DIY_EFI Digest Monday, October 18 1999 Volume 04 : Number 587 In this issue: Re: DIY_EFI Digest V4 #586 RE: EFI for 71 vette See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Sun, 17 Oct 1999 14:12:31 -0600 From: bearbvd@xxx.net (Greg Hermann) Subject: Re: DIY_EFI Digest V4 #586 >DIY_EFI Digest Sunday, October 17 1999 Volume 04 : Number 586 > > > >In this issue: > > Re: DIY_EFI Digest V4 #584 > >See the end of the digest for information on subscribing to the >DIY_EFI or DIY_EFI-Digest mailing lists. > >---------------------------------------------------------------------- > >Date: Sat, 16 Oct 1999 23:39:47 -0400 >From: "Gary Derian" >Subject: Re: DIY_EFI Digest V4 #584 > >I haven't seen it but I've heard about it. It seems to me to be similar to >what Greg H described in having an expansion chamber to fool the exhaust >into thinking it has reached the end of the pipe. Also the megaphones cause >pressure waves to be reflected back to the engine over a larger rpm range. >4 stroke motorcycles have used megaphones. The design is not quite like a 2 >stroke pipe, though. I don't think a 2 stroke style will work on a 4 >stroke. A megaphone is also a pretty effective (and efficient) device for converting gas velocity back into static pressure. Since the atatic pressure at the end of the megaphone is pretty much equal to atmospheric, that means that the convergent (nozzle) point of the collector, at the small end of the megaphone, will be at a static pressure below atmospheric, and the engine will effectively be running against a lower back-pressure than it does without the megaphone. As always--lower backpressure equates to less pumping losses in the engine, and therefore higher net output, particularly at high engine speeds/flows. Greg ------------------------------ Date: Mon, 18 Oct 1999 01:00:54 -0700 From: "Mike" Subject: RE: EFI for 71 vette what kind of throtel body are you going to run? Im interested in doing a efi for a 454 im building. Right now im doing a 72 chevy p/u with a tpi. what kinda cars did th 7730 come in? mike > Date: Sat, 16 Oct 1999 19:39:08 -0700 > From: "Carl Summers" > Subject: EFI for 71 vette > > Hi Doug, > There are some really nice units out there but I still haven't seen > anything I like(under $5000.00) better than a GM computer for a daily > driver,,,it offers you closed loop for better gas mileage, spark knock > control and even checks for octane upon start up to just name a > few.....the > downside is without software to make the job easier you have to do a bunch > of work in hex once you locate the tables..(the breakdown of the 7730 is > completely available) Use any manifold you want, get the correct size > injectors(we can help with that) Use a Gm distibutor and > sensors,,,,you can > buy an eprom burner and erasure cheap on ebay( http://www.ebay.com ) do a > search under eprom....I will go into further detail on how to do > this job if > you are interested...I am currently doing a 68 camaro with a 396 multi > port(my own, basically a tunnel ram and a custom plenum) and am > even having > the GM 7730 control the fuel enrichment and spark table for the > nitrous(still working on that but close) This car should run 11's without > nitrous and 10's with(traction a factor)......ttyl > - -Carl Summers > p.s. you can do this very reasonable and have an awesome RELIABLE > system.....check the aftermarkets failure rate....then think again about > using a proven GM system...... > > ------------------------------ End of DIY_EFI Digest V4 #587 ***************************** 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".