Why do we choose Benson sleeves.....
What makes a Benson signature series sleeved block better? Several sleeve manufacturers have working designs. Each manufacturer comes about their design by different means. They all work to some degree. All sleeves are made out of the same strength and quality nodular iron as it a necessary material to seat rings. Therefore sleeve strength is determined by bore size and bore centerlines. No matter how fat the sleeve may be, the weak spot is between the cylinders. Nothing is secret about that.
What sets Benson apart from everyone else is the precision of his machine work and his method of installation. First, Benson has no employees, so no rookie or uninterested machinist touches your block. Only Benson. His method of installation insures that a sleeve can never drop, shift or leak. You never have to align bore your block with his sleeves because of the block core shifting. This is because he takes less material from the block during installation than other sleeve designs require. That keeps the block stronger by default and does not let the main saddles move, thus causing the need for an expensive align bore.
The important thing is his name is on every block and there are no excuses. He uses a sleeve designed by himself, manufactured by Darton to his specs and no one else can purchase it from Darton. It has been perfected over the last 10 years to work flawlessly. The real secret is in the person that does the install and the precision quality they demand of themselves. This is what sets Benson way apart from the others.
The original sleeves done by Benson (at least 12 years ago) were closed deck. He soon discovered that within the block, the aluminum, when heating up, was expanding at a different rate than the nodular iron sleeves. This caused the sleeves to distort out of round at operating temperature, thus hurting ring seal. Another benefit of keeping the deck open (as Honda engineers designed it) is the extra cooling that is afforded to the head gasket, thus less gasket failure and more efficient head cooling.
Certain sleeve installers seat their sleeves to the block using only a wedged fit to hold the sleeve in place. They do not butt them to a ledge cut into the block. As the aluminum block heats and expands, the crush can change and allow the sleeve to drop. Others manufacturers use an o-ring for sealing. The o-ring has a receiver groove cut into the outside of the sleeve. Unfortunately this groove weakens the sleeve to the point that high boost cannot be used safely. Benson uses a precision machined interference fit along with a proprietary sealer to insure no sleeve movement or leaks.