DIY_EFI Digest Wednesday, 11 September 1996 Volume 01 : Number 269 In this issue: RE: Ancient History Re: O2 Sensor-Leaded gas [none] [none] re: Re: hi compressions re: Re: hi compressions Re: more water injection Re: Water Injection for power? water injection interesting web site re: Fuel Economy Re; Ancient History re: re: Propane Injectors Re: Re; Ancient History Re: Playing... Re: Ancient History Radial- Diametral Head See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Markus Strobl Date: Tue, 10 Sep 1996 14:39:53 -0500 Subject: RE: Ancient History > Its = > a real shame only having 1.5 litres (but my body weight is so low I = > still get performance enough to scare me down the little lanes). > > Mark I thought having *negative* body weight was in violation of the laws of physics? :-) - ------- Markus '96 Z28 w/ mods. Proof that OBDII is not the end of performance. ------------------------------ From: Markus Strobl Date: Tue, 10 Sep 1996 14:52:55 -0500 Subject: Re: O2 Sensor-Leaded gas > Is the O2 sensor affected by leaded gas or is it just the cat conv? me > *************************************************************************** > * Mark Eidson Voice: (602)752-6513 * The O2 sensor will fail. Not after the first tankful but within a few months. The Cat will get clogged both with lead and also with soot since the O2 sensor will start sending weird data to the PCM/ECM. Markus ------------------------------ From: cloud@xxx.edu (Tom Cloud) Date: Tue, 10 Sep 1996 15:56:59 -0500 Subject: [none] ------------------------------ From: cloud@xxx.edu (Tom Cloud) Date: Tue, 10 Sep 1996 15:55:07 -0500 Subject: [none] ------------------------------ From: "Woodd, Michael" Date: Wed, 11 Sep 1996 09:17:00 +1200 Subject: re: Re: hi compressions >You could spline a single shaft to keep it from spinning also. But, valves >rotate now by design, right? Why, and what would happen to an oddly shaped >valve that couldn't rotate? >- --steve I guess your thinking that cos valves rotate, that they more or less self-lap themselves to ensure a continued seal over a longer period of time. Probably right too, I guess only experimentation would show to what extent. Mike ------------------------------ From: dave.williams@xxx.us (Dave Williams) Date: Tue, 10 Sep 1996 06:52:00 +0000 Subject: re: Re: hi compressions - -> Well there are a few engines out there that have valves that DON'T - -> rotate. These are the old Boss engines from Ford (302,351 and the - -> 429). These valves are held in place by keepers that pinch the valve - -> stem (ie the keepers don't butt against eachother). Actually, the vast majority of engines are like this. Engines with valves free to rotate are the exception. ====dave.williams@xxx.us========================DoD#978======= can you help me...help me get out of this place?...slow sedation... ain't my style, ain't my pace...giving me a number...NINE, SEVEN, EIGHT ==5.0 RX7 -> Tyrannosaurus RX! == SAE '82 == Denizens of Doom M/C '92== ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Tue, 10 Sep 1996 18:10:19 -0500 Subject: Re: more water injection >> OK, here's a really dumb (but interesting to me) question: If water >> injection is so great, why is water in the gas considered so bad? [ snip ] >I am led to believe that the reason you do not want water in the >petrol tank is that water is heavier than petrol, and will therefore >sit at the bottom of the tank and make it go rusty. [ snip ] good grief! water and gas don't mix!!! that's why the water has to be squirted in whilst the intake is open. adding methanol, isopropanol, or ethanol doesn't get rid of water in the tank and fuel lines, it allows the water to dissolve into the alcohol / gasoline mixture (I think it's called 'miscible' in chemistry class). tom ------------------------------ From: Arnaldo Echevarria Date: Tue, 10 Sep 1996 19:23:33 -0400 Subject: Re: Water Injection for power? >I Remember two relevant curves - holding fuel constant, power went up >linearly with water on a percent by percent basis. 100% fuel 10% water, >+ 10% power etc. until a practical limit of about 50% was reached. > >Holding power constant, each percent of water displaced a percent of >fuel until about a 50 50 ratio was reached. So if I went out to my car and fed my 455ci engine a 50/50 mix of water/ fuel I'd get the same power? I have a hard time believing this at full throttle - plus I cant afford that much water :(, but will it work for part throttle, ie cruising, speeds? I think I can get around the mineral buildups with a weekly trip to the track w/ high octane gas..... >WTF does it work? 70% plus of chemical energy released by combustion >leaves the engine as excess heat. Absorb any of that EXCESS heat and >turn water to steam and you gain either power or fuel economy or both. But won't the added water particles reduce the ability to create a complete combustion? > >PS Ever wonder what is really going on during combustion. Check the >pressure temp curves of the three major gasses present after combustion. >CO2, N2 and H2O. Check out how much partial pressure each contributes >to the mix. Then remember, that as a rough approximate, one gallon of >gasoline makes 2 gallons of water in the exhaust. That much water comes out of my tailpipe? Arnaldo ------------------------------ From: jac@xxx.us Date: Tue, 10 Sep 96 17:17:03 PDT Subject: water injection Within the last few months I read an article about recent efforts to perfect an agent to maintain naptha and water as a stable colloid. In addition to being useful as a fuel, the criteria for acceptability include multiple transitions from high to low temperatures without separation. The magazine may have been MACHINE DESIGN. I believe that the University of Arizona and Caterpillar were both mentioned. Did any one else see the article? I would like to read it again. John Carroll - ------------------------------------- jac@xxx.us 09/10/96 17:17:03 ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Tue, 10 Sep 1996 19:06:35 -0500 Subject: interesting web site Check out http://reality.sgi.com/employees/rck/PhOR/01-Weight-Transfer.html It is a series of pages written by Brian Beckman on auto handling. ------------------------------ From: oecar1@xxx.au Date: Wed, 11 Sep 1996 08:54:22 +0800 (WST) Subject: re: Fuel Economy >>If you choose to run a 400+cid engine, then to produce the sort of >>power necessary for cruising (10-20 hp), you will be running >>relatively low manifold pressures compared to a smaller engine >>producing the same power. Remember, the manifold depression is >>un-recovered, therfore represents a power loss. > >At the same RPM? Could you clarify this? Exactly! at the same RPM >An engine requires a minimum a/f ratio to overcome frictional losses, >keep inertia (accel=0), and move the drivetrain not a/f ratio, this is constant at 14.7 or so, but a minimum fuelling level, or fuel flow rate (= power) >The manifold pressure is just a function of the throttle position and the rpm, >not of the load, at least I don't think. Manifold pressure is the best measure of load (aside from direct airflow measurement). That's why many people in the world use MAP sensors. >>The slower you spin the engine, then the higher the manifold pressure >>is for the same airflow (power), hence your pumping work (losses) is >>less. Dropping the axle ratio (numerically) will give you benefits in >>fuel consumption at the same (road) speed simply because you have your >>foot on the throttle harder (strange but true! :) > >Wait. You said that the higher the manifold depresion, the higher the >power loss. Now you say that the higher manifold pressure you get less pumping >work (ie better fuel economy)?? Now I'm really confused. Which is it? It's both! (I must apologise for the confusing choice of words) When I say manifold pressure, I mean Absolute Pressure, however manifold depression is measured relative to atmospheric pressure which is 101.325 kPa Absolute. Depression/Vacuum and Absolute pressure are effectively the inverse of each other. > >OK then you say that dropping your axle ratio gives you better gas mileage, >which I agree (when I went from a 2.79:1 final drive ratio to a 2.05:1 ratio on a 305 >I went from 16 to 21.5MPG). But then you say it is because you have your foot >on the throttle harder? No way. On that same car I remember barely touching >the gas when cruising at 75mph (about 2000rpm or so) when before I would have to get >on it at least 3/8 pedal. > OK, throttles are notoriously non-linear devices, and the characteristics at 2000 rpm are not the same as at 2720 rpm, therefore maybe you did have your foot less on the 'gas' but I bet your manifold pressure was higher (or your manifold depression/vacuum less!) ------------------------------ From: RABBITT_Andrew@xxx.au Date: Wed, 11 Sep 1996 09:05:46 est Subject: Re; Ancient History >I believe the point that is trying to be made is that if HP = Torque >only at 5252 (which is agreed). Then this is the only place where >they CAN both be a maximum. Not that they are a maximum. But that >this is the only point where they can both be a maximum at the same >time. OK, now try the calculation in kW and N.m and see if you come to the same conclusion! ------------------------------ From: RABBITT_Andrew@xxx.au Date: Wed, 11 Sep 1996 09:03:28 est Subject: re: re: Propane Injectors >>>> >>>> But diesel injection needs around 25,000 psi of fuel pressure, >>> >>>Aaah, I see why "EFI diesels" are only recently appearing. Do they >>>really use 25000 PSI?? I thought it would only be a few hundred >PSI. >>> >I questioned this too -- asked a diesel mechanic who said pressure >was 1700 to 1800 with upper limit of 2700. Maybe above figure has >one too many zeroes (I can tell you I used to work in very high >pressure area of a chemical plant and the 27000 number is W-A-Y out >of line!). Bosch Automotive Handbook (good reference for heaps of general questions guys!) say that "the fuel injection pump must supply fuel at a pressure of between 350 and 1200 bar" which works out to be between about 5100 and 17600 psi. ------------------------------ From: Matthew Lamari Date: Tue, 10 Sep 1996 21:13:38 -0500 Subject: Re: Re; Ancient History At 09:05 AM 9/11/96 est, you wrote: >>I believe the point that is trying to be made is that if HP = Torque >>only at 5252 (which is agreed). Then this is the only place where >>they CAN both be a maximum. Not that they are a maximum. But that >>this is the only point where they can both be a maximum at the same >>time. > >OK, now try the calculation in kW and N.m and see if you come to the >same conclusion! > That's where the lines cross for those units; but hp does not equal torque as their units are different. You could say two powers are equal, or two torques are equal, or two areas. . . . Yeah, I was having a strange time believing that 5252 was some sort of universal constant, when everyone knows the answer to life, the universe and everything is 42!! Matthew "References to Hitchiker's Guide to the Galaxy are purely irrational" Lamari ------------------------------ From: Darrell Norquay Date: Tue, 10 Sep 1996 21:34:47 -0700 (PDT) Subject: Re: Playing... At 08:04 AM 9/10/96 -0500, Mark Pitts wrote: >>Is there any reason why I can't build my own mass meter wth some nichrome >>wire, and a foot of 6" drain pipe? And Tom Cloud replied: >Okay, can I speculate too?? I know that liquid and gas measurements >have been made by using a heated wire (or thermocouple). The concept This is the way most thermal mass flowmeters work. Often, they use two identical thermistors, one in the aistream with a large enough current forced through it to cause self-heating, the other with minimal current at the same temp as, but not in the gas stream. Then, either measure the resistance difference, or servo the current into the sensor to maintain the same voltage as the reference, and measure the current. I read an application note somewhere about a group that made a relatively accurate flowmeter out of a couple of #47 panel lamps. They broke the glass envelope off one of them (sensor), and put it in the airstream, and left the other bulb intact (reference). Force a constant current through the two in series, and measure the voltage across the sensing element. This would be the ultimate in cheep MAF's! I'm not sure if the reference element was also in the gas stream, but I know they limited the current to a value low enough so they didn't burn out the filaments (no light). Let me know if you try this, I'd be interested in the results. regards dn dnorquay@xxx.com ------------------------------ From: Chuck Tomlinson Date: Wed, 11 Sep 1996 01:25:43 -0400 Subject: Re: Ancient History >I believe the point that is trying to be made is that if HP = Torque >only at 5252 (which is agreed). True. If power is measured in hp and torque in lb-ft, then the torque and power curves must cross at 5252 rpm. No exceptions. >Then this is the only place where >they CAN both be a maximum. Not that they are a maximum. But that >this is the only point where they can both be a maximum at the same >time. Not true. At peak hp, the torque vs rpm curve has a slope equal to (-Torque/rpm). That's the only requirement. So if the torque curve peaks at some rpm and assumes that negative slope immediately after the peak, then hp and torque will both peak at that rpm. In theory, that can occur at any rpm. In practice, it is unlikely to happen at all. Having peak hp and torque at the same rpm means that the torque curve *must* have a discontinuity in its slope. IMHO, this is so unlikely that it's difficult for me not to use the word "impossible". Math crap follows... P(ower) = T(orque) * n(rpm) * k(constant). In USCS, k = 1/5252. P = T * n * k. At peak hp, power curve's slope dP/dn = 0. But dP/dn = k * d(T.n)/dn = k * (T + (dT/dn * n)) So dP/dn = 0 when dT/dn = -T/n - -- Chuck Tomlinson ------------------------------ From: "Hans Hintermaier" Date: Wed, 11 Sep 1996 09:25:12 MET Subject: Radial- Diametral Head Hi head builders, because of the big resonance for the radial- diametral head of "Apfelbeck", I put the GIF images on the web. http://www.nefo.med.uni-muenchen.de/~hiha/gif/ The ISBN's and book titles are Ludwig Apfelbeck Wege zum hochleistungs Viertaktmotor ISBN 3 - 87943 - 578 - 2 and L. Apfelbeck / H. Weichsler Ventilsteuerungen fuer Hochleistungsmotoren ISBN 3 - 613 - 01272 - 3 Both have ~200-250 pages and cost around 25$ He discribes many simple ways to tune and new-build an engine. 40 valve curves for different purposes are added. Regards Hans hiha@xxx.de Munich / Germany ------------------------------ End of DIY_EFI Digest V1 #269 ***************************** 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".