The PCM and harness combination used in '01+ Chevy Express vans is unique. Since it's an LS1-era PCM (part # 12200411), it can be tuned by software such as HPTuners or its competitors. The harness and flash programming that came on the Express Vans is designed to work with an SBC motor that has an LT1-style front cover.

First, some relevant reading material:

http://forum.efilive.com/showthread.php?t=3261
http://forum.efilive.com/showthread.php?t=3306
http://forum.efilive.com/showthread.php?t=276

So, L98 guys have done it, but it doesn't look like anyone with an LT1 has posted up any attempts. Has anybody on here taken a shot at this conversion? It might open up a whole new tuning market for guys who wanted more choices to tune their LT1 cars.

Thanks!

 

nice information.

 

Craig Moates and I where discussing this earlier today. You might want to shoot him a email as he may have a solution for in the future (not nessisarly any time close)

 

Shouldn't be much to it. Just use a '96/'97 OBD2 timing cover, crank position sensor & reluctor, then use a 350" Vortec truck cal. They are also 4 pulse per rev. It will be in batch fire mode, and you will have to turn off the high resolution & cam position sensor failure codes. Likely have to adjust the crank off-set angle to get the spark advance right (You'll need a timing mark & pointer to verify it.), other than that there should be nothing to it. The Mexican pickups still used the 350", even with the newer body style. They came with both 4L60E & M5 trans. Closer to what you would need than an express van cal. I use those cals for late S10/350" swaps. Some wiring changes, and you should be in business.

 

Awesome. I'll start hunting for a PCM and harness.

 

You don't need a harness, just new connectors. The metal terminals on the LT1 wires are the same, just back them out of the LT1 plastic connectors, and put them in the LS1 connectors. Get a plastic '99/'02 F body PCM mount and locate it the same place as the LT1 box. If memory serves, the low resolution signal in the optispark is also 4 pulses, but I have not looked at the wave forms with a lab 'scope, so don't know if the signals are compatible. Batch fire mode (No cam sensor signal) won't be a big deal, as I don't remember seeing individual cylinder fuel adjustments in the 0411 box's code. Batch fire will drive just as well, and run just as fast. Sequential mode is mostly an emissions deal. If I get some free time (yeah, right) I'll poke around some more. If you had a single plane intake, you could ditch the Opti and have sequential mode back using a 350" Vortec truck dist. You would loose the OBD1 "stall wall" and the 7000 RPM limit. Shouldn't be a big deal. Cheaper than a F.A.S.T. ECM & TCM, for sure.

 

The 4 pulse from the low resolution side is uneven. They are equispaced but each are different lenghts.

This is very very interesting. I may convert my eaton supercharged LT1 over just to have better control in boost.

 

That is to identify #1 cylinder, for sequential mode. I think the 0411 box just "looks at" the leading edge, since it has the cam sensor in the dist. Haven't really looked into it that much. Down side of the crank trigger in the timing cover is the required narrow timing chain. I can't imagine how it could be all that big of a deal to do.

 

Humm.. that is interesting. I do believe the low res side all start in 90 degree increments.

 

Does anyone have pictures of these parts? I'm unfamiliar with the Vortec timing cover.

 

Trax, Go to Thirdgen.org>TPI. Search OBDII TPI thoughts/opinions.

 

We've done a few 411 conversions on the L98 engines and should have pictures of the conversion available soon on our website. We're very excited about the tuning benefits of these systems.

The Vortec timing cover will not work with the LT1 block. We're also interested in this conversion for the LT1, but haven't gotten our hands on an LT1 to try it out.

If all goes well, my AWD V8 S-10 will be converted to the 411 system soon. We've been busy with this conversion on a 33 ****** and should have the installation wrapped up after working out the VSS signal tomorrow. After the Easter weekend it should be tuned on the dyno with EFI Live.

If you've got any questions, just let me know.

Mike
EFI Connection

 

any news on this for us LT1 guys?

Eric

 

Just an update for guys who run across this thread in the future...

This swap is definitely promising, but I have a LOT more to learn about tuning and EFI in general before I personally take on something of this scale.

On a related note, I'm still very eager to learn more about EFI through datalogging... hence this project.

 

Update, Update, Update

 

Didn't the first versions of the LT1 use a 4x wheel on the crank and a crank sensor mounted low in the timing cover on the pass. side. If so, you could convert to the earlier cover and modify the intake for the Vortec distributor.

 

or a single plane conversion

 

It's the later LT1's (the 96-97 OBD2 engines) that had the added sensor on the crank...ALL LT1 PCM's used the opti to run the engine...the sensor was just added for misfire detection with OBD2...but it seems like the PERFECT solution to running the LT1 with a better PCM...the 8051 is great for an NA engine staying under 7000 RPM...but after that it kinda sucks bad. I'm all for 411 conversions.

 

WHAT PCM CONTROLED THE 8100 AND HOW DID IT DO IT? The 8100 is the closest thing that I've seen to a conventional gen 1 engine operating like a LS1

 

big block has a 24 tooth wheel on the crank snout to make it look like a Gen3 engine. The Gen1e engines, IE 5.7 with distributor, have a cam sync in the dizzy and a 4x crank wheel. Same PCM runs either, just gotta tell it what you're running.