To start, I searched the forums and couldn't find an answer so that's why I'm posting. Living in Texas has it's ups and downs, the latter being pretty consistent upper-90ºF to 100ºF temperatures for a good chunk of the year. I need to upgrade to Spal Extremes to help compensate, as well as relocate my battery to the trunk. Quick math says that 2x 12" Spal Extremes (40amp each) plus 1x 7" Spal puller (15amp) on my oil cooler plus a Walboro 450 (14amp) and finally an estimated 100amp draw for the base car puts me up to 209 total amps.

Most of the trunk-mount battery setups I've found on the site run 2awg to 4awg power wire with a 150amp breaker, which seems fine for normal cooling setups but I couldn't find anything referencing a trunk mount with a Spal Extreme fan setup. I'm looking at going with a factory battery, an external power cut-off switch, a 250amp breaker at the battery followed by 1/0 awg power cable to a junction box in the engine bay where i'll wire the main power, the starter and the fans.

My first question is whether or not this plan is reasonable, or if there's a better option. My second question is whether or not the factory battery can handle the amp draw, or if I need to jump to a 550cca or higher battery.

Thanks!

 

I'm curious why you think you think you need to replace the fans and hide the battery? The OE fans aren't keeping the engine temps in range? Also never seen any real benefit of putting the battery in the trunk. Some weight and balance changes so it you're constantly finishing road races at the back of the pack it may help to move up a place or two.

-- Chuck

 

Chuck, I neglected to include that I've got a sidewinder manifold on a 62mm turbo w/ A/C in place. I've got a Mishimoto radiator, shroud and fans but it can barely keep up without the A/C on, let alone trying to run A/C. Turning on the A/C when it's over about 92ºF whether cruising on the highway or crawling through traffic will push my coolant temps up past the safe range.

Moving the battery from the trunk will let me go from an Odyssey PC680 to a proper battery to support better fans with the intent of bringing both underhood temps and coolant temps back to normal, independent of the ambient temperature or A/C being on. Further, i can better relocate the fuse box to prevent any potential melting, though I fab'd a heat shield and was generous with the wraps and tapes so it seems to be holding okay for now on that front.

 

@Billman250 just posted in a related thread he found the bottom 8 rows of fins "welded closed" on his car's AC radiator which not only limited AC operation but also restricted airflow thru to the engine radiator. Worth a quick check. If yours are similar replacing the AC radiator will solve both problems.

Had a car with a rear battery once. Was a factory setup but still a PITA.

The car is overheating now? What's it showing? (There's a chart somewhere.) Or just in the high end of the normal range. Two different things.

We get these temps in Virginia some of the time but I rarely drive in them as the car isn't much fun with the roof up and the AC on.

-- Chuck

 

Chuck, I ran thermocouples under the hood and at low speeds I could see temperatures near the fuse box approaching 220 F. Turning the AC on would push coolant tips over 210 before I would turn the AC back off and it would drop back down to normal, at least based on the AEM V2 read out which assumes I pulled the right table from the forums which I'm fairly confident I did.

It is the factory condenser it has 146,000 mi on it, So it is likely to be in relatively poor condition. I had planned on replacing it as a precautionary measure after the battery relo as I had planned to tuck the AC lines afterwards. Sounds like tucking the AC lines and replacing the condenser may be a better first option .

That said, I'd still like feedback on the battery reload setup with the SPAL extreme fans from anyone that has experience with it.

 

Not sure what you're considering as the "safe range" for engine coolant. Coolant temperature of 210°F is normal. Gasoline engines are generally designed to run efficiently in the 195°-220°F range and 240°F is high but not abnormal. 50-50 glycol antifreeze doesn't boil in a 1bar (14.5psi) pressurized radiator until 253°F, well above your temps. And I know my OE (I assume) radiator cap shows 1.1bar (16psi) so that boiling point is even higher (but I've forgotten the computation physics here )

Turbocharger dumps a lot of heat but that heat can't be controlled by engine coolant or radiator fans in systems I'm familiar with. Heat shields and wraps are an option.

Relocating the battery is the last thing I'd want to do. Unless you go AGM you'll need a vented box. Same with using the little PC680 battery to save a couple of pounds, but you have a good reason for that, no doubt.

"Too bad" it's cooling down this time of year as any changes will have to wait 10 months to see if they were worthwhile.

-- Chuck

 

Stock alternator is rated at 105A, going above that seems like a bad idea.
Does the fans you talk about really pull 40A each? I don't think the base car functions pulls anywhere close to 100A, more like 20-30A.
Do you got a dual pass radiator? If not, that is the first upgrade you should go for as that helps a lot, you might not need any crazy fans at all.

 

Flanders is on the money.

My Battery is relocated and im on spal fans. 150amp breaker is fine. Get a AGM battery if going in the trunk, and make it a larger one than stock. A dual pass radiator is where it's at. The CSF dual pass is a VERY nice unit and it comes with fans

 

This. The car has a 100 amp main fuse. That does not mean the car ever draws anywhere near 100 amps if you turned on every device that can consume electrical power to its max.

Its typical for fuse ratings to be double what the system is capable of consuming. So that implies if every system was on at its max possible consumption it would be less than 50 amps (they don't make 92 amp fuses. So if say all systems together were 46 amps, they would have to round up to 100, since there isn't a 2x 46 amp (92 amp) fuse that exists).

Further, it may not even be possible for all systems to really be at their max at the same time.

150A is likely to still be way more than needed. I bet you would be fine with a 100A trunk breaker.

 

All, fantastic feedback, thank you. I've got a Mishimoto radiator, shroud and fans, and I'm fully aware of their limitations so I'll look at the CSF dual pass setup so I can stick with the lighter wiring and breaker.