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Old 05-20-2014, 10:26 AM   #16
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Understood... The only time a light lipo pack is necessary is when the chassis is already superheavy like a tc4...... Making weight is the most important issue.....
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So you guys are either running Mi5s and need to save a lot of weight, or running without a minimum weight rule, which is rarely a good idea as it results in lots of expense on lightened parts.

With a 7200 lipo I still need lead to make the 1350g BRCA minimum weight, so a shorty would save zero weight for me (Xray T4'14).

There are other benefits of a shorty, but only if you redesign the car to make the whole layout more compact.
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Old 05-20-2014, 10:38 AM   #17
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On an Xray T4 w/ RSD upgrade, HW v3.1 Stock Spec, Savox 1251, D3.5, lightweight body, and a R1Wurks 7200mah lipo, my car comes in at 1370g with stock steel screws (never felt like I needed to pay for titanium) so I still needed to add weight no matter what.

Do what Mclarein said. Get the biggest battery that gets you to weight. Voltage is pretty important in stock racing, but if your car is a tank at 1440g or something, it kinda defeats the purpose, too.
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Old 05-20-2014, 10:46 AM   #18
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If your car is a tank at 1450 or even 1500+ grams with a decent pack, get hacking or get a different car. I can't think of one car that needs to be that heavy, even plastic tub stuff like old school TC4's can get the dremel, mill, and swiss cheese chassis treatment in addition to a few bucks spent on aluminum screws going a long way.
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Old 05-20-2014, 12:17 PM   #19
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Blinky spec classes are a nightmare to get the best power to weight ,esc curve, battery punch and duration and motor timing. It's getting where I appreciate my nitro cars more all the time.
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Old 05-20-2014, 01:17 PM   #20
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Blinky spec classes are a nightmare to get the best power to weight ,esc curve, battery punch and duration and motor timing. It's getting where I appreciate my nitro cars more all the time.
I agree with this. Even though I'm nowhere near as fast as others in Mod TC, I prefer it because I don't have to fight with gearing, bodies, esc settings, or even batteries. I run 6000mah packs that I only charge to 4.0 per cell. Stock is just a hassle.
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Old 05-20-2014, 02:47 PM   #21
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One of my cars needs around 85g added to make minimum weight (it would weigh around 1295g with no lead added). That's with a 305g 6900mah battery.
Just curious, what car is that ?
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Old 05-20-2014, 03:00 PM   #22
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Just curious, what car is that ?
xray T4 (2013) with a tekin RS pro, Team Scream 17.5, Savox 1251, Airtronics 471 rx, ReVtech 6900 100C, Sorex 28 JB on Revlite rims and a PF mazdaspeed6 lw shell. Kit screws.

I'm transferring most of the electronics over to my T4'14 now(minus the savox servo), but I suspect I'll still need to add close to the same weight to make min.
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Old 05-20-2014, 07:24 PM   #23
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I run a carbon tub tc4 that weighs 1330g ready to race with a 4200 60c shorty pack. I never worry about voltage drop. I don't push it on my fdr so Im not as fast down the straight but I make up any lack of top end in the infield. A super free efficient drivetrain helps immensely also.
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Old 05-20-2014, 07:43 PM   #24
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I haven't done a discharge test but I did do a race test. My 65c/4600 shorty only shows 7.7 volts after a 6 minute USGT run. I put in a full size 80c/7600 pack and rebalanced the car. The finishing voltage was 7.9 after the 6 minute run. Same car, same motor, same gearing and same layout. Big difference was a little faster up front and very little fall off. I ran a lap within .3 seconds of my fastest 2 laps from the end.
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Old 05-20-2014, 07:48 PM   #25
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I run a 6000 pack on my 2014 BD7 in 17.5 blinky. It has great balance. Anything above 6000 will weigh the battery side down. I also run 20g under the Rx to keep that side balanced with the 6000 pack.
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Old 05-20-2014, 08:13 PM   #26
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xray T4 (2013) with a tekin RS pro, Team Scream 17.5, Savox 1251, Airtronics 471 rx, ReVtech 6900 100C, Sorex 28 JB on Revlite rims and a PF mazdaspeed6 lw shell. Kit screws.

I'm transferring most of the electronics over to my T4'14 now(minus the savox servo), but I suspect I'll still need to add close to the same weight to make min.
You have to add 90g to a stock t4'13? My t4'13 came in right at weight... Seems kinda odd.
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Old 05-20-2014, 08:59 PM   #27
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Quote:
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You have to add 90g to a stock t4'13? My t4'13 came in right at weight... Seems kinda odd.
Seems about right, that RS speed control is tiny, the low-profile servo, light body, and other stuff add up quick to 90g.
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Old 05-20-2014, 09:25 PM   #28
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yup. ESC makes a big difference. I only have 42g added on my Mod car, also a T4'13. It has an ORCA vx in it.
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Old 05-21-2014, 01:45 AM   #29
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To conclude, its a trade off between having the lightest car with a stumpy pack (better power to weight ratio) Vs better voltage with a higher C rated regular size pack and then throwing into the picture how long you're using it for each race.

We only race 3 minute qualifiers and anywhere between 4 and 6 minute finals on a small carpet track, so a shorty pack can have its advantages.
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Old 05-21-2014, 03:04 AM   #30
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wow, lots of great info, keep it going

The chassis I plan to start racing with is a Tamiya TB04 Pro V2, which is a heavy car compared to all the double deck belt drives. I kind of understand why almost everyone is using big 6000mah+ LiPo's, better have more battery than more lead weight.
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