turbopanda

Here's the story.

Had a B18C engine (top and bottom half) running with JE pistons and Eagle rods. Spun a rod bearing. Bought a B20B shortblock. Now running with stock B20B pistons and rods, boosted.

I'm scared something is gonna break, and wish I could've used my old rods/pistons, but they won't work in a B20B.

So.. I thought of getting another B18C crankshaft and putting that in my B20B, along with my existing B18C eagle rods, and buying a set of 84/84.5mm JE pistons. Should it work okay? Any downsides? Opinions please..

InfamousRS

It will work just fine...the only down side is you will loose a bit a displacement due to the shorter storke. On the up side your R/S ratio will be slightly imporved, not much thogh.

avividmemory

how do you determine r/s ratio? is there a chart or formula for it? im curious...anyway, that setup should work just fine

mos

The bore center to bore center of the rod is the rod length, the stroke is the farthest distance the crank moves the piston (or the big end of the rod) from top to bottom. So say you have a rod thats 150mm and a 100mm stroke. you divide 150 by 100 and get 1.5. Your r/s ratio is 1.5:1.

Do the b18b/b20b blocks have the same deck height as the b18c/b18r?? I didnt know that.

boosted hybrid

Yes same deck height, its possible to use the gsr crank. Just use gsr specific rods and pistons and your set. No downsides to using the crank, other than losing a little bit of torque.

turbopanda

I imagine if you installed "GSR" specific pistons into a B20B, you'd have a little bit of a problem don't forget B18 pistons are 81mm and B20 pistons are 84mm..

I want a low C/R in my engine anyway, around 8.5:1, so I'll just get a new headgasket made, or mill the head if the headgasket won't get my desired C/R.

I'll be buying a set of 84mm JE pistons from DamonBoost soon once I gather up enough cash - for now, i'll be running low boost on stock B20B pistons/rods