Post by thread:[TECH]: What is involved in making a selectablecyl

Back around 1980, Ford Cleveland Engine plant that made the 302 C.I. D. (5.0) 1955- 1996 (now makes the 2.5L 4 OHC V-6), as a demonstration what could be done with the cast iron V-8, to try and sell to management what the plant could do at very little extra setup costs, made several inline 4 cylinders. Some of the issues were: Firing order of the cylinders so you got even power pulses. To change one needs a custom camshaft, it's not just moving sparkplug and injector wires around. Balance of crankshaft and other moving components. Airflow in intake manifold. These are designed for the pulses of air to each cylinder melt together for smooth flow through the intake system. In the case of a carburetter, it's design may not allow the low air velocity of half the cylinders. For injection, their probably is a mass airflow sensor that would have similar issues,and the computer might not know how to handle that situation and generate an error signal (OBDII code) Long term valve stem wear since some of the lubrication comes from the fuel. There are plenty of small engines around that could be fitted to vehicles, but that may not result in better mileage. My experience has been a big engine, driven reasonably will get at least and probably better mileage with optimal gearing. Our 1996 Ford Bronco weighs 5300 lbs, 5.8L cast iron V-8, 4 speed overdrive automatic tranny, torque convertor lockout, cruises at 65 mph at 1500 RPM on very little throttle, easily 18 MPG. It goes up and down hills staying in overdrive with the converter locked. Best mileage was Atlanta to Cleveland was 24.2 MPG with many miles at 35 - 45 mph parkway, and easy interstate. This is with the 4WD front hubs unlocked. With them locked mileage drops at least 3 MPG (17%). And if you don't mind a little gas guzzling, 0 - 60 mph is 9 seconds for that heavy iron! I would look in other directions than cutting cylinders off. The vehicle has air and mechanical drag, thinner lubricants, some low friction tires are available. A properly tuned engine, which today means sensors (oxygen, temperature, mass flow, etc.) that are feeding the computer data in proper calibration. In the air drag, many little things will add up, and don't have good input on that, other than check out the homebuilt aircraft area, in particular the Longeze. There are some real gurus in that arena. Check after market equipment, if it's a small vehicle the"Tuner" area, larger try Summit Racing. Not all the equipment in those areas is for the drags. M.L. wrote: {Quote hidden}> First of all, don't do it if you rely on the vehicle.. > I think you can just disconnect the fuel injectors on one bank of > cylinders (one group of 4 adjacent) > This is done for thermal reasons I believe. Cadillac has been doing > this for a long time. The issue is that you don't save 50% of fuel > because the pistons are always going up and down, and that's a lot of > friction. If I had a big old V8 to try this on, I would. I'd be very > interested to see what your results are. > I think I would put 4 DPDT relays one on each of the 4 injectors (normally ON) > Start the engine, and see what happens as I sequentially turn off the > 4 injectors. The ECU will probably go crazy, don't you think? > > - > ML > > > On Mon, Dec 29, 2008 at 7:26 PM, Michael Algernon <spam_OUTpicTakeThisOuTnope9.com> wrote: > >> What is involved in making a internal combustion ( gasoline or >> diesel ) engine with '"n" cylinders operate on "n" divided by two >> cylinders ? Does one just turn off the injectors ? Are there other >> requirements ? Does one vary the cylinder usage to reduce noise and >> wear ? Can a DIY meddler attempt such a project on a 1997 8 cylinder >> gasoline fueled SUV ? What are the fuel saving ramifications ? >> Ideally I would like to drive around on "4" cylinders and switch to >> "8" cylinders to pull a trailer. >> MA >> >> WFT Electronics >> Denver, CO 720 222 1309 >> " dent the UNIVERSE " >> >> All ideas, text, drawings and audio , that are originated by WFT >> Electronics ( and it's principals ), that are included with this >> signature text are to be deemed to be released to the public domain as >> of the date of this communication . >> >> --

There are at least 6 variations of fuel injection for gasoline engines out there. 1: One injector at the throttle body ( where the throttle butterfly is located) Early Ford Escorts (1981 >>)had this. The Injector sprays continually at varying rates. 2: Mechanical fuel injection, I don't know about this, but I think they have a mechanical injection pump, like some (many newer are electronic injected) diesels with a nozzle before each intake valve. Don't know whether these sprayed continuously. Not really sure about -Early after market (Hilborn), Mercedes (300SL), Corvettes?? Had this. In the mid 1950's the electronis as we know them today were non existent. :) 3: EFI (Electronic fuel injection) - Each injector was located before an intake valve, sprayed continuously at varying rates. Became common in 1980's. My 1989 Ford Bronco with 5.8L Windsor (Ontario, Canada) engine had this. 4: SEFI (Sequential Electronic fuel injection) - Each injector located before an intake valve, Sprayed intermittently, timed to spray only when intake valve open at varying rates. Became common in early mid 1990's. My 1996 Ford Bronco with 5.8L Windsor (Ontario, Canada) engine has this. 5: I have seen recently some manufacturers (BMW, Mercedes ??) advertising direct fuel injection. I am assuming this is like a diesel engine where the injector sprays directly into the combustion chamber. If that is the case, possibly spark plugs are not required. 6: A constant pressure pump with a throttle body that regulates fuel pressure (flow) with throttle opening and vacuum. Fuel is distributed to all nozzles located before each intake valve. Fuel flows to all nozzles all the time. Most injected aircraft engines use this method. The move to more efficient injection method has been very slow due to reliability (an engine failure is not pleasant) and certification issues. Sean Breheny wrote: {Quote hidden}> Hi Howard, > > I believe you are correct about injecting into the intake manifold BUT > I was under the impression that the injector timing still mattered so > that must mean that the fuel/air mix is sucked into the cylinder very > fast, so it may still be specific to each particular cylinder. > > Sean > > > On Fri, Jan 2, 2009 at 10:22 AM, Howard Winter <.....HDRWKILLspam@spam@h2org.demon.co.uk> wrote: > >> Also, while diesel engines inject direct into the cylinders petrol injection sometimes (usually? always?) injects into the inlet manifold, so you can't just stop a >> particular injector and expect that to exactly starve one cylinder - remaining fuel vapour in the manifold could result in a very weak mixture entering the cylinder, >> with possibly detonating results - or unburnt fuel passing out into the exhaust. >>

Yea, Dodge, does fancy stuff, but misses the easy stuff. Nearly every Dodge pickup I drive behind, I can see the front axle U-joints turning. while they drive down the highway. That's a lot of drag. With the front hubs locked on our 4WD vehicles, the mileage was down more than 25% compared to hubs and transfer case in neutral. Herbert Graf wrote: {Quote hidden}> On Fri, 2009-01-02 at 15:22 +0000, Howard Winter wrote: > >> Having (say) a V8 running on 4 cylinders doesn't make economical sense, because you'll need the same energy from the 4 cylinders to achive the performance your >> right foot is demanding, and the 4 non-running cylinders will be wasting energy as air pumps - all the suck-squeeze-nobang-blow energy would be wasted. Added >> to which you're pumping slightly warmed air into the exhaust system, which would upset the electronics trying to set the mixture, and may cool down the catalytic >> converters to a non-working temperature. If you had a completely separate exhaust system for each half you could hold open all the exhaust valves on the >> non-running cylinders to minimise the pumping loss, but it's still not zero. But I still thing the only time you'd be saving fuel would be while idling in traffic. >> > > FWIW, "shutting off half the cylinders" is done with some engines, and > works. The Dodge Hemi (5.7L) comes in a version that can shut off half > the cylinders when not needed. There are various names for this > technology: > > en.wikipedia.org/wiki/Variable_displacement > en.wikipedia.org/wiki/Multi-Displacement_System > en.wikipedia.org/wiki/Variable_Cylinder_Management > http://en.wikipedia.org/wiki/Active_Fuel_Management > > The technology DOES work. However, the fuel savings are no where near as > good as some hope for. I've seen numbers between 5 and 20% savings. > Doesn't sound like much, but considering we're talking about some > engines that normally consume 14-16L/100km on the highway, this can be a > substantial savings over a fleet. > > A friend of mine has a car with MDS. His usage on the highway goes from > 16L/100km to about 13L/100km (MDS has the most effect on light load > driving, i.e. cruising on the highway). TTYL > >