[RKDinOKC]

Don't know much about fire suppression systems, but think most work by replacing the air in the engine bay with something that doesn't burn. An external fuel shut off is required on race cars.

When the engine bay on my Ford station wagon caught fire it was a gas leak from a old brittle fuel line that then set off the oil residue from oil leaks. A dry chemical fire extinguisher put it out and it did not re-light. That yellow powder stuff from the fire extinguisher was everywhere.