Paul
What has been the discussion so far concerning air assisted direct fuel
injection stratified charge for the Wankel.
It would seem that the wide circumferential depression of the rotor would
allow for optimizing the injection timing and that less loss would occur
from sealing than that of a spark plug with proper tip configuration for the
air-fuel injector nozzle.
This would seem to have the optimize the possibilities of a true stratified
charge with no fuel on the walls of the Wankel to optimize the BSFC.
The injector would possible be of Australian Orbital Tech Group type to be
used in the GM XV-8 Opel Signum 2011. Now since the German
Government owns Opel this is probably in question. Have you heard is GM
planning to use the XV-8 in any US car or truck
Norm
To my knowledge3dge nobody has tried that in a rotary.
The Wankel is naturally stratified charge as the rich mixture
is thrown out towards the plugs due to the rotating combustion
chamber. That is probably why it will run a couple of hundred
degrees F lean of peak. Mixture ratios of 20:1 air fuel.
Paul Lamar
Paul and Norm,
I investigated the Orbital technology, and it would be workable. The biggest
problem is the Orbital people only want to sell to big OEM operations under
license. The minimum that it would cost you to get started is 25K. They
flatly refused to allow any discount to small engineering or prototype
shops. The only way to get what you need otherwise is to get the parts from
a Mercury or other 2 cycle outboard. The trouble is you don't know if the
injectors are going to be close on volume, so you couldn't use the Mercury
control box you would have to use Tracy's or SDS or Megasquirt. The last
item is that you need to run an air pump to feed the injectors which is
engine driven. The cool thing is that Mecury has paired the air pump with the
oil injection pump and you could use that to provide the apex seal oil
without pre-mixing. I was going to do this until I priced some of the
Mercury parts otc. The prices on replacement parts are so jacked up that it
wasn't worth it. I do look for available outboards at the marine shops
occaisionally, but these are the high end of the model line and you don't
see outboards crashed or blown up as often as cars, making parts harder to
come by. I believe that it will be easier to get the direct injection off of
a newer Audi or VW wreck running the Siemens system since there will
be thousands more of them on the road.
Bill Jepson
Don't get your hopes up on direct injection. Getting that to work let
alone work in such a way that it improves the BSFC would take many
thousands of dollars worth of R&D. You can't just install direct
injection and expect it to pay off. I know what Porsche went through
and it was not cheap. I was there when they presented the results. Besides
that they were lucky to get a 5% improvement.
Paul Lamar
Paul,
Provided I could make the through housing port without trouble. (And thatIS
a big question.) I would be happy to get a 2% improvement. The biggest
advantage would be no concerns about how to orient the injectors in the
tubes or the throttle body. Followed by the ability to change the tubes to
test tuning with minimal trouble. Something that should be mentioned for the
Orbital system is that it is a maximum 2 bar system. You can inject after the
intake port closes, but not near full compression. The Siemens system is
designed to inject right up to the point of ignition.
Bill Jepson
Any high pressure air pump is going to take some HP at the volume
required. It takes really high pressure to vaporise the fuel to the
point the mixture homogeneously better than injecting at the start
of the runners. 2 bar is not going to cut it. Simple two cycle engines
get the fuel/air mix in strange ways. It comes up from the crankcase
so any fuel injection might be better.
You may wind up with worse BSFC rather than better in the rotary.
Not a shade tree job.
Here are some ideas that address a specific rotary problem
using high pressure air injection.
http://www.rotaryeng.net/Strat-charge.html
Paul Lamar
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