[Diy_efi] Seqential or Batch??
life_speed at yahoo.com
Sun Jun 6 18:06:34 GMT 2004
You've listed many reasons why sequential is only
incrementally better than batch.
Sure, it's not like switching from a carb to EFI. But
the improvement from sequential is noticeable and
worthwhile. Idle quality, part throttle response and
economy are all improved.
A performance engine can especially benefit, as the
uneven airflow caused by a lumpy cam has less impact
on mixture consistency. A good sequential ECU can
also adjust injection angle to employ sufficient lead
on the valve event to get the full load of fuel into
the cylinder before the valve closes.
Large, low-Z injectors are appropriate. This makes a
proper injector drive circuit a must. Correctly
driven, even large injectors can be metered accurately
at idle. I use 96 lbs/hr injectors with a 241 degree
@ .050 cam, and the engine idles clean and smooth at
fired system has the advantage of being able to inject
fuel for the
entire period of crankshaft rotation whereas the timed
only has the time available that the air is flowing in
runner. This is determined mainly by the camshaft
characteristics. On an
average performance cam having 220 degrees of intake
duration measured at
.050 valve lift, the sequential system has only 61% of
the time to
inject the fuel as the batch fired system. As such,
true, timed, sequential
systems must have larger injectors fitted for a given
hp. It should be
remembered that there is little airflow and velocity
in the port and
runner until the valve is open a fairly significant
amount. Starting the
injection sequence early and finishing late, partially
supposed advantages of timed injection. On a high
revving engine, there are
only a few milliseconds available to inject before the
Do you Yahoo!?
Friends. Fun. Try the all-new Yahoo! Messenger.
diy_efi mailing list
diy_efi at diy-efi.org
More information about the Diy_efi