Thanks for the tip!

It's been a while but I finally got a chrono! I chronoed my p90 running the stock spring, gears, a G&P 9.6V mini battery and of course the G&P m160. I held my breath as a pulled the trigger, expecting piston stripping and gearbox shattering performance. I got 17rps. To say I'm disappointed is an understatement. I was hoping to break at least the 20s since u says are saying the the M160 is a beast. It doesn't even sound that much faster! What could possibly be the cause of such mediocre performance? Does having a ported piston in a gun with an Ak47 length barrel have anything to do with it?

nope. barrel length has nothing to do with it. Your problem is most likely the mini battery. The motor wants more current, but your battery isn't capable of outputting it. If you have one avail, attach a 9.6 large (for comparison) and you'll see the difference (or a 7.4-11.1v lipo, wich will will fit in the p90 np)

you need more power, like a 9.6v large, a 10.8v mini, or an 11.1v 20C LiPo
The motor has plenty of power, it's just not getting enough gas :p

7.4v 20c lipo maybe

That's strange b/c I've read in other forums ppl easily getting 20+ rps on weaker motors and min batteries.

What brand and gearbox setup do you have for your p90? Also, you'll have to understand that people do modify their gearboxes somewhat to improve performance. Whether it's as involved as re-shimming the gears to perfection or a simple excess grease removal.

I recommend LiPo power. mini batteries do not cut the cake for what you area asking from your gun.

Venom, Reedy, and china brand packs are excellent at the 20-30 C, 7.4-11.1 range and will fit your gun. You don't need to buy a high end hyperion/flightpower pack, something mediocre to entry level for the RC world will do.

IF you are going 11.1v lipo I HIGHLY recommend a MOSFET or Trigger Master from DonP or Gandolf from ASM for your gun. The P90 has piles of space for you to fit either of these options and with the external switch it's not a big pain in the ass to install.


As to this there are LOTS of factors. There is the internet Bullshit factor. And how did you measure your ROF? What power supply did they use? The only accurate way to measure ROF is with the sound wave form method.

http://www.airsoftmechanics.com/home...nt/view/24/26/
http://unconventional-airsoft.com/20...e-measurement/

I used a madbull chrono to measure ROF on my old setup:

magnum motor
M120 Spring
9.6v 2200 mah crane battery
standard ratio gears

The chrono always gave me a reading of 9-11 ROF.
The paintball Chrono at a field we play on gives me 18 ROF.
The sound form method gave me a ROF of 24.

At the end of the day I learned to no longer use the BPS feature on the handheld chrono's.

That's really useful to know! Now I have a new issue: I've tried installing 13:1 high speed gears and it refuses to cycle. It always jams up after a few shots. After hours of tinkering, I found out that my anti-reversal latch is the culprit since my mechbox cycles perfectly w/o it. Is there anything I can do such as increase/release the tension on the spring? My stock XYT gears cycles fine so that's why I don't think my ARL is damaged.

That's funny, I have no issues at all fitting an M160 in my Echo1's motor cage...

Zippy lipos are awesome, too!

heh. Tribute to shotty clone quality control. The line of g&p motors would not fit in my cage.

I suggest you don't run your gearbox without the AR latch unless you have some kind of fancy shmancy electronic device that is slowing and stopping the drive train without causing the gears to move in reverse.

Check your shimming. and check the shimming on the AR latch. I had to shim up my ARL on my P90 because the AR tensioning spring was contacting the spur gear.

I installed a G&P M120 into my teammate's SCAR, and it fires FREAKING fast. It's in the high 30 rounds per second range.

I had no clue u were suppose to shim the ARL :( Oh well, a Prometheous ARL is coming in the mail soon, hopefully it'll sort things out!