LS1b (411) PCM Swap - Page 2 - ZR-1 Net Registry Forums

VetteVet · 03-08-2012

Ron,

I don't know what Jerry has. It was probably for some type of Engine Management System retrofit and it does have 24 slots, but it won't be able to produce the signal that the LS1 PCM would need. See below:

The complete document from which this was taken can be downloaded here:

http://www.bowlingss.com/DownLoads/P...Holden_LS1.pdf

Jep

RHanselman · 03-08-2012

Got it...

Merlot566jka · 06-07-2012

Following this, and have borrowed some of your material. And have some to contribute. http://forums.*************.com/c4-t...post1581004077

I don't know if this is any contribution, but seeing as we both are working to use the same PCM on the same car, maybe we can help eachother.

RHanselman · 06-08-2012

Jep,

Any updates?

Cheers,
Ron

Merlot566jka · 06-08-2012

Hey guys, how does the lt5 get its crank trigger pulse for the icm?

If its a pressed on disc around the crank, look at GMs 3400,3500 v6 engines. They have a large inner diameter wheel with the 24x wheel pressed onto the center of the crank. This is in the same place as the old 2.8/3.1 crank reluctor wheel. The significance is that the old cranks had the grooves for the reluctor machined into the crank, but the newer wheel can be pressed on over these old machined marks.

Now take this info and use it as you will, but I have a good feeling that GM kept things universal in some aspects. I would bet that if the lt5 has a machine 9x reluctor or a pressed on reluctor on the crank, that the outside diameter of this part onthe crank is around 5.75". Anyone know if this is true?

Tyler Townsley · 06-09-2012

Quote:

Originally Posted by Merlot566jka

Hey guys, how does the lt5 get its crank trigger pulse for the icm?

Merlot566jka · 06-09-2012

Right, the LT5 was a fresh design. I suppose the point I was getting at was the crank reluctor wheel is inthe middle of the crank, like I had thought. This design was used on many other GM vehicles during that era. While the lt5 ignition system wasn't used on any other GM v8, it was a similar design to what they had existing in other DIS systems. I knew lotus designed the engine, merc manufactured the engines, but I have a good feeling GM had a hand in the ignition, fuel and ECM. But I am in no way an expert on the LT5, I know very little about this amazing machine.

On the GM designs that were similar, they had a reluctor cast into the crank, and the grooves were machined. The v6s used 7 notches, similar to how the LT5 used 9, one for the reset. The used an ICM that controlled much if not all of the spark control using the signal that was returned from the ECM. I would Almsot bet they have the same connectors on the LT5 ICM with the same in and outs that the other GM DIS systems had.

Not to dispute the information you have provided, but this design is extremely similar to other GM designs of the time.

Regardless, the information I was providing is that GM made a 24x reluctor wheel, than can be heated an pressed over the existing crank on an older 60* V6. If, by chance, the cast reluctor inside of the LT5 is about 5.75 inches, this reluctor that was used on the V6 could be used on the LT5 for 24x conversion. I have one of these reluctor wheels that I am working with, and just thought I'd share that with you guys, just in case someone wants to give it some more research.

XfireZ51 · 06-09-2012

Merlot,

The LT-5 ICM is unique to this motor. It uses a very similar 14 pin connector however it is quite a bit different from other ICM. Viewing the circuitry, you can think of the DIS as a co-ECM. The base of the LT-5 ECM is the L98. Remember, the L98 ran w 1 coil and a distributor. So something else had to be developed for multiple waste spark coil setups. Buick has their own for the GN but that's a six and the ECM dealt w issues like dwell from the start. The secondary injectors are driven by a secondary injector power circuit controlled by the ECM grounding the power relay. Firing of the secondary is strapped to the primary injector rather than ECM having a separate driver circuit for them. My point is that some
things may look the same but not necessarily analogous.
As for the slip on reluctor wheel, sounds like an expensive and cumbersome solution for using a CnP setup IMO. How about on the balancer?

Merlot566jka · 06-09-2012

EFI connections tried the 24x reluctor wheel on a dampner and they had too much noise on the hall effect for it to work properly. But I have used a 7x that I made and it was bolted on the outside of the dampner. I didnt have any noise issues, but that's a fairly low resolution compared to the 24x.
GM says they placed the reluctor on the LSx engines towards the back of the block because this is the "quiet" zone. If GM went through this kind of trouble, I imagine there was a good reason.

But at the same time, EFI connections 24x and 58x kits for the LT1/4 engines use the reluctor behind the timing cover. Their system seems to work, even if it's in the "noises" zone.

Thanks guys for all the info on the LT5 ignition. It's always good to see how it was done differently.

XfireZ51 · 06-10-2012

Is there any doubt as to why the LT-5 reluctor is in the middle of the crank?!
7-8k rpm and that's the most stable spot on the motor. Someone else here would know more, but Marine did have an LT-5 w CnP.
Who would know about that?

03-08-2012	#11
VetteVet Join Date: Jan 2009 Location: Mandeville, LA Posts: 340	Re: LS1b (411) PCM Swap Ron, I don't know what Jerry has. It was probably for some type of Engine Management System retrofit and it does have 24 slots, but it won't be able to produce the signal that the LS1 PCM would need. See below: The complete document from which this was taken can be downloaded here: http://www.bowlingss.com/DownLoads/P...Holden_LS1.pdf Jep

03-08-2012	#12
RHanselman Join Date: Jul 2005 Location: Cresson, TX Posts: 970	Re: LS1b (411) PCM Swap Got it...

06-07-2012	#13
Merlot566jka Join Date: Jun 2012 Location: Norman, oklahoma Posts: 10	Re: LS1b (411) PCM Swap Following this, and have borrowed some of your material. And have some to contribute. http://forums.*************.com/c4-t...post1581004077 I don't know if this is any contribution, but seeing as we both are working to use the same PCM on the same car, maybe we can help eachother.

06-08-2012	#14
RHanselman Join Date: Jul 2005 Location: Cresson, TX Posts: 970	Re: LS1b (411) PCM Swap Jep, Any updates? Cheers, Ron

06-08-2012	#15
Merlot566jka Join Date: Jun 2012 Location: Norman, oklahoma Posts: 10	Re: LS1b (411) PCM Swap Hey guys, how does the lt5 get its crank trigger pulse for the icm? If its a pressed on disc around the crank, look at GMs 3400,3500 v6 engines. They have a large inner diameter wheel with the 24x wheel pressed onto the center of the crank. This is in the same place as the old 2.8/3.1 crank reluctor wheel. The significance is that the old cranks had the grooves for the reluctor machined into the crank, but the newer wheel can be pressed on over these old machined marks. Now take this info and use it as you will, but I have a good feeling that GM kept things universal in some aspects. I would bet that if the lt5 has a machine 9x reluctor or a pressed on reluctor on the crank, that the outside diameter of this part onthe crank is around 5.75". Anyone know if this is true?

06-09-2012	#17
Merlot566jka Join Date: Jun 2012 Location: Norman, oklahoma Posts: 10	Re: LS1b (411) PCM Swap Right, the LT5 was a fresh design. I suppose the point I was getting at was the crank reluctor wheel is inthe middle of the crank, like I had thought. This design was used on many other GM vehicles during that era. While the lt5 ignition system wasn't used on any other GM v8, it was a similar design to what they had existing in other DIS systems. I knew lotus designed the engine, merc manufactured the engines, but I have a good feeling GM had a hand in the ignition, fuel and ECM. But I am in no way an expert on the LT5, I know very little about this amazing machine. On the GM designs that were similar, they had a reluctor cast into the crank, and the grooves were machined. The v6s used 7 notches, similar to how the LT5 used 9, one for the reset. The used an ICM that controlled much if not all of the spark control using the signal that was returned from the ECM. I would Almsot bet they have the same connectors on the LT5 ICM with the same in and outs that the other GM DIS systems had. Not to dispute the information you have provided, but this design is extremely similar to other GM designs of the time. Regardless, the information I was providing is that GM made a 24x reluctor wheel, than can be heated an pressed over the existing crank on an older 60* V6. If, by chance, the cast reluctor inside of the LT5 is about 5.75 inches, this reluctor that was used on the V6 could be used on the LT5 for 24x conversion. I have one of these reluctor wheels that I am working with, and just thought I'd share that with you guys, just in case someone wants to give it some more research. Last edited by Merlot566jka; 06-09-2012 at 12:50 PM. Reason: Posted with an iPhone, it spells things on its own

06-09-2012	#18
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,708	Re: LS1b (411) PCM Swap Merlot, The LT-5 ICM is unique to this motor. It uses a very similar 14 pin connector however it is quite a bit different from other ICM. Viewing the circuitry, you can think of the DIS as a co-ECM. The base of the LT-5 ECM is the L98. Remember, the L98 ran w 1 coil and a distributor. So something else had to be developed for multiple waste spark coil setups. Buick has their own for the GN but that's a six and the ECM dealt w issues like dwell from the start. The secondary injectors are driven by a secondary injector power circuit controlled by the ECM grounding the power relay. Firing of the secondary is strapped to the primary injector rather than ECM having a separate driver circuit for them. My point is that some things may look the same but not necessarily analogous. As for the slip on reluctor wheel, sounds like an expensive and cumbersome solution for using a CnP setup IMO. How about on the balancer? __________________ [SIGPIC][/SIGPIC]Former Membership Chairman Former ZR-1 Registry - BOD 1972 Corvette 4speed base Coupe SOLD long time ago 1984 Corvette Z-51/4+3 SOLD 1992 Corvette ZR-1 Aqua/Gray #474 SOLD 1992 Corvette ZR-1 Black Rose/Cognac #458 2014 Honda VFR Interceptor DX

06-09-2012	#19
Merlot566jka Join Date: Jun 2012 Location: Norman, oklahoma Posts: 10	Re: LS1b (411) PCM Swap EFI connections tried the 24x reluctor wheel on a dampner and they had too much noise on the hall effect for it to work properly. But I have used a 7x that I made and it was bolted on the outside of the dampner. I didnt have any noise issues, but that's a fairly low resolution compared to the 24x. GM says they placed the reluctor on the LSx engines towards the back of the block because this is the "quiet" zone. If GM went through this kind of trouble, I imagine there was a good reason. But at the same time, EFI connections 24x and 58x kits for the LT1/4 engines use the reluctor behind the timing cover. Their system seems to work, even if it's in the "noises" zone. Thanks guys for all the info on the LT5 ignition. It's always good to see how it was done differently.

06-10-2012	#20
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,708	Re: LS1b (411) PCM Swap Is there any doubt as to why the LT-5 reluctor is in the middle of the crank?! 7-8k rpm and that's the most stable spot on the motor. Someone else here would know more, but Marine did have an LT-5 w CnP. Who would know about that? __________________ [SIGPIC][/SIGPIC]Former Membership Chairman Former ZR-1 Registry - BOD 1972 Corvette 4speed base Coupe SOLD long time ago 1984 Corvette Z-51/4+3 SOLD 1992 Corvette ZR-1 Aqua/Gray #474 SOLD 1992 Corvette ZR-1 Black Rose/Cognac #458 2014 Honda VFR Interceptor DX

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