Originally Posted by peter_robinson
2S 17.5 non-boosted seems a little faster than brushed stock used to be. however 1S 17.5 non-boosted is way slower than I remember brushed stock being...
That's all because of battery voltage and current delivery....NO WAY can round cells get anywhere near the performance level of today's average 2S lipo. The voltage/current delivery curve of even the best matched cell pack only compares in the first minute or so with a lipo, after that, the round cells begin dropping off quickly...and the lipo will still be going strong at a higher voltage level. So in essence, yes, lipo powered brushed motors seem faster because they get a higher voltage and greater current delivered to them for a longer period of time compared to nimh round cells.
My track allows 27T brushed/2S with the 17.5 non-boosted if that's all you have, and we run 27T/2S with our Muscle Car class (basically VTA). Geared in similar manner, the brushed motor can hang with the slower half of the field....but like I said earlier, you have more room in temps to overgear with a brushless than you do with a brushed motor wether you put a heatsink/fan on it or no, so in the long run if the brushed motor tries to overgear and hang with the brushless.....it's going to let the magic smoke out!
You'll do OK in the colder weather, but if you're running outside in the heat, the 17.5 will take the win easily.
Wanna beat a 17.5 with a 27T? Drive better lines! But it's got you in the long run. Sooner or later, heat, brush wear, and simple magnet aging will make maintaining a 27T in the long run a false economy. There are TONS of gently used or nearly new ones for sale everywhere, usually cheap, but I'd only run one if I had to. For the cost of the proper
support equipment ALONE for a brushed motor, you could get a Tekin RS/17.5 combo! Oh, and while replaacement brushes are a dime a dozen.......it's getting harder and harder to find decent replacement 27T armatures that are worth owning. Heck, dollar for dollar, if you simply have to run a 27T and had no other equipment, I'd replace the brushes until the arm smoked, throw the whole thing in the trash, and replace it with a like item.
Of course, it's easier to smoke check a brushed ESC, too, so figure if you're dedicated to a season of NON-silver can brushed racing, have a replacement motor or two, lots of extra brushes, and a spare esc on hand for quick swap out! If you already have motors, brushes, and all the support equipment, maybe it'll be economical for you, at least until your consumables (replacement brushes, and more importantly, armatures) runs out.
Figure the OP is wanting to put a 27T/nimh combo in a modern chassis and run in the 17.5 TC class......and unless you have mad motor tuning/tweaking skills, are relatively masochistic, and are an ace at the wheel....you're gonna be outclassed in weight and motor performance. I have a box FULL of 27T motors of darn near every flavor, and the only ones that consistently perform well enough to put with the brushless 17.5s are the CO27s. You can find 'em on ebay usually for at or under the $25 mark in new to gently used condition.
Or just bite the bullet and go brushless as soon as your budget/interest allows.....you'll be much happier!
ETA: Integy has some (4 or 5 different offerings) 27T arms for sale mega cheap...for a reason. EVERY can I've ever tried one in they dyno like crap.
As a bench mark, my Robitronics measures, in Watts, most good stockers in the high 80s to low 90s. GREAT stockers in the mid 90s to low 100s. With a handfull of rare exceptions (I number all my motors, and keep full records of every one, from new through every brush replacement and rebuild), I've NEVER gotten an Integy replacement arm in ANY can, with ANY brushes, with EVERY TRICK IN THE BOOK (the Black Book, for those of you in the know or with long memories!!) thrown at it, above the mid 70s for peak watts. Fine for bashing, crap for racing.