GP4 - Tamiya USA

Howdy my fellow Awesomatixians. Had a chance to do some testing at the Tamiya USA track over the weekend, and wanted to share my findings. I'm going to be running 17.5 at the Reedy TC race being held at Tamiya in May, and I have been unsure which car I want to run; shaft or belt? So I setup both cars with near identical electronics and setup. Both cars running Reedy ESCs with two Team Powers motors set to produce similar numbers on an analyzer with identical FDR. I ran the same body, tires, and battery for all runs. Both cars were completely rebuilt with new bearings and fresh grease/oil, and both weighed in at 1390 race-ready (weight added to both, and balanced with a 4 corner scale) sporting carbon chassis.

I drove both cars using the same line, but at the end of it all the A700 was able to pull off .2 faster lap time, with .1 faster average time over a 7 minute practice run. Throughout the weekend my average lap times were within a tenth or two of my fast lap, so both cars were extremely consistent.

Both cars were stuck to the track (the track was incredible on Saturday; perfect conditions and high grip all day) but the A800 was noticeably easier to drive and seemed impossible to get out of whack. This would be the car to drive if I was super nervous about making a mistake and just wanted something easier to drive and completely predictable.

On the A700 if you really irresponsibly hammered the throttle at the wrong time the rear end would step out, but this seemed like an acceptable trade off for how noticeably quicker it was accelerating out of turns with proper throttle application. I didn't have either motor dialed for optimum performance, I just wanted them to run as similar as possible, and even with the same FDR the A700 was able to hang better with other cars in the straight. Even though the A700 felt quicker, it came off the track 10-15 degrees (F) cooler than the 800.

So, while I couldn't love my A800 more in mod, the good old A700 is still my choice for asphalt stock racing.

Edit: One final thought as I re-read my post was "of course the shaft car would do ok with an underpowered motor", so I just wanted to point out that even after dropping in the properly tuned motor I plan to run at Reedy the A700 had no on throttle traction issues whatsoever (and I lowered my fast lap another .4)

Did you remove the rubber bearing seals??? If not, you got more speed in that A700... Teflon sealed ceramic bearings is what's needed...

I used the same new metal shielded Yeah Racing bearings in both cars to put them on an even playing field. Not ideal I know, but I was more interested in testing the design differences, so I tried to eliminate as many other factors as reasonably possible. I would agree and say the 700 would receive an even greater advantage with better bearings since it uses more of them and that's probably the main source of drag. I use dry Teflon lubricant on the metal gears.

Source: W. Raven