|
Title: highest/optimum CR recommendation Post by: pupjoint on March 29, 2017, 17:24:25 pm just opened up my old 2027 motor for some updates/upgrades . old motor lost power, lifter and cam issues.
new specs as 41 mg case, Hoover oiling mods, berg case conversion , full flow, Scat 8mm studs, bushed lifter bores berg 30mm pump with csp relief cover, Scat 2 quart sump 82mm forged Scat crank, 10.5lbs Cr-Vn flywheel, Berg Archiever front pulley, Berg crank and pulley bolt 5.5 H beam CB rods 90.5mm forged Mahle Tims Stage 2 42 x 37.5, CB Snakeskin Valves, cb 650 springs, titanium retainers, CB 1.4 rockers , 56cc chambers but i need to recheck on this Logmech HD dual tapered aluminium pushrods, CSP pushrod tubes Thorsten Piper 56gm lifters, JPM cam 108LC 54 deg lobe angles for both intakes and exhaust 274 duration bearings, oil pump, pistons WPC treated. 45mm Jenvey throttle bodies, crank trigger EFI wasp stage 1 header and muffler on the old motor i was running same oiling setup , same oil pump, stock doghouse , full flow with thermostat to a Setrab single pack. available pump fuel RON97 , RON 100 is available but only on selected stations in the city street driven only gearing would be mostly stock 3.78,2.06,1.32,0.89 and 4.125rp; full steel body 66 beetle, full interior i was aiming for 10.1 initially, but would like to ask for more opinion before completing the long block thanks Title: Re: highest/optimum CR recommendation Post by: neil68 on March 29, 2017, 20:40:26 pm I've been running a JPM 274-degree cam,108 LC for five years. Currently at 10:1 CR and was as high as 10.7:1 with 98 RON pump fuel. Engine ran cool with no issues :)
Cooling is via OEM 1975 FI doghouse shroud (with venturi) and no external oil coolers. Title: Re: highest/optimum CR recommendation Post by: pupjoint on March 29, 2017, 21:26:33 pm I've been running a JPM 274-degree cam,108 LC for five years. Currently at 10:1 CR and was as high as 10.7:1 with 98 RON pump fuel. Engine ran cool with no issues :) Cooling is via OEM 1975 FI doghouse shroud (with venturi) and no external oil coolers. ;D Title: Re: highest/optimum CR recommendation Post by: DWL_Puavo on March 31, 2017, 16:35:10 pm As for the "old" static CR recommendations, for example Engle W100 "7,5 - 8,25:1" - I've built two engines with W100 cam on 8,5:1 and 8,6:1 static compressions. Both run cool and without detonation on RON 95E10 fuel (about the same as US "91 octane", eg. "91 AKI" ?). Under a lot of stress in T2 doppelkabiner with ~1500 kg trailer towed on hot weather. Ignition max. advance has been about 32-34 degrees under stress (low vacuum high rpm) and probably a bit more with carb butterflies barely open on high rpm.
Also I'm quite sure that JPM's recommendations are just correct and at least shouldn't be exceeded that much. Is ethanol fuel available there, you'll have to to tune your EFI anyway so maybe a step to more ecological? BTW your part list sounds awesome, your aimed 10.1 ET maybe a bit optimistic with full interior and steel body ;D |