RPM limits of GM computer/ignition module?

[Christopher Bennight]

    Both those examples sound like mechanically the engine is just past
it's rpm range though - this is with a solid roller/ported heads 396, etc. -
e.g. with a fel-pro dfi it would turn 7500-7600 (would be the ideal
shift points anyway based on extrapolation)  Or am I reading
your examples wrong - they just sound like stock motors that are
"done".
    The 6375 value is definitley not limiting - this happens between
7000-7100 (as reported by an autometer tach).   

     Chris Bennight


| Two examples:
| 
| The 85-86 Fiero 2.5 L4 ECM has a hard rev limit set way high.  But, at
| 4800 rpm, it stops giving additional timing advance.  Reports are that
| 2.5's with non-restrictive exhaust will rev up to around 5K but not any
| higher.  Neither the fuel nor ignition is ever cut - the engine just
| won't spin any faster.
| 
| The 88 Fiero 2.8 V6 turned off the rev limit (which was 6000 in previous
| years).  Reports are that the 88 2.8 will spin to the low 6K's, but not
| any higher.  Perhaps the intake is too restrictive to go higher - the VE
| in the tables falls off a cliff approaching 6K.  Or perhaps the 6375
| value is limiting.
|

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