Felpro System (was Street/Race EFI Article) (fwd)

[Frank F Parker]

DIY Group: The message below is from Jay Carter, a much respected
Buick GN tuner, who does GM ecm chips and much fuel inj experience.
It outlines very well the new FelPro fuel injection and may be of
interest to this group:
Regards,

frank parker


From: Jay Carter <jcarter at gte.net>
To: gnttype at gnttype.org
Subject: Felpro System (was Street/Race EFI Article)

I have setup and programmed several of these units on different vehicles
and I have to say that this is the slickest unit I have ever seen. Not only
is it relatively simple to calibrate compared to other units, it's also
very user friendly, very fast and has some really trick features. One such
feature that is the slickest thing I have ever seen is the ability to
record a run and the come back and overlay it on top of your base fuel
table and play it back in slow motion. This lets you analyze what happens
every step of the run and make changes if necessary.  It even has a
simulated engine sound that climbs in tone as the RPMs go up! The closed
loop setup also makes calibration a snap. Just plug in the A/F ratios you
want to use and the ECM will correct itself back to the commanded A/F
ratios as long as your within the (user defined) correction limits. This
way, you can play the run back, change the base fuel map as needed and
eventualy remove the O2 and have a system that's 100% dialed in. The timing
table is also much more detailed than the DFI and allows much more precise
control of the timing. It also has an adjustment that allows you to set the
timing precisely and remove all the guesswork from what your timing REALLY
is (Unlike the DFI).

While on the surface, this unit may seem like a jazzed up DFI. Well, its
not. There is SO much more going on here than meets the eye. This system
uses an entirely different approach to delivering fuel to an engine than a
DFI. Instead of setting up your fuel table according to base pulse width,
the Felpro system works on a volumetric effiecient approach. There are
many, many factors used to calculate fuel delivery instead of just plugging
in a base pulse width and going like the DFI does.  Engine size, injector
size, etc all play an important role in the fuel delivery algorithm on the
Felpro system. Let's say for example your car is running 55lb injectors and
the calibration is perfect but you wanna switch to something different.
So.. you go out and buy a set of 83s and install them in the car and change
your injector constant to 83lb/hr. Now.. while this won't get you DEAD on
the money, it will get you very, very close so that only small adjustments
will need to be made. Pretty slick, huh? This is a TRUE speed density
system.. not a lookup table system like the DFI has. Also, because the
system is true speed density and uses the VE table, the smallest increment
of change is 8 uS (microseconds), while the DFI is 64 uS. This is very
important for cars running big injectors.


Another great feature of the system is the aforementioned data logging
system. It allows recording of a "dashboard" during a run. There are 15
"dashboards" that are preset but can be altered by the user. You can pick
and chose between which ones you want to record and also how many frames
per second you'll be recording. You can also set the sensor that triggers
the recording process to start (Most every sensor on the car can be used as
well as RPM, etc) and you can set where the threshold is. Also, all data
recording is handled INSIDE the Felpro's PC software (Calcom). You dont
have to exit the program and load the data file into a text editor to read
it and analyze it. You also get nice graphs that can be stepped through a
frame at a time as opposed to a big column on numbers. However, the data
can be exported in a text file if you so desire.  The number of frames per
second can be adjusted from 1 to 50 frames per second but is somewhat
dependent on the speed of the PC you're running Calcom on. 50 frames on a
fast 486 is not a problem, tho. The limiting factor is the number of
recordable frames per second which is right now at 150. However, with a 10
second car, that's still about 13 frames per second.

Another great feature of the software is the editing ability to cut and
paste, manipulate blocks of data and interprolate.  You can cut blocks of
data  from an offline calibration and paste in into your existing cal file,
change values in blocks of data without having to change EVERY valve (like
DFI made you do) and you can even interprolate data by highlighting four
corners of your map and telling the software to interprolate between the 4.
Very slick.. similar to working with a spreadsheet. Constructing a base
calibration is a snap. You can set every valve in the VE table to 60-70 and
the car will most likely start and run because the wideband O2 will bail
you out of trouble.


Sorry to be long winded but hopefully this will help answer some of the
questions that people have concerning this system.

Jay

Jay Carter
10.92 @ 123 through the muffler

Mail To : JCarter at GTE..NET