Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - What do you guys think about a grill block behind the grill?

ChrstphrR · 01-31-2009, 05:07 PM

I'm driving a 2000 TDI, and here's been my situation with static grill blocks, to compare with the need for an active one:

I'm up in Alberta, dealing with a temperature range between -40C to +38C (-40F to 100F).

Since November 2006, I've had two pieces of coroplast stuffed against the radiator, behind the upper and lower grill, and behind the bumper, and the radiator support in front. About 2/3 of the radiator has been blocked internally.

In the summer of 2008, I blocked off the lower grill entirely, and then covered the lower half of the upper grill (avoiding the upper driver's side quadrant, where the stock engine air intake is).

The only time I had an issue with being too blocked off, was with the lower grill entirely blocked in the summer during a long highway drive (4-1/2h each way, 35C, very humid, and driving 90-100kph). After that drive, I made a gunslit in the centre of the lower block, about the size of the hole on the plastic grill piece -- so, about 1/9th the original open area. And as an extra precaution, I removed one of those two interior coroplast rad blocks.

At colder temperatures, in the winter, I had to tape up that 1/9th hole when temperatures approached freezing.

Summer peak temperatures:
Air temperature at 30C-38C
Highway cruise: 70-85C
After highway city stop-and-go: 75-90C

Winter temperatures IF I could warm up:
Air temperature -40C to 0C
Highway cruise:
65C-72C when lower grill was 8/9ths blocked.
58-64C when the lower grill was full open.
City stop and go: 55-70C.
When temperatures approach 0C (freezing point), the engine would be 65-75C.

An active block would probably be more ideal for the TDI. There are times you need the grill more open

mainly city driving after a long highway cruise
in a near standstill city stop and go where you're inching ahead

Again, all of this was done with 2/3 of the radiator blocked off, topped off with exterior blocks.

Being dremd's stomping grounds are MUCH warmer than mine in Alberta, he'd have more need for an active grill, than I would.

Myself, I really don't see there being much room to work with behind the grills. That's why I originally went with radiator blocks (to let the engine warm up faster in winter). I'd concentrate on an active slot or flap off a blocked lower grill, and there'd be a few inches of working room. I'd suggest dealing with the lower grill or space behind for any sort of active/motorized block.

I do think there's merit in pursuing a grill block with your TDI, dremd. The TDIs benefit more from faster warmup, summer, OR winter. So, a near 100% block benefits the car in almost all seasons and temperatures. The active block ends up being a "safety" for ensuring you get enough airflow to avoid having the fans running and/or overheating.

P.S. My 2 cents are TDI-centric. YMMV for other vehicles, of course.

01-31-2009, 05:07 PM	#7 (permalink)
ChrstphrR EcoModding Apprentice Join Date: Jul 2008 Location: Sault Ste Marie, ON, Canada Posts: 128 Schwartzejetta - '00 Volkswagen Jetta TDI GL 90 day: 52.87 mpg (US) Thanks: 19 Thanked 16 Times in 16 Posts	I'm driving a 2000 TDI, and here's been my situation with static grill blocks, to compare with the need for an active one: I'm up in Alberta, dealing with a temperature range between -40C to +38C (-40F to 100F). Since November 2006, I've had two pieces of coroplast stuffed against the radiator, behind the upper and lower grill, and behind the bumper, and the radiator support in front. About 2/3 of the radiator has been blocked internally. In the summer of 2008, I blocked off the lower grill entirely, and then covered the lower half of the upper grill (avoiding the upper driver's side quadrant, where the stock engine air intake is). The only time I had an issue with being too blocked off, was with the lower grill entirely blocked in the summer during a long highway drive (4-1/2h each way, 35C, very humid, and driving 90-100kph). After that drive, I made a gunslit in the centre of the lower block, about the size of the hole on the plastic grill piece -- so, about 1/9th the original open area. And as an extra precaution, I removed one of those two interior coroplast rad blocks. At colder temperatures, in the winter, I had to tape up that 1/9th hole when temperatures approached freezing. Summer peak temperatures: Air temperature at 30C-38C Highway cruise: 70-85C After highway city stop-and-go: 75-90C Winter temperatures IF I could warm up: Air temperature -40C to 0C Highway cruise: 65C-72C when lower grill was 8/9ths blocked. 58-64C when the lower grill was full open. City stop and go: 55-70C. When temperatures approach 0C (freezing point), the engine would be 65-75C. An active block would probably be more ideal for the TDI. There are times you need the grill more open mainly city driving after a long highway cruise in a near standstill city stop and go where you're inching ahead Again, all of this was done with 2/3 of the radiator blocked off, topped off with exterior blocks. Being dremd's stomping grounds are MUCH warmer than mine in Alberta, he'd have more need for an active grill, than I would. Myself, I really don't see there being much room to work with behind the grills. That's why I originally went with radiator blocks (to let the engine warm up faster in winter). I'd concentrate on an active slot or flap off a blocked lower grill, and there'd be a few inches of working room. I'd suggest dealing with the lower grill or space behind for any sort of active/motorized block. I do think there's merit in pursuing a grill block with your TDI, dremd. The TDIs benefit more from faster warmup, summer, OR winter. So, a near 100% block benefits the car in almost all seasons and temperatures. The active block ends up being a "safety" for ensuring you get enough airflow to avoid having the fans running and/or overheating. P.S. My 2 cents are TDI-centric. YMMV for other vehicles, of course. Last edited by ChrstphrR; 01-31-2009 at 05:08 PM.. Reason: Post Script!