Now that we have all of the new battery cables installed, our battery relocation is complete. The engine bay now much cleaner and more open, with upgraded and thicker wires that will make our RX-7 start more reliably and run better, especially at higher power levels.
Relocating the battery freed up a lot more room for a bigger intercooler to be mounted in the engine bay.
Removing the battery also greatly improves airflow through the radiator since the battery blocked the air from exiting the radiator. Note the large gap between the radiator and frame rail. This is a major inefficiency that greatly impacts the cooling of the car. Air seeks the path of least resistance and there’s less resistance going around the radiator though this gap than there is going through it. Proper ducting will greatly improve the cooling of the car. We will address this and the radiator in an upcoming article, so stay tuned!
TESTING
With the new AntiGravity ATX-30-HD battery relocated in the rear bin of the car, we were ready to fire the engine up for the first time. The second we turned the key to crank the engine, it was immediately apparent how much better the electrical system of our car was working. The starter motor was spinning significantly faster than it ever has before, thanks to receiving all 970 cranking amps of our AntiGravity through the low resistance “00” AWG wire. Since the engine was cranking faster, it fired up much sooner with more authority than ever before.
In the canyons, the front of the RX-7 feels even lighter, thanks to the 38lb lead battery being removed from the nose of the car. The car turns-in sharper with even better response, which says a lot since the RX-7 already has a low polar moment of inertia due to its small, light, and low-slung engine.
Overall, we are very happy with relocating the battery with AntiGravity Batteries, MeleDesign Firm, and Battery Cables USA. Our FD RX-7 starts significantly stronger and more reliably than it did before, our handling and cooling is improved, and now we have opened up more space in the engine bay to take the next steps towards keeping this engine cool. Stay tuned!
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