[Supras] 57 trim driveability

[Rockey Fox]

Bernie, I think you should research the MAFT-Pro a bit as all of this is programmable plus you get to remove the AFM. Supra Sport has the entire install solution including the electronic boost control for ~ $700.
The boost control has a gain feature and rpm set points, etc.. Maybe I'll have a chance to install mine in the next couple of weeks so I can speak more intelligently on the subject.

Rockey 91T

----- Original Message ----
From: "berniek at technicaldevelop.com" <berniek at technicaldevelop.com>
To: "Supras at supras.com" <Supras at supras.com>
Sent: Tuesday, January 29, 2008 1:25:24 AM
Subject: [Supras] 57 trim driveability



For 
the 
last 
two 
days, 
I've 
taken 
the 
'91 
out 
on 
the 
road 
again 
after 
most 
of 
the 
salt 
has 
washed 
off 
the 
roads.  
Mods 
are 
based 
upon 
a 
57 
trim 
CT26, 
550cc 
injectors, 
Lex, 
Walbro, 
3" 
exhaust, 
Treadwell 
Spearco 
knockoff 
and 
the 
usual 
supporting 
changes.  
Raising 
the 
boost 
to 
16-18 
PSI, 
the 
car 
feels 
absolutely 
great, 
sometimes 
breaking 
loose 
in 
second 
gear 
on 
a 
dry 
road 
(need 
to 
fill 
the 
gas 
tank).  
For 
straight 
line 
acceleration, 
I 
could 
not 
ask 
for 
more, 
once 
into 
second 
gear, 
since 
first 
is 
unusable 
at 
WOT 
as 
stated 
before.  
I 
may 
add 
a 
microswitch 
and 
solenoid 
valve 
in 
addition 
to 
a 
second 
boost 
controller 
to 
reduce 
first 
gear 
boost, 
but 
that 
is 
only 
a 
partial 
fix 
for 
the 
real 
consideration 
which 
follows.


Most 
of 
the 
controllability 
regarding 
power 
occurs 
in 
perhaps 
the 
first 
20-30 
degrees 
of 
throttle 
opening, 
notwithstanding 
the 
"digital" 
way 
the 
boost 
comes 
on 
at 
3000 
RPM.  
Although 
I'm 
well 
satisfied 
with 
the 
power, 
the 
car 
is 
hard 
to 
drive 
from 
a 
power 
modulation 
standpoint 
in 
the 
real 
world 
as 
compared 
with 
a 
normally 
aspirated 
engine 
of 
the 
same 
power.  
I'm 
curious 
if 
anyone 
has 
come 
up 
with 
a 
more 
linear 
way 
of 
controlling 
boost 
as 
a 
function 
of 
throttle 
position 
to 
make 
the 
car 
more 
drivable 
when 
getting 
into 
corners 
at 
high 
speed.  
Ideas 
that 
come 
to 
mind 
(some 
are 
hairbrained) 
are 
as 
follows:


1.  
Modification 
of 
manual 
spring 
type 
boost 
controller, 
where 
spring 
preload 
is 
a 
function 
of 
throttle 
position 
through 
a 
lever 
link 
to 
match 
spring 
compression 
to 
throttle 
position.


2.  
If 
elecronically 
inclined, 
develop 
a 
pulse 
width 
modulation 
circuit 
to 
drive 
a 
high 
speed 
solenoid 
valve 
to 
modulate 
boost 
bleed 
as 
a 
function 
of 
TPS 
potentiometer 
position.


3.  
Revise 
throttle 
linkage 
to 
provide 
most 
of 
the 
opening 
within 
the 
last 
10% 
of 
accelerator 
pedal 
travel.  
That 
could 
be 
done 
with 
a 
progressive 
radius 
cable 
saddle 
on 
the 
throttle 
shaft.  
Ford 
accomplished 
the 
same 
thing 
with 
linkage 
angles 
and 
a 
bellcrank 
in 
the 
'50s 
and 
early 
'60s 
when 
they 
had 
the 
Paxton 
blown 
312 
CID 
engine.


  
 
Looking 
forward 
to 
ideas.


  
  
  
BernieK

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