idea, 4 cylinder to 2 cylinder engine conversion

[EdKiefer]

Originally Posted by Frank Lee

I know how deac works but that is not what we are doing here.

My 4 cyl won't start with 2 disabled via valves and injector disabled. But I suspect it would work with 2 pistons gone altogether. It wants to start but couldn't overcome the compression of the dead pair.

while that might help I still think it will be extremely rough and hard starting .

For a test disable 2 injectors and pull the 2 spark plugs, that will take compression out of the equation .

See how it works . IT going to be way to much work to get it to work and even if it works the out come won't be good IMO .

[saand]

Thanks for all the replies, looks like this mod may not be the best idea. Lots of work, and id get a very unreliable engine at the end. I am still going to try out pulling the 2 injectors see how it runs anyway. Maybe when the car is about to die ill try it out the full mod just for the curiosity.

I may try out deactivating one cylinder by pulling the injector connector, and deactivating the valves, I guess if honda does it for efficiency then there might be some gains hopefully the mod works and they just aren't doing it for marketing. Ill have to research this a bit and read through the replies properly when I have more time.

Edkiefer just out of interest how have you found info about compatibility of parts between different cars. I have never known how to find out if a part from one car is suitable for mine.

[EdKiefer]

Originally Posted by saand

Thanks for all the replies, looks like this mod may not be the best idea. Lots of work, and id get a very unreliable engine at the end. I am still going to try out pulling the 2 injectors see how it runs anyway. Maybe when the car is about to die ill try it out the full mod just for the curiosity.

I may try out deactivating one cylinder by pulling the injector connector, and deactivating the valves, I guess if honda does it for efficiency then there might be some gains hopefully the mod works and they just aren't doing it for marketing. Ill have to research this a bit and read through the replies properly when I have more time.

Edkiefer just out of interest how have you found info about compatibility of parts between different cars. I have never known how to find out if a part from one car is suitable for mine.

hi , On the vehicles with deactivation cylinder mods , just remember they start out with all cylinders firing and go into various mods when cruising .

Well I don't know that much on compatibility, I did work on many Mazda back in 85-95 timeline, mostly Rx7, 323 and 626 (ones that were turbo mostly) .

There a lot you can find online, like parts catalogs or even Google it just takes some searching and reading time .

I now have a 08 Accord so I read up on there features .
Thats about it.

[Zerohour]

I would say the engine maybe not even run if you pull just one injector and spark plug. Have you even driven a car with a lost cylinder? It doesn't end well. Especially if you keep driving.

You would have to do two, and even then the engine management system will know something is wrong. You'll get misfirecodes and with only half the cylinders firing your O2's and emissions system would most likely end up showing codes. And as I remember most cars dump into a preset mode once you have the CEL for emissions. The settings are not the most efficient but a generic default for the car. This is done incase the engine management losses single from vital components.

So long story short, it won't work. You would have better luck pulling a large motorcycle 2 cylinder and going from there. But even at that rate the build cost will be $$$.

What mileage are you currently getting versus your goal? Even if you could acheive a 60HP engine in a 626, I doubt you're going to break 35-40mpg. Simply power/weight/gearing. And 60hp in car that size would pretty much be unsafe on the highway.

There are other ways of getting more MPGs. What else have you tried?

[EdKiefer]

Originally Posted by Zerohour

I would say the engine maybe not even run if you pull just one injector and spark plug. Have you even driven a car with a lost cylinder? It doesn't end well. Especially if you keep driving.

You would have to do two, and even then the engine management system will know something is wrong. You'll get misfirecodes and with only half the cylinders firing your O2's and emissions system would most likely end up showing codes. And as I remember most cars dump into a preset mode once you have the CEL for emissions. The settings are not the most efficient but a generic default for the car. This is done incase the engine management losses single from vital components.

So long story short, it won't work. You would have better luck pulling a large motorcycle 2 cylinder and going from there. But even at that rate the build cost will be $$$.

What mileage are you currently getting versus your goal? Even if you could acheive a 60HP engine in a 626, I doubt you're going to break 35-40mpg. Simply power/weight/gearing. And 60hp in car that size would pretty much be unsafe on the highway.

There are other ways of getting more MPGs. What else have you tried?

You must disable the intake valve or the sensors like MAF or even MAP will be reading the suction of the disable cylinders , which for sure would pull code .
The 626 I don't think measure crank movement for misfire code (as AFAIK is a distributor ignition system ),but if it does that would be a issue .
But your right I can't see it being drivable in 626 or worth while in long run.

[saand]

Thanks all,
I agree with the MAP or MAF sensor issue, so if i do deactivate a cylinder i will leave just the exhaust port open and close up the inlet port which should stop any issues with the ECU.
As Edkiefer suggests the 626 91 year may not have crank movement measurement, it is relatively old and it has had some problems in the past and no codes have come up so im not too worried about this one.

my car currently gets about 28 mpg or something close to that, i do not have an MPG goal i more take the approach that i will do anything i am physically able to do to help the MPG of the car and when i have nothing else i can change ill stop.

Looks like ill just have to test out a few things and see what happens, ill try to run the tests tomorrow and post the results.

[euromodder]

Did they ever import the diesel versions in Oz ?

[saand]

I tried out some tests tonight, disconnected 1 and then 2 injectors and the car still ran. I moved around the plugged in injectors to ensure that I got the worst case firing sequence (2 on then 2 off) and the car still started to my surprise.
The engine did however vibrate around a lot, I do have the RPM turned down so I guess that is expected and can be improved a little.
If I was to remove the piston the vibration would only get worse as it would have the uneven firing which was causing vibration in my test tonight and it would have the unbalanced pistons.
During my previous research one of the websites mentioned a 2 cylinder would sound like a Harley and it definitely does, not sure I mind though. makes it sound like it has a bit of guts even though it will take off really slow.

when I get some more time and there aren't so many cars around I shall have to take the car out for a spin on 3 and 2 cylinders only see how it goes.

Euromodder, Im not sure about the diesel version in Oz, I got this one second hand and I didn't really look around at alternatives at all but I haven't seen all that many diesels until recently in the last few years so doubt there would be many in 91.

[Patrick]

When you take out the pistons you could cut the conrods off near the big-end bearings, them bolt then back around the crank. That would plug up the oil holes in the crank so you don't have to weld it and put some of the mass back on the journals so that it wouldn't be so unbalanced.

[EdKiefer]

Originally Posted by saand

I tried out some tests tonight, disconnected 1 and then 2 injectors and the car still ran. I moved around the plugged in injectors to ensure that I got the worst case firing sequence (2 on then 2 off) and the car still started to my surprise.
The engine did however vibrate around a lot, I do have the RPM turned down so I guess that is expected and can be improved a little.
If I was to remove the piston the vibration would only get worse as it would have the uneven firing which was causing vibration in my test tonight and it would have the unbalanced pistons.
During my previous research one of the websites mentioned a 2 cylinder would sound like a Harley and it definitely does, not sure I mind though. makes it sound like it has a bit of guts even though it will take off really slow.

when I get some more time and there aren't so many cars around I shall have to take the car out for a spin on 3 and 2 cylinders only see how it goes.

Euromodder, Im not sure about the diesel version in Oz, I got this one second hand and I didn't really look around at alternatives at all but I haven't seen all that many diesels until recently in the last few years so doubt there would be many in 91.

AFAIK your firing order is 1342 , so if you started with 1 firing the next one would be 4 , (2 an 3 disabled) , I think that would work best .

The problem is when driving will you be much more into throttle than before driving around , I think in city driving with weight of 626 and only half the engine, plus the fact the ECU is not optimized anymore (the sensor data will be way out of normal ranges) there be good chance of using more fuel .

To bad you can't hook up SG2 and do quick check of mpg driving around (before after) .