DIY_EFI Digest Saturday, 30 August 1997 Volume 02 : Number 298 In this issue: epoxies Re: injector bosses valve needed See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: James Weiler Date: Fri, 29 Aug 1997 22:41:14 -0700 (PDT) Subject: epoxies I just surfed the DuPont page and found a product called Vitron. They claim it to be the cat's meow for sealing and automotive fuel resistance. Anybody know anything? later jw ------------------------------ From: garfield@xxx.com (Garfield) Date: Sat, 30 Aug 1997 06:10:22 GMT Subject: Re: injector bosses On Fri, 29 Aug 1997 21:50:15 GMT, garfield@xxx.com (Garfield) wrote: >but "high temp epoxy adhesives" especially the >aluminum-filled varieties, would be ideal. OK, I posted a source for some high temp stuff in another post, but I thought I should clarify something that I noticed a couple of ya are assuming I meant. The fact that an epoxy is alum-filled doesn't of itself mean that the epoxy is high temp. There are lots of lower Tg epoxies that are alum-filled (which does help them to carry heat without as high a temp rise, if the epoxy is in the heat path). What I meant by the above, is that IF you start out with a high temp epoxy, that would work good in this application, and IF you could IN ADDITION find one that was alum-filled that would of course be even better. Clearer now? The alum-filling just makes the epoxy more physically stable (kinda like a course matrix of alum bonded with vewy vewy thin layers of epoxy) AND more thermally conductive, so if you have a hot part (a head) and a cool part (an injector, hopefully cool) then the epoxy's thermal conductivity helps it to not get so hot as heat is conducting from the head to the injector. Oh, you knew that's what I meant already? Well, then what did you read this for then, silly. 8) Garfield ------------------------------ From: john_carroll Date: Sat, 30 Aug 97 00:33:59 PDT Subject: valve needed I need suggestions for an appropriate, available and affordable valve to bypass some fuel from the distributor block in a port injected CIS system. The object is to manage the mixture control of an aircraft engine. The CIS system is from Airflow Performace and much like the old Bendix systems. This injection system is used because it is not dependent on electrical power. The main pump is mechanical. The pressure is set at 25 psi, so the distributor block pressure will always see <25. With the system I am building, the manual mixture control will always be able to override the electronic control, again relieving the system of ultimate reliance on electrical power. We electronically spark one plug per cylinder and let a magneto continue to operate the other for the same reason. The challenge is to find a valve that operates much like an injector so that a PWM signal can slightly modify the injector pressure. Other than power requirements, the flow rating of the valve is not critical,the flow can be controlled with an orifice. The valve needs to pass a maximum of 2 gallons of fuel per hour, so if the duty cycle is maintained at 30% for cruise, a valve rated at 7 gph and capable of following a signal from 4 to 8 ms wide repeated as often as every 25 ms would be perfect. Is this in the range of injector performance? Perhaps I could simply inject back into the fuel system, using an off the shelf injector but the fittings and hardware would likely require a lot of machine work. Perhaps a better alternative is to set the manual mixture control slightly lean and then inject a small amount of additional fuel into the induction system just past the throttle body with a conventional injector. Will the available devices operate at such low pressure? Is the hookup hardware available for a single isolated injector used in this fashion? I agree this is a simplistic approach, but it avoids modifying the existing hardware. Your thoughts? - ------------------------------------- John Carroll jac@xxx.net 08/30/97 00:33:59 ------------------------------ End of DIY_EFI Digest V2 #298 ***************************** 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".