Glossary, Questions – Paxton Superchargers Street User Manual
Page 3
P/N: 008574 © 2008 Paxton Autom otive Corporation. Al
l
Righ ts Re s e rve d, Intl
.
Copr. Se cure d (Stre e t Supe rch arge r Sys te m O w ne r’s M anual
(008574V4.0))
QUESTIONS?
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GLOSSARY
Afte rcool
e r: A h e at e xch ange r w h ich re duce s th e
te m pe rature of th e com pre s s e d ch arge be fore it
e nte rs th e com bus tion ch am be r.
Air By-Pas s Val
ve : D e vice de s igne d to e l
im inate
com pre s s or s urge . It functions by al
l
ow ing air to be
dum pe d (or route d back to th e s upe rch arge r inl
e t
on MAF e ngine s ) from th e dis ch arge s ide of th e
s upe rch arge r. It e m pl
oys pre s s ure s e ns or l
ine s th at
ope rate an inte rnal
diaph ragm conne cte d to a
val
ve . Th is is an e s s e ntial
pe rform ance im proving
de vice th at al
s o im prove s durabil
ity.
Air Fue l
Ratio: Th e am ount of air com pare d to th e
am ount of fue l
in th e air fue l
ratio m ixture , al
m os t
al
w ays e xpre s s e d in te rm s of m as s (s e e
s toich iom e tric). Ide al
air fue l
ratio at idl
e and l
ow
e ngine l
oad is 14.7:1 (s e e Fue l
rich /l
e an).
Am b ie nt Te m pe rature : Th e curre nt te m pe rature of
th e s urrounding outs ide air.
Atm os ph e ric Pre s s ure : Norm al
pre s s ure in th e
s urrounding atm os ph e re , ge ne rate d by th e w e igh t
of th e air above us pre s s ing dow n. At s e a l
e ve l
, in
ave rage w e ath e r conditions , atm os ph e ric pre s s ure
is approxim ate l
y 100 k Pa (about 14.5 ps i) above
vacuum or ze ro abs ol
ute pre s s ure .
Barom e tric Pre s s ure : Anoth e r te rm for atm os ph e ric
pre s s ure . Expre s s e d in inch e s of Me rcury (in.H g.).
H ow h igh atm os ph e ric pre s s ure (re l
ative to ze ro
abs ol
ute pre s s ure ) force s Me rcury up a gl
as s tube .
14.5 ps i= 29 .9 2 in.H g.
Bl
ow e r: Te rm ofte n appl
ie d to al
l
type s of
s upe rch arge rs .
Boos t: Condition of ove r pre s s ure (above atm os ph e ric
in th e intak e m anifol
d) caus e d by intak e air be ing
force d in by a s upe rch arge r.
BTM : (Boos t Tim ing Mas te r) D rive r com partm e nt
adjus tm e nt for re tarding ignition tim ing. Incl
ude d
w ith s om e s upe rch arge r k its to control
ignition
tim ing to pre ve nt de tonation. A boos t/ vacuum
re fe re nce d ignition tim ing control
.
Ch ok e Line : Are a on com pre s s or m ap w h e re th e
com pre s s or can no l
onge r e fficie ntl
y de l
ive r th e
am ount of airfl
ow th e e ngine ne e ds . It is th e point
w h e re boos t pre s s ure fal
l
s off on a com pre s s or
m ap, e ve n th ough air fl
ow continue s to incre as e .
Can be caus e d by re ach ing th e capacity of th e
im pe l
l
e r, th e capacity of th e com pre s s or h ous ing
pas s age w ay, or th e inl
e t. Prope r com pre s s or
m atch ing to th e appl
ication e l
im inate s th is
probl
e m .
Com pre s s ion Ratio: Th e ratio of m axim um e ngine
cyl
inde r vol
um e (w h e n th e pis ton is at th e bottom
of its s trok e ) to m inim um e ngine cyl
inde r vol
um e
(w ith th e pis ton at TD C). Th us , th e th e ore tical
am ount th at th e air to fue l
m ixture is com pre s s e d in
th e cyl
inde r.
Com pre s s or H ous ing: Th e h ous ing w h ich m ak e s up th e
e ncl
os ure portion of th e com pre s s or. Al
s o re fe rre d to
as th e vol
ute , s crol
l
or s nail
.
Com pre s s or M aps : Graph ic s um m arie s of s upe rch arge r
pe rform ance data (w ith re s pe ct to pre s s ure and
fl
ow ) ge ne rate d us ing te s t e q uipm e nt and
proce dure s .
D e ns ity: Th e ratio of th e m as s of s om e th ing to th e
vol
um e it occupie s . Air h as l
e s s de ns ity w h e n it is
w arm , and l
e s s de ns ity at h igh e r al
titude s .
D e tonation: (Knock ) Sudde n incre as e in cyl
inde r
pre s s ure caus e d by pre -ignition of s om e of th e air-
fue l
m ixture as th e fl
am e front m ove s from th e
s park -pl
ug ignition point. Pre s s ure w ave s in th e
com bus tion ch am be r cras h into th e pis ton or
cyl
inde r w al
l
s . Th is re s ul
ts in th e s ounds k now n as
k nock or ping. Strongl
y infl
ue nce d by fue l
octane
rating, ignition tim ing, and com pre s s ion ratio as w e l
l
as boos t l
e ve l
. May be caus e d by h ot carbon
de pos its on th e pis ton or cyl
inde r h e ad.
EFI: (El
e ctronic Fue l
Inje ction) A com pute r control
l
e d fue l
s ys te m th at dis tribute s fue l
th rough an inje ctor
l
ocate d in e ach intak e port of th e e ngine . Th e fue l
inje ctors are us ual
l
y fire d us ing individual
circuitry.
Efficie ncy Is l
ands : Th e pe rce ntage val
ue s th at
de s ignate th e e fficie ncy e xpre s s e d in an is l
and
re pre s e ntation on a com pre s s or m ap. Th e are a
ins ide th e is l
ands de s ignate m axim um e fficie ncy,
th e are a to th e l
e ft of th e e fficie ncy is l
ands
de s ignate th e te m pe rature is too h igh on th e s urge
s ide , and th e are a to th e righ t of th e e fficie ncy
is l
ands de s ignate th at drive h ors e pow e r is h igh on
th e ch ok e s ide .
Fue l
Rich /Le an: An e val
uation of air to fue l
ratio bas e d
on an air-fue l
val
ue k now n as s toich iom e tric or
14.7:1. In m os t fue l
inje ction s ys te m s rich /l
e an is
de te rm ine d by vol
tage s ignal
from th e oxyge n
s e ns or. An e xce s s of oxyge n l
e an is a vol
tage of l
e s s
th an .4 vol
ts . A rich condition is indicate d by a
vol
tage of gre ate r th an .6 vol
ts .
FM U: (Fue l
Manage m e nt Unit) A vacuum /boos t
re fe re nce d fue l
pre s s ure re gul
ator. Us e d to incre as e
th e pre s s ure by re gul
ating fue l
fl
ow re turning to th e
tank from th e s tock fue l
pre s s ure re gul
ator.
Im pe l
l
e r: Th e finne d or bl
ade d rotating w h e e l
h ous e d
ins ide th e com pre s s or h ous ing.
Induce r: Th e air inl
e t portion of a ce ntrifugal
com pre s s or.
Inte rcool
e r: A h e at e xch ange r w h ich re duce s th e
te m pe rature of th e ch arge air be tw e e n s tage s of