Plasma plugs and hydrogen as an economy enhancer?
Plasma plugs and hydrogen as an economy enhancer?
(OP)
Gentlemen,
This thread post is prompted by the 'melting pistons and lean fuel mixture' thread as it has mentions of plasma plugs and hydrogen which are things I have been thinking of lately.
As a long lurker and, more recently, occasional poster; My impression of this forum, especially the automotive areas, is that you get well informed, zero BS answers.
Some background first. I have a late 60's Triumph with a 2 litre, in-line, 6 cylinder, ohv engine. I have modified this over the years and now run multipoint EFI and 3D mapped ignition controlled by Megasquirt. It also has a (fairly poorly designed) 6-3-1 extractor manifold and some light cleaning-up of the valve throat areas, but no heavy porting. The bottom end is stock and retains the OE 270º duration camshaft.
It goes well enough and fuel efficiency in particular is improved from 28mpg (IMP) to 34.5mpg in mixed driving. As the car gets used in endurance events and fuel is expensive here, I'm always looking out for ways of improving mileage though. Couple of thoughts/questions:
First:
Recently I tried some 'plasma plugs' sourced from somewhere in Eastern Europe (They were free!). These have an inner, partly enclosed chamber with the electrode sat down inside it and angled drillings through into this chamber. Presumably the theory is that the charge in the inner chamber lights first and burning gas is ejected at speed through these drillings and the centre bore, forming plasma jets to rapidly and completely ignite the rest of the charge. The hope was that I would be able to run far leaner in most areas apart from max load and rpm. Initially results seemed good and I was able to take alot of fuel out of the map and acheive part throttle cruise at 17 - 17.5:1 afr (according to the on board wideband O2 sensor) before going flat and another .5 before lean hitching set in. On conventional plugs hitching set in around 16:1. However, at very light or trailing throttle it misfired badly and to eliminate this actually required more fueling than before in the relevent areas of the map. The net result of this is actually worse fuel consumption under normal mixed driving conditions. On a 2000 mile run earlier in the year we ran the first 1000 on the plasma plugs and the second 1000 on conventional plugs (with relevent map tweaks) returning 34.3 mpg and 36.7mpg respectively. My take is that although these plugs may be partly effective at medium and higher loads, they are actually poor at lighting very low density charges, probably due to the recessed electrode. I've now gone back to my usual triple electrode Bosch plugs. Has anyone experimented with this kind of thing or have any thoughts on the subject?
Second:
I was talking to a guy a week or so back with an elderly turbo diesel 4wd, who had a very doubtful looking 'coffee jar' electrolysis set in his passenger footwell and a pipe running the hydrogen and oxygen produced into the intake upstream of the turbo. He swore blind that his mileage had increased from 28 to 65 mpg with this rig. The shoddy nature of the conversion and the fact that he proudly informed me he was now going to plumb it in downstream of the turbo (how are you going to keep the lid on your coffee jar pal?!) made me dismiss the whole thing, although I must say that I was concerned for his personal safety! However, I did google it. There are, of course, many similar claims out there, even one linked from this very site just now. So, my question:
Is there anything to this? Could the "HHO" even in quite small amounts, aid efficiency by making previously unlightable AFRs ignitable and giving more complete combustion? Has there been any real detailed work done on this that doesn't require $50 for 'the secret plans'?
Would need quite convincing arguments to have me try such a rig as the one thing I do know about hydrogen is that it ignites very readily!
Regards
Nick
This thread post is prompted by the 'melting pistons and lean fuel mixture' thread as it has mentions of plasma plugs and hydrogen which are things I have been thinking of lately.
As a long lurker and, more recently, occasional poster; My impression of this forum, especially the automotive areas, is that you get well informed, zero BS answers.
Some background first. I have a late 60's Triumph with a 2 litre, in-line, 6 cylinder, ohv engine. I have modified this over the years and now run multipoint EFI and 3D mapped ignition controlled by Megasquirt. It also has a (fairly poorly designed) 6-3-1 extractor manifold and some light cleaning-up of the valve throat areas, but no heavy porting. The bottom end is stock and retains the OE 270º duration camshaft.
It goes well enough and fuel efficiency in particular is improved from 28mpg (IMP) to 34.5mpg in mixed driving. As the car gets used in endurance events and fuel is expensive here, I'm always looking out for ways of improving mileage though. Couple of thoughts/questions:
First:
Recently I tried some 'plasma plugs' sourced from somewhere in Eastern Europe (They were free!). These have an inner, partly enclosed chamber with the electrode sat down inside it and angled drillings through into this chamber. Presumably the theory is that the charge in the inner chamber lights first and burning gas is ejected at speed through these drillings and the centre bore, forming plasma jets to rapidly and completely ignite the rest of the charge. The hope was that I would be able to run far leaner in most areas apart from max load and rpm. Initially results seemed good and I was able to take alot of fuel out of the map and acheive part throttle cruise at 17 - 17.5:1 afr (according to the on board wideband O2 sensor) before going flat and another .5 before lean hitching set in. On conventional plugs hitching set in around 16:1. However, at very light or trailing throttle it misfired badly and to eliminate this actually required more fueling than before in the relevent areas of the map. The net result of this is actually worse fuel consumption under normal mixed driving conditions. On a 2000 mile run earlier in the year we ran the first 1000 on the plasma plugs and the second 1000 on conventional plugs (with relevent map tweaks) returning 34.3 mpg and 36.7mpg respectively. My take is that although these plugs may be partly effective at medium and higher loads, they are actually poor at lighting very low density charges, probably due to the recessed electrode. I've now gone back to my usual triple electrode Bosch plugs. Has anyone experimented with this kind of thing or have any thoughts on the subject?
Second:
I was talking to a guy a week or so back with an elderly turbo diesel 4wd, who had a very doubtful looking 'coffee jar' electrolysis set in his passenger footwell and a pipe running the hydrogen and oxygen produced into the intake upstream of the turbo. He swore blind that his mileage had increased from 28 to 65 mpg with this rig. The shoddy nature of the conversion and the fact that he proudly informed me he was now going to plumb it in downstream of the turbo (how are you going to keep the lid on your coffee jar pal?!) made me dismiss the whole thing, although I must say that I was concerned for his personal safety! However, I did google it. There are, of course, many similar claims out there, even one linked from this very site just now. So, my question:
Is there anything to this? Could the "HHO" even in quite small amounts, aid efficiency by making previously unlightable AFRs ignitable and giving more complete combustion? Has there been any real detailed work done on this that doesn't require $50 for 'the secret plans'?
Would need quite convincing arguments to have me try such a rig as the one thing I do know about hydrogen is that it ignites very readily!
Regards
Nick





RE: Plasma plugs and hydrogen as an economy enhancer?
Your experience with the so-called "plasma" plugs is much more worthy of comment. I'm not surprised to hear that this design required more fuel under conditions when the mixture is weak because of trailing throttle. There's too much heat loss inside that mini-chamber. It's also quite interesting that you were able to extend the lean-misfire limit. But, probably what's happening is that although it extended the lean-misfire limit, the shape of the combustion chamber probably isn't matched to the direction that those jets were aimed, so the burning rate was probably not optimum.
A sequential-injection setup with the injector nozzles aimed and timed to get a stratified charge, and inlet ports arranged to give good swirl (not tumble) during light-load conditions, would be interesting when combined with plugs like that. If done right, under light-load conditions, you could get the little chamber filled with a near-stoichiometric charge and lean everywhere in the main chamber.
RE: Plasma plugs and hydrogen as an economy enhancer?
RE: Plasma plugs and hydrogen as an economy enhancer?
RE: Plasma plugs and hydrogen as an economy enhancer?
RE: Plasma plugs and hydrogen as an economy enhancer?
Mike Halloran
Pembroke Pines, FL, USA
RE: Plasma plugs and hydrogen as an economy enhancer?
However, an ideal Otto cycle says the entire pressure rise from combustion occurs completely at TDC. In practice, we know this doesn't happen. I can see where the HHO would bring the cycle closer to an ideal power map. Hydrogen, as a fuel, has a VERY high reaction rate. Smokey Yunick said on tappet valve engines he did Hydrogen R/D work on, he had to run essentially zero valve overlap due to the high speed flame of the HH. That's why Mazda did their HH engine on their Wankel. HH is a great fuel for Wankels.
RE: Plasma plugs and hydrogen as an economy enhancer?
On the HHO question you are tending to back up my initial thoughts; no worthwhile gain on a conventional piston engine especially so if the thing is decently designed and properly tuned. I do still wonder if there could be some (probably small) gains to be had as an aid to running very high AFRs (ie non-standard engine or least engine mapping) and also whether it could show gains on an engine that is poorly designed or badly tuned. Think of a diesel with tired injectors and poor atomisation perhaps. These are the types of engine most likely to see this kind "snake oil" applied after all. Anyhow, I'm not planning to try it any time soon!
Regards the plasma plugs, I've posted a few pics as I'm not sure my description was that clear.
[IMG]http://
[IMG]http://
Also a pic of the combustion chamber I'm asking them to work in. (piston has a flat top)
[IMG]h
I think its fair to say that they stand a much better chance of doing some good in a 4 valve chamber with a central plug (as pointed out by BrianPetersen above). The 'Kaehni ignition' pointer was interesting and turned up a number of slightly different technologies.
- Multispark - not really on topic
- Twin plug - kind of analagous in that this is another (and likely the better) way of lighting marginal charges and getting a faster burn.
- Plasma prechamber (a little like the pre chamber on an indirect diesel as I understood it.
All interesting stuff. I was reminded along the way that the guy I got these from was using them in 90s 4.0L Jags (4 valve) and Rover 827 (using the Honda 2.7 24V V6) and was finding that he could run them on much lower octane fuel (including some very poor eastern European stuff) without the usual power loss caused by the knock sensor backing off the ignition timing. This in turn reminds me that I probably should have played with the timing more than I did. May revisit this, although I suspect I can still get the best gains by optimising the fuelling and ignition maps on a rolling road rather than by datalogging on the road.
Regards
Nick
RE: Plasma plugs and hydrogen as an economy enhancer?
Therefore,it is unlikely that application of an off-the-shelf prechamber plug design to an existing engine would be successful.
RE: Plasma plugs and hydrogen as an economy enhancer?
Thanks
RE: Plasma plugs and hydrogen as an economy enhancer?
And it does look like a 4-valve head with a central vertical spark plug would be a better match.
I've got a couple engines that I could try this in, but they need to be 10mm (equivalent NGK CR9EA). I'd also be interested in the source. A Google search wasn't constructive (too many useless hits).
RE: Plasma plugs and hydrogen as an economy enhancer?
6thgencivic, I got these from Triumph/Jag tuning specialist friend to try as part of an ongoing debate, so did not buy them from a company. I can ask about getting more though. Not sure who the manufacturer is as I don't read Cyrillic! I believe they are also available with 10mm thread.
Cheers
Nick
RE: Plasma plugs and hydrogen as an economy enhancer?
as Dicer rightly says, the computer will richen it up,.
but only to the point of the stoichiometric value that is put into the computer,.
if you lower the stoich figure ,the engine will run weaker,.
i found this out ,because i too have a tr engine on full management, and i can get more mpg/easier running ,without the lamda mode on,
hope this has been of some use
Marcus
RE: Plasma plugs and hydrogen as an economy enhancer?
If you think about it, the effeciency loss in the splitting, and recombining of the H20 would have to be made up in the increased flame rate, and I just don't see that happening.
In my particular case, it was always under vacuum. I would consider it dumb in the LEAST to hear anyone claim they had HHO injection under pressure. This means he had a high pressure jar of Brown's gas; HIGHLY Explosive. On top of that, it seems HHO would really only be entering the engine when it isnt under boost, and the rate of vaporization could not keep up with the rapid intake pressure changes to be able to accurately map such a thing with a megasquirt.
Interesting, none the less.
-Theron