DIY_EFI Digest Thursday, August 12 1999 Volume 04 : Number 463 In this issue: Re: Home Dyno Re: DIY_EFI Digest V4 #462 wiring diagrams See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Wed, 11 Aug 1999 11:07:06 -0500 From: Clarence Wood Subject: Re: Home Dyno I have just received an update notice from "Mike Glover" 1982 280ZX Turbo GL 1966 El Camino 1982 Yamaha Maxim XJ-1101J Motorcycle 1975 Honda CB750 SS (black engine) 1986 Snapper Comet lawn mower Clarence Wood Software&Such... clarencewood@xxx.net Savannah, TN. ------------------------------ Date: Wed, 11 Aug 1999 19:11:25 -0600 From: bearbvd@xxx.net (Greg Hermann) Subject: Re: DIY_EFI Digest V4 #462 > >Date: Tue, 10 Aug 1999 16:56:01 -0600 >From: "Kevin Yachimec" >Subject: Re: Turbo header design > >I missed the part of this post that stated the intended use of the vehicle >in question, so the following information may not apply. >If the header/manifold is for a street turbo application there is no >measurable gain by using a tuned the length header unless you using a pulse >type turbine and housing designed for receiving exhaust pulses. Most turbos >you find on production vehicles have the best results if the manifold >smoothes out all the pulses into a constant flow with heat lost being >minimized. I have a promotional paper from Allied Signal outlining manifold >design for their turbos. It covers both their new pulse type turbos (like >the ones you see on all those 10 second Honda's with equal length headers) >and their standard turbos, if I can find it I'll post it 'incoming'. > >>Greg Hermann wrote: >> >> >> FOR THIS PARTICULAR V-8> (IT HAS A 90 degree crank) >> > Firing order >> > 1 8 4 3 6 5 7 2 >> Kevin-- I don't remember how far back in the archives you must have dredged to get that post, but it applies to about any kind of engine service, if one cares to spend the money, do the work and can fit the headers into the vehicle. It applies to turbo headers just as well as to NA headers. A "pulse" type turbine is a crutch to get better turbine performance at lower speeds and pressure ratios as a trade off against top-end performance. A header of the type I described will let the ENGINE perform the best. A turbine will perform most efficiently if it has a steady flow rate through it. The way to get from a to b is to empty the header collector into what is known as a pressure recovery accumulator--basically a device which evens out the gas pulses before feeding the gas into the turbine. This evening out is essential to turbine efficiency because the turbine funtions most efficiently with an inlet velocity in the Mach 0.75 neighborhood. Too much pulsing with that sort of a flow rate, and the nozzle begins to get choked (reach a flow velocity of Mach 1) at the peak of the pulses, with the attendant backpressure and efficiency problems. A variable vane turbine is a much better solution to the (poor efficiency at below design flow rate) problem than a pulsed type turbine, because it gives far better low flow response and efficiency than a pulsed flow unit ever dreamed of having without compromising the top end flow situation. Garrett has been working on VATN turbos for some time now, and apparently does not have them quite right yet. I suspect that their published opinions on the subject may change as their product development cycle progresses. You might check out Obert's info, brief though it is, on pulse turbos , pressure recovery accumulators, etc. Very interesting stuff. As to the headers--almost exactly what works best on an NA engine will also work best on a turbo motor. Only small dimensional changes, so as to accommodate the higher flow losses which happen with a denser fluid (bigger tubes) are necessary. Otherwise, the intake/engine/header system operation with a turbocharger is really no different from operating the same engine at the bottom of a very deep mine with no turbo. A log type exhaust manifold on a turbo motor will degrade performance, compared to headers, just as much as it would on the same engine at the bottom of a mine. The performance degradation is roughly the same, percentagewise, as it would be on an NA engine at sea level. Regards, Greg ------------------------------ Date: Thu, 12 Aug 1999 21:02:39 -0600 From: cwagner@xxx.net Subject: wiring diagrams I appreciate all the help I got when looking for some wiring diagrams, thanks. Know, so I don't have to bother you as much as I have been, where could I get a book with nothing but wiring diagrams for nothing but fuel injection. I have part of one of these books but half of it is missing. The book is put out by a company named Hygrade Division of Standard Motor Products Inc. and made by Mitchell International. I would like to get an updated and complete book like the one I have. ------------------------------ End of DIY_EFI Digest V4 #463 ***************************** 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".