Project NSX: Part 3 – Building a Race Proven C32 Engine

To fix the cylinder issues, Darton MID sleeves were used.  The MID sleeve butts against the walls of the block and adjacent cylinders so the cylinders are fully supported.  The MID sleeves are wet sleeves meaning that they are standing freely in the water jackets.  The fins you see machined in the sides of the sleeve are called  register fins, these give the sleeve support and still allow coolant to flow around the sleeve to improve cooling.

The buttress you see at the top of the sleeve prevents the sleeve from moving or flexing even under high loads.  The buttress is grooved and drilled to allow coolant to flow freely around the top of the cylinder and the head.  This gives far better cooling and detonation resistance compared to regular sleeves.

The C32 V6 Honda motor powering the NSX although being over 13 year old is still a pretty high tech powerplant, even by today’s standards. It displaces 3179cc with a 93 mm bore and a 78 mm stroke. It has a 10.3:1 compression ratio and a light alloy block and heads. It was also the first Honda engine to feature the revolutionary Vtec variable cam timing system. The C32 pumps out 290 crank and 224 lb/ft of torque in stock form. Of course we plan to more than double this!

In this top view of the MID sleeve you can see the buttress grooving and drilling.  The MID sleeve is made of centrifugally cast  ductile iron.  This gives a finer grain to the metal for better wear, better frictional and ring compatibility properties.Follow us as we show how FX Motorsports Development gets it done, building both rock solid reliability and outstanding power.


The FX Motorsports Development modified block with the MID sleeves in place with the decks machined.

Underneath you can see the bases of the MID sleeves.  The sleeves are secure with a large machined register and sealed against coolant leaks by twin silicone O-rings.
Related Topics

Leave a Reply

Your email address will not be published. Required fields are marked *