Mounting battery in trunk

[Black Box]

I was wondering how I should hook up the 2 small wires coming off of the positive battery cable. I haven't traced them to where they go yet, but if I'm correct one of them is the ECM lead, right (the fusible link)?
I'm also installing a Flaming River disconnect switch (per NHRA rules) but don't like the idea of clearing the computer memory every time that I flip the switch off. Is there a way around this? Can I run the wires to the hot side of the switch so the 'puter doesn't loose it's memory (but that doesn't sound 'legal')? Also, should I run common 14ga wire from the back of the car to the fusible link or should I run fusible link wire all the way from the back of the car (if so, what rating of fusible wire)? And what kind of/gauge wire for the other lead?

I did a search for this topic but didn't find anything.

Thanks in advance.
Steve

 

[azgn]

the best way to do this is with a good old fashioned Ford solenoid mounted ahead of the starter and everything else. That way, you don't kill the computer and 12 V is not present on the starter all the time. Remember, you have to kill the alternator excite wire with your switch or the car will keep running on the alternator after you cut the battery.

IMHO, this is a mod that should only be done when you have a full blown race car......there are very few advantages to the average TR......including 10 sec cars

 

[Black Box]

Call me dense but I'm nor sure if I follow ya. How would I wire in the Ford solenoid? And, would I have to run the alternator wire all the way to the back of the car to the switch? I'm guessing that the other wire coming off the positive cable is the alternator excite wire.
As you can probably tell I'm no electrician.

I just wanna do this to get that extra 50lbs off the front of the car and in the back where it'll do more good (even if it's a neglible amount). Plus, I'm not concerned with maintaining a sleeper look, I like the 'racy race' image.

Thanks for your input tho.

 

[TurboDave]

Originally posted by Black Box
Call me dense but I'm nor sure if I follow ya. How would I wire in the Ford solenoid? And, would I have to run the alternator wire all the way to the back of the car to the switch? I'm guessing that the other wire coming off the positive cable is the alternator excite wire.
As you can probably tell I'm no electrician.

I just wanna do this to get that extra 50lbs off the front of the car and in the back where it'll do more good (even if it's a neglible amount). Plus, I'm not concerned with maintaining a sleeper look, I like the 'racy race' image.

Thanks for your input tho.

Take my opinion for what it's worth, but all the headaches you'll go through getting this job done so it's legal and allowed to be used at the track will FAR out weigh any advantages to be gained by moving it back there!! Unless you're worried about 1/100ths (not 1/10ths) you'll notice absolutely no difference in performance at the line (traction).
You will be plagued by headaches and problems how to get everything wired right and LEGAL at the tracks.

 

[49-blues]

contact M.A.D. ENTERPRISES-559-539-7128,theyt have everything that you need including the info on how to wire everything up.

 

[Black Box]

Thanks to everyone for their help.

Steve

 

[S2V6RACER]

According to what I have read, you must be able to kill ALL 12v power from the switch and the battery be mounted in a NHRA approved BOX.

Mine has the switch that disconnects the battery ground from the frame.

I agree that the ECM will be a pain in the but, I would just rig up a 12v lead to the ECM and hide it from the tech guys.

The alternator lead will be directed to the starter 12v wire and back feed through the cable. Position L on the alternator plug(if my memory is correct), gets a BALLAST resisored 12v switched from the ignition, unless you use a self exciting alternator. But I would think that shouldn't be a issue being it is working now.

Turbodave is correct, there is a list of things to do and it's a real pain in the A$$. Definatley not what I would recommend for a street car, only if you are conforming to the rules.

Of course, with the F.A.S.T you don't have the memory clearing issue.

 

[wyk3d]

Dont do it. We bought my car with the battery in the trunk and will now be moving it back because its a PITA. We have some strange 11.8 volt draw on the car from his poor wiring job. Just leave the battery where it sits and spend your time elsewhere.

Dan

 

[gnXfan]

Originally posted by TurboDave


You will be plagued by headaches and problems how to get everything wired right and LEGAL at the tracks.

Tell me about it. 2 alternators in 2 years and........my battery blew up in the trunk. Why? No one knows - nice cleaning acid up!

_BOB

 

[Chuck Leeper]

Batt. in the trunk

I Agree 100% w/ the thots on the "REAL race car only" for the batt. move.
ALL the wiring has to be increased in size due to the length of the runs, the alt. power wire that feeds the batt. has to be interrupted, the neg. cable should be run to the engine AND the frame from the batt., the box has to be designed and mtd as per NHRA specs. YADDA, YADDA.

Ted A. BBBZZTT on the negative side being cut w/ the switch. Section 8.4 of the NHRA book calls for the POSITIVE cable to be interrupted.[The reason I typed "positive" in caps, is the book has it that way ]
The alt "charge cable" has to be interrupted too, so putting it to the starter stud will not work. It has to go to the batt. side of the cutoff.

GNXFAN, I have seen the batt. blowup deal too. I found that if the battery is mounted w/ the plates across the trunk, then the G-forces of a launch pushes the acid towards the rear of the battery, thus forcing the plates to contact each other, causing a short and you know what happens next. This repeated force application can actually break the plates loose.
To avoid this, I ALWAYS mount the batts so the acid will flow between the plates.
The alt. failure could have been from these shorts.[IF that's what was happening.]

HTH,

 

[strikeeagle]

Sounds like good advice to me. Some things are best left to race cars. Too many of these cars are just being hacked to death. That's what Camaros and Mustangs are for...

 

[salvageV6]

I would use an Optima battery if trunk mounting.

Steve you going to the track rental on Friday?

 

[pwrhws]

It was my understanding that the battery only needed a disconect switch if it were mounted in the trunk.

I was under the impression that if the battery was left in the stock location that a switch is not rquired.

 

[Chuck Leeper]

Stock batt location??

Mike, you are correct. If the batt is in stock location and the key is still in control, then the system does not need a cutoff. 1 caveat there.. If the fuel pump is NOT controlled by the key, then it has to be killed by a cutoff located at the rear of the car.

 

[Black Box]

Who you callin' a hacker?

Well I guess that about does it for that mod. Even tho I really wanted to do it it does not seem worth the hassle!

strikeeagle, I know what you mean about cars getting cut up and hacked....I've done it before and learned my lesson the hard way on a different car tho....a Camaro! But I gotta say that since my car is a 30K original, there is no hacking on it whatsoever. All the mods I've made are easily reversible and I still have all the stock parts, and I'm pretty meticulous about clean, neat installs. My friends all wonder why it took me all winter to do what I did to it!

salvage, no, I can't make it Friday, but I would have loved to. Would've been nice to get a decent amoung of runs in, especially since I'm on alky now (thanks to Chuck ). We were gonna go on Saturday but there's a frikkin Mustang Shootout, so we're kinda undecided at this point. I do have your spare coil pack (picking up a replacement this week), so maybe we can get together sometime. Are you going to the cruise at Mark's Auto Parts on Memorial Day? I'll be there, so if you go, just look for a GN with a '01 True Blue 'Stang GT next to it.

Thanks to all for the advice
Steve

 

[MAP]

Greetings folks,

I'm not sure it's apropos to this thread, but it's probably worth mentioning that moving the battery to the trunk generally makes an improvement in handling which is noticeable to most driving enthusiasts.

Best,
MAP

 

[wyk3d]

what impovement in handling can be seen by taking the small amount of weight from the front to the back?? We arent talking about 200lbs here......its a battery.

 

[Black Box]

MAP,
That's why I was considering it. Not to mention that's another 50lbs on the rear tires instead of the fronts (better launch traction). For handling purposes it helps to attain a ideal 50/50 weight distribution front to back.

But in this case it seems like it's just too much work.

Just out of curiosity, what does the NHRA deem acceptable as a suitlable battery box? I'm sure they don't mean the "marine" style polyethelene battery cases.

Steve

 

[S2V6RACER]

Re: Batt. in the trunk

Originally posted by Chuck Leeper

Ted A. BBBZZTT on the negative side being cut w/ the switch. Section 8.4 of the NHRA book calls for the POSITIVE cable to be interrupted.[The reason I typed "positive" in caps, is the book has it that way ]
The alt "charge cable" has to be interrupted too, so putting it to the starter stud will not work. It has to go to the batt. side of the cutoff.

GNXFAN, I have seen the batt. blowup deal too. I found that if the battery is mounted w/ the plates across the trunk, then the G-forces of a launch pushes the acid towards the rear of the battery, thus forcing the plates to contact each other, causing a short and you know what happens next. This repeated force application can actually break the plates loose.
To avoid this, I ALWAYS mount the batts so the acid will flow between the plates.
The alt. failure could have been from these shorts.[IF that's what was happening.]

HTH,

I guess the tech's know about as much as me . I can EASILY change that over to the positive side. I ASSume you mean the battery should be mounted so it is lengthwise or parallel to the rear bumper, mine is down in the spare tire area. The power lead must go from the alternator lug to the battery + but that would be after the cutoff switch if i'm on the right page, correct?

What difference does it really make if you just backfeed through the starter cable to the battery anyways? I know rules are rules, but I am one to question authority.

Back to hacking and cutting up the car.

 

[MAP]

Greetings wyk3d, bb,

Yes wyk3d - moving the battery to the trunk doesn't make a big change. For a street TR with a typical 58/42% F/R weight distribution, moving the battery to the rear will change this to about 57/43%. Many, if not most, driving enthusiasts would notice the improvement. Every little bit helps for these nose-heavy cars.

From what I'm reading in this thread, it does seem like a lot of time and effort to do this to NHRA spec's. OTOH, if it's solely for the street, the conversion is relatively easy to do, and I also like freeing-up the space in the engine compartment.

HTH,
MAP