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Hi folks!
I was having trouble locating the original post of RNSCRS from 1998, post #12455, describing the LPT to FPT conversion so I took the liberty of reposting it. Hopefully this will help others on this board.
First, a few questions:
Is it necessary to clamp the hoses on the BCV & at their respective fittings on the turbo? The hoses seem to fit pretty snug.
Is it critical that the hoses from the BCV be the same length?
Is it necessary to connect a turbo boost gauge (missing from the CS instrument panel) or is that just for FYI?
Here's the post:
[#12455] LPT Conversion
• From: rnscrs (view other messages by this author)
• Date: Sun, 28 Jun 1998 12:00:00
LPT TO FULL TURBO CONVERSION
Conversion of a LPT to full turbo can be accomplished with the expected
results, full turbo boost of 10 –11 PSI.
The conversion requires addition of boost control valve with hoses and
changing the TRIONIC engine ECU to a regular turbo ECU. My total cost was
about $270.
It was assumed the LPT engine and turbo engine are the same. Discussions
on the TSN chat site confirm the LPT and full turbo short blocks are the
same. I went on the assumption that the volume of these turbo types was too
small for SAAB to support different hardware for the LPT. The LPT has the
wiring and connector for the boost valve, same turbo, same exhaust system,
etc as the full turbo. Even the auto transmission is the same. Basically
the LPT is a full turbo minus the boost valve and hoses and an ECU that has
the full turbo boost adaptation disabled. It’s ironic, the LPT made Wards
Auto World Engine Of The Year” twice, when it’s just turbo running on base
pressure. The other item the LPT is missing is the instrument panel boost
gage. Changing the instrument wasn’t considered, I rigged up a digital
boost gage which is described a separate posting. In the end changing the
“combined instrument” as SAAB calls the boost gage assembly may have been
just as easy.
Acquiring used parts for the conversion required some searching. I didn’t
price new parts but they would cost more than $500 with a reconditioned
exchange ECU from SAAB. The boost control valve is common on all 9000
full turbos from 1990 up (part # 74 85 576). I got the boost valve and
hoses (# 40 22 224) with clamps from Mile High for $90. Get the mounting
plate, screws, etc with the valve, I didn’t, and ended up buying them from
a dealer. The boost valve was installed before the ECU change to check for
any response. There was some response, the valve buzzed and changed
frequency above 2500 RPM, but after a few days it was apparent no
adaptation was taking place. The ECU does not know if the boost valve is
connected, it only knows if the boost pressure is responding correctly for
the ECU version..
Finding a used ECU took a while. Most places didn’t have one and said most
newer cars are rebuilt rather than parted out. I did some checking around
to see if some creative manipulation with an ISAT might convert the ECU,
but couldn’t find anyone who had tried it. The TRONIC ECU is
electronically programmed (no removable chip), SAAB USA can reprogram the
ECUs. I suspect the program for LPT and full turbo are the same with a one
byte software switch to enable full turbo boost adaptation . A break came
when a fellow at work showed up with a Locator magazine. This magazine is
for junk yards, it’s full of ads for rebuildable cars, parts, etc. In the
classified section were a couple of ads from outfits that specialized
automotive ECUs. One ad said they buy ECU’s for up to $90, a nice hint for
what you should pay. One of advertisers did a search on their net which
resulted in one response, for a 1996 Aero ECU. They wanted $160 for the
ECU, which I bought immediately. The donor Aero had an automatic
transmission which uses the same ECU as a full turbo.
The ECU for 1994 and newer full turbos is the same for manual and automatic transmissions, with the Aero manual transmission having a different turbo and ECU. The part number for a production 1996 and newer full turbo ECU is 43 00 836, the # for a SAAB exchange reconditioned 1996 and up ECU is 88 28 592.
Installing the conversion parts is quite easy, the only tricky part is
connecting the hoses correctly at the turbo. The short LPT hose between
the waste gate actuator and compressor outlet must be removed along with a
rubber cap on the top of the compressor inlet. The boost valve hoses are
marked C, W, and R in that order from top to bottom. C goes to the
compressor outlet, W to the waste gate actuator, and R to the top of the
compressor inlet. The ECU is under the left side of the cover just forward
of the wind shield wipers. Undo the braided ground wire, unclip the ECU,
then pivot the connector clamp lever away from the connector. Do not touch
the ECU pins (electrical contacts) at any time. When reconnecting the
connector be sure the connector is positioned properly then carefully
rotate the clamp lever towards the clamp, do not use force. Be sure to
reconnect the braided ground strap, when this strap is disconnected the ECU
does not have full protection against electrostatic discharges.
Electrostatic discharges you cannot feel, see, or hear can kill electronic
components.
We recorded 3 acceleration runs with an old G analyst. The full turbo was
definitely faster than the LPT. The real surprise was the added
acceleration premium fuel gave. Even the LPT may benefited from premium
fuel. Cutbacks in acceleration (ignition timing?) occurred in all runs.
Peak acceleration appeared to be traction limited to about .5 G in first
gear (LPT tires ?). The full turbo automatic would do 0 to 60 in 8.0
seconds starting from engine idle.
The end result has been quite satisfactory, the LPT launch followed by the
full turbo lunge. Yes there is some turbo lag about a half seconds worth,
it can catch you by surprise. Just don't stick your foot into it around
town.
posted by 68.199.229...
, Tue, 15 Nov 2005 16:23:55, Tue, 15 Nov 2005 09:50:38
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