Grill and valence block, summer port opening size?
 

Grill and valence block, summer port opening size?

For those who have blocked off air access to the radiator with grill and valence blocks, what size is the opening that you leave for cooling air?

I have two 4" diameter ports, which are about 12.5 square inches each for a total of 25 square inches open area. This is the only open area leading to the radiator, other than cracks around the edges of grill trim. The radiator is in a "tunnel" so from the front end, there is no other large place for air to enter.

I am seeing coolant temps running about 198F to 206F during highway driving, with ambient temps between 40F and 60F. I do not see coolant temp cycling much so I do not believe the fan is kicking in much. These are acceptable coolant temps to me for now, but I wonder about summer.

25 square inches seems to be not quite enough of an opening. The motor is a 1.6 liter Nissan.

Summer is coming, what do you think is a good port size for summer weather? It gets up to about 100F max ambient here in MI.

http://cruisenews.net/whacked/versa/7.jpg

Does it have a temp gauge? I'd keep a utility knife in the glovebox and if it gets hot, open her up a bit.

Hi,

If it doesn't have a temp gauge (like my xA), this is a great reason to get a ScanGuage II or the new Kiwi gauge.

I think it totally depends on the vehicle. How much airflow can get through the radiator in other ways like from beneath. How much airflow is even needed, some vehicles have a radiator that is more oversized and some don't. Also the type of driving you do, if you sit in traffic a lot you are going to need more cooling. I can block off nearly everything on mine and it hardly makes any difference in operating temps.

Best thing to do is just experiment like Frank said. If it gets too warm, cut some more open. Also keep some tape with you and try covering a little more and see how it goes.

BTW, where in Michigan are you?

You get more air through a smooth duct with rounded edges, and one has less drag than two. It might be worthwhile to get an indoor/outdoor thermometer, and put the probe just behind the rad.

I am monitoring coolant temp with a ScanGauge. The radiator has a tunnel between it and the grill and valence, so not a lot of other air is getting in. There are some holes and gaps but not a lot.

I'm interested in what port size others with a similar sized engine are using.

I have another valence cut and am ready to put an opening in but trying to decide how big. I will probably wait until I see what the current ports run in hot weather. But if I see a lot of temp cycling (fan use) or temps much over 210, I will probably go two times the area of the current ports with one oval opening in the middle.

The location here is So Haven, tropical southern Lake Michigan.

Hi,

The opening on my xA grill is 14" x 4" = 56 sq. in. It has a 1.5L engine, and the highest temps I have seen with this (in cool weather so far) is ~184F. I think the thermostat is 180-182F, and I typically run 177-179. The fan comes on at 204F.

I'd suggest doing a radiator indicator light like I just put on my Paseo (check the build thread in my sig). That'll tell me when my complete full block is too much once it starts warming up more. So far, I've driven in 40F weather with no problems.

Nice job on the grill blocks! It looks factory. I did some experimenting using pieces of pipe insulation (available in various sizes at any hardware store) split and stuffed over the factory grill bars. That way if you are running too warm it is a 5 second fix to open up more of the grill and you don't have to take a knife to your good grill blocks.

I think I need to adjust my lower grill opening. It's been fine all winter but, with temps getting near and above 60F some days, I heard the fan come on the other day. I'd have to measure to be sure, but it's just slightly larger than a license plate, but with no front undertray to make sure the air actually gets to the radiator.

Just too bad the days start at 30F before getting up that high... gotta start looking into that Arduino controlled grill block.