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post #1 of (permalink) Old 01-18-2004, 01:48 PM Thread Starter
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Anyone using a relay to give TFI coil 12 volts??

I have been reading lots of ignition stuff the past few days. There is lots of conflicting information on the TFI upgrade and the required coil voltage. I have read many posts on this, and I don't want to start a "great debate". I am just curious if anyone is running their TFI coil on a relay and applying a full 12 volts? This would keep the resistance wire in the harness, but isolate the coil. Let me know.

Thanks,
Tom

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post #2 of (permalink) Old 01-18-2004, 02:54 PM
 
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Re: Anyone using a relay to give TFI coil 12 volts??

you need some form of current limiting.
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post #3 of (permalink) Old 01-18-2004, 09:36 PM
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Re: Anyone using a relay to give TFI coil 12 volts??

</font><blockquote><font class="small">In reply to:</font><hr />
I am just curious if anyone is running their TFI coil on a relay and applying a full 12 volts? This would keep the resistance wire in the harness, but isolate the coil. Let me know.

[/ QUOTE ]

Do you have a diagram of this? Could you explain this a little better?

I put a full 12v to my coil after the TR upgrade and fried a few coils, put the resister wire back in and was good. I don't have the spark I had w/o the resister wire but it is still an improvement.
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post #4 of (permalink) Old 01-18-2004, 10:30 PM
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Re: Anyone using a relay to give TFI coil 12 volts??

</font><blockquote><font class="small">In reply to:</font><hr />
I am just curious if anyone is running their TFI coil on a relay and applying a full 12 volts?

[/ QUOTE ]

I don't think a mechanical relay can switch fast enough for the ignition.
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post #5 of (permalink) Old 01-18-2004, 11:25 PM Thread Starter
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Re: Anyone using a relay to give TFI coil 12 volts??

Hey Will,

I was thinking of using the resistance wire to power the relay, the relay would apply 12 volts to the coil. I am not sure if there is a need for this, but I read a lot of conflicting information about the resistance wire, and the E-coils need for 12V. Anyway, I was just fishing for information.

Later,
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post #6 of (permalink) Old 01-18-2004, 11:36 PM
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Re: Anyone using a relay to give TFI coil 12 volts??

The way I understand the TFI coil, it can take a full 12 volts but it had better be in a very cool place under the hood. They don't like heat very much. They also have a tendency to overheat the ignition module.
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post #7 of (permalink) Old 01-18-2004, 11:41 PM
 
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Re: Anyone using a relay to give TFI coil 12 volts??

</font><blockquote><font class="small">In reply to:</font><hr />
I don't think a mechanical relay can switch fast enough for the ignition.

[/ QUOTE ]
its called ignition points. just like the old time days, but with that much current you are going to weld them contacts together.

you have got to limit the current. the dura spark uses a 1.35 ohm worth of resistor wire.

the HEI limits current in the control module. as RRICH has said.

and I'll add that ST micro (L484) and Motorola (MC3334) make monolithic chip sets just for the task. [img]images/graemlins/40BEER.gif[/img]

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