After a year of thinking about it, I finally did it!

It took all day and went into the night. My buddy and I didn't have any circular saw blades to cut it, so we basically took a hammer and chisel and pounded the stock battery box away!

After doing this, we cut an 18"x22" .22 gauge steel sheet to size. After filling our bellies with mexican food and a trip to the hardware store for screws, epoxy, and silicone, we were ready to seal it. We had to cut and remeasure a few times, but it turned out really well.

The hardest part was dealing with the battery cables. I bought a Taylor battery box (part #48200) to seal my stock battery. I wanted to keep my stock battery for reliability purposes, but those cables wouldn't allow that. In order for the cables to reach it, I had to cut into the battery box, rendering the ability to keep the stock battery useless (since it leaks gas and poison).

Off to Auto Zone to get a new battery!

I opted for an Optima 35, which fit perfectly in the Taylor battery box.

We disconnected a few parts of the positive battery cable and planned and pondered on how to go about the situation. When we figured out a solution (one better shown in pictures), everything went smoothly. We even got the fuse box in the battery box! The trunk looks very clean and cable free! In fact, the only thing you see in the trunk is basically the battery box sticking out! I'm really happy the way it turned out.

Step 2: The Straight Exhaust!

 

This pic shows the process of how we "cut" the sunken box out. Basically hammered it out with a chisel.



Laying and measuring the stainless steel sheet



Here you can see the battery box as well as the small hole we cut to let the front cable go into the box. The box came in 3 pieces: 1 top, 1 body, 1 bottom. We had to cut a portion of the bottom as well as the body where it connected.



Everything coming together! Notice the absence of the negative battery cable. We had to desolder the battery clamp on the oem cable and re-solder it to a longer one.



Nice and clean



Close up of the fuse cable going into the battery box.



Close up of the battery cable going into the battery box



Close up of the bent portion of the stainless steel sheet. Why did we do this? We messed up and cut too much and had to compensate





Close up of the negative terminal. We used some shrink wrap to have a clean look.



Rerouted the fuse cable and bent the connector straight to line up



The fuse box sits snug in place. I'd make it straight, but the thick cables won't allow it!

 

What exactly does this accomplish?

 

Looks good, the OEM location sucks. One note: you might want to grommet the hole where the red battery cable enters the box. From the picture it looks like it could chaff the cable which can happen surprisingly fast.

 

Allows a straighter exhaust....

Looks ok...
Second the Grommet ASAP...would hate foir the car to burn..
I also suggest some undercoat spray on the bottom of the stainless part...reduce noise and reject some of the heat (a battery killer) from the new exhaust to come...
Choice of battery is interesting....
I do use an optima....
But the excess weight compared to the oem or even a light "sport battery" will likely MORE than negate the gain from the straight exhaust!

 

Zippy, what kind of spray would I need? I also kept some shielding from the oem box to cover it when the straight exhaust is in place.

Also, I chose that battery because auto zone didn't have anything else. The battery barely weighed more than the stock one did so it's fine.

And I'm pretty sure that my car will lose weight when I change to a straight exhaust. I'll have less piping and 1 less muffler.

 

My question also. Raise CG and reduce trunk space? I don't get it.

- Mark

 

1) I never use my trunk anyway so it didn't really matter to me.

2) I want a straight exhaust so relocating the battery is necessary. Most people use small and light racing batteries so it doesn't take up space in the trunk, however the battery is extremely unreliable for daily use. Since I don't use my trunk, I thought I'd just use a more reliable battery (I wasn't expecting to get an optima, but I needed a sealed one and I'll see how long it lasts).

3) I plan on adding diffusers to my bumper and a straight exhaust is needed for that.

My friends and I are into cars and love modding our cars for fun. It kills time and we make our cars sexier

 

Depends on the $$ you want to spend...
A $5 can of rubberized undercoating will do fine if you fabricate up some heatshields when you install your exhaust.....
But if you want to keep the heat/sound out (or make it less boomy)there are some nice products around...I recall "lizard skin" as one of the better ones ...
One word of warning....many single exausts drone badly at some speeds....but sometimes a resonator upstream of the mufler can help....
Saw a nice diffuser paired with a 50% battery box deletion a few years ago when my car was custom tuner by RMW down in CT a few years ago....was from a couple of guys at a new company that was checking folks reaction to it....haven't heard of them again, but for my use/speeds it was overkill....like you I value reliability.... Every mod is about compromises....
I would make 100% sure you sealed the open metal with rust preventing primer....might still get some sprayed on there from below...stopping rust in a location like the trunk that sees lots of water should be high on your list.....and cutting off the box did open a wound that can start the downward spiral of rust as a cut compromises the factory rust protection in that area...
Have fun...but be SURE to check any possible chafe locations from moving the cables.... Grommet ANY edge, and keep stuff snug...arcing wires can cause big issues....

 

Thanks for the info! We sealed the edges of the sheet in the trunk and outside with silicone, but the rubberized undercoating seems promising. I'll probably spray some rust primer and finish it off with the rubberized undercoating.

It actually rained the day after I did this and there were no signs of leaking, but I'll do it just as a precaution.

I'll grommet the holes down the same time I do the sealing, but so far, everything looks good. I forgot to mention that we hammered in the edges of where we cut and where the battery cables come in contact with said edges so it's pretty smooth, but again, I'm not taking any risks and grommeting those cables.

As for the resonator, I'm planning on getting magnaflow's longest one. If I have to I'll put two resonators plus the muffler. I also have resonated exhaust tips so it should finish it off nicely.

 

Battery cables against cut edge of metal with no protection!!!!!!!
Big NO NO

 

What is the battery box bolted in with? I see sheet metal screws holding that bottom stainless plate in, but can figure out the boxes attachment or the battery clamps.

 

It's held by two long "screw" sticks of metal that the bolts run through. Essentially it's going through the box with a battery clamp in between and goes straight thru the sheet metal. The weight of the battery is also something holding it down. When everything is tightened it's pretty stable.

Here's a link of the battery box:

http://www.taylorvertex.com/battery/boxes/

 

But is this track legal ?

 

Reason why I ask is because i plan on doing something like this myself.

 

If the battery is properly secured, I can't see why not. Depending on the track and class you're in, safest bet is to read the rules. Where I go, there isn't any classes or major rules about the cars, it's 5$ for about 10 minutes. Think that they only check that convertibles have a proper rollbar. Hell, my battery was "secured" with straps and they never even bothered with it.

Don't mind the ground bolt and the straps I've changed the setup after getting my red top (battery bolted from corners and not moving at all) and will change it again this spring. Getting a thinner plate welded in rather than "glued" and bolted, as well as searching for a lighter battery that can handle blasting music while washing it and not go dead (A proper daily driver battery).




Getting at least the catback done this year, most likely with an XForce Varex muffler as the cops are a pain in the neck about mufflers here.

 

This.

 

I get the message guys... going to O'reilly's tomorrow to get the grommets for the cables and ani-rust paint for underneath.

As for being track legal, it should be. It complies with NHRA regulations so it should be ok.

 

ODYSSEY PC680MJT w/RENNLINE battery hold-down. Low CG and net weight savings=15 lb. Battery is 8 years old and hasn't failed yet.

 

My next mod as soon as my battery goes bad !!

 

Nice! I was thinking of getting the odyssey PC925mjt before deciding to stick with the stock battery. That obviously didn't happen since I had to cut holes in the box and had to get a sealed battery ASAP to go home, but if my Optima craps out after the warranty, then I'd totally go for odyssey.

 

I'd recommend insulating that positive cable & if you are going to track your MINI revisit your battery hold downs just to make sure they are strong enough to hold in an incident. I like your idea.

 

to me it looks like you did just fine on the plate... i wouldnt personally bother re-doing it. bolted and glued is just as good as welding... hell, half the car is bolted and glued together! lol

now we want to see your diffusers and exhaust install!!!

 

Thanks! I'm probably going to have the exhaust done in 2-4 weeks. Didn't expect to buy a new battery so I'll have to wait a paycheck or two to buy the muffler, resonator, and piping. I mean, technically I can buy it now...but realistically, I don't wanna be spending $700 within the month on my car.

As for the diffusers...I have a separate project for that and my bumper which will have to wait until the summer.

I'll probably post the exhaust and diffuser stuff to a different section in the forums, but will post the links here

 

you doing a header too?
you dont really "need" a resonator... it just muffles the sound some, takes some of the rasp out. you should be able to get it all installed for about 150, thats what i was charged for 2.5" piping and cat install from my header to the stock muffs.

get some honda exhaust bits, way cheap, its just exhaust anyway!