Drax240z Posted November 30, 2008 Share Posted November 30, 2008 Bringing one up from the dead here, but with a new twist. I am looking at doing something similar with a turbo engine. In the end, I will give up 63cc's worth of displacement from my current configuration, however, rod/stroke ratio will go from 1.65 to 1.80. At the same time, compression ratio will go from 8.3:1 to 8.5:1. I'm of mixed thoughts on this setup. The idea was that I could broaden my power band, by adding a bit more usable top end without losing much down low. I like the idea of slower piston speeds, less piston side loading and increased detonation resistance that goes along with the longer rod option as well. Option A: 2690cc 8.5:1 CR 1.80 rod/stroke 88mm bore x 73.7mm stroke Option B: (current) 2753cc 8.3:1 CR 1.65:1 Rod/stroke 86mm bore x 79mm stroke And for giggles, I'll throw out another option: Option 3: 2883cc 8.6:1 CR 1.65 Rod/stroke 88mm bore x 79mm stroke Application is autocross/street (turbocharged) and the goal is a modest 300rwhp with seamless power delivery. Quote Link to comment Share on other sites More sharing options...
Daeron Posted December 1, 2008 Share Posted December 1, 2008 My thought had always been to throw the L20a crank into an 89mm bore N42 block with LD 140mm rods and KA pistons.. I have never (to my satisfaction) determined whether the diesel rods had a different pin. (according to this thread it appears so, for my purposes thus far I can ignore it) If it would pin together, it would produce a 2602cc motor with just over 2:1 r/s, 14.4 degree max rod angle, and using an E31 head and flattops, 11.2:1 compression. Yes, that is high compression, but with a massaged E31, or a massaged P90 (shaved, about the same chamber volume as an E31) and a good fuel tune, and factoring in the detonation resistance from the piston speeds, I think 93 octane might work? If not, small piston reliefs mirroring the combustion chamber to reduce a few ccs of chamber volume could drop compression down to a more manageable level. I wouldn't presume to try and tune this on carbs, and it would probably take a GOOD standalone with a GOOD tune and the right camshaft.. BUT as was said above, if it can be assembled from junkyard parts and tried out, the head and block can be re used with a different reciprocating assembly. If I can get the crank I pretty well have my heart set on building this motor sometime, just to get it done. I know that if it can be done right, I can do it, and I want to. Pre-RB, No D! Quote Link to comment Share on other sites More sharing options...
Xnke Posted December 1, 2008 Share Posted December 1, 2008 Drax, how about: 2883cc's 88mm bore, 79mm stroke 133mm rods ITM P/N RY-6116 piston, Z22s 1mm oversize With E88 head and Fel-pro gasket, 9.1:1 With P90 Head and fel-pro gasket, 8.0:1 1.68:1 rod/stroke Quote Link to comment Share on other sites More sharing options...
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