idea, 4 cylinder to 2 cylinder engine conversion

[Frank Lee]

I'm into this mod more than most of the others!

If the modder is happy with what is likely to be <25% fe gain, then I say GO FOR IT! Just be forwarned that the compromises in power and driveability are great... they may even seem disproportionally great vs the fe gain.

I'm opposing this notion that just killing a few injectors leads to anything constructive, because 1. it's been tried, tried, tried, and tried again 2. it's failed, failed, failed, and failed again. 3. the theory behind it isn't any good either. How do I know? Because I've read about all the failures over the years, as well as many tech articles on DoD (BTW there are many of them online). And I went out and failed myself, by doing the injector disable, and by doing the injector disable plus the valves disable. For just injector disable you don't have to install a thing. Pop the hood and pull the wires off a few injectors. Start it, go for a drive. It practically takes less time to do that then it does to sit here at the puter and dream about it. If you leave it that way long enough to get an fe reading, get back to us. I'm quite sure the O2 sensor compensating for the extra exhaust fresh air is only part of the reason fe didn't go up... it is the fact that the remaining working cylinders are having to do extra work in uselessly pumping all that air. Remember, engines are basically air pumps. Find a recoil start engine and pull on the rope. It does take substantial work, even with various ports left open.

To try yet again to disable while pumping air: perhaps an EFIE-type device could spoof a "normal" O2 sensor signal for this test/mod? Just take the sensor out of the equation for a while? Or, perhaps another sensor bung could be added to a runner off a working cylinder prior to the collector without too much effort. I don't know if O2 sensors have to be a certain distance away from the cylinder... wouldn't think so.

ALL the DoD systems close BOTH valves. They HAVE TO. Otherwise it DOESN'T WORK.

Speaking of air pumps... we are talking about small amounts of hp, like 6 hp for aero and 2 for r.r. or something like that... and think about air pumps- air compressors, in order to move any amount of air, require quite a bit of power; most of the decent ones need 220v. So without touching any "real" calculations on it, to me it appears that if one is trying to DoD with the dead cyls still pumping, even if the pumping uses only, say, another 4 hp vs shutting the valves down, that 4 hp might be the difference between a 20% fe bump and a 0% "bump".

It appears an engine swap has the best chances of returning real gains/per unit of effort and expense. Motorcycle engines, though, are generally not all that efficient, as they tend to be biased more towards high rpm hp output than BMFE.

[EdKiefer]

Originally Posted by Frank Lee

I'm into this mod more than most of the others!

If the modder is happy with what is likely to be <25% fe gain, then I say GO FOR IT! Just be forwarned that the compromises in power and driveability are great... they may even seem disproportionally great vs the fe gain.

I'm opposing this notion that just killing a few injectors leads to anything constructive, because 1. it's been tried, tried, tried, and tried again 2. it's failed, failed, failed, and failed again. 3. the theory behind it isn't any good either. How do I know? Because I've read about all the failures over the years, as well as many tech articles on DoD (BTW there are many of them online). And I went out and failed myself, by doing the injector disable, and by doing the injector disable plus the valves disable. For just injector disable you don't have to install a thing. Pop the hood and pull the wires off a few injectors. Start it, go for a drive. It practically takes less time to do that then it does to sit here at the puter and dream about it. If you leave it that way long enough to get an fe reading, get back to us. I'm quite sure the O2 sensor compensating for the extra exhaust fresh air is only part of the reason fe didn't go up... it is the fact that the remaining working cylinders are having to do extra work in uselessly pumping all that air. Remember, engines are basically air pumps. Find a recoil start engine and pull on the rope. It does take substantial work, even with various ports left open.

To try yet again to disable while pumping air: perhaps an EFIE-type device could spoof a "normal" O2 sensor signal for this test/mod? Just take the sensor out of the equation for a while? Or, perhaps another sensor bung could be added to a runner off a working cylinder prior to the collector without too much effort. I don't know if O2 sensors have to be a certain distance away from the cylinder... wouldn't think so.

ALL the DoD systems close BOTH valves. They HAVE TO. Otherwise it DOESN'T WORK.

Speaking of air pumps... we are talking about small amounts of hp, like 6 hp for aero and 2 for r.r. or something like that... and think about air pumps- air compressors, in order to move any amount of air, require quite a bit of power; most of the decent ones need 220v. So without touching any "real" calculations on it, to me it appears that if one is trying to DoD with the dead cyls still pumping, even if the pumping uses only, say, another 4 hp vs shutting the valves down, that 4 hp might be the difference between a 20% fe bump and a 0% "bump".

It appears an engine swap has the best chances of returning real gains/per unit of effort and expense. Motorcycle engines, though, are generally not all that efficient, as they tend to be biased more towards high rpm hp output than BMFE.

right , no way it will be a FE gain if valves are not disabled . My7 comment on O2 was with valves disabled, which is not hard to do.
On rocker system you just remove rocker and on cam follower types remove follower which is easier and less likely to have any oil pressure issues like rocker delete (you might need a sleeve/bushing to replace rocker if oil ports are large on rocker shafts )
I be curious to see results but 25% seems like a lot to be in such heavy vehicle for 1.1L engine .

[Frank Lee]

I pulled the rockers off cyls 1 and 4 (easy to do) on my 4 cyl; it juuussst wasn't able to start then. Perhaps it would have with a heavier flywheel and/or with DoD that disables after it's started. So no road test of it.

There may be a good reason why there are no factory 4 cyl DoDs on the road. I have read that the mfgs are looking at it...

[Frank Lee]

Re: yet another test with pumping air and the O2 sensor: I wonder if simply unplugging the O2 would keep it in open loop; at least then the ECU would be running off the map and not try to correct the "lean" condition...

[EdKiefer]

Originally Posted by Frank Lee

I pulled the rockers off cyls 1 and 4 (easy to do) on my 4 cyl; it juuussst wasn't able to start then. Perhaps it would have with a heavier flywheel and/or with DoD that disables after it's started. So no road test of it.

There may be a good reason why there are no factory 4 cyl DoDs on the road. I have read that the mfgs are looking at it...

Yeh main most are V8 or V6 . What was the issue , slow cranking speed ?

[Frank Lee]

No actually it cranked over faster than usual. It juuuuuust wouldn't keep running after releasing the starter. It was sooooo close to starting I could taste it. But it wouldn't keep running.

So I tried it with one disabled cyl. Then it started, and I was able to drive it. WOW DID THAT SUCK!!! The vibes and the sounds were just AWFUL. But, there was enough power to go down the road OK.

[EdKiefer]

Originally Posted by Frank Lee

No actually it cranked over faster than usual. It juuuuuust wouldn't keep running after releasing the starter. It was sooooo close to starting I could taste it. But it wouldn't keep running.

So I tried it with one disabled cyl. Then it started, and I was able to drive it. WOW DID THAT SUCK!!! The vibes and the sounds were just AWFUL. But, there was enough power to go down the road OK.

ok, sounds like something with fuel system, sensors .
What type of system was it ?
Speed density (map sensor ) or MAF , (flap door/hot wire ) ?

[Frank Lee]

I think it just couldn't overcome the compression of two dead cyls at that low rpm and with that amount of flywheel.

[saand]

Ed, good point about the MAF sensor, i had not considered the flap vibrating back and fourth with the deactivated cylinders.
Frank it looks like we got to the same point when disabling 1 cylinder, I only removed injector signal but it did like to vibrate a lot and still had plenty of power to get moving on the road.

[bestclimb]

I realize an engineering challenge is neato but the vibrations caused by the thing running unevenly can't do good things for longevity.

on a slightly unrelated note I have had a little experience with cylinder deactivation that does not necessarily have any bearing on this conversation.

A buddy and I had a POS nissan 2 seater (pulsar perhaps) that we would rally through the woods. One of the cylinders deactivated it self when, through no fault of our own, (rev limiter, bouncy mucky "roads" free flow oil exchange and what is that red light on the dash with an oil can?) a piston departed the side of the block. Anyway we added some oil stuffed a rag in the hole after removing the remaining bits of the rod depositing most of them safely in the oil pan we decided we would drive it out.

By pumping the gas pedal and cranking till about 1500 rpm we were able to get the thing to run. if you revved it to about 2500rpm (quite a racket) it would move under it's own power at not quite as an alarming rate as before. It worked "fine" till the oily rag resting against the exhaust did the inevitable where upon we got out and threw mud on the flaming bits. We removed the smoldering rag, and drove the last little bit to another friend's house that had a number of junkers where it rest in peace.