I want the help of someone familiar with performance building the B230FT. I have plenty of info on external mods to increase power. It's a 1993 block (with piston cooling oil jets) going into a 1989 body. I'm leaving the LH 2.2 and Garrett T-03 alone, replacing the Turbo+ system with Saab APC, adding fuel enrichment-a cold start valve (engaged at >.6bar/9PSI boost), VX3 camshaft with mild port polishing, late type exhaust manifold and 3" downpipe back exhaust.

The block is bored to +.024" (96.6MM/3.80") for use with 2nd oversize, standard weight, Mahle replacement pistons.


>>My questions for the experts are about modifying the bottom end...

I am seriously considering using aftermarket (Manley) Chevrolet small block 6" aluminum connecting rods (2.000" journal) with the forged steel B21F/B23F crankshaft for weight savings and stroke increase.

The OEM Volvo heavy (late type) conn rods weigh 721gms. The Chevy rods are 588gms. That's more than a 1/4 lb per cylinder (133gm) lighter. The early crank, with 4 counterweights vs. 8, is nearly 6 lbs. less mass - and stronger.

I know the "rule of thumb" that says shaving 1 pound of rotating mass is like stripping 100 lbs from the body. I would think that lowering the reciprocating mass would have even more effect. Here are my options...

0: Build it with strong but heavy OEM B230FT bottom end.

1: Machine the steel crank to 49mm/1.929" rod diameter from 53.98mm/2.125" and use Volvo steel rods. Save 6 lbs rotating.

2: Machine the steel crank to 2.000" rod diameter at original 80MM stroke and use aluminum rods. Save additional 1-3/8 lb reciprocating.

Larger journals of steel crank and necessary boring of the existing hole in aluminum rod for wrist pin bushing allow for some offset to increase stroke (at more cost, of course).

3: Increase stroke +2mm/.080" to 82MM/3.23", max offset of rod while using OEM Volvo wrist pin bushings.

4: Increase stroke +3mm/.120" to 83MM/3.27", max offset of crankpin without using undersized rod bearings, using custom wristpin bushings.

Each option is more costly than the one before it so I'm trying to weigh (no pun) the power benefits against the cost of each step...especially 3 & 4 before tossing an extra grand into this project for little return. All input from experience or engineering knowledge is welcomed.