Lt1 => Ls1?

[Cougar281]

For you experts out there... How hard would it be to make a 96 LT1 Firebird work with a 97 or 98 LS1 PCM? I know someone that converted his to run with a Pre-OBD-II PCM for tuning, but EFI would be a good way to go if he could make it run with the LS1 PCM.

[dfe1]

It should be relatively easy. All you really need are LS1-compatible cam position and crank position sensor pulses, eight coils and a wiring harness. But, you'll have to do a little rewiring to accommodate the difference in firing order, (unless you change the camshaft) and you have to change some of the sensors or connectors, unless you have a custom wiring harness built.

[N0DIH]

Been wondering the same thing. I do a lot of PCM tuning on the LT1 now with TunerCat OBD1, but have thought of it. But being the Optispark has a lot of good capabilities, you would lose all of that.

From what I have read the LT1 PCM/Opti treats the engine like 8 1 cyl engines, not 1 8 cyl. The grainularity in cyl to cyl timing tuning is excellent. You might lose some of that with the LS1 PCM. BUT, you would gain coil on plug....

[joecar]

If you are going to do a harness, and if your LT1 is worn out, you may well want to drop in an LS1/2/6, it would fit wouldn't it...?

:cheers:

[Cougar281]

If you are going to do a harness, and if your LT1 is worn out, you may well want to drop in an LS1/2/6, it would fit wouldn't it...?

:cheers:

I suspect it would since it's more or less the same engine... Kinda like with my Cougar. I put a 2002 4.6L in it with PI (Performance Improved) heads, which was a direct drop in, with just some wiring changes due to the different intake.

[dfe1]

I suspect it would since it's more or less the same engine... Kinda like with my Cougar. I put a 2002 4.6L in it with PI (Performance Improved) heads, which was a direct drop in, with just some wiring changes due to the different intake. Negative-- the LT1 is a traditional small block, the LS-series has completely different architecture. In Fordspeak, the differences are like those between a 5.0 and a 4.6. Unlike the Fords, both of the GM engines are of the pushrod persuasion, but the blocks are totally different. Swapping an LSx in place of a conventional small block isn't terribly difficult, but does require some adaptation. Corvette Fever magazine is doing a project that includes installing a 5.3 LSx engine in an '87 Corvette, so that should shed some light on what it takes to do a quality conversion.

I think it would be a kick to run an old-style small block, or any other engine for that matter, with an LSx PCM. I think that will really show off the capabilities of EFILive. I've been talking with a few people about doing a project like that. If it happens, I'll post the results.

[Cougar281]

I see said the blind man :). Thanks for the correction! Learn something every day!

[ChipsByAl]

If your main interest is using EFI Live to tune, you can use your current crank sensor with the Express van program. You would need a high voltage switch (ie. distributor) to handle the single coil. Setting up a cam sensor to trigger the sync signal if desired would be the only fabrication necessary.
AL

[joecar]

For the cam sensor, could he fab up something off the optispark distributor...?

[dfe1]

For the cam sensor, could he fab up something off the optispark distributor...?
I don't see why not, but I think some electronics are required. The Opti-Spark distributor has high and low resolution pulses. The pulses are generated by a shutter wheel inside the distributor and if I remember correctly, the high res section of the wheel has 360 slots. Somehow you have to boil all this down to two pulses-- one for crank position, the other for cam. Someone with a solid electronics background should be able to figure this out pretty easily. There are a few systems that have done that and they use the OptiSpark distributor to generate the triggering pulses, feed them into a control module and then route them to four or eight individual coils. These systems are designed to work with the original LT1 PCM, but they wouldn't be necessary if you switched to an LSx PCM since you only need cam and crank position pulses. Any electronic wizards care to comment?

[N0DIH]

The 360 pulses are actually used on on the rising edge and trailing edge, so it is 360 slots making 720 degrees of res. Phenomenal resolution, best in the business, I don't think any engine ever got better. Then there is another slot in the wheel, a 10, 20, 30 and 40 (IIRC) degree res, which is used solely to determine where #1 is, so that there is the ability to start firing the engine within 90 degrees of engine rotation. Providing killer fast start ability.

So you would need to translate the 360 pulses to the (24x?) res pulses the LSx needs, probably just as easy for any LSx PCM. And somewhere in the middle of that pulse, you need to introduce the additional pulses the LSx uses to determine where #1 is. Basically it has a fairly complex wheel that gives good detail at where it is while keeping the basic 24x resolution (like used as 48x, like the LT1 does by using the leading and trailing edge pulses.

http://www.compstarcomponents.com/Cranks/LS1-Rear.jpg Study the wheel, you will see the 24x wheel, and the other wheel next to it, those together make the complex 24x that carries high res and discrete crankshaft location. Hard to explain really, but it is pretty cool how they did it. The LT1 is superior though for absolute precision, but the LS1 is dirt cheap and that is the name of the game.

http://www.charm.net/~mchaney/optisprk/optisprk.htm

So, can it be done? Sure. Take a little bit of thought, but honestly I don't feel it would be too hard. Might be a neat project to get looking at. I'll dig up in my 99 Truck FSM and see what the LS1 needs for signals and bounce it against my 94 Fleetwood LT1 FSM.

[Cougar281]

Looks like one problem with the Optispark is if/when it goes bad, it's not cheap to replace...

[Doc]

Interesting stuff. Thanks for sharing.

[GMCfourX4]

Sorry to bring up an old thread here, but I too am curious to know what's involved in this... Also, Cougar281, the vast majority of Opti problems revolve around the distributor function of it (basically the cap/rotor). The optical sensors seem to be pretty reliable.I have a Del-Teq conversion on my '96 Impala, which uses the optical sensors on the Optispark, but fires the plugs via a Northstar-style coil pack setup. It seems to work well, I just wish they hadn't sent me wires that route the same way as the factory setup (but that's another story...). Anyone look into the LT1/LSx computer thing any closer?

-Chris

[GMPX]

ChipsByAl was on the money with the Express Van tune as a base.
I think all the puzzle pieces are there to make it work I just don't know if anyone has gone ahead and taken the plunge.
There was also a fella here in Aus that was looking at running one on a local Holden 5.7L, that also runs a dizzy with a cam pos sensor in the dizzy too, I think that is very similar to the Express van setup?
Not sure how that ever ended up though.

Cheers,
Ross

[gto_in_nc]

Negative-- the LT1 is a traditional small block, the LS-series has completely different architecture. In Fordspeak, the differences are like those between a 5.0 and a 4.6. Unlike the Fords, both of the GM engines are of the pushrod persuasion, but the blocks are totally different. Swapping an LSx in place of a conventional small block isn't terribly difficult, but does require some adaptation. Corvette Fever magazine is doing a project that includes installing a 5.3 LSx engine in an '87 Corvette, so that should shed some light on what it takes to do a quality conversion.

I think it would be a kick to run an old-style small block, or any other engine for that matter, with an LSx PCM. I think that will really show off the capabilities of EFILive. I've been talking with a few people about doing a project like that. If it happens, I'll post the results.

If I understand it, the World Products LSx block (they calit WarEagle or something?) has all the holes & mounting surfaces for both LS and SBC configurations, which might make things interesting. I believe I remember the GMPP LSX was planned that way, too, but not sure whether it stuck. Of course, I've slept since I learned all that so every bit of it is suspect...

EDIT: OK, slept again... Remembered what I forgot, maybe.

The WarHawk has both SBC and LS engine mounting provisions. The GMPP LSX block has ALL the holes of both the SBC & LS blocks.