DIY_EFI Digest Thursday, 19 September 1996 Volume 01 : Number 279 In this issue: Re: DIY_EFI Digest V1 #277 Re: Hardened Valve Seats See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: talltom Date: Wed, 18 Sep 1996 21:36:50 -0700 (PDT) Subject: Re: DIY_EFI Digest V1 #277 >------------------------------ > >From: "Robert J. Harris" >Date: Tue, 17 Sep 1996 10:25:23 -0700 >Subject: Timing - Ignition > >Subject: Ignition timing in conjunction with EFI > >There appears to exist a number of sensors to build >an excellent self tuning EFI, yet the only sensor that >anyone talks about for ignition timing is a knock >sensor that just tells me - oops too much - >self destruct sequence initiated. Not me! I'm full of it! But I'll definetly have to agree with your synopsis so far! >Factory curves and random published curves are all >that most without dynes have to work with. Back in >the bad old days, (pre computer) the killer secret for >street tuning was to advance the static initial timing >watching rpm and vacuum, until you got the max >you could get and still start the engine, then put a >sping kit in adjust the mechanical until the total was >the same as what ever your guru of choice had >dicated. Look for ping or knock, then put some >more in. It works but had too much PFM (Pure F___ng >Majic) to be reliable for all engines. Since then, many >bandaid seem to have appeared. Hear here! The BS never stops! >Since we now have computers, we should be able to >monitor something other than self destruct imminent and >tweak and peak the timing in conjunction with the fuel >to get optimum power and economy. YEAH! >I truly hope that there are some good ideas out there. > All kinds of stuff! 84 Datsun z cars had a factory g-meter on board, although limited to .5 g's.(A good hard launch at the strip is at least 3g's.) It may be that the current gear may be needed to be taken into account, but I don't see it as mandatory. Vacuum is still a viable indicator, although one needs to consider that an efficient engine will be throttle per cyl. Another thing to keep in mind is system speed. To fast will read pulsations in vacuum, to slow will adjust timing after destruction, at which point it's immaterial. It would also seem to me that the thing should have a learn mode that would be able to tune for varying load.(In my case from 7000lb-17000lb, without trailer) I have to think that there is already out there somewhere some dyno loading/ running software that could be used to avoid reinventing the wheel. My inclination would be to set up a graph of rpm/vacuum and have the processor wiggle the timing and pulse width within a percentage to achieve best acceleration. It may even be possible to setup the jigling parameters so that they are done as a subroutine that is specifiable for a vacuum or rpm range.(Hope ya'll excuse the 1977 basic terminology:-) >Remember the Reichstag I do, and see the same mo happening frequently today. >- ---------- > ------------------------------ From: lambs@xxx.au (Stephen Lamb) Date: Thu, 19 Sep 1996 17:16:44 +1000 Subject: Re: Hardened Valve Seats >Wie Gehts? Just wanted to let you know I hadn't forgotten about the >seat >material. Checked the SAE books we have--specs for valves, but not >seats. Checked the General Motors Materials books, but no mention I One material used for 'hardened' valve seats is Stellite, which is a Cobalt based alloy. Also used a facing material on the valve itself. I can get specs if you want. Stephen Lamb Dept. of Defence DSTO, AMRL 506 Lorimer Street Fishermans Bend VIC 3207 Australia Tel: +61 3 9626 7525 Fax: +61 3 9626 7089 IZCC #180 ------------------------------ End of DIY_EFI Digest V1 #279 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".