some thin strips in which to make the L-bracket for the track.

money is tight and time tighter for me right now so that one will take a while. I did block off that area with coroplast before and my car almost immediately overheated. the temps just kept rising. I ripped it off and went back to the drawing board.

*edit* I found the post where it was briefly discussed
https://www.gassavers.org/showthread....ighlight=block

By adjusting the slot widths, you can theoretically accommodate different strokes. It may require connections in the middle to add back in some more strength, depending on the exact dimensions.

I considered some much more radical designs but this seemed easiest. Linear slots and a washer/standoff combo could provide an easy track. On of the weirder ideas was for arms that had a rubber membrane stretched very tightly over it. That could allow in theory for greater than 50% opening. I explored a few rotary ideas but they didn't accommodate a curve very nicely.

I don't plan to implement this myself. I just don't drive enough to justify the effort.

50% ought to be fine for most hypermilers in most vehicles. If you're towing a camper up a mountain in the summer, maybe not.

A bicycle derailer cable should work to operate it, and using a bicycle shifter it may be possible to get enough travel. If so, a modern bicycle shifter will offer indexed, partial movements, allowing you to adjust it quite finely. You may need to buy a length of bulk cable and housing from a local bicycle shop or online retailer instead of a pre-cut kit, in order to get it long enough.

If you're not familiar with modern bicycle shifters, I'm thinking one like this:
https://cdn.mos.bikeradar.com/images/...-90-480-70.jpg
It has one lever that pulls the cable, ratcheting up to three clicks in a single push, and another lever (not visible in that picture) that releases it one click at a time. It's also got a display to show you what gear you're in. There are other designs, but I think that one (except maybe with a different display) would work great.

Come to think of it, if it doesn't provide enough travel, a bicycle derailer could multiple the travel and is already setup to work with that cable.

Does anyone know how Basjoos put his adjustable grille block together?

I wish he (basjoos) was more active here. he has a lot of knowledge to share. he would probably be easier to find at ecomodder but I only have time for one forum.

he has comented on here a few times but not on that (I don't think)

He has that extended front to work with, so it gives you a lot more design possibilities, so I'm not sure how much would trasnlate.

it may not for you, but for me it would translate almost perfectly. I have an opening on the underside of my car between the bumper and the radiator. that is the only place that air is getting in. I do have a 6 inch gap between my hood and bumper but the purpose for that is to be able to unlatch my hood.

I think that you could still apply the concept. I am sure he tried some stuff that didn't work and he could at least steer us clear of those things.

I think I am going to try and PM him. I doubt it will be answered but it would be cool if it did get answered. we shall see.

6"? That gives you a lot of choices. I'll start thinking thinking along those lines.