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Antigravity ATX-30HD
Andrew Zieger mount
MSEL solid state relay/cutoff
00 gauge cable that runs to the firewall near the blow and transitions into the engine bay via bulkhead
The MSEL is a great addition - short protection, remote cutoff switch, monitor load via CAN, etc.
Painted the stock fog light switch and wired it to act as the battery cutoff
So I’m going through this battery relocation this week. Have all the parts arriving, including the WestCo miata size battery.
One deviation I’m including is a mount/jump point in the engine bay, where the stock fuses will mount to as well. Will probably do an external battery maintainer/charge point as well, since this car gets driven infrequently.
quick question: is the aluminum rod/plastic mount considered to be the best mounting solution? Or are there other better ideas in the years since the original guide?
quick question: is the aluminum rod/plastic mount considered to be the best mounting solution? Or are there other better ideas in the years since the original guide?
Since I wrote this, there have been a number of aftermarket battery trays developed. I think they would be more secure.
This one may not work with the WestCo but you might find something equivalent. Ideally, you want something with a very compact base so you do not have to cut the bins.
Figure I could ask here before starting up a new thread - I relocated my battery behind the rear divider on the left and also fitted a cutoff switch to the battery mount. The battery itself is fairly close to the fuel pump with this setup. Right now I have the stock wiring running to the pump for power, but would it be an awful idea to run power from the battery to the pump via a relay triggered by the stock fuel pump power wire? Wiring it that way, I feel like the pump would not suffer from voltage drop with the stock wiring. AEM 340lph pump in the tank now.
Figure I could ask here before starting up a new thread - I relocated my battery behind the rear divider on the left and also fitted a cutoff switch to the battery mount. The battery itself is fairly close to the fuel pump with this setup. Right now I have the stock wiring running to the pump for power, but would it be an awful idea to run power from the battery to the pump via a relay triggered by the stock fuel pump power wire? Wiring it that way, I feel like the pump would not suffer from voltage drop with the stock wiring. AEM 340lph pump in the tank now.
In addition to the noise, your pump will be running wide open all the time. If you're cool with that, wire it that way.
340Lph is quite a bit of pump.
I thought it was fairly common practice to ditch the resistor setup for simplicity and removing a point of failure on near 30 year old equipment.
The stock system is a 2-stage voltage delivery system. Low load path sends voltage through a resistor, and the stock pump doesn't have much at that load. Under load, the other path activates, and goes straight to the pump. This is already well documented.
People who intend to do what you want use the stock primary path wire to trigger a relay that pulls straight from the battery. Again, well documented.
I went through a bit of pain figuring out the problems with using stock wiring configuration (a little revised) with 450L/hr pumps in a surge tank setup. I was all set to do what you're doing when I realized that my power level didn't call for much more than something like a 255L/hr pump. I have BNR twins, stock primary injectors with ID2k secondaries, greddy v-mount, and no cats.
if you're not running a monster engine, ditch the big pump.
There was a thread in the PowerFC Tuning email group that went through pros and cons of a direct wire vs using the stock resistor.
TL;DR of that is essentially:
Direct wire results in more pump wear, more difficulty tuning at idle (running rich), higher fuel temperatures. But it's also simpler, and results in maximum voltage so possibly more consistent fuel delivery.
Some things that I hadn't seen mentioned in most threads are:
-Direct wire and a bigger fuel pump may require rewiring of the bulkhead connectors. There are lots of pictures of melted connectors and that near the fuel tank is terrifying.
-If trying to retain the fuel pump resistor with a new fuel pump, you will need to correctly wire in a parallel resistor in order to compensate for the additional amperage. I don't remember the specifics of the conversation but the calculation's a simple parallel resistors equation that you solve for.
I did the parallel resistor wiring but used some sub par wire that's very bulky and it looks horrible even though it works. So I might just go to the direct wiring just to clean things up and eliminate a bunch of butt splice failure points.
Off thread topic but anyways, i believe the major issue with FP voltage drops is the ignition key which can be bypassed (below). The stock wiring is supposedly sized large enough for most applications
I recently ran a dedicated ground from the engine block to the battery. The path is as follows:
Attachment to the block at the typical LHS location, through firewall, and to a buss bar underneath my tunnel cover / console, then to the battery. I included the buss bar because I wanted to ground the ECU and some gauges. Instantly noticed that my inconsistent idle issue went away.
I also started daisy chaining my interior chassis sections together with 10GA wiring.
I worked with Battery Cable USA to create a plug and play FD RX-7 battery relocation WIRE kit; sized and finished with crimped ends that makes for an easy install. I will be posting the install instructions in an upcoming article on MotoIQ:
(i'm not a vendor and do not get $ for this kit. I was excited and grateful that such a great company like Battery Cable USA was willing to create a premade wire kit for our community).
Last edited by Billj747; Feb 14, 2022 at 01:07 PM.
I updated the first post of this thread with the updated PDF since the hosting sites have varied over the decades of this thread.
Should be much easier for everyone to find now.
