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.

Back when I was building racing V8s, you never ran aluminum rods on the street - stretched too much. My advice is to make sure you can run AL rods. Things may have changed, but better safe than sorry.

Hi,

You might want to check out Dave Barton's tubo motor page at http://www.linkline.com/personal/dbarton/B23FT.html (copy and paste link into your browser). He built a nice b26FT and has a few BTDT's for your consideration.

FWIW, I think he used pauter x-beam connecting rods . . . . among other pieces.

Dave was also a big help in sourcing a wiring harness for our 83 244Ti.

Hope this helps!

Steve A-

Hello

I have no experiance with stroking the engine in question, but, With the good ol chevy small block I do. A longer stroke will increase torque, and produce a slower revving engine theoreticaly. A lighter rotating mass increases an engines willingness to rev and indeed produces more power. The cautions I would impart to you are first get VERY VERY GOOD references for your machine shop before even thinking about step 3 or 4, have everythig ballenced as a set including the flywheel, harmonic ballencer, clutch ect... Altering the location of the centers of the connecting rods creates stresses on the crank that it was not designed for, a large risk to take, with potential for great, or disasterouse results, your call.

Merci

Yvan
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65 122s/73 1800es/80 262c(350ci v8)/89 745t/87 780/89 740/89 740t/ 86 745 and too many parts cars and projects to list

Try turbobricks.com
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90 744ti, Airbox, K/N, Cold air, G-Valve, Dual boost control, VDO, Modified exhaust.. 88 745 gle.

There is no information on building a stroker B230FT with lightweight parts, and that's what my question is about. I am not looking for info on the bolt-on stuff right now, but thanks for replying.

My point although I did not convey it correctly was that turbobricks has a better souce of information where that is concerned.
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90 744ti, Airbox, K/N, Cold air, G-Valve, Dual boost control, VDO, Modified exhaust.. 88 745 gle.