Basic Grill block on a budget (fiberglass & bondo -- Geo Metro)

[EVmetro]

First, I masked off the bumper opening with masking tape, and sprayed it with mold release. Then I wrapped some fiberglass down into the opening and let it set up a little. Then I covered the opening with some fiberglass.



Once that was set up, I skimmed it with some polyester body filler.



and then blocked the filler down.



Here it is all shaped and fitted



And here it is primered and painted semi gloss black



This is grill block works out well, but after monitoring the temp through my OBD2 connection and my ipad, I was able to see that the temp cycles up and down by about 10 degrees F about every two minutes, which is hard on the motor. I don't recommend a full grill block one one of these cars. I can still use this on one of my electric conversion Metros, but those don't need the airflow. Best bet on a gasoline powered Metro is a partial block.

[Miller88]

Could it be cycling because it is hitting the temperature of the fan and the fan has to run to cool the car down?

[EVmetro]

Originally Posted by Miller88

Could it be cycling because it is hitting the temperature of the fan and the fan has to run to cool the car down?

Yep. The lack of airflow to the radiator lets the motor heat up quickly and the fan kicks on to cool it down, which happens quickly as well. With no grill block at all, the temp is very stable. If you rely on a fan to cool the motor this much, much of any aerodynamic gains get consumed by the extra resistance of an alternator that is working much harder to run the fan. No free lunch with this mod. Sometime I may experiment to see what size grill opening works right. It is almost like the oem bumper was made by a bunch of engineers or something, who took all of this kind of stuff into consideration when they designed the car...

[Daox]

Looks beautiful! How did you fasten the grill block to the car?

[EVmetro]

Originally Posted by Daox

Looks beautiful! How did you fasten the grill block to the car?

I never snapped a pic of the back, but here is a pic of the back of another grill block that I have on my 93 Metro. The grill block above has similar attachments. The 93 bumper has vertical supports to zip tie to and the 96 guppy mouth one does not have these. I have similar attachment points on it, glassed into the grill block, but I had to make some special cross pieces on the back side of the opening to hold it on.




Here is the grill block for my 93 metro EV conversion...

[Daox]

Did you add anything to the rear of the grill block to pad / protect the bumper paint? I'd think that constant rubbing would be an issue over time.

[MetroMPG]

To me "grille block on a budget" involves duct tape and garbage bags.

I should have known better when I saw whose thread this was! Very nice work.

Have you done one of the post-'98 bumpers as well? I'd be interested in seeing that.

FYI: our driving is of course different, but I find that a 4x6 inch opening on the bottom directly in front of the radiator works fine in my '98 Firefly 1.0L, and my fan rarely comes on. Upper slot is completely blocked also.

[Vekke]

If the fan kick in time is already about 2minutes its not far off on the cooling side. I would try to bring the block 10mm offset towards front to allow little cooling flow to radiator from the sides.

Very nice finish on the construction .