DIY_EFI Digest Thursday, November 25 1999 Volume 04 : Number 661 In this issue: Peak and hold injector drivers Re: Peak and hold injector drivers See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Wed, 24 Nov 1999 14:30:32 -0800 From: garwillis@xxx.com (Garfield Willis) Subject: Peak and hold injector drivers On Wed, 24 Nov 1999 10:27:48 -0500 (EST) Andris wrote: >I'm upgrading from my 30 lb saturaturated SVO injectors to 75 lb/hr peak >and hold injectors. The batch fire DFI is meant to use saturated >injectors. Rather than spend $400 on the Accel VIC to drive the low >impedence injectors, is there a (much) cheaper way to do this? I figured >if an injector driver uses the saturated signal from the DFI as an input >it could spit out the peak/hold signal. Timing issues aren't critical, >since it is still a batch-fire system. Thanks for any help/insight :) Those sound like pretty big whoppers, but the Cherry Semi CS-453 Injector Solenoid Drivers might still work for you. They are a 4Apeak/1Ahold devices, which I've used the smaller variety of (CS-452) on some ordinary peakNhold mpfi injectors. They have alot of nice attributes going for them (logic-level inputs, tho the inputs can swing between supplies, load dump safe, wide supply range, heat sink tab is ground), and yes you could easily drive their inputs from a previous ECM output driver for sat injectors, except the polarity is wrong (they're low = on), and would require an inversion (CS drivers are high = on); that is easily done, tho. After talking to Dr. Pelican about the Accel box, I was thinkin bout making some of these as another product; but it appears the Accel box also includes timing-per-injector to allow pulse stretching/narrowing. The real question I have is just how necessary/desirable is THIS particular pulse stretching/shrinking feature, or would there simply be a place for 4/6/8 ganged "translators" from SAT to PnH? Admittedly, in EITHER case, these gizmos are mostly a packaging issue, not much of a circuit design problem, so it's not atoll clear it makes sense to "productize" them. The thermal/vibe design of the packaging is probly the most important thing, really. I guess I'm really wondering just how safe/effective/useful/sane it is to consider tweaking your fueling by an overall shrink/stretch of the injector's pulse width? Sounds like an awfully global whack to the fuel map; under what conditions is this hitting the nail on the head, or is this a case of the proverbial "hitting a big nail, not quite on the head"? Gar ------------------------------ Date: Wed, 24 Nov 1999 20:10:12 -0500 From: "Bruce Plecan" Subject: Re: Peak and hold injector drivers - ----- Original Message ----- Subject: Peak and hold injector drivers Man, that is a ton of injector. At a glance 1200HP... How close to dialed in with the 30's we're you?. How much boost have you been running?. Batch firing, yeha Grumpy | >I'm upgrading from my 30 lb saturaturated SVO injectors to 75 lb/hr peak | >and hold injectors. The batch fire DFI is meant to use saturated | >injectors. Rather than spend $400 on the Accel VIC to drive the low | >impedence injectors, is there a (much) cheaper way to do this? I figured | >if an injector driver uses the saturated signal from the DFI as an input | >it could spit out the peak/hold signal. Timing issues aren't critical, | >since it is still a batch-fire system. Thanks for any help/insight :) ------------------------------ End of DIY_EFI Digest V4 #661 ***************************** 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".