for anybody that may be intrested (or understand more then me lol)
For Info
Henko Racing/Walbro Fuel Pump and general fuel system information
Weare commonly asked "what is the difference between the Henko
Racing/Walbro pumps? I thought they only had a 190lph and a 255lph
pump...?" Well, there are actually quite a few different pumps that
they offer. First, we have the 190lph, the 190lph-HP, the 255lph, and
the 255lph-HP. Then we have the "flipped" versions of the 190lph, the
255lph, and the 255lph-HP (no 190lph-HP). SEE PIC BELOW.
These pumps have the inlet rotated 180 degrees from the inlet. The
reason is to allow for a greater number of fitments. With these 7
pumps, Henko Racing/Walbro can fit numerous vehicle applications. Other
than that, each "series" of pumps is the same in terms of fuel flow
characteristics.
Fuel Pump Matrix
190lph
190lph-HP
255lph
255lph-HP
GSS250
F20000141
GSS317
GSS342
GSS278 (flipped)
N/A
GSS315 (flipped)
GSS341 (flipped)
Anotherquestion we are asked is "what pump do I need and what is that HP
about?" That questions is simple but technical at the same time.....to
be continued
Regardingthe HP question, that is fairly simple. If we take the two 255lph pumps
and look at the pressure curves we see that they are very similar until
about 60psi. After that point, the standard 255 pump starts to die off
whereas the HP keeps going.
Touse an example to illustrate pump choice, we will look at a
turbocharged Acura application. On these vehicles, the OEM fuel
pressure regulator is referred to as a 1:1 regulator. What this means
is that for every pound of manifold pressure (boost) there will be a
corresponding 1 pound increase in fuel pressure. If the base fuel
pressure is set at 40lbs and we introduce 10lbs. of boost, the total
fuel system pressure at boost will be 50lbs. That sounds good and will
work fine with a standard 255 pump but there is one small problem.
Theproblem is that we still need more fuel than the 1:1 regulator can
effectively deliver. One way would be to add a larger set of fuel
injectors and use an aftermarket engine management system to control
them. The other, more commonly used method of fuel enrichment is the
rising rate fuel pressure regulator or FMU. This device functions in a
4:1 (or more) ratio and will increase the fuel pressure 4 pounds for
every 1 pound of boost. If we once again set our base fuel pressure at
40 lbs. and add 10 lbs. of boost we will now see 40 additional pounds
of pressure for a total of 80lbs. of fuel rail pressure. This goes
beyond the capabilities of the standard 255 pump and mandates the use
of the 255HP pump. From this we can see that given two different
engines, both with a hypothetical 400hp, the one with the larger
pressure requirements will need the HP pump, the one with the smaller
requirements will not.