Straight antifreeze does not conduct heat very well. That could explain low heater output.

Cavitation is the product of too thin cylinder walls vibrating from the ultrasonic sound waves coming from inside the combustion chamber.

 

I would not run staright anti-freeze. It's purpose is to give water freezing and boiling protection. Teh water is what transmits the heat.

Cavitation is a non issue. The 53 block is suseptible no matter what you do. Best bet for coolant is to run it to manufactures recommendations for the area you live in.

I only run Zerex G05 and it's been flawless. Do some research, there's options.

Dave

 

I hope you did not use tap water. I would test your mixture for proper protection.