crankshaft offset grinding?

[welshpug 1,657]

what with the donors of 2.1 cranks getting seriously thin on the ground now, given they were worth nothing being in large French saloons of the late 90's, a thought occurred that it may be possible to offset grind a freely available 88mm crank from the DW10 HDI engines, which are still used today,   does anyone know if this is feasible?

 

obviously to achieve anywhere near the 92mm stroke a rod with a smaller journal bearing would be required, and I know 45mm is available as the mitsubishi EVO 4g63 engines use that size,  but is there enough material/case hardening there to do this I wonder.

 

or should I stick to 88x87 and build a 2.1, and just rev it

[petert 586]

An interesting topic. Good thinking! Here it is, theoretically it works perfectly, with 0.5mm to spare. You'd need to ask a crankshaft grinder about the metallurgy though.  I think Honda B series might also be 45mm.

 

I personally think 87 x 88 is a great combination and easy to build.

 

Another option could be to grind a 48mm pin and use K20 rods? That would be 87 x 90 = 2140cc. A problem could be that DW bearings are 20mm wide and K20 bearings are 18.5mm wide. Thus too much thrust clearance. 4G63 bearings are 23.5mm wide, thus potentially a lot easier.

Edited June 28 by petert

[welshpug 1,657]

I'll ask a few people,  see what I can find, I wonder if any surface treatments could be reapplied without bending the crank also.