The engine is a B23 block, with a custom stroker crankshaft, Scat H-beam rods rods for a Mitsubishi engine, and Diamond custom forged pistons. Total displacement is about 2680cc. The motor has a 16 valve head from the Volvo B234; it has been ported a bit and larger ‘PZ’ cams from a Volvo Penta Marine engine are installed. I fabricated a stainless turbo header to fit a Garrett T3/T4 from a Buick Grand National. The turbo was replaced in 2007 with a Garrett GT30R and a nicer designed turbo header with an external wastegate from an Audi 5cylinder turbo.

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Shortblock details

This is how you build a strong Volvo Red Motor

Block

I started with a 1984 B23 block. At the time of assembly, this was considered the strongest foundation to start with. The block is a little heavier than the late blocks due to more iron in some spots, and it also has a forged steel crankshaft that doesn’t come in the later motors. Since then people have proven that the later blocks and cranks are strong enough for just about anything you can throw at them. But I started with the best at the time:

Block Specs:
1984 Volvo B23FT
Bore: 3.800″ (.030″ over)
Deck Height from crank center to top: 9.125″

Crankshaft

The backbone of a strong motor is the crankshaft. I started with a B23 forged crank. My machine shop did an offset grind on the rod journals to use Mitsubishi 4G63 connecting rods. The rod journals now hold the mitsu rods with about .010″ side clearance. Much nicer than the Volvo setup which guides the rods from the piston. The crank was heat treated after grinding.
Stroke: 3.496″
Rod Journal dia: 1.771″
Rod Journal width: 1.130″

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Pistons

The pistons are custom from Diamond Racing. I specified the dish shape to match the combustion chamber of the 16 valve head. And they fit the Mitsubishi 4G63 rods I am using. The piston to head clearance should be about .040″, just about right for good squish. This was a priority for me, since I’ll be trying to maximize power with this turbo motor running on pump gas. Tight squish motors help keep detonation away. As a curious observation, there are 3.800″ bore pistons for small block Chevy motors with very close compression height. It could be worth looking into if you are trying this type of build on a tight budget.

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Rods

The engine uses a set of Scat H-beam connecting rods for a Mitsubishi 6-bolt 4g63. These rods are nice and strong with an ARP 3/8″ cap screw holding the caps on. They also have a small hole drilled in the big end that sprays oil on the pistons. A nice little bonus feature.
The rod dimensions are:
Scat Rods for 4G63 Mitsubishi
Length: 5.906
B.E. dia: 1.890
pin bore dia: .827
Big end width: 1.117
Small end width: 1.010

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