Question about grille blocking

[cbrer]

I live in the hot and humid south east. How much condenser efficiency will I lose by partially blocking my front grille on those muggy days?

My typical driving includes stop and goes. My typical trip length is ~ 10-20 miles. The vehicle is a 1995 Nissan hardbody with a 3.0 V6. 433,000 miles. The A/C blows ice cold, and is in great condition. The condenser and radiator are clean, undamaged, and fully unblocked.

I'm trying for 25-30 MPG as a first goal. So far tire pressure, an electric fan, 5W30 oil, and a vacuum gauge are getting me ballpark. I'm experimenting with a IAT resistor, but my first tests leave me a little skeptical.

Thanks for all input!

[mcrews]

great job!
do you have a scangaugeII?

you need to keep an eye on the numbers. Gauges are never accurate enough.
and w/ 433k on the engine I would want some exact numbers.

[Cobb]

Id be more worried about the water temp over heating. Like the guy above said, get something to read your exact water temp and work from there. Id think you could safely do half to begin with, then work you way down to a 4x4 inch slot.

[JRMichler]

You have to test your specific vehicle. Use an Ultragauge or Scangauge to watch the coolant temperature.

My truck, for instance, had the upper grille, the lower holes, and the slot between the grille and bumper fully blocked. The only opening was the slot behind the license plate. The AC worked fine at 100 deg F on a level road, and at 93 F on a sustained upgrade.

[XYZ]

Originally Posted by cbrer

I live in the hot and humid south east. How much condenser efficiency will I lose by partially blocking my front grille on those muggy days?

My typical driving includes stop and goes. My typical trip length is ~ 10-20 miles. The vehicle is a 1995 Nissan hardbody with a 3.0 V6. 433,000 miles. The A/C blows ice cold, and is in great condition. The condenser and radiator are clean, undamaged, and fully unblocked.

I'm trying for 25-30 MPG as a first goal. So far tire pressure, an electric fan, 5W30 oil, and a vacuum gauge are getting me ballpark. I'm experimenting with a IAT resistor, but my first tests leave me a little skeptical.

Thanks for all input!

Grille blocking is done to conserve heat in cold weather and promote faster warm up of the engine.

You don't live in a place with a very cold climate. Besides, summer is fast approaching.

So what do you hope to gain by blocking your grille?

[cbrer]

So what do you hope to gain by blocking your grille?

Well, maybe I'm carrying a good concept too far. It's my understanding that grille blocking leads to improved air flow, and increased operating temperature leads to the ECU being "fooled" into leaning out the fuel mixture a little.

Please correct me if those are misconceptions. Thanks for the reply.

[cbrer]

Originally Posted by mcrews

great job!
do you have a scangaugeII?

you need to keep an eye on the numbers. Gauges are never accurate enough.
and w/ 433k on the engine I would want some exact numbers.

No scan gauge yet. I'm cheap!

But I appreciate the tip. She is getting up there in miles...

[WesternStarSCR]

Originally Posted by cbrer

So what do you hope to gain by blocking your grille?

Well, maybe I'm carrying a good concept too far. It's my understanding that grille blocking leads to improved air flow, and increased operating temperature leads to the ECU being "fooled" into leaning out the fuel mixture a little.

Please correct me if those are misconceptions. Thanks for the reply.

You are on the right track for sure. Aero improvement is secondary to the faster warm up time, which gets the engine into a 'closed loop' condition quicker.

Closed loop is a good thing, it means your emissions and fuel control are working together to keep your air / fuel ratio running its best.

So I agree that faster warm up times may be less of an issue in your climate, but it still is important.

FWIW, I use my engine block heater in fall, winter and spring, for the same reason, to get to closed loop quicker and allow TC to lock up sooner since tranny warms up faster too.

Good luck and welcome !!!

[Cobb]

Grill blocking helps with aero, radiator blocking helps with heat. I have almost all of my front end blocked off for aero and you can really feel it when you do a 50-70 acceleration.

What I did was use a turkey bastor to suck out some rad fluid and add a bottle of water wetter to help keep things cool and I got a sg2 to watch water temp.

[XYZ]

Originally Posted by cbrer

So what do you hope to gain by blocking your grille?

Well, maybe I'm carrying a good concept too far. It's my understanding that grille blocking leads to improved air flow, and increased operating temperature leads to the ECU being "fooled" into leaning out the fuel mixture a little.

Please correct me if those are misconceptions. Thanks for the reply.

Maybe you are carrying a good concept too far. Grille blocking reduces air flow under the hood. Theoretically it might improve aerodynamics in a minimal way, but not to the extent that it will produce significant gains in FE.

Blocking the grille can produce under hood temps that are higher than normal once the vehicle is at operating temp. That will cause the cooling fan to operate more often.

It's probably best to have a grille block that can be in place during winter, but removable in summer.