Paul,

Sorry. Mouseititis again.  It appears NKH is working on a 10 mm size
spark plug for the rotary though they wouldn't commit on when it would
be available for the racing community. They did show me long narrow ten
mm plugs but they where the bent tang type normally found in piston
engines.  A good guess is they made some  concentric iridium tip types
for Mazda engine research use only.  Speaking of which.  If you follow
the course of Mazda engine development you can understand why they are
playing with dual fuels, specifically the addition of hydrogen.  The
all-hydrogen engine was for testing and probably good PR. Hydrogen or
better yet, on board generated H00H makes sense if injected in small
amounts (less than 0.4% by weight) right after gasoline is injected and
the intake port closes.  This would imply the hydrogen fuel is injected
at the top of the housing. Looking at the 16X housing pictures you can
see this is so.  The H2 burn rate is so rapid  that it solves a lot of
problems associated with trailing plugs and multi sparks.  The hydrogen
or Hydroxl gas fuel first ignites and this in turn ignites the fuel
droplets.

My interest in smaller footprint dual plugs was in trying to make the
dual plug insert a bit narrower  to minimize both the liner welded area
and inner  water passage  restriction.  Closer together also brings both
sparks into the central rotor depression area instead of near the rotor
edge.  Having the sparks nearby in my thinking would minimize an
asymmetrical pressure on the rotor face in case one ignition system
failed.

Dual fuels adds complexity, as do sequence fired capacitors without a
doubt, but a loss of the hydrogen injection would not be a show stopper.

Doug in Japan

Doug:


I'm very interested in the "hydrogen-on-demand" fuel assist and I'm
wondering where the "less than 0.4% by weight" numbers came from.
The concept makes perfect sense to me but haven't found any percentages
in my research.  Can you please direct me??

Greg in Canada--

There are some SAE papers that address Hydrogen enhancement.  Round
numbers, they used 5% - 10% hydrogen by weight.  The hydrogen was
generated by cracking gasoline.  A 25% improvement in gas mileage was
achieved by leaning the engine until WOT was required at the HP
needed for cruise.  To accelerate or climb a hill would require
richening the mixture.  With hydrogen I believe they were able to get
air:fuel ratios up to around 30:1.

The electrolysis cells can't provide anywhere near that amount of
hydrogen.  They do provide a hydrogen oxygen mix.  I still haven't seen
any credible research showing great improvement using electrolysis
cells, but a lot of anecdotal reports, so I would also be interested in
any more scientific reports you have Doug.

The SAE papers I looked at are:
SAE 750027 An Examination of the Performance of Spark Ignition Engines
Using Hydrogen-Supplemented Fuels

SAE 740600 On-Board Hydrogen Generator for a Partial Hydrogen Injection
Internal Combustion Engine

SAE 960603 A Study of Combustion of Hydrogen-Enriched Gasoline in a
Spark Ignition Engine

The first two digits represent the year the papers were published.

Bob W.