12 Volt relay to feed the coils???

[Bearly Flying]

A popular mod on Motorcycles is to install a 12 volt relay and run heavier gauge wire direct from the battery to feed the coils, The existing 12 volt feed is used on the trigger side of the relay.
This puts approx 12.5 volts direct to the coils, reducing current on the switchgear and reducing voltage drop through the system.

Would this be a benefit to Our ZR-1's, would there be any risk to the ECM?

[XfireZ51]

Originally Posted by Bearly Flying

A popular mod on Motorcycles is to install a 12 volt relay and run heavier gauge wire direct from the battery to feed the coils, The existing 12 volt feed is used on the trigger side of the relay.
This puts approx 12.5 volts direct to the coils, reducing current on the switchgear and reducing voltage drop through the system.

Would this be a benefit to Our ZR-1's, would there be any risk to the ECM?

What would the benefit be?

[Bearly Flying]

Higher voltage to the coils means a longer and hotter output from the secondary windings, better ignition of a somewhat not ideal mixture??? also less current on the existing wiring and switches.

I know my bike( 85 FJ1100, with a big bore 1250 kit, 11.5 comp, 150 hp rwhp) seems happier with the mod. But it is a pretty easy mod on the bike, not sure about the ZR-1, but the principals should be the same.

[XfireZ51]

Well, the schematic for the coil POSITIVE can be found here. It goes directly to the coil driver and through to the ICM. Not sure I would want to bypass or if there is a real need to.

[Paul Workman]

A relay, used as you've described, has demonstrated advantages in the 90-92 cars to i.e., "reducing the current in the switchgear" - as it applies to the LT5 starter (in this case). In fact, the 93-95s the switchgear was (in effect) isolated in a fashion similar to what just as you are describing. So, in general theory, your using a relay to isolate large current paths from "switchgear" is a valid endeavor...generally speaking.

However...

• In this specific application, such a relay would be redundant, due to the use of the "coil driver module" doing the job of you relay mod
  
• Lead lengths between the DIS and the coils is already very short (by design), thus minimizing line resistance losses in the wiring and other issues*, so there's no practical advantage there
  
• *Pains are taken to shield the critical wiring from EMI (pulses) in the proximity of where such a relay would have to be placed to have any hope of doing any good; which would expose the relay (and more importantly) the wiring to the DIS to the introduction of EMI...a bad thing at high RPM especially.
  
• Perhaps (to me, anyway) the main reason not to mod is the fact there is no problem with the factory setup - far as saturating the coils goes**. (Parts that don't exist never fail, and they don't cost much!)

Now, IF we want to address ignition in a truly positive way, going to a CNP like the LS motors use, or COP like Ford uses on some of their performers...is worth a thought; some performance gain might be had there (but a topic for another discussion/thread)

That said, I bow to anyone with actual experience with this mod as applied to the LT5 SPECIFICALLY.

[Bearly Flying]

Thanks for the schematic and the info.

On the bike it is very simple, the 12 volt feed goes direct to the Pos side of the coils, the Ignition module is on the Neg side to ground,so very straight forward.

Oh well, live and learn...

Thanks Guy's