I would like to lay all the A20 specs out because they are a little hard to find. Some of these measurements may not be 100% accurate, I will mark those, but as far as I can tell it is good enough for a compression calculator program. Input is very welcome. The purpose of this thread is largely due to the fact that B20 pistons fit in the A20 with an overbore. B20 pistons are 84mm, but B18 pistons can come in 83mm sizes, but options are limited. This thread also assists in blueprinting the engine I am building soon and I will post progress here.
Service manual:Section 6-3 to 6-21 (pg 49-68) Section 7-3 to 7-18 (pg 72-85) Dropbox - 1989 Accord Service Manual.pdf - Simplify your life
Useful threads: https://www.3geez.com/forum/performa...hlight=pistons
Is high compression on the cheap possible on an A20? (pump gas)
A20 Head Build Thread | Honda Prelude Forum
Useful apps: CR Calculator - Apps on Google Play
Punch in A20 custom specs as if it were a B series.
Delta 272: .415" lift, 220 duration @.050" lift
Intake valve dia: 30mm
Exhaust valve dia: 35mm
Valve stem dia: 6.6-7mm ??
Valve OAL: 120.4mm
Valve guide OD: 12mm
Combustion chamber volume: 47cc ??
Deck height: 213.25mm ??
Bore size: 82.7mm
Max recommended bore: 83-84mm. Most pistons come in 84mm.
Piston to cylinder clearance: .02-04mm
Piston to cylinder service limit: .08mm
Service manual does not specify a maximum overbore or service limit. The cylinder walls should be strong. Bore at your own discretion, pistons can come as large as 85.5mm
Main journal min std size: 49.985mm
Main journal max std size: 50mm
Main bearing clearance 1, 2, 4, 5: .026-.55mm
Main bearing clearance 3: .032-.061
Main bearing service limit: .07mm (the only time this matter is with a min size bearing and your crank is FUBAR)
Main bearing width: 20mm
Main journal width:
Rod journal min std size: 44.981mm
Rod journal max std size: 45mm
Rod bearing std clearance: .026-.038mm
Rod bearing service limit: .07mm (the only time this matter is with a min size bearing and your crank is FUBAR)
Rod bearing width (A20): 19.5mm*
Rod bearing width (B18/B20): 18.5mm*
Rod bearing width (B18B): 19.5mm*
Rod journal width:
*Not to make this confusing, but I have varying bearing widths, yet I've seen B series rods fit snugly on an A20 crank. First measurement is More Information for ENGINETECH BB2200, 2nd is More Information for ENGINETECH BB2208, 3rd is https://www.rockauto.com/en/moreinfo.php?pk=2989791. GET THE RIGHT BEARINGS!
Rod length: 137mm
Wrist pin size A20: 20mm
Wrist pin size B20: 21mm ??
Piston comp. height: 30mm ??
Stock piston flycut depth:
Stock ringland height:
Rod big end width (B20): 23.7mm*
Rod big end width (A20):
Stock piston dish (A20A1):
Max piston dome/height:
Stock head gasket manufactured height: .0470" - .0530"
Compressed height: ~.030" (.762mm) ??
Stock head gasket bore size: 83.82mm (3.3")Careful with an 84mm bore, Cometic suggests .01" larger than your bore. 83mm bore works with stock head gasket, any larger and you will require a custom gasket or carefully scribe and cut the stock one.
Rod/stroke ratio: 1.51:1
B series piston list
83mmCP-Carrillo SC7112 +.1cc / 10:1
CP-Carrillo SC7013 +4.9cc / 10.87:1
Supertech P4-H83-P6 +5.9cc / 11.07:1
JE 338090 +3.5cc / 10.6:1
JE 338092 +8.2cc / 11.57:1
84mmWiseco K623M84 0cc / 10.17:1
Wiseco K594M84AP/Skunk2 316-05-0017 +8.25/8.26cc / 11.8:1
Wiesco K567M84AP/Skunk2 316-05-0013 +2cc / 10.52:1
CP-Carrillo SC7120 +5.8cc / 11.26:1
CP-Carrillo SC7117 +1.6cc / 10.45:1
Supertech P4-H84-P1R +1.4cc / 10.41:1
Supertech P4-H84-P5 +5.5cc / 11.19:1
JE 302413 +7.4cc / 11.6:1
JE 302412 +3.2cc / 10.74:1
Arias A3330521 +7.3cc / 11.58:1
Arias A3330511 +5.29 / 11.15:1
Arias A3330490 +.5cc / 10.26:1
If you would like dished pistons see SpeedFactory's site
Compression ratios based on 47cc combustion chamber and 213.25mm deck height
Manley 14412-4 I beam
Speedmaster PCE274-1108 I beam... but cheap?
Crower B93728B-4 I beam
Saenz PS-HB18B-A00-T I beam
Brian Crower BC6019
Brian Crower BC6029
Intake valves: Supertech HIVN-1102
Head Diam: 31.00mm (+1)
Stem Diam: 5.48mm
Intake valve springs: Stock exhaust valve springs
Intake valve retainers: Manley 23100
Intake valve lash cap: Supertech LC-55 Required due to shorter valve than stock
Intake valve guides: B18C
Intake valve seals:
Exhaust valves: Stock
Exhaust valve retainers: Stock
Exhaust valve guides: Stock
Exhaust valve seals: Stock
Cam: Delta 272
Pistons: Arias A3330511
Rods: Skunk2 306-05-1130
Rod bearings: King CR439AM
Main bearings: King MB5168AM