screen material over front grill - aero mod
 

Decided to test the idea of using home window screen material over the front Grill on my 99' civic during a road trip from Dallas to Denver. This was purposely a temporary mod so it was installed with Duct Tape!

The theory is that at low speeds or at a stop enough air can make it through the holes and retain cooling. At higher speeds the air cannot make it pass the screen and diverts around the bumper as a solid grill block would.

This drive was over night due to my 2 yr old son sleeping in the back seat. This ended up being a good thing since it was about 70 degrees leaving dallas and closer to 50 degrees in high elevation. I use a Ultra Gauge on my car and was closely watching the coolant temp. My normal is 183 degrees (+/- 3 degrees) almost the whole way i was running about 199-205 degrees with the screen installed so this deffinily blocked to much air flow.
I was seeing about 3mpg increase over my norm though..... My numbers are not great since i had my wife, son, + several hundred pounds of luggage for a weeks vacation on top of the climb up 4500 ft elevation change. = 43 mpg at 72 mph on cruise control.

For what its worth this mod seems to do what it should, but the screen mesh/size for a regular home window screen appears to be to tight and blocks to much air flow.

* Another thing to note: Blocked lots of bugs from splating on my radiator/ and ac condensor :)

Hm... I might look into that, then. I was considering getting some perforated aluminum sheet and cutting it into shape.

I like the idea. Going to have to do some testing on mess sizes.

What is the airflow when air is not going through the radiator? Is there an escape route under the car? I wonder if the improvement was from higher temps and not airflow related. It is interesting that this subject of air flow through the engine compartment gets relatively little attention, and yet testing has shown that about 30% of the drag on the front is produced by the air flowing into the engine compartment. The wheels are another 25%. That, they do pay attention to.

Years ago there was a race car called the Shelby Daytona. It had a big opening in the hood behind the radiator, and a partition between it and the engine. All the air that went through the radiator exited out that hole and over the car. The car was not particularly successful, but I thought the cooling concept made sense. I have seen no other car like it on the road. You can see kit cars now at car shows.

Sam

Many people on this forum have proven solid plastic grill blocks with legitimate ABA testing showing MPG improvements.
Of course the issue with a solid grill block is zero air flow at any speed.

I think there is an ideal mesh size opening that will yeild optimal performance to flow a little but not allot, effectively working like a solid grill block.

It would be good to see their engine temps before and after the grill block. I wonder if part of the improvement is from higher engine operating temps. I don't question the airflow improvement at all.

Sam

I have always planned on installing a fan indicator light before testing a grill block.

I agree temps play a part in effiency. My ultragauge showed normal air intake temps. (cooler than usual due to high elevation ranging from 50's to 90's (farenheight)

I believe air flow within the engine bay was ok since i dont have an belly pan, mainly just the radiator that was effected. I could hear the electric fan kicking on often as it was needing air desperately.

I had a 97 Civic which my daughter still drives. I am certain my mileage was never as good as yours is. Good work so far.

Sam

That's actually a really good idea!

What about using the old aluminum / metal screen? I recall that having bigger openings.