[ReidB]

Hi!
I have recently bought a 95 k2500 with a blown motor and a 94 lt1 350. They will be going together very soon. I am new to the forumn so I apologize now if this has been covered but I am really tired of searching old posts.
Please don't turn this thread into a shoulda bought a LSX... I have a whopping $600 invested in this project so far and am gunning for a 325hp 4x4 for under a grand.
I have built numerous old school cars but this is my first ecm/fi project.
The truck has all tbi hardware intact, the engine is complete with ecm and trans.
The motor is an iron headed lt1 out of a 94 Fleetwood which has been modded with Vette internals and cam.
For simplicity sake, I am tempted to install the tbi, ditch the optispark and worry about boring the tbi and tuning later. I don't know how difficult it will be to get the tune right.
If the tbi route sucks, swapping in the LT with computer opens a lot more questions...
Can I keep the original ecm to run the trans and dash, and install the new ECM to run the engine? I know both need VSS and tach inputs. From what I have gathered, the 95 4l60e is different than the 94 so plug and play is out. Also, with this route, I have an optispark to deal with.
Has anyone successfully replaced an opti with a computer controlled hei? It seems like it should work...
Thanks in advance for your input!

 

[axisT6]

The TBI ECM in your 95 is the best of the TBI ECMs and can be modified to run port fuel. I believe the ECM for the 94 LT1 is also well supported. Look at Moates.net to see what your tuning options are.

I would also look at the TBI tuning thread on GMFS, and read the tuning threads on thirdgen.org as they cover the 87-95 tuning stuff in depth. FWIW, I am using a modded TBI ecm to run a MPFI 406 in my 95.

 

[11MPG]

^I second that. TBI is fine if you have a built motor underneath it. Sounds like you got a nice build underway. Don't listen to the LS people. Yeah an LS is nice but I still loved my 96 K1500 with the LT4 hot cam and 4.56 gears. Truck made a lot of torque. On thing I would say is when you do the swap spring for the long tube headers and do a dual 2.5 inch. It will be worth while with your cam.

 

[ReidB]

Axis
How did you add the mpfi wiring to your harness? I can figure out how to swap in the Lt1 ecm but I have no idea how the additional wiring would pinout.
Thanks

 

[ReidB]

Hey 11,
TBI would be a total plug in solution. I would have to modify the intake but the tbi and distributor would drop in and plug in without any wiring mods. BUT the stock tbi will not support the cfm requirements and I'm not sure how difficult it would be to get it properly tuned.

 

[Hogg]

I would go with AxisT6 recomendation. This gets you away from the limiting TBI and also allows for Port Fuel Injection rather than a full wet maniofld like with TBI.

IIRC The stock ECM is used, but there are mdoifications to fire the 4 PFI injectors in a bank for bank AKA "Batch-fire"m just like the 85-92 TPI V8's. 1,3,5,7 fire at once then 2,4,6,8 injectors are fired at once.
This is the basis for the Edelbrok TBI to MPFI.

The 1st GM Sequential injection in a gas engine (where the injector firing is timed to the intake valve opening) was started with the 1996 4,3/5.0/5.7 and 454.

If you really wanted to retain the TBI wet style intake, you can buy specific intake manifolds for the GEN 2 1993-97 Y-body Vette 5.7L LT1, 93-97 F-body Camaro/Firebird aluminum headed 5.7L LT1, 1994-1996 iron headed 5.7 LT1 in the B-body(Caprice), D-body Cadillac, and the 1994-1996 iron headed 4.3 V8(265cid-vee-eight) from the B-body(Caprice).

Description from the CPP(Chev Performance Parts-was-GM Performance Parts) Catalog.
Dual plane Chevrolet Performance Parts' Carbureted LT1 intake manifolds make it possible to take advantage of the advancements found in Generation 2 Chevy engines. They allow you to install a carburetor on your LT1 engine without the hassle of running a computer or emission controls. They accept both Holley and Quadrajet carburetors, and feature longer runners that increase engine torque by up to 30 ft.-lbs. without sacrificing top-end power.

Good thing about that intake is that it is already has the mount and hold down bolt boss for distributer usage.

You are going to need a proper ECM (chip) recalibration mo matter what you do.


$292 from Summit
http://www.summitracing.com/int/parts/nal-24502592/overview/

You could also swap to the the 0411 PCM and then enjoy a multitude of people who have the ability to tune it.

peace
Hog

 

[ReidB]

Thanks for the input guys. I'm leaning towards complete install with wiring & ecm swap. The LT1 is a Gen 2 engine and already has sequential MPFI and a decent tune.
Wiring looks like a major PITA.