How much of a difference does grill block make?

[jared1970]

I was wondering, on a car like a Chevy Lumina, how much of a difference would blocking off the grill make? Would it even be noticeable? It seems like a pretty easy first step toward aerodynamics and I'm thinking about trying it.

[Daox]

My third ecomod to my car is always a grill block (first and second are tire pressure & a scangauge). The grill block is a staple in any ecomodding endeavour.

According to our wiki page on grill blocks. A grill block will give you from about 1-6% gain depending on your vehicle and how much you block off.

[mcrews]

I would follow DAOX's advise
PSI increase
Some type of gauge(see the first link in my sig)
and a grill block

[Weather Spotter]

just do it.

then you will find out how much it will help

[Pandaf]

Scangauge or similar tool to monitor exact engine temp is definitely recommended. You cannot trust built-in dash temp gauges these days anymore. In my car it stays at exactly the same position between 78 and 97 degrees Celsius....Of course my car is a cheap one
Try first without grill block to establish normal engine operating temp, then check the temp with grill block. Few degrees higher is no big deal, even increases engine efficiency somewhat.

[WesternStarSCR]

Definitely worth it.

It is a good aero mod (hard to measure its EXACT aero affect for most people, but it is better aero).

But of the same, or greater value, is how it keeps the engine warmer, lets your auto transmission warm up sooner, and lets you turn your heater on quicker without impacting economy. This helps your Torque Converter lockup sooner in automatics (assuming Lumina is auto), and gets the engine running in what is called 'closed loop' for emissions.

All positive things in terms of fuel economy, both from what I read here, before I put mine on, and from my experience now, running with a partial one the last 2 months.

One thing to remember:
Radiators and cooling systems are over sized - designed for worse case: towing up Baker Grade in California / Nevada / Death Valley

Baker Grade Google Maps

Las Vegas Road Trip - Baker, CA | out of las vegas

Baker, California - Wikipedia, the free encyclopedia


So, it is OK to close SOME of the air flow off to the radiator, even if you do not have a scangauge etc. I don't have one yet either.

[mcrews]

I would just put in a caveate.....
Without a digital gauge of some kind I (IMHO) would not do a TOTAL block.
(just from a potential problem point of view)
My Kia Sportage got to 226 at 90% block.
this....notice 3 of 4 are blocked (bottom one is open) lower grille is 100%


then I removed the top.....
Temps only got as high as 220 and stayed around 205.
In my infiniti, 230 was the warning light
most car thermostates open at 18-185.

[aerohead]

Originally Posted by jared1970

I was wondering, on a car like a Chevy Lumina, how much of a difference would blocking off the grill make? Would it even be noticeable? It seems like a pretty easy first step toward aerodynamics and I'm thinking about trying it.

Every vehicle is different and cooling system drag numbers published in past research reflect a 'fleet' average for the aggregate of vehicles tested.
A loose rule of thumb would be that the Lumina's entire cooling system drag constitutes about 12% of the cars overall aerodynamic drag.
In loose numbers,if you were to completely block off the grille,you'd be shaving 12% off drag,and at 55 mph this would equate to a 6% improvement in highway mpg.(With a melted engine of course!) City mpg would essentially be unaffected,aerodynamically speaking,however,a quicker warmup can add thermal efficiency to the power plant.
Racing cars may have fully ducted and 'tuned' airways which can add as little as 2% to the cars overall drag.
It's been mentioned a number of times,that the cooling system of North American Aviation's P-51 Mustang actually produced a modicum of thrust do the the thermal expansion of the air coming off the heat-exchanger.
You wouldn't expect to see this in a car.

[Cd]

Originally Posted by mcrews

I would just put in a caveate.....
Without a digital gauge of some kind I (IMHO) would not do a TOTAL block.
(just from a potential problem point of view)
My Kia Sportage got to 226 at 90% block.
this....notice 3 of 4 are blocked (bottom one is open) lower grille is 100%

then I removed the top.....
Temps only got as high as 220 and stayed around 205.
In my infiniti, 230 was the warning light
most car thermostates open at 18-185.

How much of a gain did you see with that grille block ?

[AeroModder]

If you can also build some ducting to direct the air into the radiator instead of allowing it to spill around it, that will allow you to have an even smaller grille opening.