trunk mounted battery and aluminum rad. question

[dusterbd]

im planning on moving the battery from its stock location to the center underneath the package tray. whats the best way to do this? what gauge wire do i run? how about the ground? whats the best routing? is there any easy way to mount the dang thing?

about alum. rads. ive only seen em for 400+ bucks, and thats a little steep. is there any cheaper alternative? like a universal dirt track rad or something? also, what should i look for? eventually, the car will have 400-500 street driven horsepower.
thanks, guys
mike

[charger_dan]

Mike,
On the battery relocation:
Summit, Jeg's and others sell a kit to locate the battery in your trunk. Cost is about $40-$50. Basically, you can do the same thing yourself by purchasing a battery box (they're available in a variety of materials) and some high-quality 1- or 0-gauge battery wire from your local auto electric store. They'll also be able to answer any other questions you have about the swap.

On the ground wire:
I ran my ground from the battery box down through the trunk floor and bolted it to a clean area on my frame rail. You'll also want to purchase a good quality ground wire or strap for the front of the car to ensure a good ground between the engine and chassis.

On the aluminum radiator:
You don't need to shell out $400 to step up to an aluminum radiator. Do a search here (performance chat) for a recent thread by BakedMopar entitled "Radiators". It'll answer some of your questions about universal radiators.

Best of luck.

[lenweiler]

Above reply is correct. One more addition perhaps.
According to IhRA rules the battery should be placed parallel to the bumpers with 3/8" rod hold downs. And why not take advantage of the battery weight and place it further back in the trunk?

[rumblefish360]

When I mounted my battery in the trunk, I placed it over the rear right wheel. This helps in weight distabution and tire bite. When putting the cable through the floor, use a grommet to keep wires from grounding out on the bare metal.
Use cae when doing this. It will avoid fires and other problems later.

[Dart]

Mounting over the rear right (pass side) is the way to go. It would be a pain to remove/install a battery that far into the trunk. If you are going to run that much power you should think about adding a battery cut off switch. I am not sure on the rules, but if you car is faster than a certain ET you will need a battery cut off switch at most tracks.

You can run the wire through the subframe...

[The Dartman]

The can of worms is officially opened...

Both of my last two street/race cars have had the battery relocated to the trunk. I have raced at both IHRA tracks and NHRA tracks, and they both have the same rules for relocated batteries:

1. The battery must be held down with 3/8 rod.
2. ANYTIME the battery is relocated to the trunk, the car must have a battery shut off switch. NO MATTER HOW FAST. My car ran 14.70's and the tech actually made me start and run the car as he attemplted to shut it off. Hint: Traditional wiring of a Battery shutoff switch won't turn your car as intended becuase of your alternator.
3. It must be in a battery box of some kind.
4. It must be vented to the outside of the trunk.

Sometimes techs can be lenient of items #1 (I have 5/16 threaded rod) and #4 (I have no vent), but my wife always says that if you do it, do it right. One way to get around #2 is to have an alternator cutoff switch so the master switch will shut off the car (or you can just unplug your alternator wire before going to tech - oops! did I say that?).

I am not aware that mounting the battery parellel the bumper is a rule, but it is a good idea. This helps in battery life since the battery acid is flowing back and forth between the cells (or lead plates), not agaist the cells when the car is launched. Also the plates have the ability to move slightly, so if they move against each other thier is a possibly that they may touch and cause a fire or other failure.

In my car (73 Duster) I have the ground wire grounded right to the floor of the trunk, in the thickest part I could find that was close to a frame rail. Unibodies are all one piece so this works fine, however on a framed car a grommet and direct frame ground is the way to go.

Dartman

[ehostler]

An easy thing to do with the shotdown, is to wire in a realay on the field lead(s) of the alternator. Put a switch in the dash. Then you just disable the alt (with the switch) for tech inspection and for the 1/4 mile blast. It's safe and it reduces the parasitic drag of the ALT, during the run.

Think about this, the next time you run the 1/4 with the alt running. You wreck the car. You are unconciuos <sp>. The engine is still running. A fuel line has cracked open. The emergency team turns your master shutoff. The engine contiues running and the electric fuel pump is causing alot of gas to be srayed on the car and ground. Why??? Because you decided to fool the tech inspector and put it all back to normal after the inspection.

[gotcha]

The battery question has been answered well by several.

One battery....I use right rear.
Two batteries....right and left rear.

The rules for hold downs are correct at 3/8's.

No box is required if you have an aluminum firewall between trunk and passenger compartment. (The box is still a good idea)

The cutoff is mandatory regardless of ET, and must kill engine as stated. The switch on the field wire works and improves ET as stated.

I use 00 welding cable as it has many fine copper wires, and is very flexible. The gromet mentioned is a good idea.

Ground to unibody or rollcage in trunk (if applicable).

Ground strap from engine to body (good one).

Aluminum radiator.. (I use Griffin, but Summit and others have a good one for about $189.00) 18 X 26

Have fun.

[dusterbd]

thanks for all the help, guys. you rock.
mike

[lenweiler]

Excellent suggestion by Eholster!. I will make a point of doing so in my next round of to do's to the Dart this winter. Thanks.

[The Dartman]

The alternator cutoff switch is a pretty good idea IF your charging system is 100%, and the car does not have a ton of electrical devices. Many street/strip/drag only cars have both an electric fan as well as electric fuel pump, which is taxing on many stock or near stock charging systems and batteries. Eliminating the charging during a 1/4 mile run may not seem like much, but when you really start to go rounds it keeps adding up to a dead battery or loss of ET since you can't get enough juice to your Ignition box, etc. It is very easy to forget to turn the damn thing off and on as well, which really messes with your consistancy as well. I can't tell you how many times I almost missed the call because my charging system was left off after a run, and I left the fan on to cool my often hot running 12.5:1 318. Or on the flip side, not cooling between rounds becuase my charging system was not keeping up... I've done them both and it sucks. My car now has found a happy medium between staying cool and staying charged, and I haven't had any problems making the call in 5 years.

I suggest unless if you really want the 1 to 5 hundreths that not having an alternator charging will bring you, go ahead and splice in a switch into the ballast resistor and bring it into the car. The is a little simpler that having a relay and has less parts to fail. Hot "Chevy" Rod actually had an article about 10 years ago that listed the correct way to put a cutoff switch for a charging alternator in most of the 60's, 70's and 80's charging systems.

On the other hand, does anyone have a good setup that they would like to share to turn off the alternator from a trunk mounted relay? I have seen setups that utilize a Phord starter relay to power another relay that cut the alternator, but a starter relay may be a little overkill. So how about it? Anyone have any good relay alternator cutoff wiring ideas? I'd be interested in seeing everyone's slant on the fix to this problem. Give part numbers/applications if you have a specific relay.

Dartman

PS Both IHRA and NHRA rules kind of miss a big area with the cutoof switches and also make certain street cars fall under some strict guidelines. Case in point: Any car with an electric fuel pump that will not shut off in a rollover needs to have cutoff switch, regardless where the battery is mounted. So a car with a mechanical fuel pump can have a trunk mounted battery and not have a rollover problem, but a car with an electric pump and a stock mounted battery is basically a bomb waiting to go off...

Like I said, they kind of miss the mark...

[leon441]

Just run a #4 welding wire from the output terminal to the battery side of the battery disconnect switch. Note the switch is required to be on the positivew battery lead. The battery needs to be mounted parallell to the bumper so when your car leaves hard enough it doesn't bump the plates into each other and the acid has less room to slosh.

[70Ted]

how are you charging the battery, thru the main cable? or by a second wire from the starter relay?

[dusterbd]

umm...actually, i dont know how to wire up the system. id assumed that i would just follow the way the origonal wires were done, and just redo that, only much longer.
is there a better way? what else should i watch out for?

the reason its going under the package tray is more for weight distribution that traction. the car is going to be what popular hot rodding refers to as a "g-machine". a car that handles well, huns mid twelves, and is drivable anywhere, anytime.
at least thats the plan.

mike

[The Dartman]

The "main" wiring is easy.

Just take the extended battery cable (welding cable, etc) and run it from the trunk switch to the starter. Then the primary cable continues to feed the starter relay and power the rest of the car. There is no need to make your extended battery cable co all the way to the relay when the primary starter power wire powers the car.

I have only closely looked at about 4 cars with relocated batteries and this was how they were all setup.

So no one has any plans/ideas for an automatic battery cutoff then? No one has put forth any ideas on how to turn off the car with a cutoff switch, yet. I'm all ears....

Dartman

[The Dartman]

I just found this article on the internet about correctly hooking up a battery disconnect. Now that I see a good diagram I realize that a relay cannot cut power to the alternator because both sides of the cutoff switch will be powered either by the battery on the positive side or the alternator on the car side. Most of the articles I found on the subject had the main output from the alternator run to the positive side of the switch.

Here's a diagram:

http://members.cox.net/caprirs/battery.htm

Any other thoughts on this?

[ehostler]

Summit racing sells a cutoff for the alt, that works with the cutoff switch. I'm not sure how it works.

You could always put a relay or a switch in line with one of the field wires. Turn the switch off, before you run and turn it back on at the end of the run. With the switch off, the field circuit is open, so the alt will not send out a charge. The only concern then, is can your battery properly support all of your electronics, for the run. Alot of ignition computers won't perform well on just the 12VDC from the battery. Many of them like the extra voltage from the alt.

[72Charger440]

Only have comment on radiator.
I found a company selling Nascar Griffin radiators on Ebay for $160 bucks.The one I bought still had racing tire rubber wedged in the front of core.
Best money I have spent on my car no more overheat
Good Luck