Block Fillers

Strengthen your engine for high-performance use with premium block fillers from Phantom Motorsports. Block fillers are specially formulated compounds poured into your engine’s water jackets to increase the rigidity of the cylinder walls—reducing flex, improving ring seal, and allowing your motor to handle higher horsepower and boost levels. Ideal for race engines, drag cars, or extreme performance builds, block fillers are the secret weapon for getting more power and durability out of your engine block.

At Phantom Motorsports, we offer easy-to-mix, reliable block filler solutions trusted by engine builders and racers alike. Our products are engineered for optimal flow and curing, helping reinforce your block without compromising vital cooling in street or strip applications. Whether you’re filling up to the water pump holes or running a partial fill for improved streetability, our block fillers make your engine foundation race-ready and robust.

FAQ

What is block filler and why is it used?
Block filler is a cement-like compound used to fill the coolant passages (water jackets) in an engine block. It adds strength and prevents cylinder wall flex, especially in high-horsepower, forced induction, or racing applications.

Is block filler only for racing engines?
While commonly used in drag racing or boosted motors, partial block filling can also benefit high-performance street engines that need extra bottom-end support without fully compromising cooling.

Will using block filler affect my engine cooling?
A partial fill still allows for coolant flow in the upper jackets, maintaining typical street engine cooling. A full fill is reserved for dedicated race engines where maximum strength is needed and cooling demands are managed differently.

How do I install block filler?
Block filler is mixed to the correct consistency and then poured into the engine block’s water jackets with the engine upright or at the correct angle. Always follow the manufacturer’s mixing, pouring, and curing instructions for best results.

Can block filler be removed after installation?
No. Once set, block filler is a permanent modification to your engine block.

How long does block filler take to cure?
Curing time depends on product type and temperature. Typically, it requires at least 24–48 hours. Always check your block filler’s instructions.

What if my block filler arrives damaged or unusable?
Customer satisfaction is our priority. If your block filler arrives damaged or has set up in the container, contact us within 7 days for a replacement, exchange, or refund.