DIY_EFI Digest V4 #607

[rpettibo at hpubs.com]

Doug - I can not find my dyno sheet from the session with the the fuel
injection so I will just give you rough numbers based on memory.  I do have
the dyno next to me for the same engine when I compared a Performer RPM Vs
a Bowtie single plane (similar to a Victor Jr.).

The dyno I ran on would only pull down to 3000 to 3500 RPM so all runs were
begun at 3500 and ran through 6500.  The minimum gains with the fuel
injection were in the 30 to 35 lb/ft range even at 3500.  There was no loss
in power compared to the carb at any piont in the pull.  I know the
increase in power has carried down in the powerband because after the
conversion the car no longer hooks up from a standing start.  I run about
2300 stall with a built 700R4 and it will light it up, in smoke, to 6500
right now.  It did not have those beans before.  I shift at 6500 to 6850
and I think the drop is to about 4000 in second,  I just have never paid
attention to the tach after the shift.  I will check it out this weekend
and E-mail you directly.

Part of the success I have had is spending the time (2-3 hours at a time)
driving and tuning the fuel curves at various loads and rpm points.  This
has made a big difference.  I probably have 40 to 50 hours in tuning time
dialing things in.

Your thoughts with the single plane Vs dual plane with carb are accurate
based on the dyno runs I made with the same engine comparing a Performer
RPM to a Bowtie single plane.  When I first built this engine I ran the
Performer and a carb.

In essence they were both about the same on the bottom end (5 to 10 lb/ft
diff. max at some RPM points) but I gained on the top end (above 5000) 10
to 20 HP.  One thing which put the Bowtie at a disadvantage was the dual
plane was port matched and the bowtie was not.   When we were putting on
the Bowtie I could see the ports were not matched very well.   At that
time, if I had not spent the money to port the dual plane, I would have
gone with the Bowtie/carb combo.  I know I would have gained back what I
lost on the bottom and gained more top end if everything was ported.

On another note I am just beginning to build a 440 small block and am
anticipating going with the Speed Pro system.  Anybody have any thoughts or
experience with this system?  To me it seems to be the most up to date and
well thought out system out there especially with the wide band O2
capability.