DIY_EFI Digest Saturday, 24 February 1996 Volume 01 : Number 053 In this issue: Variable intake runners Re: Turbo Lag Re: GM Model 700 Throttle Body Injector Pulse Width Resolution 16 bit or 8 bit Re: Turbo Lag Re: B&S fuel-pump Re: GM Model 700 Throttle Body Re: FW: Buick DIS coil drivers other performance automotive maillists Re: Turbo Lag (electric Super charger) Re: Injector Pulse Width Resolution 16 bit or 8 bit See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: einarp@xxx.no (einarp) Date: Fri, 23 Feb 96 14:46:56 CET Subject: Variable intake runners Mark, So you have convinced me. Not that I hadn't expected this. But _how_ do I go about it the DIY way? Anybody done this? Hey! Where can I buy 6 cheap used trombones for hacking? Seriously, I imagine lots of problems keeping such a device from sucking false air in through the runner splices. What about using runners tuned for say 2000 RPM, to give me some more shove before the turbos cut in at 2000-3000? Using the web page that calculate runner lengths, I found that they would need to be really long to do that. Would that have any adverse effect at higher RPM? I realise I should have read the SAE paper(s), but I don't have them. (I'm a DIY'er you see. Not working in the automobile field at all.) Could you give some concentrated wisdom here? I will swap to an injected engine this spring, and next winter I plan on converting the current engine to injection. This will include making a new intake manifold to take the injectors, so I might as well make them the "optimal" length. I'm also "brainpicking" the Weber Marelli ignition and injection computers to gain some insight, and find what tables I can play with. Anyone here who know these units? Both the boxes have unused analog inputs, so it would be possible to influence them by hanging pots on these ports. (And modify the software to look at them of course.) > What do you think Mazda used to win Le Mans (1993 I think). Their >triple rotor engine had a servo system like you propose. They had a >serperate map just for inlet position (length). There is an SAE paper on >this I will see if I can find the number. F1 has used this for a while. I >think you guy's have to read more it's all out there if you look. - -- einarp@xxx.no ( Maserati Biturbo Spyder ) ------------------------------ From: ffmd@xxx.net (Charles North @ Function First Motorsports) Date: Fri, 23 Feb 1996 10:28:24 -0500 Subject: Re: Turbo Lag >What you are looking for is called an Anti-Lag System (ALS). It is >used in many rally-race cars that compete in the WRC. There are a >couple of different systems I have heard about, but the easiest to >implement requires only a modification to the ECU on the engine. > >This system actually causes an intentional mis-fire by not firing one >of the cylinders. The air/fuel mixture is still injected, and ends up >getting pumped out the exhaust. When it hits the very hot turbine >blades in the turbo, it ignites and works like a jet motor. > >The system is currently used on several Rally cars in the US. It is >supposed to keep the boost always running atleast 10-12 lbs. > >The biggest draw backs to this are the noise and the flames that shoot >out the exhaust. (I wonder how a Catalytic converter would react to >this.) > >-- >John Werner | Disclaimer: The opinions expressed here > INet: werner@xxx.com | are not necessarily those of my employer, > XNS: werner@xxx. > Work: (716)422-5054 Home: (716)436-3607 > >Hi John Interesting system, how difficult is this to implement into a system or should it be an add on. I am working with both Motronic and Electromotive units. Any imfo would be of great use. Charlie at Funtion First Motorsports ------------------------------ From: orin@xxx. Harding) Date: Fri, 23 Feb 1996 10:35:33 -0500 Subject: Re: GM Model 700 Throttle Body >that is regulator output pressure i have a haynes too >remember that car uses an intank pump that easily will generate 40 psig >when new the excess fuel is returned to keep the tb and lines cool. >its not easy to generate those pressure levels without an intank pump >this was disscussed a while back on this very forum. >question : are you using the mgs original fuel pump does yours >originaly have an electric one ? are you using the return line >on the t.b.? No, I'm not using the original pump..I'm using a Holly pump that they supply with their ProJection throttle Body injection system and I have installed a return line from the TB to the tank..The GM700 pressure regulator adjustment screw has been spot welded in place so I am going to drill out the spot weld and replace the screw so I can make pressure adjustments...I think the pressures you're talking about would be "dead headed" pressures and not "regulated" pressures. To adjust the pressure a guage would be placed in the supply line and with the return line connected, the pressure adjusted...Look at the Haynes book again and I think you'll see what I'm talking about.. Orin Harding - Greensboro, NC ('74 MGB-GT - '79 MGB Roadster with Electromotive TEC II) ------------------------------ From: Derrick Early Date: Fri, 23 Feb 96 12:06:29 "EST Subject: Injector Pulse Width Resolution 16 bit or 8 bit Hello diy_efi'ers How many bits should be stored in the lookup table for a injector pulse width map? Should I use 8 bits or 16 bits? I know 16 is better, but is it necessary? Yours, - -- Derrick Early early@xxx.mil ------------------------------ From: Clint Sharp Date: Thu, 22 Feb 1996 21:47:02 GMT Subject: Re: Turbo Lag In your message dated Thursday 22, February 1996 you wrote : > Hello all, Hi > Motec injection system fitted. An idea which we have been discussing is > injecting fuel into the exhaust manifold during periods of closed throttle > in order to keep the turbine speed up and reduce turbo lag. > Has anyone tried something like this? Ford Motorsport in the UK use just this technique on their Escort Cosworths if my memory serves me correctly. > Would the burning fuel damage the > turbine blades? Probably, but with mega money and re-builds between events, I suspect they don't really care about killing a turbo or three. > What type of injector would be suitable? (maybe a Diesel > injector.) I don't think they use an injector, just let a cylinder misfire. > All ideas appreciated! Don't try this at home. > Chris Howard > Mechanical Engineering > University of Sydney > email: choward@xxx.AU > Web: http://www.usyd.edu.au/~choward Good luck, hope you have deep pockets if you try this! - -- We apologise for the lack of coherent humorous comments. Normal service will be resumed shortly. clint@xxx.uk ------------------------------ From: "Jim Staff" Date: Fri, 23 Feb 1996 22:14:21 GMT Subject: Re: B&S fuel-pump In message <144BFA177C2@xxx.de> writes: > > Jim Staff wrote on Sat. Feb. 17 > >...... for my single cylinder 3.5 HP Briggs & Stratton engine .. > > I would be interested what kind of fuel-pump i could use on my 10HP > '56 NSU single. It's alternator brings 6V, 60W, and there is no space > to build in a larger one. 12 V would not be the problem, I have got a > 6V to 12V DC-DC converter. > I believe that the fuel pump really doesn't matter. As long as you have a fuel rail with a pressure regulator. With the regulator set to the desired pressure. A 10 HP engine should have no problem taking standard pressures from a car fuel pump. Jim Staff ------------------------------ From: arthurok@xxx.com (ARTHUR OKUN ) Date: Fri, 23 Feb 1996 15:13:22 -0800 Subject: Re: GM Model 700 Throttle Body DONT ADJUST THE TB REGULATOR ADJUSTMENT I AM SURE ITS OK i will check the specs on that holley pump in a summit catalog over. ------------------------------ From: jwharris@xxx. Harris) Date: Fri, 23 Feb 96 18:26 EST Subject: Re: FW: Buick DIS coil drivers >training manual, publication 16009.10-1. Mine is dated 1986. The operation of a >number of other peripherals is covered as well as wiring diagrams and signal >descriptions. > >The coil base is controlled by several signals and emits a 6 pulse per revolution >tachometer signal. > >Timing comes from a notched disk that stimulates a cheap ($20) probe to produce a >positive then negitive pulse at six symetrical locations pluss one additional, oddly spaced >notch to track tdc/tbc of cyl #1. This is the 3.1, 3.4, 3.4 DOHC sensor. The Buick 3800 module uses an 18x hall sensor and a 3x sensor which produces three pulses of unequal width. refer to the manual described above. If you want to distinguish between cylinders you will have to look at the cam >with another sensor. - ---------------------------------------------------------------------------- J.W. Harris Delco Electronics Corp. Project Engineer One Corporate Center Powertrain Electronics M.S. CT40C Kokomo, IN 46904-9005 jwharris@xxx.com jwharris@xxx.com Of course, all responses are my own and should not be mistaken for those of Delco Electronics or General Motors. ------------------------------ From: Brad Martin Date: Fri, 23 Feb 1996 22:37:34 -0500 Subject: other performance automotive maillists Can anyone tell me of other performance related mail list servers? Racing related? I enjoy the diy_efi list & would like to see similiar stuff for other related topics... Thanks in advance! Brad Martin bmi CAD Services 8E Herman Drive POB 522 Simsbury, CT 06070-0522 ==== Also, you may want to check out: http://www.win.net/bmicad/welcome.html http://www.win.net/bmicad/strahome.html http://www.win.net/bmicad/nehahome.html http://www.win.net/bmicad/icetrial.html ------------------------------ From: MTaylorfi@xxx.com Date: Sat, 24 Feb 1996 01:42:13 -0500 Subject: Re: Turbo Lag (electric Super charger) Let's see. Takes about 10 hp (at a bare minimum) to run, which translates to 7500 watts. Divide 7500 watts by battery voltage (i.e. 12 volts) and whamo 625 AMPS!!!! This I gotta see!! See ya, Mike ------------------------------ From: MTaylorfi@xxx.com Date: Sat, 24 Feb 1996 01:57:33 -0500 Subject: Re: Injector Pulse Width Resolution 16 bit or 8 bit Hey there, On my working DIF system (MAF sensor) I use 8 bit for pulse width resolution. 8 bit gives you 0.4% step resolution, while 16 bit gives you an overkill of 0.002%. Keep the math simple, plus you only need 14.7 to 1 ratio, not 14.700000 to 1. See ya, Mike ------------------------------ End of DIY_EFI Digest V1 #53 **************************** 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".