Amp Draw I can safely add

[feydjm]

I have a stock 73 240Z in terms of the electrical system. No added parts to draw extra power. Is there a standard amount of draw I can safely add to the car without affecting other systems? I mean, if I add a 20 amp draw will it cause significant loss across the rest of the system?

I'm specifically thinking about removeing the clutch fan and putting in an 8.5 amp draw electric fan. I just want to make sure I won't run into any problems.

I'm also thinking about better stereo, etc so I'm trying to make sure I'm OK with what I have.

Thanx for any info!!!

Justin

[Zedrally]

Is there any particular reason why you are wanting to replace the fan?

If the OEM unit is in working order, then there would be little gained by a swap? Perhaps it's at the end of it's life and the clutch is frozen?

The easiest way of gaining more amps is to upgrade your altenator.

Upgarde to a 60 or 80 amp internal regulated one.

HIH

[Bambikiller240]

I can't help you with specifics, but the 240Z's electrical system was marginal as delivered from the factory 30+ years ago. After all these years, many of our electrical systems are even less robust. I don't have my FSM here, but I believe that the 73 240Z had only a 50 AMP Alternator. Even if you replace the Alternator with a higher output unit, the wiring harnesses are not designed to handle higher current loads.

If you are going to add anything that uses significant current, I'd seriously consider wiring in relays to power the new components.

[feydjm]

I've got some play in the whole fan setup and it's causing some vibration at the front of the motor. I have a few things to check, but I was thinking about replacing the water pump pullery and getting rid of the whole fan setup. Free up the motor a little bit...

[Zedrally]

Contary to most views, it doesn't free up the motor at all!

The power to drive the fan still has to come from somewhere, ie the altenator.Which you again would need to upgrade. Whatever HP you may gain you will again loose to the altenator.

As I wrote the factory unit in good working condition is perfect for all conditions. It's a viscous type clutch which is engage when hot and dis-engages when cold. Generally speaking it is dis-engage in forward movement, after all there is already air flow through the radiator, engaging when standing.

HIH

Factory Altenators whhere either 45 or 55 amp from memory, 55 upgrade was with A/C.

[Bambikiller240]

If your fan clutch vibrates/wobbles, replace it before you end up replacing the radiator too.

If you replace the viscous fan with an electric fan, you will notice the noise from the engine compartment will be less, but as for "freeing up" the engine; any difference will be infinitesimal.

[26th-Z]

My parts book shows the Hitachi and Mitsubishi alternators at 50 amps begining 7 / 72. Canada cars got 60 amp Hitachis begining 7 /72. Begining 8 /73, the parts book shows a 50 amp Hitachi for the L26.

This is begining to sound like a water pump issue. If the water pump shaft moves / wiggles at all, replace it immediately.

Back to the amp capacity thing....There is a good article in the latest issue of SportZ magazine about this very subject. Bottom line is that there is VERY LITTLE capacity to spare in both alternator capacity and wire gauge. I'll go read the article again and report back. This is the second or third time this issue has come up in the last month.

[Murph]

If you do end up using a thermofan, just make sure you're getting the power directly from the battery and not any other source on the loom. I do agree with the others however, that sticking with the clutch fan would be wise.

[26th-Z]

I just went through the SportZ article again - volume 4, issue 4, fall 2004, "Crank Up The Power". The article incorrectly states that the 240 -280 Z came with a 60 amp alternator. As I stated previously, 50 amp for most of the 240Z population. The early cars like mine came with a 40 amp alternator.

When you add up the amp draw on the alternator, fully loaded, it is easy to climb past the 50 amp mark. Head lights and running lights will draw more than 15 amps alone. Wipers draw about 5 amps. Fog lights, another 5 or more. Electric cooling fan - 8 amps. And finally, stereo system - 20 amps at a minimum.

The main wire from the alternator with the fusible link is #10 gauge and is not adequate for current applications over 40 amps. The spade - lug connectors used throughout the wiring harness are rated for less capacity than the wire they service.

Their recomendations include replacing the alternator, increasing the main alternator wire gauge, adding fusible links / circuit breakers, capacitors, and addressing the battery capacity. A very informative article.