Sequential vs Batch Fire

[Roger Heflin]

On Sat, 28 Oct 2000, Nicholas Parker wrote:

> Hi List,
> For sequential injection you need big injectors as all the fuel has to go
> through an open valve.  Does using big flow injectors have an adverse impact
> on the efficiency of fuel atomisation and controlability at idle?
> I have heard for instance that with my car (365cc/min stock injectors) that
> someone using 550cc injectors (big h.p. application)  could not get a smooth
> idle, -mind you that was with a 2-batches of 2 injectors E.F.I setup (on a
> 1600cc 4cyl supercharged engine).
> 
> Nick Parker.

At WOT none of the Sequential ones I have heard use anywhere near big
enough injectors to get it all through the open valve.  Sequential is
pretty much the same as batch at high PW's.   At idle the sequential
makes a difference and is shooting at an open valve, and it makes a
bit of difference on fuel economy.

Assuming the valve is open during 1/2 of the revolution then the
injectors would need to be twice as big and no one uses injectors that
big on the production vehicle (for f-bodies/mustangs you are talking
about 45+lb injectors to dump all fuel at wot through the open valve).

See a 94 Camaro Z28/Firebird formula vs. a 93 Z/formula,  The 94 is
sequential with 24lb injectors, the 93 is Batch fire with 22lb
injectors (2 separate sides each fired 1x per revolution, but timed
separately).   The HP is exactly the same on both (same
motor,exhaust, the 94 has a MAF the 93 does not).   The fuel economy
is I believe 1mpg better on one of the 4 ratings (hwy/city/A4/M6) on
the 94, so it does not make a major difference.

			Roger

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