In modern motorcycle engines they use big "pre-chambers" before the
intake tubes. Such a chamber in a 1200cc Motorcycle can have a
volume up
to 4500 cc. And this is really only for tuning (not for air
filtering) and helps a lot getting out 175HP from a 1200cc
production bike.
Reiner Nikulski
Unfortunately it confuses the heck out of the carburetor.
I am about to give up on any kind of venturi sensor.
The automotive industry did it years ago.
Paul Lamar ...No rotor no motor.
This is also one of the reasons that even a low pressure version of the
direct injection has merit. If we want better economy we need to avoid
spraying the surrounding environs with fuel! This is also the reason that
most modern cars/bikes/boats use large air boxes to contain the
reversion mist if carburetated.
Bill Jepson
Well I had fully intended to do that but I don't think it will
stop the mixture instability of the air flowing back and fourth through
a venturi. I could be wrong.
Paul Lamar ...No rotor no motor.
May be you can add a filter element on top of the carbs. In our small
Sachs engine with p-port we hadīnt that problem with the mist, but with
a small K&N filter element (same carb, jets and tube dimensions) the
engine ran better, the driver could really feel it. The Power was a
little bit higher (measured) and the mixture was stabilized over
the whole rev range (not going up and down, seen with a lambda sond).
With our equipment we couldnīt find out more about this phenomenon, but
since then we always use a filter, also at our race engine.
Reiner Nikulski
Well perhaps but we don't intend to use carb. We want to use mechanical FI
using a manifold air pressure tap or a positive drive mechanical fuel
pump for control. We are trying to keep it simple so anyone can fix it.
Until that happens I am thinking of using a Megasquirt 1 from:
http://www.diyautotune.com/ for about $240 plus injectors which I have.
I'll use it for RX8 p-port engine dyno testing.
It is one quarter to one half the cost of a 58 mm Weber which cost $1200 US.
Perhaps they are cheaper in Italy.
Anybody on here now using a Megasquirt?
Megasquirt systems are open hardware and software so there is a lot
of help on the Internet and the programs can be debugged or changed by
anyone. For example: one could sample the MAP at any time or take a lot
of MAP samples and average them.
The Magasquirt 1 uses an Motorola assemble language I am familiar with.
There is also a stimulator so you can set up your system on the bench
and program it.
Paul Lamar ...No rotor no motor.
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