coaster wrote: ↑28 Nov 2022, 12:38
I have long pondered an engine design dreamt up out of bits of scrapyard junk.
The old blueprint images released by Honda of their late 80's V6, V10 and V12 all share a similar design dna, namely the 75 degree bank angle.
Isuzu built a 75 degree V6, built under licence from Hondas design bench, the cylinder heads water passages have a nice entry manifold similar to a motorcycles, nice shallow valve angle, nice high port roof, cross bolted main caps.
If you were to obtain 2 early blocks with the short deck, cut a split line in middle of rear 2 cylinders of one block and the front 2 cylinders of the other you have the basis of the V10 block.
Naturally that pair of bores need sleeving after the tig welding unifies both blocks, a turned aluminium bar bolted in the crank tunnel with the caps should keep everything lined up.
The bar should be aluminium as the block needs pre heating before tig welding, steel has a different expansion and would leave 'walk' marks.
I found this out trying to weld a motorcycle crankcase which was holed.
Ok, so block done.
Now the crank, a Volvo crank, shortest stroke obtainable, cut the crank dead centre of main journal on all 5 main journals, this could be done with an edm wire cutter to keep as much parent metal, these 6 segments are set up on a rotary table and the half main journal milled to an ideal stroke and diameter for the new hollow bush to be pressed on.
The hollow bush should be a hardened and ground bush with press fit interference on Volvo crank segments new diameter.
Hardened and ground bushes are easily obtained from bearing manufacturers (skf) as inner races for needle roller bearings.
Now to find some motorcycle conrods to suit this bush outer diameter?
Some motorcycle pistons, Crf450? Drz400?
The camshafts are going to be billet, no easy solutions here.
Bmw throttle bodies, M5?
If i had the keys to a well equipped machine shop.