Construct

iTrader: (4)

In my case, it's just the stock motor with factory map values for fuel and timing down low.

The battery used will also impact the current measurements somewhat. The voltage of my DEKA motorcycle battery probably sags a bit more than the big OEM battery during cranking. I'd expect a good Lithium Ion battery to handle the instantaneous current demands quite well, though.

Dave W.

Be aware of the fire hazard when running a Lithium-Ion battery.
https://www.google.com/webhp?sourcei...battery%20fire

Construct

iTrader: (4)

I"m well aware of the potential danger, but not all Lithium battery cells are created equal.

Modern LiFePO4 cells are much safer than the older lithium chemistry cells that became famous for catastrophic, fiery failures. They can still fail and cause damage at the extremes, but they're much more stable. The better cells will have been tested for puncture, crush, and other physical damage tests.

The more likely failure mode in a car application, IMO, is an unbalanced pack resulting in overcharging of a single cell. When a cell is damaged (e.g. from allowing the pack to go completely dead) then the series of 4 cells in the pack no longer splits the voltage equally. Eventually one cell will be charged past the maximum voltage, and the extra charging energy will be dissipated as heat. Your alternator will gladly keep pouring current in to the damaged battery, which can eventually result in fire. That's why a good balancer is important, IMO. It won't fix damaged cells, but it should let you know when the pack is getting far out of balance.

mantella

iTrader: (6)

last year on the scales at willmington my x weighed 3300 and still had ac, full size battery, ac, none sss radio and factory seats. Even with lighter wheels 315s are a bit heavy so nothing saved there. Since then I have picked up a cf driveshaft, pulled rear speakers, removed all of the ac, and gotten new seats which I have not installed. I use a evo 8 rear diff which saves a lot of weight but just like last year at willmington it is broken again so I will not be there.

psushoe

iTrader: (8)

You are breaking the viii rear diff? What is the failure? Make sure you are getting enough oil in it to keep the pinion bearings happy. I always lift the rear of the car way up with the front on the ground to fill. You could also get a TRE cover with the modified fill hole.

I broke one rear diff (so far). It was a shep built unit that came with my car, so it had a lot of track days on it plus all my pro solo/solo abuse. It was a pinion bearing that cracked.

Construct

iTrader: (4)

I couldn't get my finds on a proper oscilloscope probe with enough range, but I did find a semi-decent handheld current clamp meter.

First pass shows about 150-160A peak during cranking on my stock 2.0L. That's with the 2Hz update rate of the meter, so average current during cranking is likely a bit lower but the initial but brief current spike is probably higher.

I've got a few more ideas for logging some actual higher-resolution current/voltage waveforms during cranking, but that's probably good enough for now.

Shooting from the hip here, but the minimum reasonable battery would probably be eight of these: http://www.a123systems.com/lithium-i...rical-cell.htm arranged as 4S2P. That's still less than 2 lbs. Just don't leave your radio on in between runs.

Balrok

iTrader: (15)

Build-a-batt lol. That'd work but wouldn't the case/frame/terms/etc all add up quickly? I'm seeing more of these at the track: http://shop.antigravitybatteries.com...ries-ytx12-20/

mantella

iTrader: (6)

the most recent I have no clue the cause of failure. has a hole in the top of the case like something hit it from outside and the debris went inside it messing things up. the one before that was a wier or tre 12 plate that was slipping super bad. and before that was either rear diff cover or drive shaft did the damage. on launch the u joint snapped and driveshaft hit the front of the diff doing a bunch of damage but it also could have been the rear diff cover let go and the flex is what took out the driveshaft.
I wish they had brought the x rs to the states. It would have been super easy to get down to 3100 or below weight wise

mantella

iTrader: (6)

the x diff not only was I breaking cases and killed a cusco rs diff but also killed the ayc side as well<br/>

Dallas J

iTrader: (1)

Time to go out and double check those t-case fill plugs. Just lost one on course at Packwood tour and haven't touched it for over a year.

Meathooker

iTrader: (2)

Damn.

Aside from that how are you doing? Is Hyman there?

Dallas J

iTrader: (1)

Was a super great event even considering all the chaos. Cliffs from Packwood tour,

• The car is so close to amazing. I think at this point the single adjustable shocks are letting me down to get the lift rotation without instability. Working on it.
• Drying conditions in the AM with lead changes every run on all top for drivers except last. Best course conditions, if you're going to throw away runs do it when everyone else does the exact same thing. I had 2 near spins before calming down and still went 1/10th faster my 3rd run day one.
• I gotta just drive at this point with minor tweaks to dial things in. I'm not use to it being this fast I'm having a hard time putting it all together consistently.
• Oil fill plug will also let fluid out if its missing.
• Jason Merritt's 240sx on fresh 335s is really fast! He coned away a 1.3 sec improvement I dont think I could have matched even if I had my last run.

For next weekends pro I'm just going to try the stiffest setting on rear bar (one step more than today) with a little more front rebound. Gotta love pro's, will be able to dial things in over a few sessions.

LetsGetThisDone

iTrader: (1)

Super lucky that plug come out at an autocross. That would've been a wasted a tcase and possibly a fire if that happened at an HPDe or TA event. The direction of rotation of everything in the tcase flings fluid up to the fill plug...lol

Dallas J

iTrader: (1)

Seriously, wouldn't have been good. And I'm doing the SCCA Track Night at PIR at the end of June also. Luckily just a lot of smoke and a bit of a mess to clean up this week before Packwood ProSolo.

Dallas J

iTrader: (1)

Does anyone know if the wavetrac lsd is a 1way or 1.5way? 1.5 way would make sense to me in not getting the car to tuck in with lift. I've always had issues getting the front to tuck in and usually have to touch the brake to get the back to move instead.


Its the only handling quark I cant seem to get dialed out right now.