Will be testing a jet spark system

[94touring]

I talk with a guy in Sweden who is a full time high end engine builder and very big in the VW scene as well.  He has been putting together some kind of enhanced spark kit which he's sending to me to do testing. I will be running them in the minis and once he makes a smaller version for the m12 plugs in the bus, I will do testing on it as well.  I will need to hit the dyno for results so thinking a good time to dyno the innocenti.  From what he's noticed on some engines he's tried these on, he's seeing upwards of 6% gain in torque/Hp, which comes in sooner and last longer.  Also can squeeze out more fuel economy in the neighborhood of 11%.  Wide open throttle timing can be reduced, and lean cruise leaned out about another point on the AFR. 

[MiniDave]

So this is just some sort of end to put over the end of the spark plugs?

I dunno.....reminds me of one of those things you plug in your cigarette lighter to get 30% more power or sumthin......or magnets you put around your fuel line to align the fuel molecules and get 50 mpg out of your 7 litre V-8!   

So you think we'll see demonstrable results on the dyno then? This looks like it steps the electrode quite a ways back from the combustion chamber.....

[Willie_B]

Sounds interesting. Looking forward to your results.

[94touring]

Yeah he's already tried it on some other types of engines and has seen results.  He sent this saying it's more or less like what Mayle has put together for some newer engines.

The plugs used will be different than standard mini plugs, but he gave me the ones to use.

https://www.mahle-powertrain.com/media/mahle-powertrain/news-&-press/brochures/mji/mpt-jet-ignition-passive-mji-2.pdf

[MiniDave]

So it looks like compression forces a mix into the little chamber where the plug ignites it sending little tongues of flame to ignite the main mixture in the combustion chamber.....I wonder if you have to adjust your timing any to compensate for the delay in lighting off the main mixture? I know it's only milliseconds.....

This reminds me somewhat of Honda's CVCC design of the late 70's, where they lit off the mixture in a prechamber, which them burned the mix in the combustion chamber. It allowed them to get a more complete burn, better fuel mileage, more efficiency and not use a cat converter to meet emission requirements.

[94touring]

He says retarding timing a few degrees seems to get the best results. But it's something I'll have to test on the dyno to see on a mini. 

[BruceK]

Does it change compression ratio at all? I realize only a small extra piece of metal is being added into the combustion chamber, but that does take up some volume, right?

[94touring]

Does it change compression ratio at all? I realize only a small extra piece of metal is being added into the combustion chamber, but that does take up some volume, right?

In theory yes, but I would have to spec it out. Probably not much either way I'm guessing.  He did say it prefers higher compression.

[MiniDave]

Need to be careful the tip doesn't impact with the piston on TDC, given where the dish is on these pistons I doubt it's an issue.....but put one in and roll over by hand!

[94touring]

Dimensionally should be the same reach as a standard plug. The plug that goes in the insert is shorter.

[94touring]

Here's a dyno sheet from a guy overseas that tried this jet ignition on a 1275cc.  My buddy said he didn't want to share his combo or even the rpms to the chart which he found funny, but blue is the before and red is after.  Timing was all in at 28°, so relatively retarded from nornal.

[MiniDave]

Incremental improvement - I'll bet fuel economy goes up a little too.....

[94touring]

Apparently it was running rich also, around 10:1.  Not sure how much the ignition system helps that flaw in his comparison.  But yeah, around 5ft lbs improvement.

[94touring]

Got them on hand...

[John Gervais]

Hi - thanks for sharing this!


Wow, that looks really neat! 

Have you any data or opinions from your trying them out thus far?

[94touring]

I'm waiting for the innocenti to get back to me.  Once I get it tuned up I'll try them on it when we hit the dyno.

[MiniDave]

Are you still planning to come up here for the dyno or use one locally?

[94touring]

I'll probably go up there.