Undergearing Motor

[DaveG28]

Does doing this do any harm or just affect performance?

Reason I ask is using a Speed Passion V3 5.5 last week I went from a 10.4 FDR to 11 FDR and it had a bigger effect than I expected, really seemed to lose the sweet spot, didn't seem to have any extra acceleration and lost more top end than I'd expect!?

Anyway, as it happens I don't find that a bad thing as on most indoor tracks I'd probably want this, but don't want to use it as a tuning aid if I'm also damaging the motor in anyway?

[chris_dono]

you can undergear a motor so much that it gets hot and/or revs too high, that's when it's in danger of being damaged.

[samd]

I always thought that undergearing was as bad as overgearing but im geared at 11.3 to 1 with a novak 5.5r for indoors in 4wd now dave and motor comes of quite cool no probs. I used to gear a 5.5 at 10 to 1 but its too fast for me indoors.

How do you find the speed passion v3 compared to your X12?

[DaveG28]

Well for 5.5's I've run Novak, Wave, X12 and Speed Passion V3's. The X12 seemed mentally fast compared to all of the others! So much punch and top end, the only place it wasn't too much for me was Southport outdoors.

My favourite was the Wave, smoother than the X12 but just as good top end, but it blew up

Speed Passion seems very good, love the plug system, but not as insane as the X12.

Have been considering a 6.5 X12 with 12mm rotor to help top end, am confused by the stats though, based off revs pr volt the speed passion is way higher and I'd not want to lose top end, do some companies talk bull in the specs like revs per volt?

[Dazzler]

You would think it is very accurate as the motors are sensor'd which should provide an accurate readout. But they could be quoting theoretical values and most certainly an average.

[samd]

Values are always unloaded so in the real world they dont mean too much as far as comparison brand to brand. Look at the X12's low KV rating but in practice they are fast as.

[SlowOne]

Revs/volt unloaded is like saying a Honda S2000 sportscar engine will do 9,500 rpm on so much fuel, and a Bugatti Veyron will only do 9000 rpm on the same amount of fuel - when both are standing still! Both those statements are true, but have no bearing on the performance of the vehicles they are in!

Forget the revs/volt (and come to the battery C rating and servo speeds!) and look at the performance you want in the car. Go with the recommendations of others, or experiment for yourself. Relying on the numbers on a box or label is unreliable unless you can get all the data behind the results being published. HTH

You would have to undergear by a large amount before doing significant damage to a motor. The situation is worst when you undergear a lot and use a lot of timing advance. If you want to soften motors up a bit, go for reducing the timing first, and then the ratio. HTH