Heatshield Products FR Shields wrap around the fuel-injector rails, deflecting heat and keeping the fuel rails and fuel inside them cooler. This improves engine performance, reduces the risk of vapor lock and decreases the likelihood of pre-ignition.  Sitting atop the engine – and in the case of inline engines, sometimes right above the exhaust manifold – fuel-injector rails are exposed to high heat. Hot temperatures can rob an engine of power because the hot fuel inside the rails has reduced density. Fuel that is too hot can also lead to vapor lock and can contribute to pre-ignition. On return-style fuel systems, heated fuel is passed back to the gas tank, a cycle that leads to fuel temperatures continuously rising as the vehicle is driven.  FR Shields kits fit single-rail and dual-rail fuel-injection systems. Custom lengths and diameters are available upon request. Heatshield Products has engineered and manufactured heat-barrier products for more than 30 years, serving the performance and racing industry with the highest quality products at competitive prices.