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  1. #1
    RC Turnbuckle Jr. Wolfslash16's Avatar
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    Arrow O.S .21M and larger big blocks...

    Well, after finding out the most likely cause for my weird slayer problem is a cracked piston skirt, I looked into getting a big block for my slayer. I read that a O.S .21M will fit into a slayer (or revo) without any mods, but is the O.S .21M any good? What is the pros. and cons. of getting it? But, the O.S .21M costs over $250 new. Is that incorrect, or is there some where I can get one cheaper? (I hope not ebay, I've gotten burned on ebay deals) Or, is there any other big blocks that will fit without mods or changes that cost under $150? Any help would be nice! Thanks! -Wolfslash16
    Sl2sh Slayer Summit Sl4sh Teton/Rally T-Maxx Pnde

  2. #2
    RC Turnbuckle Jr. fallonguy's Avatar
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    For under 150.00 the only choice would be the 3.3 engine as a drop in with no mods. You can find the Os .21 TM on Tower hobbies for 269.97 + 30.00 off and free shipping and is a drop in with no mods. You can get the Picco MAX .26 Red-Dot it's 219.00 and get 25.00 off and free shipping but you will still need a motor mount. the ofna mount is 20.00 but the better choice would be the new era mount because the ofna mount doesn't have much adjustment and limits the choice of spur gears you can use but that's 40.00
    I wanted to put a really cool signature but I ran

  3. #3
    RC Turnbuckle Jr. CarGuy7a's Avatar
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    I run the OS 21TM on mine and it's a great little motor. Much easier to tune than the 3.3. It seems the adjustments on the carb aren't as finicky. Power wise it is comparable to the 3.3. I didn't notice a ton more power but it does spool the rpm's up faster.

    Break in is a little weird as well. The OS manual doesn't really go into specific detail like traxxas does with their motors tank by tank. The OS manual just states "run it on the track with small throttle inputs" for 5 tanks leaning the HSN 20 (or 1/8th turn) each tank. So what I did was I followed the "Traxxas method" of break in and added the "OS Method" of leaning the HSN 1/8th turn after each tank and it's holding up great.

  4. #4
    RC Turnbuckle Jr. fallonguy's Avatar
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    I had a .21tm in mine with the Buku pipe and it was so squirrely on take off I took it out and put this setup in my revo.
    I wanted to put a really cool signature but I ran

  5. #5
    RC Turnbuckle Jr. Nitronaught's Avatar
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    The O.S. .21tm is NOT a big block... It's still a small block.... Direct drop in. And 2X the price of the 3.3....
    Robin Williams
    He will be greatly missed...

  6. #6
    RC Racer
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    Don't let one ebay burn keep you off ebay. Ebay provides plenty of info for you to make a wise purchase. If you send money to a guy with 5 negative feebacks out of 12 or from anyone that has no feedback as a seller, then you're just gambling. I've made at least 600 ebay transactions, at least 10 purchases in the last few weeks. I just got a new Slash in today from ebay.

    I have an STS 28 with roto-start back plate in my Revo and my Savage (both engines from ebay). It is a great engine. Always starts easily, was easy to tune, I don't tinker with it much, lots of torque and speed. It's a true big block, so you will need a mount for it, but the engine is only about $100 brand new.
    Last edited by metoo2; 07-09-2012 at 11:03 AM.

  7. #7
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    have a friend with the os.21 for revo/slayer and it rips.. dynamite makes a .19 drop in one also.. gotta love the picco too.. .26's and .28 The .21 and .26's are mid blocks tho, not true big blocks. $150 wont cut it..

  8. #8
    RC Turnbuckle Jr. Wolfslash16's Avatar
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    $150 wont cut it..
    Ya, sadly $150 is all I have at the time... I guess I'll just get another TRX 3.3.
    Sl2sh Slayer Summit Sl4sh Teton/Rally T-Maxx Pnde

  9. #9
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    the dynamite mach2 .28 big red i have was $130 u would just need the New Era mount to clear the rear arm..

  10. #10
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    the O.S. .18tz turbo is big power over the 3.3 its $175 at Amainhobbies

  11. #11
    RC Turnbuckle Jr. Wolfslash16's Avatar
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    Ok, thanks guys! I'll look into them!
    Sl2sh Slayer Summit Sl4sh Teton/Rally T-Maxx Pnde

  12. #12
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    NewEra has a package kit for revo/slayer pro with - mount and ofna .28 force engine header n pipe for $220

  13. #13
    RC Racer
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    You can also look at the 3.4 from Losi.

  14. #14
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    I have the OS .21, its a great motor once i broke it in, it started easy and seems to rev higher.

    What i've learned about break in from RC to dirt bikes and so on is break it in like your going to use it, I took my first tank easy then started having fun right away. did the same with my 2.5 Tmaxx it still runs after 5 years, I only swapped it out a while back because i wanted a little more power but it ran almsot as good as my 3.3

  15. #15
    RC Turnbuckle Jr. Nitronaught's Avatar
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    Quote Originally Posted by Ckeithnitro View Post
    the O.S. .18tz turbo is big power over the 3.3 its $175 at Amainhobbies
    Don't forget your starter box.. The .18TZ is a bump start motor....
    Robin Williams
    He will be greatly missed...

  16. #16
    RC Champion
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    Or u could just put a better carb on the 3.3 and have a great, powerful, easy to tune 3.3 motor :/

  17. #17
    RC Competitor
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    What would be a direct fit better carb for the 3.3?

  18. #18
    RC Champion
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    The OS 11k carb the losi 3.4 and the best is the tm 523

  19. #19
    RC Competitor
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    I found the losi carb for sale by iteself but cant for the lif of me find the others. WOuld love to have a nicer carb. I love my 3.3 but if I can put a better carb on I would love to

  20. #20
    RC Champion
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    The other 2 are a little hard to find there was a tm 523 motor for sale on eBay a couple days ago...

  21. #21
    RC Enthusiast
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    Is new era always out of the mounts?! Anyone know where I can find one? I would like to run a .28 dynamite or STS. Engine in the Maxx decided to scrap out so to solve 2 problems move the 3.3 from the pro to the Maxx, and get a big block for the pro. Well thats how I'm justifying it to the wife anyhow...

  22. #22
    RC Enthusiast
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    Just saw the Traxxas big block conversion kit on tower hobbies. Any thoughts?

  23. #23
    RC Qualifier
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    you will very limited for engine selection with trx big block mount...

  24. #24
    RC Enthusiast
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    Any sites that may have the New Era one in stock?

  25. #25
    RC Qualifier
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    i just emailed them to see when stock will be availible..

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