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Every design starts out with some system level requirements. They describe the "end
product" in terms that are important to the customer (myself). In most cases, these
customer requirements don't dictate the detailed specifications or design as most
customers don't have the technical knowledge to do so. Therefore, most system level
requirements focus on final performance objectives (what's desired and under what
conditions) and other factors important to the customer. That's why there are so many
different approaches to FI, as each caters to a different set of customer requirements.
The customer in my case is me, the customer for most other systems is "the market",
which is most likely someone's interpretation of what most some potential customer(s)
would want. In my case I developed the following set of FI System Requirements
1) System shall be capable of producing 425 RWHP and 325 ft/lbs (adjusted) with only
the following performance "add on"
a) Headers
b) No Cats
c) Free flowing exhaust (streetable)
The hp and torque goals weren't numbers that just fell off the tree. They were chosen
for two main reasons. First, they represent a significant increase over stock and
second, they are still well within the "saftey margin" most auto manufactures design
into their individual components, subsystems and systems.
2) System shall not alter shape of stock powerband and shall produce 90% of said
torque by 3000 rpm (290 ft/lbs). Not wanting to change the basic torque curve
characteristics of the NSX forced this requirement.
3) System shall have all air handling components within engine bay for accessibility
4) System shall not require substantial re-location of any major component making a
potential "kit" version more viable
5) System shall not significantly block rear view as this is a safety issue
6) System shall perform reliably with stock bottom end under typical track and driving
conditions using a mechanically sound platform (engine)
a) Track conditions
1) Road race track typical of Willow Springs
2) Ambient conditions 105 degrees F
b) Driving conditions
1) Twenty minutes at 100% (race or TT)
2) 4 hours at 80% (enduro)
c) Mechanically sound platform
1) Good compression (200 + & +/- 10psi/cyl)
2) Little to no oil consumption
3) Clean combustion chambers (carbon)
4) Good fuel injectors (spray & atomization)
5) Baseline dyno run within stock variability
5) Minimum blowby (as observed on dyno)
7) System shall exhibit "drivability" similar to stock while not under boost
8) System shall allow access to typical maintenance items
a) Air cleaner
b) Spark plugs
c) Oil filler cap
d) Fuel filter
9) SMOG certification is not a requirement
To see how the System Requirements translate into design specifications see (design
specifications)
