Where to remove weight from a track only car?
#362
That's 2.5 lb at one of the farthest points forward on the car though. I'm doing the same thing for mine since I basically had to cut half of it for the intake anyway. I wonder if you could do thinner, I know FM just replaces it with some angle stock when they do their conversions. Thought I saw somewhere that it really didn't provide much of any reinforcement to the chassis, could be remembering things incorrectly though.
#369
Odd thing to remove.....but if you ever wondered the battery pocket weights it's 5.6lb's. I imagine the pocket on the other side is about the same, and the spare tire well would be a good bit more than that. Not sure I'll remove either right now as they aren't in the way of my exhaust.
Bumper beam and mounting brackets are right at 11 lbs.
Bumper beam and mounting brackets are right at 11 lbs.
#370
Ahh very nice. I did the same thing, but didn't stop with just the battery area, I kept going... also removed the spare wheel space but kept the two rails as they are currently my wing mounts. I supposed they offer no other purpose and could probably be replaced with something lighter?
I even video'd the result:
I even video'd the result:
#371
Made a little progress on the "race" battery. These are lifePo4 batteries rated at 30c continuous and 40c burst. So with two of them in parallel like I plan I"ll have 252 continuous amps and 336 cranking with a decent 8.4 AH capacity and none of the spontaneous combustion LiPo batteries are known for. I honestly think you could get by with one of these in a trailered car. I have a balance charger for the R/C cars so I'll pull these out and balance them every now and then until I trust them not to get too far out of wack.
https://hobbyking.com/en_us/zippy-fl...epo4-pack.html
You can also get this in a single battery form factor but I didn't like the idea of running all those amps through a single pair of 10 gauge wires.
https://hobbyking.com/en_us/zippy-fl...epo4-pack.html
I kinda lost track of the real reason I was doing this (weight) and added some nice terminal blocks and a disconnect which added quite a bit of weight relative to the battery.
OEM like battery
Still a significant 17lb savings overall for 100$ spent.
https://hobbyking.com/en_us/zippy-fl...epo4-pack.html
You can also get this in a single battery form factor but I didn't like the idea of running all those amps through a single pair of 10 gauge wires.
https://hobbyking.com/en_us/zippy-fl...epo4-pack.html
I kinda lost track of the real reason I was doing this (weight) and added some nice terminal blocks and a disconnect which added quite a bit of weight relative to the battery.
OEM like battery
Still a significant 17lb savings overall for 100$ spent.
#372
Not clear done with the install but enough to test it out, cranks better than it does with the full size lead acid with both batteries. It's a little sluggish with just one but plenty of grunt to start the car, so I'd do just one in a trailered race car. Very similar to the ETX-9 I ran in my old NA when compared to one of these. There's roughly another 2.5lb's to be lost if I would move the battery under the hood and strip out the power cable. Not quite worth the hassle for me at this point.
Last edited by Bronson M; 11-26-2017 at 06:46 PM.
#373
Not clear done with the install but enough to test it out, cranks better than it does with the full size lead acid with both batteries. It's a little sluggish with just one but plenty of grunt to start the car, so I'd do just one in a trailered race car. Very similar to the ETX-9 I ran in my old NA when compared to one of these. There's roughly another 2.5lb's to be lost if I would move the battery under the hood and strip out the power cable. Not quite worth the hassle for me at this point.
#374
I'm not the first to use lifepo4 batteries, think I've seen a few folks on here using them actually. Yes this will "hurt" weight distribution since removing weight from the lightest corner but I'll take a less balanced car that is overall lighter. You'll never be faster adding in weight just to balance the car.
#377
Lots and lots lifepo4 batteries running around being charged with alternators. Alternators actually follow the charge pattern that lithium batteries need in that they maintain a Target voltage and decrease amps as you approach that Target. Don't use a trickle charger or lead acid charger in them though as most of them charge to too high of a voltage . Most if not all of the commercially available lifepo4 and lipo car batteries being sold don't have battery management systems, there's some photos in this thread of the inside of a Braille battery.
https://www.miataturbo.net/race-prep...s-83673/page3/
Where you have problems is if you get the cells unbalanced, then it's possible to overcharge or over discharge cells in the pack. We're talking about a 35$ or 70$ pack here if you run two of them...... They could last an awfully long time with no attention at all, and I'll balance mine a few times a year just because it's easy.
https://www.miataturbo.net/race-prep...s-83673/page3/
Where you have problems is if you get the cells unbalanced, then it's possible to overcharge or over discharge cells in the pack. We're talking about a 35$ or 70$ pack here if you run two of them...... They could last an awfully long time with no attention at all, and I'll balance mine a few times a year just because it's easy.
#378
I did the same thing in my car.
And, as Bronson mentioned, just the one battery seems to work OK as long as you're not cranking too much for too long or it can hurt them eventually.
(Mounted under the dash above the gearbox, so weight savings are maximized with much shorted wiring)
And, as Bronson mentioned, just the one battery seems to work OK as long as you're not cranking too much for too long or it can hurt them eventually.
(Mounted under the dash above the gearbox, so weight savings are maximized with much shorted wiring)
#380
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Lots and lots lifepo4 batteries running around being charged with alternators. Alternators actually follow the charge pattern that lithium batteries need in that they maintain a Target voltage and decrease amps as you approach that Target. Don't use a trickle charger or lead acid charger in them though as most of them charge to too high of a voltage .