Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - idea, 4 cylinder to 2 cylinder engine conversion

saand · 09-13-2010, 11:40 AM

Patrick thanks for the suggestion, I dont have a great understanding of all the terms and the details of how an engine works but i think if i cut off the connecting rods on the pistons near the big end i would have issues. The big end which i think is the part of the piston that goes up and down the shaft (please correct me if im wrong) is used to guide the connecting rod so if this was cut the connecting rod would just rotate freely and likely smash into things in the motor.
I think there are counter balances for the pistons so if there are i could remove the counter balances which would stop some of the vibration but wouldn't stop it all. I think i have to deal with the fact ill have vibration, i can counteract vibration caused by lack of balance on the shaft but the vibration i will get from 2 cylinders which are offset from each other and will cause rotation is unavoidable unless the engine was completely different. Also i will have vibration from the no so ideal firing order

Edkiefer thanks for the firing order i was going to find this out by experimentation or when/if i open up the engine.
i agree there is risk of more fuel being used but i think without the loss of 2 cylinders the fuel used will be much less idleing and at highway speeds as a large part of my losses while coasting is just the engine rotating away at very low energy output levels.
Some things that may cause issues with this assumption is the ECU being untunned due to the changes but i think if it relies on keeping the O2 sensor happy and at stoic then shouldn't be too bad, in open loop though it will probably just burn lean which i guess is a good thing for efficiency.
Another thing is if the engine now has to run at higher RPMs to get the energy to accelerate and coast.

I do have a home made scan gauge (which uses the injector pulses for fuel info) which will tell me how much fuel i have used so i can do a before and after test. But i dont think it will work for the test that involves just pulling the injectors because air will still be pumped through the unfueled cylinders so if the car tries to keep stoic it will just put more fuel in the working injectors causing those cylinders to burn rich and inefficiently. Ill take some measurements anyway, if i get an improvement it will give me an idea.

09-13-2010, 11:40 AM	#21 (permalink)
saand Wiki Writer Join Date: Jul 2010 Location: Melbourne, Australia Posts: 236 bugler - '91 Mazda 626 90 day: 35.89 mpg (US) Thanks: 15 Thanked 25 Times in 22 Posts	Patrick thanks for the suggestion, I dont have a great understanding of all the terms and the details of how an engine works but i think if i cut off the connecting rods on the pistons near the big end i would have issues. The big end which i think is the part of the piston that goes up and down the shaft (please correct me if im wrong) is used to guide the connecting rod so if this was cut the connecting rod would just rotate freely and likely smash into things in the motor. I think there are counter balances for the pistons so if there are i could remove the counter balances which would stop some of the vibration but wouldn't stop it all. I think i have to deal with the fact ill have vibration, i can counteract vibration caused by lack of balance on the shaft but the vibration i will get from 2 cylinders which are offset from each other and will cause rotation is unavoidable unless the engine was completely different. Also i will have vibration from the no so ideal firing order Edkiefer thanks for the firing order i was going to find this out by experimentation or when/if i open up the engine. i agree there is risk of more fuel being used but i think without the loss of 2 cylinders the fuel used will be much less idleing and at highway speeds as a large part of my losses while coasting is just the engine rotating away at very low energy output levels. Some things that may cause issues with this assumption is the ECU being untunned due to the changes but i think if it relies on keeping the O2 sensor happy and at stoic then shouldn't be too bad, in open loop though it will probably just burn lean which i guess is a good thing for efficiency. Another thing is if the engine now has to run at higher RPMs to get the energy to accelerate and coast. I do have a home made scan gauge (which uses the injector pulses for fuel info) which will tell me how much fuel i have used so i can do a before and after test. But i dont think it will work for the test that involves just pulling the injectors because air will still be pumped through the unfueled cylinders so if the car tries to keep stoic it will just put more fuel in the working injectors causing those cylinders to burn rich and inefficiently. Ill take some measurements anyway, if i get an improvement it will give me an idea.