1227165 with 12P on a LQ1 (3.4 DOHC)

American Delco GM ECUs and PCMs, ALDL, OBD 1.5.
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FieroWannaBe
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Joined: Wed May 23, 2012 4:25 am
cars: 2004 Pontiac GTO
1986 Fiero GT LS4
1987 Fiero GT LQ1
1970 C10 L47

1227165 with 12P on a LQ1 (3.4 DOHC)

Post by FieroWannaBe »

I am starting this to document my attempt to control my motor for my budget endurance race car. The car is built against the Chump Car series rules, with plans to compete in 24 Hours of LeMons and World Racing League events as well. The Car is a 1987 Fiero GT, 100% gutted, seam welded/reinforced and repaired from rust and previous crash damage. The engine, is a 1996 3.4L DOHC LQ1 from a US Chevrolet Lumina LS.
The engine has reground camshafts, lightweight lifter buckets, a shortened runner intake with an extra large large plenum (above 10L), a 75mm throttle body from a later OBDII spec Northstar V8. These engines are the bastard spawn of the GM 60 degree V6, adopted to DOHC by removing guts in the lifter valley, running a belt pulley of the blanked shaft where a standard pushrod camshaft would live. The camshafts ride in heavy aluminum carriers, machined like cam-in-block tunnels. They hold the 35mm lifter buckets and camshafts. Its an inefficient design that's heavy, but I'm sure GM did this to allow common tooling in their V6 plant. they have a 7x crank wheel, a 1x cam sensor, and run waste spark DIS. The heads are 24V units, with square intake ports, obround exhaust ports. No headwork has been done at this point beside a 3 angle valve job (if they the machine shop even did that) and spring shims to bring the effective rate up. the design of the timing belt setup allows for infinite adjustment of the camshafts, so I might play with that a bit.
Current timing is: 236 Degree duration (.05") with 10mm of lift on intake and exhaust . Timing is 108 Intake Centerline and 112 Exhaust Centerline.

This engine used to run a 16196401 from a 1994 Monte Carlo Z34 with a custom tune from gmtuners.com when it was stock. I attempted to retune with my AutoProm from Moates, but never had much success getting tuner pro to read the ALDL data, and the .bin from the chip with that ECU. I am ditching that ECU so that I can run a MAP sensor instead of MAF, and have better ignition and fuel control at high RPMs. The old ECU used to stall when disengaging the clutch at times. and if it didn't the idle would be around 1100rpm and slowly settle, (tricks with the IAC to raise idle after cruising and prevent the stalling)

I have a 1227165 ECU and harness from a mid 80's 5.0L Firebird, the Old harness and ECU from the 16196401 days, my autoprom, and I am trying to buy the NVRAM module from Antus currently to make tuning easier than running through the autoprom emulation. The good news for me is, I work at a Dynamometer manufacturer, http://powertestdyno.com/ and http://www.stuskadyno.com/. On weekends I can run the engine on our XS211 test dyno to work on the tune outside of a car.

Right now I still need to wire the harness to the 12P spec, make mounts for the engine stand at work, and have the driveshaft adapter cut for the crank pattern so I can run on the dyno.

Ill keep this thread update as I go through making this setup work.
Dylan
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Re: 1227165 with 12P on a LQ1 (3.4 DOHC)

Post by Dylan »

Sounds like good fun. You could possibly replace the DFI module with one from here and run multiplS1 coils. Not sure if that trigger pattern is programmed in this module.
Dylan
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Re: 1227165 with 12P on a LQ1 (3.4 DOHC)

Post by Dylan »

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vlad01
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Re: 1227165 with 12P on a LQ1 (3.4 DOHC)

Post by vlad01 »

That one damn big plenum. you'd want to reduce it down to about 2.7-3L for best performance and response otherwise its going to be soggy and unresponsive and loose overall performance.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
FieroWannaBe
Posts: 4
Joined: Wed May 23, 2012 4:25 am
cars: 2004 Pontiac GTO
1986 Fiero GT LS4
1987 Fiero GT LQ1
1970 C10 L47

Re: 1227165 with 12P on a LQ1 (3.4 DOHC)

Post by FieroWannaBe »

http://papers.sae.org/2008-01-3007/

With the plenum, I had the material, and shortening it to make it smaller is still possible. But if you take a look at the SAE paper, bigger is better for power.
I'm interested in running it to run it and see how it performs as it is.

Other wise I will cut about two inches out of the top and weld a new flange to it.

Image
FieroWannaBe
Posts: 4
Joined: Wed May 23, 2012 4:25 am
cars: 2004 Pontiac GTO
1986 Fiero GT LS4
1987 Fiero GT LQ1
1970 C10 L47

Re: 1227165 with 12P on a LQ1 (3.4 DOHC)

Post by FieroWannaBe »

I will have to look into the Ignition setup.
I do have a 24X crank sensor on the balancer as well, since my engine is an OBDII version.
MAGP
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Re: 1227165 with 12P on a LQ1 (3.4 DOHC)

Post by MAGP »

For optimum streetability and performance (so not one or the other) a plenum of the same size as the engines capacity works best. Having a small plenum makes the engine work harder to fill the cylinders and this limits max power. Having a large one slows air speed and this kills low down torque and mid range the bigger you go. All manifolds are a compromise so build it to suit your purpose.
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