Stoffregen Motorsports Posted December 9, 2016 Report Share Posted December 9, 2016 It's pretty easy to drill the dipstick hole on the correct (for L series) side of the block. Then simply drive out your old L series dipstick tube and tap it into the new hole in the Z block. I've built a few Z20/L head combos and the problem you run into is compression ratio. If you can get enough volume out of the head to bring the compression down, that's the ideal way to go about it. Cutting the tops of the pistons can be done, but be careful. The Z20 pistons have thin tops to begin with and they will crack if you take too much off. 1 Quote Link to comment
hobbes_the_cat Posted December 9, 2016 Author Report Share Posted December 9, 2016 Compression with the stock open U67 head on a stock Z20e should be 8.9... so I don't think that will be a problem? Quote Link to comment
Stoffregen Motorsports Posted December 10, 2016 Report Share Posted December 10, 2016 That's actually a bit on the low side, but perfectly ok for a street motor. I shoot for 10:1 on a street L series. You could cut the head .015 or .020 to get the compression up. 1 Quote Link to comment
hobbes_the_cat Posted December 10, 2016 Author Report Share Posted December 10, 2016 Yeah I want higher than stock compression (I think an L20b is 8.5:1 stock?) but not crazy so close to 9.0 is fine. My last LZ had around 11.0 according to the builder and that was too much for me in a street car. Going milder this time. Quote Link to comment
flatcat19 Posted December 10, 2016 Report Share Posted December 10, 2016 Z20 with a peanut would do super... I'd gladly rock an LZ20. Easier to do, and on the wallet, than my LR19 dreams. Quote Link to comment
datsunfreak Posted December 10, 2016 Report Share Posted December 10, 2016 I'd gladly rock an LZ20. Don't be that guy. 1 Quote Link to comment
datsunfreak Posted December 10, 2016 Report Share Posted December 10, 2016 This is an LZ20. When you put an L head on a Z20, you now have an L20. 1 Quote Link to comment
datzenmike Posted December 10, 2016 Report Share Posted December 10, 2016 Z20 with a peanut would do super... 10.86 1 Quote Link to comment
Stoffregen Motorsports Posted December 10, 2016 Report Share Posted December 10, 2016 Yeah, that's what I mean. Too much compression with a peanut head. 1 Quote Link to comment
datzenmike Posted December 10, 2016 Report Share Posted December 10, 2016 Bottom line for the street, it has to be 'streetable'..... docile and reliable enough to be driven under any conditions on the street. Cold starting and hot weather re-starting. Not stalling at stops and being a general nuisance to everyone else out there trying to get to of from work. Raising compression from 8.5 to 9.5 on am otherwise stock L20B is worth maybe 4-5 hp and that at top RPMs, not what you drive along at. If you have a well modified engine, then that 4-5% will translate out to more hp than the same stock engine. Raising the compression is not magical, it only increases efficiency and that, only slightly. On a stock engine you risk detonation and may have to retard the ignition, negating any gains. You can run higher octane but the gains in mileage may not equal the added costs. No one drives around with 11 to 1 compression for good reason... it's not 'streetable' enough. Quote Link to comment
Dolomite Posted December 10, 2016 Report Share Posted December 10, 2016 This is an LZ20. When you put an L head on a Z20, you now have an L20. I'd ecstatically rock the fuck out of an lz20...or an os geiken...or that ka24de head on l19 freak of engineering. Quote Link to comment
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