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Need Help choosing a relay

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Old 04-18-2007, 10:43 AM
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Default Need Help choosing a relay

I have installed a 6 Circuit fuse panel to run my major accessories (O2, MSD Box, Elec Ignition, Ect..) I am running a 8ga Power line to it and want to trigger it on with Ignition. So I need a relay. I was thinking it should pull no more then 75-80amp. It needs to be rated for continuous use also.

Anyone have any ideas?
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Old 04-18-2007, 11:23 AM
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Default Re: Need Help choosing a relay


Most places that sell relays should have what you need.

Here's one from digi-key that is rated for 70A.
http://www.digikey.com/scripts/DkSea...=69861&Site=US


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Old 04-18-2007, 11:39 AM
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Default Re: Need Help choosing a relay

http://www.txinel.com/relays_0332002150.asp I was thinking possibly that one.
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Old 04-18-2007, 01:40 PM
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Default Re: Need Help choosing a relay

Really, you want a relay rated at ~100A (so at 70A its running at 85% of max.) for a bit of safety. Some of the items you've listed will create a large inductive loading. This tends to result in relay contacts welding themselves together. Once that happens, you can't stop your car.....

Its also worth installing an inertia switch in the line either from the ignition barrel, or the line running to your fuel pump. So if you have a big shunt, it will stop the car running on (starting a fire).

Just a bit of advice, hopefully of some use to you.
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Old 04-18-2007, 03:09 PM
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Default Re: Need Help choosing a relay

ford v8/i6 starter relay.
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Old 04-18-2007, 06:18 PM
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Default Re: Need Help choosing a relay

Originally Posted by DrSeuss
Really, you want a relay rated at ~100A (so at 70A its running at 85% of max.) for a bit of safety. Some of the items you've listed will create a large inductive loading. This tends to result in relay contacts welding themselves together. Once that happens, you can't stop your car.....

Its also worth installing an inertia switch in the line either from the ignition barrel, or the line running to your fuel pump. So if you have a big shunt, it will stop the car running on (starting a fire).

Just a bit of advice, hopefully of some use to you.
Which items will pull a major draw? I previously had the Ignition and MSD box on a 20A with no problems. The MSD is just a power on trigger MSD says 5a fuse is overkill, the LC1 calls for a 5a minium fuse, the "O" meter I assume is the same a very low draw. There will also be a circuit breaker in the main feed to this panel and it will be tied into my rear mounted kill switch. The Fuel pump is on its own circuit with an inertia switch to kill it in the event of an accident. When I said 70-80A I mean got forbid I put something large on this. The Petronix Ignition unit also recommends a 10A minimum so im nowhere near 75A I guess I should have been a bit more clear.

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Old 04-18-2007, 11:30 PM
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Default Re: Need Help choosing a relay

Wire it like its supposed to be, and put a relay on each one, its not that hard and I know you can do it!!!

just grab some connectors from the junkyard instead of using all female blade connectors. Thats how i've done 3 racecars. Just make sure to sauder everything
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Old 04-19-2007, 12:38 AM
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Default Re: Need Help choosing a relay

Hah I dont needs 6 relays under the dash. Painless makes a fuse panel 7 circuit with a single relay, no reason I cant.
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Old 04-19-2007, 04:28 PM
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Default Re: Need Help choosing a relay

Try getting the glow plug relay for any diesel powered truck
NAPA sells this one, 85 chevy with 6.2L diesel.

http://www.napaonline.com/masterpage...low+Plug+Relay

for $17.95, and it's rated for under hood heat, and 100 Amps
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Old 04-19-2007, 07:04 PM
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Default Re: Need Help choosing a relay

Originally Posted by gbryning
Try getting the glow plug relay for any diesel powered truck
NAPA sells this one, 85 chevy with 6.2L diesel.

http://www.napaonline.com/masterpage...low+Plug+Relay

for $17.95, and it's rated for under hood heat, and 100 Amps

That's a nice relay. Cheap, rugged, and high curren capacity.



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