DIY_EFI Digest Thursday, October 28 1999 Volume 04 : Number 607 In this issue: Air desity over temperature Re: DIY_EFI Digest V4 #606 Re: Intakes Re: DIY_EFI Digest V4 #605 Re: DIY_EFI Digest V4 #605 Re: DIY_EFI Digest V4 #606 Blowing Thru A Holley TBI New DRAC info 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 17:07:42 -0700 From: "Damon Kelley" Subject: Air desity over temperature Anyone out there have a formula for finding air density and or weight over temperature. Could really use this. Thanks. Damon Kelley 87 Shadow ES T1 A-520 Cold Air Induction, Bleedin' 89 Sundance N/A 89 CSX #208 26,000miles in 5 months or less 96 Sebring JXi Conv 96 CBR600F3 Soon to have cute little talon turbo ------------------------------ Date: Wed, 27 Oct 1999 17:19:30 -0700 From: rpettibo@xxx.com Subject: Re: DIY_EFI Digest V4 #606 Re: Intakes On the issue of single vs dual plane, I converted a 383 Chevy from a Edelbrock Performer RPM (Dual Plane) and Holley 750 (#3310) to an EFI using a Victor JR with sequential port injectors. Torque increased over 50 lb/ft and HP by 30. Both set ups were dyno tuned. From my experience the best air-flowing manifold is the one to go with for EFI applications. I know the runners on the Victor flow much better than the Performer on the flowbench. I don't remember what the numbers were but it was significant. The other VERY interesting thing about this conversion was an increase in maifold vacuum. With the carb I ran 12" at idle, which is about right with my solid roller cam (244in, 249ex @xxx. With the fuel injection I am at 15.8 - 16". Anybody see this on other applications? I still find it hard to believe. One thing is for sure injection is worth the price of admission. ------------------------------ Date: Wed, 27 Oct 1999 14:25:30 PDT From: "Bill the arcstarter" Subject: Re: DIY_EFI Digest V4 #605 Frederic Breitwieser wrote: >>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. I'm not so sure about this. The Holley 4DI contains a MAP sensor only good up to atmospheric. To run boost I think you'd have to put in a MPA good for 1 atm of boost (or whatever) and do some serious map hacking! - -Bill ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com ------------------------------ Date: Wed, 27 Oct 1999 17:30:30 -0400 From: Frederic Breitwieser Subject: Re: DIY_EFI Digest V4 #605 > I'm not so sure about this. The Holley 4DI contains a MAP sensor only good > up to atmospheric. To run boost I think you'd have to put in a MPA good for > 1 atm of boost (or whatever) and do some serious map hacking! Well, maybe through sheer luck, my friend has pickup with a paxton (mine actually) blowing through a Holley 4DI on a boring everyday ford intake on a boring every day 460. More than atmos, but it seems to enrich enough. He just can't get it to idle right, but I think that's his intake leaking, not the EFI stuff. - -- 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: Thu, 28 Oct 1999 08:08:47 +0800 From: dzorde@xxx.com Subject: Re: DIY_EFI Digest V4 #606 >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. You'll also need to reference the fuel pressure regulator to boost, unless its very little boost and the injectors can make up for the increase in ambient air pressure. Dan dzorde@xxx.com ------------------------------ Date: Wed, 27 Oct 1999 20:22:44 -0700 From: "Walter Sherwin" Subject: Blowing Thru A Holley TBI > >> 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. > You have to be really careful when blowing thru a Holley TBI unit equipped with their "B2" style injectors (which covers almost all of their TBI units, except for their one barrel OE replacement units which use Rochester TBI injectors). The Holley B2 injectors are very intolerant of even minor fuel pressure increases, and will completely shut-down (ie: no fuel at all) at just over Holley's rated fuel system pressures. Basically, the magnetic forces and components within their injectors do not have enough "oomf" to open the ball/seat combo against the increased internal hydraulic forces created by increased fuel pressure levels. Here's a real world example (as tested on my wet flow bench) of why this is important to know................ A Holley 900 4bbl TBI is factory equipped with four B2-80 injectors mounted in a fuel injector "pod". These injectors are designed to be driven via four individual 4/1 amp peak & hold current drivers, at a max fuel system differential pressure of 15psig. Under such conditions, this setup will deliver about 310 #/Hr of max fuel through the pod casting's inlet port. In a naturally aspirated draw-thru configuration this would easily satisfy the requirements of say a 600'ish HP engine, which is well within the confines of Holley's conservative 500'ish HP rating for this unit. However, crank the fuel pressure to 18psig and you will note that the injector response/linearity begins to seriously degrade. Crank the fuel pressure to 20psig, and you will note that the injectors begin to visibly and intermittently cut-out and refuse to open. Crank the fuel pressure to 22psig and you will note zero fuel flow. This situation is worsened (happens sooner) by both hot operating environments, and reduced current levels. Reduced current levels?...............If you attempt to operate two B2-80 injectors in an electrically parallel configuration, attached to a common 4/1 amp driver (ie: typical two channel GM TBI boxes, and others), then each injector will effectively experience 2/.5 amps of driving current, which will seriously degrade both the response characteristics and the fuel pressure tolerance of each injector. Now, in an artificially aspirated blow-thru configuration, you must remember that the fuel pressure differential across the injector has to be "referenced" to the local air pressure (boost) at the injector tip (just upstream of the throttle blades) in order to at least maintain a somewhat consistent rate of fuel flow for a given injector duty cycle. If your particular combination of boost, regulator gain, injector duty cycle requirements, and net fuel flow requirements necessitates fuel injector pressures above 18psig then your setup WILL NOT WORK!!!! Also, you should know that the Holley B2-80 injector is the largest flowing injector on the face of this planet that will readily fit within the Holley injector pod. If you absolutely must have more flow and/or pressure then you will have to machine your own injector "pod" from a chunk of aluminum in order to house alternative TBI injectors. This is no small task, and is fraught with other spray pattern problems, as most of the alternative TBI injectors (ie: Bosch, Rochester, etc...) have much wider spray angles and wind up spraying a large portion of their fuel charge very "high" on the bore walls. Mind you, the prevailing blow-thru boost/heat/flow usually remedies this little quirk under most driving conditions. For reference, most of the Rochester TBI's that I have tested can be run continuously at 50psig with a 4/1 amp current driver, and for bursts at 70psig. Sorry to ramble......... Bye; Walt. ------------------------------ Date: Wed, 27 Oct 1999 23:05:59 -0400 From: Shannen Durphey Subject: New DRAC info Dracnfo.zip has been replaced by DRAC2.pdf. It's a large file, so be prepared for long d/l time. The future may bring a "lite" version, if there's enough interest. I have to share the credit for the file, but unfortunately I can't mention any names. If this bothers you, DON'T USE THE INFO. Shannen ------------------------------ End of DIY_EFI Digest V4 #607 ***************************** 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".