mark3evo Posted May 10, 2022 Share Posted May 10, 2022 idling my time looking at the Gen3 manual one for @JOHN-DYNOSTAR and @MikaS no doubt right been comparing Compression pressure by cranking , the details in the Gen3 and Gen2 are different with both Gen3 and Gen2 having the same 12.5:1 CR OK so makes sense the 'old' Gen1 with 11:1 CR so:- Gen1 has 'dry' cranking 171-228 psi limit 128 psi 11:1 (yes that makes sense lower pressure than Gen2) Gen2 has " " 199-256 psi limit 142 psi 12.5:1 Gen3 has " " 203-276 psi limit 145psi 12.5:1 ?????????????????? Question: WHY does the Gen3 have a higher cranking pressure We know the Gen3 has new cams giving reduced overlap ---- does this give higher compression as more time to pump cylinder without losses?? Quote Link to comment Share on other sites More sharing options...
Busa Harbour man Posted May 10, 2022 Share Posted May 10, 2022 I see you have your thinking cap on and answered your own question yourself BHM Quote Link to comment Share on other sites More sharing options...
mark3evo Posted May 10, 2022 Author Share Posted May 10, 2022 (edited) 3 hours ago, Busa Harbour man said: I see you have your thinking cap on and answered your own question yourself BHM or different ring design ? or smaller throttle bodies all combined Edited May 10, 2022 by mark3evo Quote Link to comment Share on other sites More sharing options...
Kzin Posted May 10, 2022 Share Posted May 10, 2022 Less blowpast, better tolerances. Throttle bodies should be off/ WO anyway - if it can't breath at cranking speed forget the rest. Quote Link to comment Share on other sites More sharing options...
mark3evo Posted May 10, 2022 Author Share Posted May 10, 2022 48 minutes ago, Kzin said: Less blowpast, better tolerances. Gen3 pistons are 0.01 mm tighter in bore than Gen2 at min / max condition same ring end gap tolerance Quote Link to comment Share on other sites More sharing options...
MikaS Posted May 10, 2022 Share Posted May 10, 2022 Quote Link to comment Share on other sites More sharing options...
Kzin Posted May 10, 2022 Share Posted May 10, 2022 5 hours ago, mark3evo said: Gen3 pistons are 0.01 mm tighter in bore than Gen2 at min / max condition same ring end gap tolerance tighter, and ability to seal are not necessarily the same thing also does it spin faster at cranking ? Quote Link to comment Share on other sites More sharing options...
MikaS Posted May 11, 2022 Share Posted May 11, 2022 16 hours ago, mark3evo said: Gen1 has 'dry' cranking 171-228 psi limit 128 psi 11:1 (yes that makes sense lower pressure than Gen2) Gen2 has " " 199-256 psi limit 142 psi 12.5:1 Gen3 has " " 203-276 psi limit 145psi 12.5:1 ?????????????????? I dont see that big difference in Gen2 vs Gen3 pressure starting from 199 vs 203 is practically the same, also limits 142 vs 145 Gen3 top pressure 276psi is just absurd, you dont want that much pressure even from built engine, if its not diesel Quote Link to comment Share on other sites More sharing options...
mark3evo Posted May 11, 2022 Author Share Posted May 11, 2022 23 minutes ago, MikaS said: I dont see that big difference in Gen2 vs Gen3 pressure starting from 199 vs 203 is practically the same, also limits 142 vs 145 Gen3 top pressure 276psi is just absurd, you dont want that much pressure even from built engine, if its not diesel so what would you expect ?? for average level Quote Link to comment Share on other sites More sharing options...
MikaS Posted May 11, 2022 Share Posted May 11, 2022 10 minutes ago, mark3evo said: so what would you expect ?? for average level We have not made these pressure tests that much, but hunch is a 210-220psi, depending if the wind is blowing from north and if the stars are aligned. Looking at the Suzuki numbers you would expect 240-260 (?) Quote Link to comment Share on other sites More sharing options...
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