[Diy_efi] Crank sensor for knock detection?

[PuffnSmoke]

Thanks for the help.  So how do production engines without a knock
sensor adjust their timing when knock occurs?  Or do they adjust at all?
I'm convinced there has to be some form of detection going on which
causes the timing to be retarded, or is the software setup for a simple
lookup table using variables such as IAT, RPM, MAP, TPS, and calculated
engine load to determine a timing?

Thanks
Mike


> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org 
> [mailto:diy_efi-bounces at diy-efi.org] On Behalf Of Mike
> Sent: Wednesday, March 12, 2003 12:15 PM
> To: List for general do-it-yourself EFI talk
> Subject: RE: [Diy_efi] Crank sensor for knock detection?
> 
> 
> I take you are talking instantaneous changes in rotational
> velocity, from what i can recall on this subject from some
> years back - the classic CAS has too little resolution
> coupled with mechanical slop (for the dizzy CAS) and DSP
> computational requirements (cost) precluded use on most common
> vehicles - maybe for the higher luxury models, but whats
> wrong with a microphone and FFT, gain selective with
> respect to engine revs/load, also how would one
> account for changes to rotational torque to feed into
> CAS instantaneous changes over the life of the engine,
> 
> Honda went to some trouble with their ring gear brushless
> servo motor to smooth out the instantaneous torque
> fluctuations and I dont recall any knock detection but,
> then it wasnt considered a performance model - 'prious'?
> I think - the battery/hybrid on sale in Australia.
> 
> On my Nissan RB30 block there are 3 knock sensor tapped
> locations between the relevant cylinders, though only
> one of them is used for my ECU. I'm told the current block
> is good for 1200hp without major mods as it already comes
> with a big end cap girdle around all 7 mains.
> Knock sensors are cheap and
> three off for an engine like that might well be more
> reliable than CAS given torque fluctuations will differ
> from one end of the crank to the other !
> 
> rgds
> 
> mike


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