XRAY - Model racing cars

Hi,

going to be doing the next round of the winter series and am after some advise on setup, as I have not raced TC before.

I think I am ok for chassis setup, but after some help on a good starting point for the esc setup and gearing,

setup as follows;

Xray T3 2011
Tekin RS
Tekin 13.5
84 spur 48dp

thanks

get fdr from 6.0 to 7.0
about speedo i dont know how to set up it
I have GM Genius 120,LOVE IT!

hey, at the winter series i found the best gearing to be 7.6 for 13.5, 21 pinion 84 spur

but the question is
whats the track?
are you the fastest on straights?
if not,it means that its not good fdr

thanks for the replies

shouldn't you have the gearing set so you top out about 2/3rds along the straight?

somethin like that, i do it by comparing laptimes

you have to have top speed just 1-2m before braking

true, but it could be worth sacrificing a bit of top end speed for more acceleration if its a very technical track, but that is a good place to start

i always had my fdr like this and i had perfect acceleration
my favourite fdr is 6.16 fo gm 120 and gm pro 13.5t

Hi

Our settings for Ardent (with a GM 13.5 motor - it is somewhat lower revving than the Tekin Redline's, but this setup should work OK as a starter)

Gearing 7.8
Boost 55
Start rpm 1600
End rpm 12000
Turbo 12
Ramp 2
Delay 0.2sec
Throttle profile 4

You need to measure motor temps after a 2min and 5min run - the GM's run cool (ca 55 degC), dunno about the Redline's, I'd keep it below 70 degC if it were me

HTH

Power programs also influence the correct FDR. With zero boost i.e. a 10.5T X11 should have about 6.6 on a small track (data from LRP). To me this means that a 13.5T should have 6.0 or even lower. But as said it's also about motor timing. With lots of timing 7.6 is faster than 6.6 at my track with a 10.5T i.e.. The harder the timing, the shorter the gearing should be.

@ CharlesF:

Do you also think that GM motors need some kind of different FDR compared to other motors? I think so as a mate rocked the 17.5T class in 4WD offroad with a Graupner Sport 21.5T and a pizza-like pinion gear. It seems that they have more torque and notionally more power but less rpm than their competition. But I think there must be some more factors as LRP motors are weak on paper but awesome on track. Maybe it's only the zero boost performance on the data sheets.

@Green Wing

I think the GM's have more torque and less rpm (maybe the Graupner's more so?). The KV values are an indication, but GM do not quote this, only max amps....
Tekin and LRP seem to like revs.

We've run LRP/Nosram's in the past, and they are fast and powerful, but they run really hot and went "soft" on us eventually.

FDR's are very track dependant and whether you are gearing for the infield or straight. We tend to gear for good acceleration in the infield (i.e. higher FDR's) - the fractions of second lost on the straight are made up in "punch" in the short straights - just my opinion and experience tho!

The other thing to bear in mind is that DC motors have max torque at zero rpm, which decreases as the revs rise. If you can control temperatures, low FDR's are still quick because of this. Conventional wisdom is to gear so that you hit max revs about 3/4 of the way down the straight.

HTH

thanks for all the help

I ran the car with the following set up

45 boost coming in at 6500 till 20000
turbo at 10 coming in after 0.4 at a rate of 2.

car was very drivable but a bit down on top speed.

Having not driven 13.5 (or TC) before, the motor felt a bit soft, don't know if this is how they feel or need some fine tuning.

I will be getting a new setup on friday, so see how it goes on sunday

@Charles, you racing on sunday?

@Gone Elvis

Unfortunately we'll not make Sunday (Eldest son's wedding )

I think you should change the setup as Skiddins advises - more boost coming in earlier. Depending on the gearing, you will be unlikely to hit 20 000 rpm on the straight. [Non boosted 13.5's top out at around 23 000 to 25 000, with the peak power at around 12 000 - 15 000 - aiming for the boost to end at or around the peak power rpm is a good starting point]

You need to bring in the timing advance early enough so that you get the torque/power boost effect, but not so soon that it just heats the coils up without any effect.

In essence (and I am not an expert!), the stator coils take a finite time (milliseconds !) to build up to maximum magnetism once the ESC fires voltage / current to them. You want the max magnetism to be achieved before the magnetic pole of the rotor passes under it (ideally 90 degrees before). As the revs build, there is less available time for the coil to "charge" - hence you have to fire the coil earlier as the revs rise = timing advance. Firing the coil too early means the peak magnetism is acheived with the rotor pole too early (at 180 degrees to the coil for example) and no torque is gained, just heat.

["blinky mode" or non-boosted ESC's do not have the ability to program the advance of the coil firing by rpm]


HTH

When I was running 10.5 at WLRC I measured the slowest corner aas being around 14mph, at the time that equated to over 11,000rpm, at eh SLOWEST part of the track.

I seem to recall when I visited Ardent the top few 13.5's were doing 42-43mpn on the straight, even at 8.0 FDR that would be around 43,000rpm!