idea, 4 cylinder to 2 cylinder engine conversion

[Accord_Guy]

Optimistically I'm aiming at and would be quite happy with 25%...
Understanding that to get any better I'd probably have to remove more mod-cons (modern conveniences) such as power steering... and have to add a Permanent Magnet Alternator.

Accord_Guy

[Accord_Guy]

OK, so I did my first road test yesterday evening with my 2cyl Honda Accord.
Recap of the mods thus far - removed 2 pistons, removed rocker arms, plugged fuel rail, and removed the A/C compressor (needed to buy a shorter alternator belt - $30).
I still need to modify the throttle body and the idle circuits so that the ECU mapping will still work properly as right now as soon as I give it any kind of real throttle (more than 10-15% throttle) I effectively get twice the O2 that the ECU/engine can handle...
This is reported by the ECU going out of closed-loop.
So my road tests were all done at as close to closed throttle as possible, meaning in the bottom of my 4th and 5th gears.

Results - with the present limitations of the throttle body/ECU mapping I can only utilise the first 1/4 of my throttle so acceleration is not ideal.
And, at highway speeds (100km/h) I can maintain even on the cruise in 5th gear.
**Good news** according to my data logger I averaged around 6l/100km - which is even better than I originally estimated.
I'll let you know how the throttle body mods go. Gotta try to do this as cheaply as possible too.

Accord_Guy

[Awd180]

Sorry to bump an extremely old thread, but I was considering this option but without the extreme overhauling of the engine. I had to run stop leak threw the radiator and fix an internal leak in the headgasket on my saab. It may or may not work this time, and I can't afford nor is it worth it to do the headgasket. Anyway the directions said for internal leaks shutoff the injector and spark to the given cylinder. It idled a little rougher but not bad for the shape the car is in, and if I fix the exhaust leak and put the intake back it probably won't be as bad. Just wondering without reading this whole list of banter if anyone else has just unplugged 1 or 2 cylinders and been able to drive without causing damage. As well as if anyone that did do the more extreme conversion how things turned out down the road.

[Frank Lee]

The injector disable has been discussed many times in many threads; the search function will reveal them. But basically it's a fail. http://ecomodder.com/forum/194636-post41.html

[Accord_Guy]

OK so the tests didn't go as well as I was hoping, as the car idled fine but wouldn't take any throttle. I played around with the sensors and the throttle body to no avail, and after a few hours of troubleshooting I just junked the whole thing and re-converted the car back to a 4cyl.

The car still had the same issues though, and after a few more hours I deduced that either the ECU or the wiring to the ECU was bad. When I lifted the carpet where the ECU sits (under the passengers kick panel) I found a pile of aluminum oxide (rusted aluminum) and rusted circuit boards/wiring. Seriously, about 1/3 of the complete ECU casing was eaten away.

I replaced the ECU and wiring and the car ran fine after that.

I archived all of the parts for this project and decided to move to a place where they don't put salt on the road.

It's 15 months later now and I've moved to Brisbane Australia where I can play with 15-20 yo cars that have virtually NO rust. I love it.

And I'm now looking to resurrect my 2cyl conversion project.

What I have:
1995 Honda Accord manual (non V-Tec)
Replacement rockers (ground down so that the valves don't open)
Modified throttle body
Modified Intake and plenum gaskets

Strategy:
1. Remove rockers and disconnect injectors, and figure out which combination of 2 cylinders gives best performance (2 outer, 2 inner or one of each).

2. Install modified throttle body and check performance.

3. Remove pistons and install hose clamps on crank instead of con-rods.

4. Remove balance shaft belt.

I'm probably 4-6 weeks away from this build.

I'll try to post photos as it happens.

[CFECO]

Old thread I know, but a couple of thoughts. Take an engine with individual intake runners, say an air cooled VW with dual port heads, build a fuel injection system with individual throttle plates in the runners, and the air intake through a common Mass Airflow Sensor near the air cleaner. Have a lever system built into the valve covers, which when operated holds both valves in two cylinders open a little bit, the pistons will need to have the valve pockets recessed enough so they didn't hit the valves. When activated, the "4 to 2" switch would turn off the fuel, and hold the valves open. The main pumping loss in a "dead" cylinder is the pulling a vacuum against a close butterfly plate and compressing the air in a cylinder by 9 or 10 times. Try turning an air compressor by hand, and then do it with the reed valve held open.
Thoughts anyone?

[Frank Lee]

Sounds like the opposite of the current proven strategy.

If you are going to mess with the valves, why not properly disable them?

[aerohead]

A neighbor had a 2-cyl VW aircraft conversion we were considering for a model to do a 2-banger to share between his Bug and my Ghia.
He died,and that was the end of that.
In the intervening years I've come to believe that the reserve power of the original engine is an important safety factor,as some emergencies require judicious use of horsepower when braking won't save you from the situation (as with motorcycles).
Passing and hill climbing will suffer immediately,and any acceleration will require longer residence time in transitory engine operation which is the least efficient in BSFC.
My 60-bhp CRX already has head-wind issues on flat highways,requiring downshifts to a higher friction lower gear.
Taking a more massive vehicle of greater frontal area to a lower hp than that of the Honda might be a recipe for disappointment.
I think you'd regret the change.
And there are dozens and dozens of vehicles which without any mods,would deliver like safety,comfort,etc.,and with higher efficiency.

[CFECO]

This would enable the engine to be easily switched between 4 and 2 cylinders while running. It would also go beyond just turning the cylinder off so it doesn't use the fuel, but also eliminate much of the pumping loss. Crank an engine over by hand with no rocker arms on it. We did it many time on an engine stand while assembling a rebuild, get up to 12 to 1 compression and even a 3' breaker bar was a struggle to turn over.

[CFECO]

Originally Posted by aerohead

A neighbor had a 2-cyl VW aircraft conversion we were considering for a model to do a 2-banger to share between his Bug and my Ghia.
He died,and that was the end of that.
In the intervening years I've come to believe that the reserve power of the original engine is an important safety factor,as some emergencies require judicious use of horsepower when braking won't save you from the situation (as with motorcycles).
Passing and hill climbing will suffer immediately,and any acceleration will require longer residence time in transitory engine operation which is the least efficient in BSFC.
My 60-bhp CRX already has head-wind issues on flat highways,requiring downshifts to a higher friction lower gear.
Taking a more massive vehicle of greater frontal area to a lower hp than that of the Honda might be a recipe for disappointment.
I think you'd regret the change.
And there are dozens and dozens of vehicles which without any mods,would deliver like safety,comfort,etc.,and with higher efficiency.

True, that is why my original X-Prize car had two, two cylinder outboard powerheads, which would run together or one only depending on load requirements. Think of a gas golf cart, the engine doesn't run until power is required, when you step on the throttle. Mine was to be; Electric to start driving initially, with one or both ICE power plants starting as the throttle was pushed farther down. If the car "Only Needs" 15HP to go 60 MPH, it can be done with a 15HP engine, passing or hills, the HP doubles or more. Harder, in some ways and not as efficient, as making one engine convert from 2 to 4 cylinders.