DIY_EFI Digest Wednesday, October 27 1999 Volume 04 : Number 606 In this issue: Re: DIY_EFI Digest V4 #605 intakes continued.... Re: DIY_EFI Digest V4 #605 Re: DIY_EFI Digest V4 #605 DRAC Fuel Injector Query See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Wed, 27 Oct 1999 08:04:17 -0400 From: Frederic Breitwieser Subject: Re: DIY_EFI Digest V4 #605 David, > I am a complete boob when it comes to electronics, but I want to ask a couple of > questions anyway. Feel free :) > 1. How many junkyard ecu options are there for a fangled port injected EFI system for a > 511" twin turbo'd engine? [Sy/Ty only?] Well, if you can change the fuel, timing, and other maps inside a certain GM ECM, then that ECM is a good choice. Nothing I did can't be done on other ECMs... I just happen to have a lot of Syty ECM information, and an awesome programmer that makes it much easier. What forced my choice on using this particular ECM were the tools... not the ECM itself. I'm not a EFI programmer, and the more the tools are designed for "monkeys" the more I like them, being an EFI monkey myself :) THe limitation(s) of a particular ECM is the number of injectors, type and quantity of sensors, and how it interprets the sensors. A V8 engine can be run on many, many different ECMs. I just chose the 1227749 syty ecm. > 2. Can two throttle bodies be used with one ecu? [I need around 1000 cfm] Yes, I did this. I used two FWD 3.8L throttle bodies, one for each turbo (I had them in a pile, what can I say!), and removed the throttle plates and the "axle" they sit on, made a longer axle (metal rod), and my friend spot welded two homemade throttle plates to the new rod. Now, they two throttle bodies are interconnected, thus allowing one gas pedal to control two throttle bodies easily. The FWD GM throttle bodies are nothing more than a neck with one 2" or so disk that rotates on a shaft - - easy fangle. > 3. If a fangled system is out for me, due to any reason, can the aftermarket Holley TBI > systems be easily made to work with a blow through turbo deal? Yes, absolutely. From a fabrication standpoint pretend the holley TPI is a carbeurator, make a plenum box above it, attach turbo hoses, and crank away. Might need a blow-off valve to relieve pressure if you are at WOT and let off the gas suddenly, but that need would be on any system. - -- Frederic Breitwieser Xephic Technology 769 Sylvan Ave #9 Bridgeport CT 06606 Tele: (203) 372-2707 Fax: (603) 372-1147 Web: http://xephic.dynip.com/ ------------------------------ Date: Wed, 27 Oct 1999 08:08:03 -0400 From: Frederic Breitwieser Subject: intakes continued.... Howdy Doug, > I too was pondering this...I'd think that it really wouldn't matter if the > carb manifold was operating wet flow or dry flow...VE and Cylinder Filling etc > would be the same regardless...and the MPI will of course improve the fuel distribution... >From a runner dimension & torque curve standpoint, it wouldn't matter. A 12" runner is a 12" runner, but wet manifolds have other issues associated with them, as in fuel can pool in certain spots depending on the runner design. > However...in talking with Arizona Speed and Marine they suggested that a > single plane is better suited for a dry flow intake...even with a mild cam... I would agree - its also easier to bore and insert injectors, because all the runners (topside) are the same height. Dual planes often have their runners at different angles so it just makes the injector bung fabrication thing slightly more complicated. The Edelbrock streetmaster 383 I used is a low-rise (almost flat actually) single plane intake made of aluminum, that can flow to about 4000 RPM so Edelbrock says. They also said that intake "sucks" which is why they don't make it anymore. I found that amusing :) > in the air stream...it seems that the highrise dual plane should still perform > better at these milder engine speeds (below 6500)... That wold be my guess as well. - -- Frederic Breitwieser Xephic Technology 769 Sylvan Ave #9 Bridgeport CT 06606 Tele: (203) 372-2707 Fax: (603) 372-1147 Web: http://xephic.dynip.com/ ------------------------------ Date: Wed, 27 Oct 1999 08:07:24 -0400 From: "Gary Derian" Subject: Re: DIY_EFI Digest V4 #605 A dual plane intake is made that way to get good intake signal to the carb, i.e. each side of the carb gets every other intake pulse. If you have TPI, you don't need that balanced flow and can benefit from the more direct single plane designs. A high performance single plane will work well on even a mildly tuned engine. Gary Derian > > I too was pondering this...I'd think that it really wouldn't matter if the > carb manifold was operating wet flow or dry flow...VE and Cylinder Filling etc > would be the same regardless...and the MPI will of course improve the fuel distribution... > > However...in talking with Arizona Speed and Marine they suggested that a > single plane is better suited for a dry flow intake...even with a mild cam... snip > What am I missing...I would think that this new Edlebrock Performer RPM Air > Gap would be the best street manifold to convert to MPI for use with milder > cams such as above...the power band is 1500 to 6500 or so for a 350ci...and > the Air Gap design should help to cool the now dry air flow that is missing > the cooling effects of the fuel...it should be even better if a heat reducing > coating is added to it's bottom...and if it's used with a lifter valley shield... > > Shouldn't it? > > Am I missing something? > ------------------------------ Date: Wed, 27 Oct 1999 16:20:40 +0000 From: Ned Williams Subject: Re: DIY_EFI Digest V4 #605 Frederic wrote... > > Howdy Ned, > > >questions though, How did you get the Injector > >bungs lined up perfectyly?(or did you) the fab > >guys over at holley seem to express this as > >absolutly critical. > Thanks for the pics of the fuel rails,but I have one questions, Why did FI abandoned running induvidual fuel lines to each injector much like the old Kinsler and weber FI systems used to do? Wouldn't lines to each injector deliver a more reliable fuel pressure? not to mention easier to install? thanks Ned Williams P.s. the only lists you will find me on is this one ahd the IFSJA list ------------------------------ Date: Thu, 28 Oct 1999 12:00:36 -0600 From: cwagner@xxx.net Subject: DRAC Does anybody know anything about a DRAC used on GM vehicles? I believe that it is a ratio adapter. ------------------------------ Date: Wed, 27 Oct 1999 19:53:28 +0100 From: "Alan Smith" Subject: Fuel Injector Query The fuel flow rates for injectors are quoted by the manufacturers at a certain fuel pressure. What I haven't seen documented anywhere is how much the flow rates vary with inlet manifold vacuum, on a normally aspirated engine, or with positive air pressure values in the inlet manifold, as would be the case in supercharged applications. Has anybody experimented with how much flow rates vary with air pressure ? Alan Smith ------------------------------ End of DIY_EFI Digest V4 #606 ***************************** 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".