GM OEM TBI up to 420hp?
Walter Sherwin
wsherwin at home.com
Thu Sep 28 02:21:32 GMT 2000
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Hey Ross there are three TBI hardware approaches that you may want to =
consider, if you want to feed a 420'ish HP V8 at reasonable [less than =
6000 - beyond is quite impractical] RPM's.......
1) My favourite, due to simplicity and reliability..........Use a BBC =
2bbl twin 2" blade TBI [say for example a 17091047 assembly - or =
anything from a post 91 application will get you the better IAC and TPS =
setup] with a set of good BBC TBI low pressure injectors [say 17112560 - =
engraved 17084304] and install a bolt-in-place post 94 BBC 26-32psig =
TBI regulator [17113079]. This will get you roughly 670 CFM @ 3"Hg =
airflow, and about 250 #/HR of maximum fuel flow. Oh, and you might as =
well buy a Holley 12-903 [or 12-903HP] gerotor in-tank EFI pump kit [or =
maybe even a Bosch GFP216 in-tank pump if you don't mind the cost of =
this rollervane unit], and be sure to run it all through a GM "spin-on" =
EFI medium duty truck TBI fuel filter assembly [15694406 - the =
replacement cartridge is 15577756 - good for 400+ #/Hr flow at less than =
0.5psig pressure drop - also allows for use of either the Rochester =
style fuel line fittings or for the use of conventional pipe thread =
fittings by screwing out the inlet/outlet adapters]. Use any GM TBI =
dual channel box that you wish, and program away. Additionally this =
allows you to use either conventional TBI intake manifolds [which you =
***really*** will want with TBI fuel , with EGR if required], or you can =
adapt quite easily to any intake manifold that you may be thinking of. =
You won't find this info posted anywhere else on the face of this =
planet, but it works extremely well, and all of the parts can be =
obtained via the local U-Pull or your friendly GM dealer, at reasonable =
cost.
2) My second choice........Is a Holley 4bbl TBI assembly [there were not =
any OE 4bbl GM TBI assemblies produced - but there were some OE marine =
4bbl TBI setups [[volvo]] which were based around the now commonly =
available Holley TBI assemblies]. Holley has a number of TBI offerings, =
with IAC, up to a max of 900 CFM @ 1.5"Hg airflow and up to 312 #/Hr @ =
15psig fuel flow. These 4bbl units work well, and can be controlled by =
any GM dual channel TBI box, but external injector drivers will be =
required. The archives are full of guys ***trying*** to run four TBI =
injectors from just the two OE GM TBI 4/1 injector drivers [in two =
series banks], but, you ***really*** want to drive each of the Holley =
TBI injectors via an individual 4/1 amp P&H driver for best/predictable =
results.
3) I have not personally tried this last approach..........Dual 2bbl =
TBI's, a couple of my colleagues have tried this with excellent results. =
About all I can offer in this arena is that they used dual 5.7 litre =
TBI's, on an old non-EGR "Offy" style dual carb intake manifold, wired =
the IAC's in parallel, and used a GM dual channel TBI ECM together with =
external injector drivers. Seemed to work well, based on their =
feedback. I'd like some driving time behind one of these, as I have a =
few unresolved misgivings pertaining to mixture distribution and =
throttle modulation.
Hope this helps;
Walt.
----- Original Message -----=20
From: Ross Corrigan=20
To: diy_efi at diy-efi.org=20
Sent: Tuesday, September 26, 2000 8:40 PM
Subject: GM OEM TBI up to 420hp?
Well I have another question, I never did see my first one "converting =
carb to an 'airdoor'" make it to the list but I did get one reply. =
While I'm waiting for a good programmable ECU to show up my interest in =
starting with an OE GM TBI setup is growing. I've read the 'programming =
101' and 'what you need' and it looks to me like one can spend $200US =
on hardware and then combine software and you can start tailoring your =
own EPROM's correct? Looked like software editing app's have come a =
ways since I last thought about this a few years ago as well.
Is their an OEM GM 4bbl TBI unit that will flow enough to support a =
roller 350 with 420'ish flywheel hp? And naturally will the injectors =
feed it and if not can they be upgraded and at what cost? I came across =
a kewl setup on a sbc 350 cross-ram intake w/ dual 2bbl's described as =
follows that I'd like any input on (not sure on writer's experience as =
car his car hasn't seen much use yet and this is a new venture for him). =
Haven't scared up a low rise cross ram intake yet but who knows
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<BODY bgColor=3D#ffffff>
<DIV><FONT size=3D2>Hey Ross there are three TBI hardware =
approaches that you=20
may want to consider, if you want to feed a 420'ish HP V8 at =
reasonable=20
[less than 6000 - beyond is quite impractical] =
RPM's.......</FONT></DIV>
<DIV><FONT size=3D2></FONT> </DIV>
<DIV><FONT size=3D2>1) My favourite, due to simplicity and=20
reliability..........Use a BBC 2bbl twin 2" blade TBI [say for example a =
17091047 assembly - or anything from a post 91 application =
will get=20
you the better IAC and TPS setup] with a set of good BBC TBI low =
pressure=20
injectors [say 17112560 - engraved 17084304] and install a =
bolt-in-place =20
post 94 BBC 26-32psig TBI regulator [17113079]. This will get you =
roughly=20
670 CFM @ 3"Hg airflow, and about 250 #/HR of maximum fuel flow. =
Oh, and=20
you might as well buy a Holley 12-903 [or 12-903HP] gerotor =
in-tank EFI=20
pump kit [or maybe even a Bosch GFP216 in-tank pump if you don't =
mind the=20
cost of this rollervane unit], and be sure to run it all through a =
GM=20
"spin-on" EFI medium duty truck TBI fuel filter assembly [15694406 =
- the=20
replacement cartridge is 15577756 - good for 400+ #/Hr flow at less than =
0.5psig=20
pressure drop - also allows for use of either the Rochester =
style fuel line=20
fittings or for the use of conventional pipe thread fittings by screwing =
out the=20
inlet/outlet adapters]. Use any GM TBI dual channel box that you =
wish, and=20
program away. Additionally this allows you to use either =
conventional TBI=20
intake manifolds [which you ***really*** will want with TBI fuel , with =
EGR if=20
required], or you can adapt quite easily to any intake manifold =
that you=20
may be thinking of. You won't find this info posted anywhere else =
on the=20
face of this planet, but it works extremely well, and all of the parts =
can be=20
obtained via the local U-Pull or your friendly GM dealer, at =
reasonable=20
cost.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=3D2>2) My second choice........Is a Holley 4bbl TBI =
assembly=20
[there were not any OE 4bbl GM TBI assemblies produced - but there were =
some=20
OE marine 4bbl TBI setups [[volvo]] which were based =
around the now=20
commonly available Holley TBI assemblies]. Holley has a number of =
TBI=20
offerings, with IAC, up to a max of 900 CFM @ 1.5"Hg airflow and up =
to 312=20
#/Hr @ 15psig fuel flow. These 4bbl units work well, and can be=20
controlled by any GM dual channel TBI box, but external injector =
drivers=20
will be required. The archives are full of guys ***trying*** to =
run four=20
TBI injectors from just the two OE GM TBI 4/1 injector drivers [in two =
series=20
banks], but, you ***really*** want to drive each of the Holley TBI =
injectors via an individual 4/1 amp P&H driver for best/predictable=20
results.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=3D2>3) I have not personally tried this last=20
approach..........Dual 2bbl TBI's, a couple of my colleagues have =
tried=20
this with excellent results. About all I can offer in this arena =
is that=20
they used dual 5.7 litre TBI's, on an old non-EGR "Offy" style dual carb =
intake=20
manifold, wired the IAC's in parallel, and used a GM dual channel TBI =
ECM=20
together with external injector drivers. Seemed to work well, =
based on=20
their feedback. I'd like some driving time behind one of these, as =
I have=20
a few unresolved misgivings pertaining to mixture distribution and =
throttle=20
modulation.</FONT></DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV><FONT size=3D2>Hope this helps;</FONT></DIV>
<DIV><FONT size=3D2>Walt.</FONT></DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV> </DIV>
<BLOCKQUOTE=20
style=3D"BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: =
0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV=20
style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
<A href=3D"mailto:280zx at home.com" title=3D280zx at home.com>Ross =
Corrigan</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
href=3D"mailto:diy_efi at diy-efi.org"=20
title=3Ddiy_efi at diy-efi.org>diy_efi at diy-efi.org</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Tuesday, September 26, =
2000 8:40=20
PM</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Subject:</B> GM OEM TBI up to =
420hp?</DIV>
<DIV><BR></DIV>Well I have another question, I never did see my first =
one=20
"converting carb to an 'airdoor'" make it to the list but I did get =
one=20
reply. While I'm waiting for a good programmable ECU to show up =
my=20
interest in starting with an OE GM TBI setup is growing. I've read the =
'programming 101' and 'what you need' and it looks to me like =
one can=20
spend $200US on hardware and then combine software and you can start =
tailoring=20
your own EPROM's correct? Looked like software editing app's =
have come a=20
ways since I last thought about this a few years ago as =
well.<BR><BR>Is their=20
an OEM GM 4bbl TBI unit that will flow enough to support a roller 350 =
with=20
420'ish flywheel hp? And naturally will the injectors feed it and if =
not can=20
they be upgraded and at what cost? I came across a kewl setup on a sbc =
350=20
cross-ram intake w/ dual 2bbl's described as follows that I'd like any =
input=20
on (not sure on writer's experience as car his car hasn't seen much =
use yet=20
and this is a new venture for him). Haven't scared up a low rise cross =
ram=20
intake yet but who knows</BLOCKQUOTE></BODY></HTML>
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