Pulse Jet Ignition - Claimed 10% increase in power - would you care to comment?

[ITSec]

I have to add this forum is a great place to seek advice but there are always a fair number of curmudgeonly responses.

Well, we have our fair share of curmudgeons (including me!) 

[Dilliw]

The reason why I linked the Mazda article is that the description of this pulse jet sounded familiar to part of what they are doing:

"What Mazda has done to solve these problems is devise a system called Spark Controlled Compression Ignition, SPCCI, a strategy in which a spark plug creates a “fire ball,” which acts to compress the homogeneous mixture of air/inert EGR gases and fuel to incite compression ignition.

The spark plug itself isn’t able to create this fireball with a lean mixture. So what Mazda has done is positioned a fuel injector close to the plug. That high-pressure injector initially shoots small amounts of fuel into the cylinder during the intake stroke.

That fuel mixes with a cyclone of air from the intake (which is fed from a supercharger and cooled EGR—both of which can be precisely controlled) to create a homogeneous lean mixture around the periphery.

During the compression stroke, a certain amount of fuel is injected into the “eye” of the lean vortex (an amount based on engine load), and spark is precisely timed to light the rich fireball, which then ignites the lean mixture around it—and voila! you have compression ignition. (Note that this late injection of fuel during the compression stroke is Mazda’s way of preventing preignition; to accomplish this requires a high-pressure injection system.)"

[Rough Edge racing]

 Hmmm, anything is possible...but unlikely from this trick spark plug ........The article has this bit of info that has more effect on performance than a spark plug     

The first modification we tried was to twin spark the cylinder heads, this gave an improvement in performance and reduced the E.G.T's, but not by enough, back to the drawing board. Our conclusion was that there wasn't enough T.D.C. turbulence (squish) to propagate the flame, we increased this which also had a benefit, but not enough. The problem with squish as a flame propagator is that the spark initiates the burn some 30 degrees before T.D.C.

                 

[acguzzi]

I found a paper on this topic, the purpose was to allow leaner burn mixtures and still get good ignition, they didn't talk about power increases, but what they said was (paraphrasing) igniting the mixture in a small compartment was easier and then the flame propagates out into the larger cylinder. It was about using leaner mixtures. Who knows, I think some enterprising chap should buy some and do a dyno test.

[Simon_London]

I had a chat with the 'inventor' Steve Scriminger. Thoroughly nice chap.

He says they have sold hundreds with no complaints including extensive racing use.

Developed for BMW boxer engines which makes them very compatible with Guzzis.

Steve explained that you wont notice much benefit if you just chug about at low revs as the improvement only kicks in at 4000 revs and above

Steve is actually going to give me a set for free and I am going to get a dyno comparison.

Will let you know.

[ITSec]

I had a chat with the 'inventor' Steve Scriminger. Thoroughly nice chap.

Steve is actually going to give me a set for free and I am going to get a dyno comparison.

That speaks well of him, and we'll all (even us curmudgeons!) be interested in the results...

[acguzzi]

I wonder if you have to adjust the timing

[Simon_London]

I am hoping that as my bike is a small valve low compression G5 (HMB fast road cam, ported, 36mm carbs, 1100 sport flywheel) there wont be any pinking.

[Tom]

Riding a stock Moto Guzzi with a heavy flywheel 4K rpms or more will yield different results for most Guzzi riders.  The experienced Guzzi riders already spin the engine up in that rpm range.  Doesn't sound like the increase would be worth the expense.  Usable power is what the Guzzi engines are all about.  10% for me wouldn't be noticeable.  Cruise between 4-5K rpms and shift at above 5K around 5500 rpms.  I think you'll see on a 5 speed bike like your G5 that 10% won't make a difference either. 

What rev's do you shift at? and do you cruise between 4K and 5K rpms?
 

[Simon_London]

Tom my bike gets a damn good thrashing on a reg basis but will also pootle about quite happily. It has a light flywheel so likes to rev.

I take your point that if the alleged extra 10% happens only at 7800 revs it wont be much use, but I'm feeling optimistic !

[flangeman_70]

The ad is hilarious , comparing this nonsense to what f1 engines use . Yeah , it's the same , only , well , it isn't . F1 engines employ 2 spark plugs per cylinder , and on does fire just slightly before the other , all controlled by a sophisticated ECU , this guy is simply lying . Fact is , internal combustion relies on turbulence to complete burning the mixture , if I am reading his claims correctly , he is stating this reduces turbulence . What a load of horse manure .

 Dusty

Unfortunately Dusty you are wrong.
See this https://youtu.be/L2Qv6wdZ9f4
Funny how old fashion can be the way of the future, you can expect to see many cars runny this in the near future.

Adam

[Tom]

Tom my bike gets a damn good thrashing on a reg basis but will also pootle about quite happily. It has a light flywheel so likes to rev.

I take your point that if the alleged extra 10% happens only at 7800 revs it wont be much use, but I'm feeling optimistic !

Okay.  Didn't know what you were riding or if you "nail" it.     My guess is that you'll see better results off the dyno than actually the seat dyno.  Good luck with the project.     I like your bike enough to have one in the fleet.   

[oldbike54]

Unfortunately Dusty you are wrong.
See this https://youtu.be/L2Qv6wdZ9f4
Funny how old fashion can be the way of the future, you can expect to see many cars runny this in the near future.

Adam

 OK , so they have gone back to a single central sparking plug , but the real trick there is the fuel injection giving one small pulse , then a larger pulse that is ignited by the already burning initial fuel pulse . Moto Guzzi ECU's won't deliver two fuel pulses , and certainly older carbed bikes are incapable of doing so .

 Dusty

[lazlokovacs]

I had a chat with the 'inventor' Steve Scriminger. Thoroughly nice chap.

He says they have sold hundreds with no complaints including extensive racing use.

Developed for BMW boxer engines which makes them very compatible with Guzzis.

Steve explained that you wont notice much benefit if you just chug about at low revs as the improvement only kicks in at 4000 revs and above

Steve is actually going to give me a set for free and I am going to get a dyno comparison.

Will let you know.

this speaks volumes.

very happy to give the free plugs a spin in my 1000 lemans on a dyno (in the interests of research) if your tests prove inconclusive.

FWIW don't think I 've ever run my lemans at less than 4k except on start-up 

 
 

[LowRyter]

I wonder how much performance I would gain with these Pulse jets + a Fish carburetor?

I was thinking about my Guzzi but what about a Corvette? 

[Tom]

 lazlokovacs.  So, you think you'd notice a 10% increase in horse power?  or would a 10% increase in torque be more noticeable?

[oldbike54]

I wonder how much performance I would gain with these Pulse jets + a Fish carburetor?

I was thinking about my Guzzi but what about a Corvette? 

 10,000 HP and 50 MPG , easy 

 Dusty

[LowRyter]

two words:

Bonneville, baby!

[Lannis]

I'd love to see Cycle World get a hold of this, hand it off to Kevin Cameron, and have him do an analysis and/or test.

His articles generally tell you where every molecule of fuel and air is flowing and swirling through the intakes past the valves, and what the flamefront looks like in the cylinder at various RPMs, and exactly how much of the exhaust gas goes where ....

Just a bit hard to believe that after a designer and manufacturer goes through everything they go through to get flow and spark and all JUST right, cheering over every fraction of a percent that they gain, that a simple screw-in thingie will suddenly add 10% to the performance.    Unless maybe it results in illegal emissions results that the manufacturer can't consider but an aftermarket maker can ... ?  (cf. custom exhausts, charcoal canisters, etc).

Lannis

[guzzisteve]

Nissan patent was from late 70's, if still not used by now means it's BS.

[Huzo]

Since time immoral, slick-talking hucksters

Immortal or immemorial,,,
(Speaking of slick talking)

[Huzo]

Tom my bike gets a damn good thrashing on a reg basis but will also pootle about quite happily. It has a light flywheel so likes to rev.

I take your point that if the alleged extra 10% happens only at 7800 revs it wont be much use, but I'm feeling optimistic !

Beautiful red wire wheeled Guzzi.
Any chance of a few shots for me to take to bed on a cold night with my torch !!!

[Simon_London]

Thank you Huzo. Ok then....

[Huzo]

Thank you Huzo. Ok then....

Shit...!
Is that all ! Come on you must have more, I was thinking to print one off but I don't know where to put the staple...

[Simon_London]

Ok here's some hardcore


how to post a picture in a forum online site

[lazlokovacs]

filthy

 

[Andy1]

Steve Scriminger is a good engineer with a lot of experience of tuning BMW twins......so the results will be interesting.  And he has the use of a dyno.
The airhead BMs all came with single plug ignitions and a common mod is to twin plug them.  A little more power but the real gain is they run sweeter.  Steve did that mod to my R80R many years ago, and my current R100R is also twin plugged.  The single plugged heads did not give an efficient burn.  When twin plugging the ignition has to be retarded as the twin flame fronts eat the mixture quicker.

I wonder if this device would effectively replicate twin plugging a single plugged engine?  It would be a lot cheaper than twin plugging.

Andy1

[Simon_London]

My thoughts also Andy

[Old Jock]

I found a paper on this topic, the purpose was to allow leaner burn mixtures and still get good ignition, they didn't talk about power increases, but what they said was (paraphrasing) igniting the mixture in a small compartment was easier and then the flame propagates out into the larger cylinder. It was about using leaner mixtures. Who knows, I think some enterprising chap should buy some and do a dyno test.

I may have this completely wrong as I am not conversant with the latest technology on IC engines.

Is the whole idea of burning the mixture in a small space then allowing it to propagate to large one not a form of stratified charge, developed by Harry Ricardo. Used in many diesels and the Rolls Royce Crecy.

I'm having a problem seeing how this particular example would work, but I'd love to hear what Simon has to say when he tests them.

Is it not a one off purchase after which you just swap the cone and screw it into another plug?

Sure it's not cheap for what it is, but if it works or mimics twin plugging then it becomes a steal compared with the cost and aggravation of modding for dual plugs

 

[Wayne Orwig]

I'm going to stay with the magnets on my fuel line. Proven performance gains.