Need some Advice for my Build (SR25 DMR - Motor)

Discussion in 'Gun Building, Modifications & Repairs' started by Chris Martin, Apr 14, 2020.

  1. Chris Martin

    Chris Martin New Member

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    Hola AirsoftSociety,

    Before I start, I'd like to assure you guys that I have done my research, and my question is not something readily available on the internet (to my knowledge).

    Build Overview:
    SR25 DMR Project
    Cyma SR25 Base
    450-500 FPS Goal
    SP140 or 150 Spring
    Siegetek 21:1 Gears
    BTC Mk2 Mosfet
    11.1V Titan Battery
    (I think that's all the important stuff for now, let me know if there are any other pertinent parts)

    My question entails what motor I should get, as I have noticed a few odd things.

    I am aiming mostly for response, as high rps on a dmr obviously doesn't matter that much.
    I purchased a Tienly GT-45000 from evike, as the page stated it can handle up to an m150 spring. Originally, this sounded like a great idea to me, but admittedly it was a mistake. With only 12 TPA, it is likely not the best motor I could have chosen. Short term, it is likely that motor would work, but I want the brushes and my batteries to last a little longer than a few months. Id also enjoy my gun not needing 40-50 amps to run.

    I'm between getting the Tienly 30K motor (20TPA) and the ASG 22K motor (22TPA). I've emailed back and forth with Louis Brill at Brill Armory (Great guy and company, I would definitely recommend). He believes that the 22K motor would be adequate for what I want, and I don't disagree with him at all.

    Would the Tienly 30K be better than the ASG 22K? I believe that it might, but I have been wrong before. My main confusion is that the evike page says that the Tienly 30K has "standard torque applications," and that it is best used with "m120-m130 springs." With 20 TPA I'm not sure that I believe that it is standard torque, and I am hoping it is more than able to handle the build that I am in the middle of right now.
    (Standard torque is like 16TPA right?)

    Well anyways, thank you guys for taking the time to read this post, it is a little lengthy. Let me know what you guys think. I have plenty of time to get one of these ordered since this quarantine looks like it will be a while longer. I just want my build up and running when we're released to flood the fields in a couple months.

    Thanks again guys,
    Chris Martin
     
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  2. aotsukisho

    aotsukisho Well-Known Member

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    By BTC MkII I'm assuming the Spectre MkII, which has a precocking feature - you will need this for best trigger response, regardless of motor and spring choice.

    Tienly has better build quality than ASG, anecdotally both of my ASG motors are slightly out of spec in terms of dimensions. I would not trust Evike's recommendations as they are meaningless, the ability for an AEG motor to successfully cycle a gearbox is more than just the spring rating. Spring rating and distance of pull (sector gear teeth) define maximum load, gear ratio and rotational friction (and mass of rotating parts to a lesser degree) define the load the motor sees, your motor system (motor, motor controller, and battery) will dictate how much electromotive and mechanical force is applied.

    Spring force needs to be taken into consideration seeing as how SR-25 uses the v2.5 extended gearbox. 19t sector gear/piston means 18.75% more pullback, which means roughly that much more peak load at the end of the gearbox.

    Your gearset is a higher ratio (20.8:1), and what this means is there's 90% of the load when compared to the stock gears (I think 18.72:1).

    It's also a guessing game with all these irregular-pitch springs how they will behave when pulled past 16t worth of distance, since they are calibrated for that standard AEG stroke under a defined starting preload. The effective spring constant may vary so you will have to test if you have a specific FPS target with minimal wiggle room.

    I ran a JG Blue motor in my v2.5 build, 18:1 19t SHS gears pulling a Prometheus MS170SP. I believe I measured 15A peak draw on 3s. The gearbox can cycle on 2s lipo as well. I have not taken measurements yet with the Tienly 25K currently in there.

    I've also driven an M160 on 14:1 15t with a Rocket 16t neo motor, it didn't like it and it gets hot but it cycles just fine on 3s.

    Precocking will put more severe stress on the system so once you confirm the gearbox works correctly normally then you can work up to the quickest trigger response you want if you are comfortable with faster degradation of parts.
     
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  3. Chris Martin

    Chris Martin New Member

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    Thank you for the quick reply!

    I agree with everything you said. So just to sum it up, do you believe the Tienly 30K will be plenty strong to handle an SP150 in my set up? Or if you had to choose, which motor out of those two would it be?

    Thanks again,
    Chris
     
  4. danerd

    danerd Well-Known Member

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    The ASG motors are ok. Ive ran them in the past and they gave alright performance. I (personally) wouldn't run them in high-stress applications. The Tienly motors are much nicer and built better than ASG.

    Do note that with the extended V2.5 gearbox, you may want to air on the side of slightly stronger springs to get your desired FPS goal. The longer cycle stroke will give lower than expected results with standard AEG springs. You'll have to do some trial and error to get it right.

    I stongly reccomend not using a Titan battery for this setup. Sure it may have the voltage on paper, but they simply cannot put out enough amps to feed really anything beyond a stock AEG. When you add precocking to the mix, your initial amp draw will be massive and will far exceed the capacity of your Titan battery. This will result in you either tripping the fuse on the Spectre over and over (depending on your settings) or your gun simply stalling and the gearbox locking up. As an anecdote, my M14 DMR is pulling about 40 amps on stock gears, 20ish TPA motor, M140 and a 37g piston assembly, and is getting a tad over 450fps.
     
  5. Chris Martin

    Chris Martin New Member

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    I'll probably go with the Tienly 30K motor then. What battery should I look in to buying? I thought that Titan was good for what I was doing, but I trust what you are saying. Would evike have what I would need?
     
  6. danerd

    danerd Well-Known Member

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    You'll want a high-discharge 11.1v lipo for best results, preferably one with a 60+amp discharge rate. Evike has garbage batteries for absurd prices. HobbyKing has a wide selection of batteries for good prices, @Guges Mk3 also has nice packs available.
     
  7. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

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    Any marketing you see about Titan Batteries is utter trash. Youtubers who endorse it are getting paid. LION cells by Titan are NOT good for high stress builds. They are just a small bunch of guys who are having packs custom labeled in China and then selling them at 5 times their cost. They are building hype and fleecing the "inexperienced" on batteries.

    Tienly 30K is an exceptional HT motor. It's not all about TPA...motor RPM and internal design are other factors people just keep glossing over.

    That is like saying all 2.0L I4 engines are the same. Which if you drive a car...you know it's not. Well TPA is being used like that...get deeper...know the details.

    Evikes information is GARBAGE. Tienly 45K is Not a High SPEED motor. It's the top end of Neo HS motors. Some "moron" at Evike must have noticed it's a NEO motor so they labeled it HT. Idiots.

    However, Tienly are built extremley well. Zombie got that 45K HS and he over drove it for 3 months with a 14.4 and a M130. When it failed...it wasn't due to material. It was because a solder joint melted and the connection loss killed the power.
     
  8. OPairoft

    OPairoft Active Member

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    Can also confirm that asg motors seem to be pretty bad. I fried the armature on my 30k boost in less that 15k rounds on a 25 amp 12:1 ssg m249. Also, it had a out of spec endbell. Also have a 30k infinity which will not fit into a tm v6 motor cage because of the endbell...

    I have heard the asg motors are made in the same factory as star wei, but if these are identical to star wei’s quality, than I’m not impressed by the hype that was built up for star wei.
     
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  9. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

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    ASG is another rebrander.
     
  10. Chris Martin

    Chris Martin New Member

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    That seems to be the consensus. I know that places like UA or other high end tech shops use star wei or asg, but Ive always been skeptical about the quality. Thank you for your response! I'm going to be ordering the Tienly motor today.
     
  11. Chris Martin

    Chris Martin New Member

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    Thank you for the response! I'm a little surprised by the consensus on Titan batteries. I'll believe the news though, since you guys have muuuuuuuuch more experience than I do. Do you have a specific battery in mind that can handle 40-60 amps?
     
  12. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

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    "High End Tech Shop" is completely subjective...for 99.55% of these places don't have the "High End" part. None of them carry Tienly.

    Rather they have the "perceived upgrade" part and they stock that for sale.

    As for what battery, it would help if you provided the compartment that you have to work with for your battery.

    Having us tell you to get battery Shape D in 2200mah is not going to help you if it doesn't fit.
     
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  13. Chris Martin

    Chris Martin New Member

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    Probably would have been smart of me to include battery space info. I have the ability to use a full stock or one of the Cyma stocks that have space for a buffer tube battery and/or butterfly style batteries. I can switch out stocks relatively easily.
     
  14. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

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    2200mah Crane will Fit in either.
     
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  15. Lefse

    Lefse Well-Known Member Supporting Member

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    If a fixed stock with room for a brick type li-po is an option, I'd take a look at Gens Ace brick li-po's. Slightly more expensive than Turnigy, but also offer slightly higher performance and quality in my experience. That Titan battery is simply abysmal in comparison.
     
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  16. aotsukisho

    aotsukisho Well-Known Member

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    It should handle it since neodymium magnet motors should handle almost anything realistic, but you want to run the motor in its proper power band for the load you put on it. There's no easy way to determine this especially since I've never seen any manufacturer put out charts for their products mapping RPM, torque, current draw, and efficiency %

    Personal feeling is that it should do well in that setup, your gear ratios are quite gentle and 30K has a high enough turn count to limit amperage and since you don't care about ROF I would actually recommend you go lower (higher turns) if you plan on using a high amount of precocking.

    First off I am not disagreeing with you regarding Titan batteries, like I said I've measured a friend's one in the past with my lipo charger and determined that it's pretty much a 10C with the IR it has.

    However the fuse/overcurrent protection will not trip because the battery will not be able to provide enough amps for it to do so. JG Blue 22t neo has ~15A stall current, and no amount of precocking will surpass that draw as stall current is literally measured using the motor armature as a dead short (0rpm constant current). This is fine for a Titan battery as your 'stock AEG' generally draws under 25A anyway, considering my KWA came with a 25A fuse and my TM came with a 20A fuse.

    This is of course assuming you can confirm your motor has <20A stall current with a much more capable power source accurately.

    Seconded on the weird endbell, that was the primary reason I say they are out-of-spec and cannot recommend them. Just like how the SHS/ZCI endbells are too 'long' to fit in most v2 grips I've tried

    I have had terrible customer service ordering basic parts from Umbrella and will never deal with them again or recommend them. They may sell 'upgrade parts' and stock parts that they replaced, but I would not consider them high end

    Gens Ace is considered top-tier in the RC hobby industry, with much higher requirements for batteries than airsoft ever will. I have never used them, but I have seen enough experienced people across multiple hobbies recommend them where I will give them the benefit of the doubt and also stand behind them.

    Turnigy Nano-Techs are price-performance good stuff for me for so long that I've never really used anything else in the past ten years or so. Everything from 2s 600mAh packs all the way up to 4s 4500mAh ones
     
  17. Lefse

    Lefse Well-Known Member Supporting Member

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    I used Turnigy before myself, but switched to Gens Ace for two reasons, they seem to have more realistic specs, and I can buy them locally. I compared a Turnigy and Gens Ace stick li-po, both rated to 11.1V 25C 1200mAh, so identical specs. Despite the identical specs the Gens Ace stick had siginficantly higher performance, so that really sold the brand for me.

    I'm not saying Turnigy li-po's are bad, they're definitely good bang for the buck, it just seems that Gens Ace is a step up in quality and performance from what I've experienced.
     
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  18. aotsukisho

    aotsukisho Well-Known Member

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    Very much so, but for most AEGs it is quickly diminishing returns for your $$ and best reserved for bonkers builds or the RC guys pulling 100+A on a throttle dump. Airsoft also doesn't have to worry about excessive ripple current brought on by brutal regenerative braking on brushless motor systems surging current back through the controller into high-IR batteries.
     
  19. Lefse

    Lefse Well-Known Member Supporting Member

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    The power to size ratio is convenient though. My smallest Gens Ace brick li-po is rated at 11.1V 75C 1050mAh, it can handle any type of setup while being compact enough to fit inside a PEQ-15 battery box. They're also not particularly expensive batteries, we're talking maybe $5 more than a Turnigy li-po and easily half the price of an airsoft brand li-po, and most of my batteries didn't cost more than a bag or two of high quality BB's.
     
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  20. OPairoft

    OPairoft Active Member

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    Didn’t know that shs/zci also had endbell problems, thanks for the warning.

    What kind of problem did you have with UA?