Gen3 cranking pressure??

[mark3evo]

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??

[Busa Harbour man]

I see you have your thinking cap on and answered your own question yourself 

 

BHM

[mark3evo]

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 by mark3evo

[Kzin]

Less blowpast,  better tolerances.

Throttle bodies should be off/ WO anyway - if it can't breath at cranking speed forget the rest.

 

 

[mark3evo]

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

[MikaS]

[Kzin]

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 ?

[MikaS]

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

 

[mark3evo]

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

[MikaS]

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 (?)