Fuel Usage Modification
I've got a V8 VS commodore sitting around collecting rust, so I am thinking of doing something with the fuel injection system, I am going to throw this out there and I wouldn't mind some feed back.
Concept:
Retro-fitting a V8 EFI motor to run on 4/6 or 8 cylinders to save on fuel consumption during city/daily driving. By restricting how much fuel is injected we restrict how much we consume.
Method:
Injectors receive an electrical signal to inject fuel into the cylinder chambers in an engine. By using relays and switches we will cut off the electrical signals to two cylinders at a time.
A three position switch will be required and six relays (one per injector).
Switch position 1 will cut off 4 of the 8 injectors (4 Cylinder equivalent)
Switch position 2 will cut off only 2 of the 8 injectors and;(6 Cylinder equivalent)
Switch postion 3 will be Full time 8 injectors (All 8 Cylinders)
Now before we go on this journey, I will need to research the optimum 2 cylinders in the firing order that will least effect the overall running of the motor if they weren't in operation. Yeah the car may idle a bit rough but I'm essentially saving a 1/3 if not 1/2 my fuel consumption.
So what are your thoughts?
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i suspect you will increase fuel consumption, unless you work out a system to keep the valves open slightly on the switched off cylinders. Otherwise the engine will be working to compress the air in the dead cylinders, with no effective power return....
Might work but it could also result in your stepping on the go peddle a bit harder to achieve similar performance to what your accustomed too. This might not be an issue but depending on the intake manifold design the pots that are not fuelled by the injectors could perhaps run lean from unburnt fuel still in the manifold from the other still active injectors. That could result in detonation and heat damage to the unfuelled pots.
Going LPG or selling it would be the better options.
but the latest Jeep Cherroke has the same technology to automaticly switch between 4 & 6 cyl operation
A reduction of mass achieves the same outcome.
Simply reduce the weight of the glass, panels,interior,spare wheel, etc.
Or use an aluminium body, or all the above.
^ What he said.Originally Posted by hoe
Thanks to Cadillac I will retire my experiment tooThe original multi-displacement system turned off opposite pairs of cylinders, allowing the engine to have three different configurations and displacements. But the system was troublesome, a rash of unpredictable failures led to the technology being quickly retired.
Without cheaking all the links and research i will put out some thoughts.
Reducing the volume of fuel to a clylinder will create a lean/ detonation situation, without reducing the air intake. If both are reduced your engine speed drops. Pointless.
Shutting down clylinders is a art in itself. Vibratons when shutting down clyinders would be dramatic unless you could sequntialy contol it by turning off injecters in an order that would maintain a reasonable vibrationless engine operation.
Id hate to see the crank harmonics if the system went wrong under power, a great way to snap a crank or throw a harmonic balancer off its wheel.
A great idea, just a little hard without some good after market ecu's and a engine dyno to test on.
Watched a Holden commercial tonight there working on a V8 that can switch to 4 cylinders .
Why would you bother george. Just sell the car and purchase another with less cylinders. A lot cheaper and quicker fix to the problem and obtain the end result. You can still buy cars with less 8 cylinders today.
Ahhhh but then he wouldnt have a V8.
His hearts in the right place and it wouldnt be impossible for a backyarder to get a 8 working smoothly in 4 mode considering the 90 degree crank throw angles.
Maybe updating to the newer model and new technology may be the answer.
The best of all worlds.
Well as I said it was one of my cars collecting rust, the idea wasn't for me personally as I own 3 V8's and I couldn't car less if petrol was $3/ltr, thats the cost of driving a car that I enjoy rather than one I'm forced to. Just thought it might be a worthwhile experiment and if successful, maybe some other v8 owners feeling the pinch that don't want to give up their car could implement on their own vehicle. But it was all but a dream for about 45 seconds.
This is how you get more horsepower and save fuel at the same time george.
LOVE IT!
The engines that switch off cylinders do it by switching between the different banks.
For example...
On one cycle the engine might fire 1,6,8,4 and on the next stroke it'll fire 2,7,5,3.
Or it might go, odds & evens..
The new honda 6cyl that can go to 4 or 3 does something like this, but it is controlled by the ECU.
This needs to be done to keep the cylinders at a constant temperature.
If you simply just switched off 4 cyls then one side gets hot and the other is stone cold, you'll end up with some funky problems.
You can gain some milage out of a commodore engine by getting the kalmaker and flashing some chips, play with the timing, etc. BUT... ultimately the compromise is horsepower.
To make an engine more fuel efficient, you do the exact opposite of what they do on racecars.
Racecars aim for maximum power by jamming more fuel in, cold air, cold fuel, more air / oxygen, free flowing exhaust.
For fuel economy, you want efficiency, so you want to burn the least amount of fuel you can.
Fuel is normally wasted because it cannot turn from a liquid to a gas quick enough, so to reduce emissions they burn it in the cat converter.
Heat up the fuel, vaporise as much of it as you can before it enters the engine, hot air going in, create intake and exhaust restrictions, etc. make it flow slowly, recycle exhaust gas so you can burn the unburned fuel... etc...
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