We ran the aftermarket fuel pump power wire directly to the circuit breaker, which previously ran all the way to the engine bay.
After connecting the Battery Cables USA power and ground wires to the AntiGravity ATX-30-HD, we successfully finished the battery relocation and could turn our attention to the engine bay to remove the OEM battery and cables.
Under the hood of our FD RX-7, we were ready to remove the OEM battery. As you can see, the 38lb battery is about as far forward as possible, which is bad for weight distribution and polar moment of inertia. Next to the battery is our aftermarket “interheater” (the intercooler is actually heated up by the radiator exhaust wash). Needless to say, this will be getting addressed in the near future, but removing the battery is crucial for freeing up much needed engine bay space for a larger intercooler.
The original battery was replaced a long time ago with a standard 35-series battery, which does not fit perfectly or use the original battery mounts. Zip ties were used to secure the battery in place, which is not safe and really needed to be addressed. Connected to the positive terminal is the main fuse box that protects the entire car’s electrical circuit.
We cut the zip ties and removed the battery. Next, we unbolted the factory battery tray.
10 comments
Great article. JP3 Motorsports makes a nice mount for the fuse block so it’s not zip tied or flopping around in the engine bay.
https://jp3motorsports.com/collections/mazda-fd3s/products/mazda-rx7-fd3s-battery-fuse-block-bracket-relocated-batteries
Awesome update. You always do such quality work. I can’t wait for the next one.
Didn’t see a fuse for the fuel pump at first glance (page 5, 1st pic ) Then I looked again.
FYI Lots of motorsports guys complain about those circuit breakers… they say they have had them vibrate open during operation. I’m running 2 on my car and haven’t had an issue yet.
I know that this is going to sound crazy, but recently I had a family member’s car serpentine belt fail and it ended up damaging the pulley. I was not able to source a new pulley in the location it was in, so we decided to try and run the car as long as possible without the serpentine belt (thus sans alternator, power steering, and AC). Fortunately, the battery was almost brand new and fully charged.
Interestingly enough, the car started and ran well for the 10 mile trip home! No issues whatsoever.
This makes me think that you could conceivably run a time attack car with the alternator removed!
Yes, this is totally crazy, but ‘racecar’, right?
Not only would you save a significant amount of weight, but you would reduce parasitic losses on the drivetrain. With a powerful enough lithium-ion battery, I am sure that you would have no issues running like this for one-lap.
Anyway, food for thought.
That is very common in SCCA sprint racing, especially in the smaller bore Prod and GT classes.
I don’t know about a modern racecar with all the electrical load. Our time attack car draws over 140 amps when everything is going full ti;t.
Was your classic to engine 2awg black ground wire able to reach north bolt holes with slack? Mine is very very tight and will not even bolt up
I think we relocated it to the 13mm bolt just below the brake master cylinder.
I have the same problem. The cable that comes with the kit is NOT long enough. Mine even came in a little bit longer at 16in. Pretty disappointing, gonna have to order another cable.
What do you do if you don’t want to remove the Electrical harness and take out the old power and ground cables? Would like to leave them in there so it can be put back to original. Thank you