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  1. #1
    RC Racer
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    May 2017
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    Engine Swap and Other Upgrades

    Hello.

    I've had my Revo 3.3 for about a year now and I'm looking to do some upgrades to it. First off, why can't I get it to wheelie? Even with a perfect tune it just won't wheelie. Can anyone else get theirs to wheelie with the stock 3.3? Is an OS.21TM really that much better than a TRX 3.3?

    Are there any other upgrades I can do to improve handling?

    Thanks
    Slash 4x4 w/TSM
    Revo 3.3

  2. #2
    RC Champion
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    Feb 2013
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    I never had much luck with getting my 3.3 revo to wheelie on command with the stock motor unless I had a 13t or 14t bell with the 40t spur and even then it took some work. The TM will definitely make it wheelie (has more low end torque and snappier throttle). For playing around wheelies are fun but for racing, not so much. The revo in stock form is a near perfect balance of power so that it doesn't wheelie every time you punch it so that when racing you can keep it pointed in the right direction on the track.
    I have an RC problem...

  3. #3
    RC Racer
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    Quote Originally Posted by rock-rod View Post
    I never had much luck with getting my 3.3 revo to wheelie on command with the stock motor unless I had a 13t or 14t bell with the 40t spur and even then it took some work. The TM will definitely make it wheelie (has more low end torque and snappier throttle). For playing around wheelies are fun but for racing, not so much. The revo in stock form is a near perfect balance of power so that it doesn't wheelie every time you punch it so that when racing you can keep it pointed in the right direction on the track.
    Ok I see. I'm not really racing, just bashing though.
    Slash 4x4 w/TSM
    Revo 3.3

  4. #4
    RC Champion
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    As far as handling upgrades - the sway bars make a huge difference in cornering ability and the variable rate shock dampers improve jumping capabilities along with a change in shock oil weight and spring rate. the stock set up is pretty soft which makes jumping kinda sketchy. Also if you can find one - the Tekno single steering conversion kit is nice because it helps balance out the chassis.
    I have an RC problem...

  5. #5
    Marshal Double G's Avatar
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    May 2008
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    14,273
    With a very good tune I could get the Revo up on a 15t/38t but more often with a 14t/38t. You can add a little power to the 3.3 by using a Losi 3.4 carb and a THS pipe and then it will stand up some more. I love my TM with THS pipe - will wheelie even when rich.

    Sway bars help - I like my Tekno, however, I've twisted apart a few front bars. Gain: stability. Lose: buying replacement parts.

    Tuning the shocks and springs will help as well. So find the balance you like. Read up on how to tune the suspension.

    Finally, after many years of staying with a single 2075 I moved onto a single Promodeler steering servo which has nearly 2.5 times more power and centers much better. There is no need for a single conversion kit, you can Dremel off the side of the steering arm that you don't need.
    The Super Derecho

  6. #6
    RC Turnbuckle Jr. olds97_lss's Avatar
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    Dec 2003
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    Get a cup of coffee... rambling is about to happen...

    I've had revo's for many years. Short chassis, long, small block, big block and now even a brushless one. I started with the 2.5R revo which was a short chassis. I never have had great luck with the 2.5 or 3.3 engines. I don't know if I expect more out of them or what the deal is, but they were always lack luster for me in a MT. A 2.5R worked fine in a jato all day long, but in a t-maxx or revo, it wasn't nearly enough power for running in grass, which is where I usually run.

    I never had a t-maxx with a 3.3, but I did get a 3.3 revo later on in life. It was better than the 2.5R revo, but marginally. Like mentioned in the other posts, I wasn't able to beg, borrow or steal a wheelie out of it without gearing very low. Then it was so slow, it just wasn't fun and even then, I had to work at getting a wheelie out of it. I tried the losi carb, the THS pipe, various springs/oils in the shocks... just never performed how I wanted it. I even bought a brand new 3.3 (got my 3.3 revo used) to break in myself to see if it was the engine being worn out. It wasn't. Performed pretty much the same.

    It was fine if I was just playing around in a skate park, but I spend 90% of my time in grass hitting natural jumps in parks and when running there, I couldn't keep the temps below 280F+ and it liked to stall a lot.

    I think part of what jaded me about it was that I did have a big block revo with the new era leaner mount and an LRP28 in it. That thing is brutal and tons of fun. It's just loud and a tank of fuel doesn't last as long, and it goes through center/outer axles pretty quick (a full set every season) which is why I liked the idea of the small block. Small blocks seem to run forever on a tank of gas and it was quieter, so I didn't feel so bad running it 75 yards from peoples houses to run at a local skate park, and it was easier on the sliders.

    After trying the losi carb, the ths pipe and upgraded to a dynamite 2 shoe alloy clutch, I basically stopped driving it for about a year, I decided to break it out again and remind myself why. I installed stock gearing to remind myself how it responded. It reminded me I liked the truck, just not the performance. Then I pulled the pin and ordered the OS21TM. Many years prior, I had an OS18TM in a short chassis revo, can't recall why I got rid of the truck, but I kept the engine. While I waited for the 21TM to show up, I put the old tired 18TM in it with the stock gearing. The 18TM has to have around 10+ gallons through it and it was far more lively than the 2.5 gallon 3.3 I took out. Could actually pull a wheelie here and there! Then the 21TM showed up. Figured now I had the best frame of mind for comparison as I ran the 3.3, 18TM and now the 21TM all back to back. Same truck, same gearing.

    I fought with it a bit at first due to shearing pins off in the transmission gears as the 21TM got broken in. The more fuel I put through it, the stronger it got. The 4th or 5th time I had to take the trans apart due to sheared pins or stripped gears, I gave up and upgraded to RRP steel gears like my big block revo. Then aside from one instance where the c-clip holding a pin in falling off, it's been fine since. The 21TM ran hot for the first .5-1.5 gallons or so, then it really stabilized and became a tried and true OS engine with reliability and predictability. Wheelies at will, runs all day without fussing with the tune and fires right up every time I want to run it. I'm still using the THS pipe with it and it's still quite a bit quieter than my big block revo, but it does run a lot longer on a tank of gas.

    Was kind of funny, at first, while the 21TM picked up speed better, ran cooler and could wheelie on pavement pretty easily, it wouldn't do it in the grass. I pulled the engine, cleaned the bell, inspected the alloy shoes for burs, roughed up the slipper pads, still no wheelies in the grass. Then I got an ERBE and I liked the SRC terrain crusher tires I had on the 21TM revo,so I swapped them over to it and put some t-maxx 3.3 wheels/tires on the 21Tm revo I had on it before with the 3.3 and 18TM. Then it wheelied all over the place. I didn't realize the SRC tires were just spinning in the grass. I had installed those about the same time I put the 21Tm in it. On the ERBE, you could hear it and see it spin the tires, but it would still wheelie everywhere because, well, brushless power!

    Anyway, long long story short, the 21TM does perform well. It doesn't perform like a big block, but it is a decent step up from the 3.3 and may require upgrading the trans to RRP. With that in mind, that puts you at $400 for the upgrade (~$300 engine, $100 RRP gears). So, is it $275 better than the 3.3? I can say that I'd probably make the change again. Especially if I didn't have a big block revo already and wasn't diving in with both feet into brushless as I am now.
    Last edited by olds97_lss; 06-11-2018 at 10:52 AM.
    https://www.youtube.com/c/olds97lss

  7. #7
    RC Champion
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    one thing about the OS engine - it has a fantastic warranty. This plus the fact that it's super easy to tune and just doesn't need the constant fiddling makes it very much worth the entry price. It's also a direct drop in motor. No muss or fuss. It's not going to be any faster in top speed over the 3.3 but it's most certainly going to hit max speed a lot faster (if you can keep the front end on the ground). When I ran one I purposely went to a 16t clutch bell and gained a few MPH in top speed and this helped tame the constant wheelie-popping. With the stock gearing not only would it jerk the front tires off the ground, but it would do it almost every time it hit second gear. Going up to the 16t clutch bell meant better control.
    I have an RC problem...

  8. #8
    RC poster
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    Oct 2020
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    Hello my tmaxx and revo 3.3 both wheelie like crazy had to install wheelie bars on both of them the good tune just right and tighten the slipper clutch I tighten it all the way tight and back it off a 1/4 turn to half turn it locks up great and wheelies

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