chester Posted April 18, 2011 Report Share Posted April 18, 2011 So I couldn't find the info I would like so here it goes. So I am planning on running a L20 block bored to 86mm with 280zx flat top pistons and a W58 peanut head. I roughly figured that it will be About 10.7:1 or so. I main concern is, is it to much to keep it a daily and also to run on premium gas. I plan on taking it everything to the machine shop this week and plan to have it in the truck before the trip to Canby. Any and all help is greatly appreciated. dan Quote Link to comment
datzenmike Posted April 18, 2011 Report Share Posted April 18, 2011 Yeah that's 10.86 a bit high for premium gas and use as a DD. I would say. Even with an open chamber head it's 10.1 Quote Link to comment
chester Posted April 18, 2011 Author Report Share Posted April 18, 2011 Alright so I should think about running different pistons then to bring it down then. So what would be a good ratio to run then. Or I should say what pistons would be best to run? L18? Quote Link to comment
datzenmike Posted April 18, 2011 Report Share Posted April 18, 2011 Probably 1mm over L20B pistons if you want to keep the peanut head on. Quote Link to comment
banzai510(hainz) Posted April 18, 2011 Report Share Posted April 18, 2011 stock pistons with closed chamber head silvolite Rockauto had some cheap also Quote Link to comment
DISLEXICDIME Posted April 18, 2011 Report Share Posted April 18, 2011 If you run closed chamber just run stock pistons with out getting the head decked . If you really wanna make it fun add 44 mm intake valves unshroud the valves and port the intake ports to 1.5 and smooth out the exhaust ports. And runn a bigger cam . But don't go over 480 lift if it is a daily. and remember if you go over 460 lift you will nead new lash pads and get every thing that rotates balncad from the clutch to the crank pully . Quote Link to comment
john510 Posted April 18, 2011 Report Share Posted April 18, 2011 My recently completed L20 has L18 .040 over pistons an A87 closed chamber ported head .488 lift cam and its not pinging on 91 octane fuel,the timing is at 12' btdc.I dont know what compression ratio it is.Good luck trying to find L18 pistons. Quote Link to comment
old-tin Posted April 19, 2011 Report Share Posted April 19, 2011 So I couldn't find the info I would like so here it goes. So I am planning on running a L20 block bored to 86mm with 280zx flat top pistons and a W58 peanut head. I roughly figured that it will be About 10.7:1 or so. I main concern is, is it to much to keep it a daily and also to run on premium gas. I plan on taking it everything to the machine shop this week and plan to have it in the truck before the trip to Canby. Any and all help is greatly appreciated. dan i have this set up and it runs vary well with a massive amount of toque, but i run it on premium 98 fuel and would not use any less. do you fellas have easy access to 98 fuel in the usa? Quote Link to comment
Farmer Joe Posted April 19, 2011 Report Share Posted April 19, 2011 ^^^lol runs good on 98 eh? the closest thing would be aviation fuel around here... 100 octane.. its spendy.. we only get 94 at the pump here locally... Quote Link to comment
Sealik Posted April 19, 2011 Report Share Posted April 19, 2011 ^^^lol runs good on 98 eh? the closest thing would be aviation fuel around here... 100 octane.. its spendy.. we only get 94 at the most locally... Premium is 91 octane here....think it's close to $1.50 a liter.....and climbing Thus the lower compression engines in this locale.......... :) Quote Link to comment
datzenmike Posted April 19, 2011 Report Share Posted April 19, 2011 My recently completed L20 has L18 .040 over pistons an A87 closed chamber ported head .488 lift cam and its not pinging on 91 octane fuel,the timing is at 12' btdc.I dont know what compression ratio it is.Good luck trying to find L18 pistons. 9.158 compression Quote Link to comment
old-tin Posted April 19, 2011 Report Share Posted April 19, 2011 ^^^lol runs good on 98 eh? the closest thing would be aviation fuel around here... 100 octane.. its spendy.. we only get 94 at the pump here locally... you porr buggers Quote Link to comment
Skib Posted April 19, 2011 Report Share Posted April 19, 2011 you porr buggers i knooow :( Quote Link to comment
chester Posted April 20, 2011 Author Report Share Posted April 20, 2011 Thank you all for the help and advice but I think I am going to still go for it worse case Is I will have to end up switching to dish pistons. My boss that owns Idaho Z in Nampa Idaho says that there shouldnt be any problem with this combo and since he is the one helping me build it and tune it I think we can make it happen. Quote Link to comment
BRE_dAtSuN Posted April 20, 2011 Report Share Posted April 20, 2011 you guys think thats bad i have l20 bored 87 mm flattop pistons and i have to run half 91 best thing out the pumps here and half 110 leaded fuel at 7.05 a gallon lol... but after i installed colder plugs retarded the timing and ran a bit richer it doesnt ping... im currently in the process of saving up for a 1.7mm copper head gasket which should lower my compression enough to be able to advance my timing and run better on 91 1 Quote Link to comment
john510 Posted April 20, 2011 Report Share Posted April 20, 2011 9.158 compression Thanks Datzenmike Quote Link to comment
banzai510(hainz) Posted April 20, 2011 Report Share Posted April 20, 2011 9.158 comp ration with L20 L18 pistons,closed head? Sure thats right. isnt a L20 about 8.4 and with closed head be close to 9. L20piston is 11 cc dish -7cc(L18 4cc dish) from piston. L20head is about 45cc and closed is 41 or 40. so subtrace another 4 or 5cc's 11-12cc of volume removed would be alot more compression youd think. Im thinking over 11 run stock pistons to be safe is my opinion.If you live in the states.YOur not wanting to tear that motor aprt again. Believe me!!!!!!!!!!! Quote Link to comment
DISLEXICDIME Posted April 20, 2011 Report Share Posted April 20, 2011 Plus who knows how much worse the gas is going to get Quote Link to comment
datzenmike Posted April 21, 2011 Report Share Posted April 21, 2011 9.158 comp ration with L20 L18 pistons,closed head? Sure thats right. isnt a L20 about 8.4 and with closed head be close to 9. Stock L20B with flattops is 8.9 but his is over bored 1mm to 86mm and that adds a little over 11cc to the cylinder volume so the compression goes up a bit. Quote Link to comment
banzai510(hainz) Posted April 21, 2011 Report Share Posted April 21, 2011 KMC63 had a L20 for sale with flatops to sale me I said NO! he didnt want it either. Xerox on 510realm had detonation proplems. hes on here also. PM hm I say dont get the flattops L18 4cc dished would be Max and that still could be Questionable if bad gas in your area. Quote Link to comment
chester Posted April 21, 2011 Author Report Share Posted April 21, 2011 hmmm. Well after thinking today I am just going to build yhe head and slap it on my L16 thats over bored .75 for now since it has a U67 head. and thank you all for helping me before I made a big mistake Quote Link to comment
Farmer Joe Posted April 21, 2011 Report Share Posted April 21, 2011 o rly? what happend? turbo l16? Quote Link to comment
Colbino Posted April 21, 2011 Report Share Posted April 21, 2011 you guys think thats bad i have l20 bored 87 mm flattop pistons and i have to run half 91 best thing out the pumps here and half 110 leaded fuel at 7.05 a gallon lol... but after i installed colder plugs retarded the timing and ran a bit richer it doesnt ping... im currently in the process of saving up for a 1.7mm copper head gasket which should lower my compression enough to be able to advance my timing and run better on 91 You think yours is bad? I have a similar setup, but with 87mm domed Venolia pistons on a U67 head. Can't even imagine what type of fuel combo I'll have to come up with. Quote Link to comment
datzenmike Posted April 21, 2011 Report Share Posted April 21, 2011 hmmm. Well after thinking today I am just going to build yhe head and slap it on my L16 thats over bored .75 for now since it has a U67 head. and thank you all for helping me before I made a big mistake Beware. The large open chamber U67 on an L16 will lower the compression to 7.72. On a 1mm overbore it's 7.88. Quote Link to comment
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