So I have some bulletproof “glass” that I salvaged from a bank demolition. I have several panels of it, just laying around. Today it hit me. Could I make a throttle body spacer out of this stuff?

On my port-injected Mustang, I wouldn’t bother. But since my truck has a TBI unit, it’s a candidate. I’m not sure just how much benefit it would grant on my otherwise stock engine, but the spacer itself doesn’t look like it would be very difficult to make (rather than spending anywhere from $30-$140 for a machined aluminum piece).


Fabricating a spacer is pretty straightforward, but there are several options for just how to cut the air passage. I could have two plain smooth holes, or cut grooves in them to supposedly “swirl” the air. I could also have one large “wide open” slot, maybe with a little ramp in the middle to direct it into the intake better. I have no idea which way to go here.

But before making any cuts, there’s still the question of material. These bulletproof sheets that I have aren’t actually glass, but probably polycarbonate and/or acrylic. I can cut it with a saw, but I don’t know what kind of heat it can tolerate.


Overall thickness is 1.25 inches, which according to my measurements is well within my truck’s air cleaner-to-hood clearance. This 1.25 inches is composed of multiple layers: two 1/2" pieces sandwiched between two 1/8" pieces.

I spent some time googling to try to identify it, and eventually happened upon something called “Hygard”, a polycarbonate sheeting that may or may not include acrylic (the description is a little vague). I’m pretty sure that’s what I have here. It’s apparently a “level 3” ballistic material, which means that it’s rated to take multiple shots from a .44 Magnum.


What do you think? Is there any reason that this material wouldn’t make a good TB spacer? I’ve got several sheets of this stuff to play around with (one 41.25"x15.5", one 40.5"x12", and twelve 18"x15.5" sheets. What would you use it for?

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