maredlin1@hotmail.com Posted March 13, 2015 Report Share Posted March 13, 2015 Have l20b, plan to use a w58 peanut head with l28 pistons. I know the cr will be high to use regular gas ( like 85 octane ) I believe the dish on a l28 is 10.9 compared to stock l20b 11.26 dish. My question is can the rim of the l28 be machined down to lower cr or would it destroy the integerty of the piston. Quote Link to comment
flatcat19 Posted March 13, 2015 Report Share Posted March 13, 2015 You will barely change the compression between the change of pistons. Hell. Install flattop L28 pistons and use premium with your peanut head. No sweat. 1 Quote Link to comment
banzai510(hainz) Posted March 13, 2015 Report Share Posted March 13, 2015 10.9 cc would be fine to run. key is finding a head gasket that dont go inside the bore when you bore that's bore out to 86mm as that's the 280zx I believe Quote Link to comment
datzenmike Posted March 13, 2015 Report Share Posted March 13, 2015 The L20B piston dish is 11.36 and stock compression is 8.4. With peanut head 8.9 With a larger bore 87 86mm L28 piston it's 8.6 and 9.12 with a peanut head. Quote Link to comment
ggzilla Posted March 13, 2015 Report Share Posted March 13, 2015 High compression is less expensive. * 10% better fuel economy + more power * only 5% more for premium vs regular Win-win Quote Link to comment
maredlin1@hotmail.com Posted March 13, 2015 Author Report Share Posted March 13, 2015 I thought L28s where 86 mm. If they are 87 mm that would be too large. Could I go with an L18 ( I think they only came in flat tops ) and are about impossible to find , plus raise my cr way to high. P.S. Everyone must be tired of this question L20b w58 peanut head 32/36 weber 1980 280zx trans and flywheel de smoged two belt front pulley instead of three. What piston should I use for a daily driver ? Quote Link to comment
flatcat19 Posted March 13, 2015 Report Share Posted March 13, 2015 L18 pistons are 4cc dish and 85mm. L28s are 86mm. The turbo pistons have the deep dish. The non-turbo L28s were flat tops. I have a friend who ran a hopped up L20B with L28 flat tops with a U67/open head. No problems. Quote Link to comment
flatcat19 Posted March 13, 2015 Report Share Posted March 13, 2015 What, and why with the concern about high compression? Turbo build? If staying N/A there should be no problems being in the 9.5 to 10.5 range. Colder plugs. Lower base timing. Use higher octane gas. Quote Link to comment
datzenmike Posted March 13, 2015 Report Share Posted March 13, 2015 What'd I type? 87? yes they are 86mm Quote Link to comment
Laecaon Posted March 13, 2015 Report Share Posted March 13, 2015 L28 NA early are dished. L28 NA late are flat tops. Also stock head gasket cleared my 87mm bore fine. 1 Quote Link to comment
flatcat19 Posted March 13, 2015 Report Share Posted March 13, 2015 L28 NA early are dished. L28 NA late are flat tops. Also stock head gasket cleared my 87mm bore fine. I forgot there was a year difference on them. Quote Link to comment
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