Battery relocation to trunk + NHRA rules

[BeeGTR]

The weight difference between 1 and 2 gauge is miniscule. What you ate that day would have more of an effect. Also you don't need to run the ground up front. Just ground the battery in the trunk using a LUG to a bare metal contact. Then take your engine block ground and do the same in the bay.

EDIT: I also wanted to add to not forget about fuses. I see too many people putting in stupid high rated ones like 175 or 200A.

I have a fuze box but cant remember the size of my fuze. I think I'm running 100amp. Anyone now what I should run? Or where do drop down to to melt it and step up a few amps?

-frankiman-

Perfect, Thanks! I'm going to switch to that!

I'm just looking at the Longacre Racing computer scales.... will be perfect for corner weighting, I was looking at buying industrial cooking scales, but there a couple hundred each and I'd need four so its only a bit more for the digital ones instead. I wont be getting it till I can get shop space sorted out next spring, but I'll post the info to help.

[frankiman]

its a dry cell type Braille Battery, the 11,5lbs model with about 900 cranking amp

positive is 00g marine cable, negative is 8g, run together underneath the car with a plastic protective jacket
negative is also grounded on the strut bar

the mount is a ready made, full aluminium, perfect fit mount from Braille themselves

it screw into the floor via 6 self-taping screws, very solid

even though the small 11,5lbs battery has enough power to easily start my RB26, it doesn't keep its charge long, so i can't event keep the radio on for 1 hour without the engine running,

so the 15lbs battery might be more suitable

[Zacho]

The weight difference between 1 and 2 gauge is miniscule. What you ate that day would have more of an effect. Also you don't need to run the ground up front. Just ground the battery in the trunk using a LUG to a bare metal contact. Then take your engine block ground and do the same in the bay.

EDIT: I also wanted to add to not forget about fuses. I see too many people putting in stupid high rated ones like 175 or 200A.

[BeeGTR]

this is how it did mine, F*ing solid

What kind of battery and mount is that? Is it a custom mount? Dry cell? What does it weigh? Is the cranking power good? So far I have been super happy with Optima's. They can handle not being used for a year, charged then there good, or leaving them on a trickle charger. They have amazing cranking power, but they are heavy....

-Zacho-

Thanks for the diagram, it's what I figured u have to do... I have one gauge wire now, and am thinking of switching to 2 gauge to save weight. Anyone have any idea if 2 gauge will be to small for the distance? What about grounding to the chassis to save weight on running a grounding wire? Has anyone done the switch to a rear mounted battery and not run the ground wire, if so did you notice any loss of response?

[Zacho]

To be track legal you have to do two runs of wire the length of the car. If you just switch one wire going up front the alternator can still provide power despite the battery line being open.


Heres how I did it

[frankiman]

this is how it did mine, F*ing solid

[BeeGTR]

I have confirmed with my local NHRA tech that mounting the switch where the rear wiper is, is NOT acceptable. I will be mounting mine behind the licence plate.

I am grounding the batter locally, and I have 2 grounds off the engine.

I haven't read any rules regarding the routing of the power wire.

Still not sure how I'm taking care of the alternator.

I can't rememeber what has to be done with the alterantor, something like it has to be tied into the kill switch to right? I guess worse come to worse you could run the wire from the alternator to the switch in the back and then it would be able to power up the system from there. Just increase the gauge of the wire a bit. When I re-do mine Im going to go down to 2 gauge for my battery and maybe 4 gauge for the alternator.

I cant think of any other way of doing it.

[BeeGTR]

You will need stop's on the right to left as well to stop side to side movement as well!

Good point... It's pretty solid, but I dont want that baby going anywhere incase of an accident . . . (knock on wood)

[Bravo]

You will need stop's on the right to left as well to stop side to side movement as well!

Here what I did to mount it. Used a 1/8th piece of Aluminum and put an extra nut ontop so when I pull the battery thru the plate wont fall out.

[Black BNR32]

I have confirmed with my local NHRA tech that mounting the switch where the rear wiper is, is NOT acceptable. I will be mounting mine behind the licence plate.

I am grounding the batter locally, and I have 2 grounds off the engine.

I haven't read any rules regarding the routing of the power wire.

Still not sure how I'm taking care of the alternator.

[BeeGTR]

Here what I did to mount it. Used a 1/8th piece of Aluminum and put an extra nut ontop so when I pull the battery thru the plate wont fall out.

[Bravo]

You can not put the switch in the window! If the window ever broke the switch will come loose and fall away! Also if the car ever ended up shiny side down it would be inaccessible as well! The best location is in the rear licence plate area, for you very rarely see a car sitting up on it's ass at an accident!
As for the gel batt, no vent needed and no box either! All that it needs is a welded in plate that has solid bolting points for the hold down straps!

[BeeGTR]

BeeGTR, I suspect you will fine without a box as there is a firewall separating the passenger compartment from the trunk. But, i'm pretty sure they will still want to see a vent. You will for sure need a master disconnect switch mounted near the rear of the car, according to NHRA rules.

Thanks! I was reading the other forums about relocating the battery to the trunk and I noticed that you cannot run your power wire into the cabin that's where I ran mine.... I'll have to move it under the car

Also a bit ago I was reading an article on weight transfer and they relocated a battery to the trunk on an AE86 and they said moving the battery to the trunk was the equivalent of moving the engine 6" back (closer to the center of the car). It makes sence, 30lbs off the front and 30lbs more in the back means 60lbs closer to a 50/50 weight distribution. When I re-build my car to make it track legal I'm going to move as many fluilds and components as I can to the trunk.

Also any opinions on grounding the battery to the firewall only or running a ground cable to the back as well? I have read many articles saying that if you direct ground the battery to all the major components it's suppose to increase your response. It's suppose to be due to all the interfearance of every electrical component trying to get to the battery. I'm just not sure if it's worth the extra weight...

[Black BNR32]

BeeGTR, I suspect you will fine without a box as there is a firewall separating the passenger compartment from the trunk. But, i'm pretty sure they will still want to see a vent. You will for sure need a master disconnect switch mounted near the rear of the car, according to NHRA rules.

[Tony-R32]

I was at the track 2 weeks ago, and the guy didn't even look at what kind of battery was in my relocation box, just told me i needed a kill switch at the back, nothing about a vent though.