Secondary relay module questions - Page 2 - ZR-1 Net Registry Forums

65ZR1 · 07-22-2008

Quote:

Originally Posted by lbszr

Who made your harness? Might need to figure out a different ignition system someday also.

The company is called the detail zone and makes conversion harnesses for street rods etc. He did have a hard time getting some of the LT5 connectors so the harness took about 8 months to complete. It was a top notch job though.

8upZR1 · 07-22-2008

There is a guy who makes some kinda EFI system called the DUCK or something like that. Howell is his name. I see his add in back of magazines sometimes. Looks cute and says he makes an LT5 harness. Has anyone heard/seen/tried one of these?

For stand alone ignition duties I have now perfected the use of MSD's 6MOD timing computer on LT5's. Its a really nice computer that is laptop programmable for curves, retard, etc. Basically a digital programmable 7. It runs coil on plug from a Mustng Cobra. Worked a lot better than distributor.

I looked into the Digital programable 7 but it runs about 2K where as the 6MOD is only 1K complete with coils and everything. The 7 needs more expensive gear and therefore more expensive. + with the 6MOD you get manual control over base timing.

Lots of the stand alone EFI companies make a Fuel Only computer. I was gonna play with the mega squirt but never got around to it.

lbszr · 08-01-2008

Quote:

Originally Posted by 8upZR1

There is a guy who makes some kinda EFI system called the DUCK or something like that. Howell is his name. I see his add in back of magazines sometimes. Looks cute and says he makes an LT5 harness. Has anyone heard/seen/tried one of these?

For stand alone ignition duties I have now perfected the use of MSD's 6MOD timing computer on LT5's. Its a really nice computer that is laptop programmable for curves, retard, etc. Basically a digital programmable 7. It runs coil on plug from a Mustng Cobra. Worked a lot better than distributor.

I looked into the Digital programable 7 but it runs about 2K where as the 6MOD is only 1K complete with coils and everything. The 7 needs more expensive gear and therefore more expensive. + with the 6MOD you get manual control over base timing.

Lots of the stand alone EFI companies make a Fuel Only computer. I was gonna play with the mega squirt but never got around to it.

All some good info to save!

Are you still running the stock ecm with the stand alone ignition? Just curious since I was thinking the ecm needs some inputs from ignition.

-=Jeff=- · 08-01-2008

just thinking about this. I had at one point a F.A.S.T. eDIST

that might work too, I think all the signals are there for the ECM.. I need to look at the document again, but with the eDIST, you would be running the LS1 coil packs.

only thing I am unsure of is if the LT5 crank trigger would work..

pretty sure everything else would though.

8upZR1 · 08-01-2008

With the MSD 6MOD I didn't use the factory ECM for fuel, I ran a QFT 750. I wanted to try a stand alone fuel computer like the one from mega squirt but never got around to it.

I looked into the F.A.S.T. XFI system for the LT5. Even with the EDist, it unfortunately will not work with the LT5 trigger wheel. XFI is a really killer system though. Top of the line. You can always mount a trigger wheel on the balancer. Thats what I did for the 6MOD. It's nice cause the sensor mount has a slot that allows for adjustment of the base timing.

XfireZ51 · 08-01-2008

Quote:

Originally Posted by -=Jeff=-

just thinking about this. I had at one point a F.A.S.T. eDIST

that might work too, I think all the signals are there for the ECM.. I need to look at the document again, but with the eDIST, you would be running the LS1 coil packs.

only thing I am unsure of is if the LT5 crank trigger would work..

pretty sure everything else would though.

I was talking to Jeremy about this yesterday. He thought that coil packs were like the GN and may be able to use that or LS system.

Paul Workman · 08-02-2008

Quote:

Originally Posted by Aurora40

Wouldn't this be about the same? Whether it's a plug wire or a regular electrical system wire, there's going to be about the same length either way. I don't think electricity travels more slowly in plug wires vs harness wires?

Anyway, I agree coil on plug (or coil near plug on the LSx motors) is definitely better. But 25hp better on a ~400hp motor? That just seems unlikely to me.

Inductive reactance (resistance) to current flow is a function of changing current over time (t) - the shorter the time, the higher the "resistance". Not quite that simple, actually. Induction tends to resist changes in current; either to initial current flow, or current stopping - the key to ignition coil operation.

The two halves of the ignition coil is the primary side and the secondary side. Of course inductive reactance applies to both sides, but there is a difference in the time each circuit half is "operating".

On the primary side, the inductance is not an issue as there is ample time (between spark signals) to overcome initial inductive reactance of the primary wiring and the primary side of the coil and "saturate" the primary winding - "cocking" it and then waiting, if you will.

The spark command comes as a sudden interruption of the charging current on the primary side; "sudden" is the key. The magnetic field in the primary collapses almost instantaneously, cutting thru the much bigger secondary coil in the process. The result is a tremendous (compared to the battery voltage that initiated it) voltage spike that is exacerbated like flood water behind a dam. The "dam" is in the form of the spark plug(s). Voltage builds up to the point it overcomes the combined resistance of the spark gap and the compressed air/fuel mix.

Once the current jumps the gap, it is like the dam broke. However, the current must first flow thru the plug wires and when current flows, the law of inductive reactance cannot be denied. The longer the plug wires, the more induction takes place, and the current flow will be impeded more.

So, due to the very short nature of the plug-side current, induction plays the bigger role on the plug side of the ignition circuit. Reducing the plug side conductors to zero would be the ideal situation.

I don't know how much hp this will make in the case of the LSx vs. the LT5. But, it couldn't hoit!!

Gotta take the dogs to the vet. Mo later!

P.

-=Jeff=- · 08-02-2008

While extra HP would be a benefit of a swap to LSx coils, My main reason for the swap to them would be to eliminate the $$$$$ ignition module and and use more readily avail ignition components

XfireZ51 · 08-02-2008

Quote:

Originally Posted by -=Jeff=-

While extra HP would be a benefit of a swap to LSx coils, My main reason for the swap to them would be to eliminate the $$$$$ ignition module and and use more readily avail ignition components

Talk about a WIN WIN!

Paul Workman · 08-02-2008

The LT5 uses a "waste spark" system; two plugs are fired simultaneously from the same coil. So, there is only 4 coil primary charging circuits in our cars. To covert to the LSx with (I suppose) 8 charging circuits would be...interesting. But! I like the idea of having a safe harbor should the spark module crap out someday on my LT5.

I like the way you think, Jeff.

P.

07-22-2008	#12
8upZR1 Join Date: Jun 2006 Location: Thunderbolt, Ga. Posts: 253	Re: Secondary relay module questions There is a guy who makes some kinda EFI system called the DUCK or something like that. Howell is his name. I see his add in back of magazines sometimes. Looks cute and says he makes an LT5 harness. Has anyone heard/seen/tried one of these? For stand alone ignition duties I have now perfected the use of MSD's 6MOD timing computer on LT5's. Its a really nice computer that is laptop programmable for curves, retard, etc. Basically a digital programmable 7. It runs coil on plug from a Mustng Cobra. Worked a lot better than distributor. I looked into the Digital programable 7 but it runs about 2K where as the 6MOD is only 1K complete with coils and everything. The 7 needs more expensive gear and therefore more expensive. + with the 6MOD you get manual control over base timing. Lots of the stand alone EFI companies make a Fuel Only computer. I was gonna play with the mega squirt but never got around to it. __________________ IT IS THE FATE OF THE INNOCENT TO MEET WITH DEATH!!!

08-01-2008	#14
-=Jeff=- Join Date: Jul 2007 Location: Bartlett, IL Posts: 7,132	Re: Secondary relay module questions just thinking about this. I had at one point a F.A.S.T. eDIST that might work too, I think all the signals are there for the ECM.. I need to look at the document again, but with the eDIST, you would be running the LS1 coil packs. only thing I am unsure of is if the LT5 crank trigger would work.. pretty sure everything else would though. __________________ 1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - 3" Magnaflow Bullet cats - LT4 Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978

08-01-2008	#15
8upZR1 Join Date: Jun 2006 Location: Thunderbolt, Ga. Posts: 253	Re: Secondary relay module questions With the MSD 6MOD I didn't use the factory ECM for fuel, I ran a QFT 750. I wanted to try a stand alone fuel computer like the one from mega squirt but never got around to it. I looked into the F.A.S.T. XFI system for the LT5. Even with the EDist, it unfortunately will not work with the LT5 trigger wheel. XFI is a really killer system though. Top of the line. You can always mount a trigger wheel on the balancer. Thats what I did for the 6MOD. It's nice cause the sensor mount has a slot that allows for adjustment of the base timing. __________________ IT IS THE FATE OF THE INNOCENT TO MEET WITH DEATH!!!

08-02-2008	#18
-=Jeff=- Join Date: Jul 2007 Location: Bartlett, IL Posts: 7,132	Re: Secondary relay module questions While extra HP would be a benefit of a swap to LSx coils, My main reason for the swap to them would be to eliminate the $$$$$ ignition module and and use more readily avail ignition components __________________ 1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - 3" Magnaflow Bullet cats - LT4 Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978

08-02-2008	#20
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,493	Yeah, I see your point. The LT5 uses a "waste spark" system; two plugs are fired simultaneously from the same coil. So, there is only 4 coil primary charging circuits in our cars. To covert to the LSx with (I suppose) 8 charging circuits would be...interesting. But! I like the idea of having a safe harbor should the spark module crap out someday on my LT5. I like the way you think, Jeff. P.