SamuraiSoldier

I just ordered a brand new Traxxas 3.3 T Maxx earlier today just wanting to get back into the hobby its been a long time.
After doing a little bit of research it seems that the 3.3 engines had major issues, some blowing up immediately after brake in. Allmost everything I could find on the subject was dated way back from 2005 to 2015.

So after 15+ years of manufacturing the 3.3 engine are they still defective? How could Traxxas use this engine for nearly 20 years and not do anything to solve the issues that this motor has? Or has Traxxas quietly fixed the problem over time?

Should I be worried about my new 3.3 T Maxx engine even in 2020?

D3MON

honestly yes, they made it worse within the last 5-6 years, the Piston rod is thinner in important areas, and the oiler hole is also not at its best location to actually do anything.
either inspect /replace the con-rod very often, make sure to run it rich so it wont hit its full potential and over-rev the con rod, or buy a different engine.
a few companies used to make aftermarket con rods, but stopped producing them.
dynamite .19 Mach 2 110$
O.S. 21TM $300
are kinda the direct replacements to go anymore.
The Losi 3.4 is a great one in place of the 3.3, but is getting harder to find.

and to answer the question, they got a bit greedy and trying to fly it under the radar is the only thing that makes sense,
offer engine for 220$,
when an engine fails offer the "power up program" selling a $220 engine for right over $130, make it feel like they got a good deal.
with the "deal" they are getting are probably not going to dig into the problem and investigate that it wasnt their fault.
keep the customer because they think they were getting a screaming deal/favor.

SamuraiSoldier

I guess I will try with the stock 3.3 for as long as I can and keep it running rich. When the 3.3 craps out I will swap for the dynamite .19 Mach 2. Anything I should know about the dynamite swap ?

D3MON

dont be too rich, but just dont run it lean. make sure good smoke trail and all that jazz.
dynamite is a direct swap, comes with everything. (if you buy new) traxxas starter system mounts right up to it.
dynamite does takes a bit longer to fully break in from what im told.

1QwkSport2.5r

The 3.3 hasnt changed much since it was released. Their quality control has suffered - no two liners have the same timing. I’ve seen as much as a 10 degree in timing from a complete factory built engine and a replacement piston/liner set. The conrods are the same ones from day 1. The small end is really small and thin and NOT BUSHED. This is the biggest problem. The stock rod will hold out, but that will require abandoning the Traxxas break-in method, and customizing your store bought fuel a little bit.

I built two 3.3s from spares and found two Sirio replacement conrods for the 2.5/3.3 engines on eBay. This so far has proven to be a good change in my modified 3.3. I have pictures of the rods in that thread in this forum.Hot Traxxas 3.3 engine build.

My go-to engine replacement for a Traxxas 3.3 would be a Novarossi 2.5SC.

SamuraiSoldier

abandoning the Traxxas break-in method, and customizing your store bought fuel a little bit.

Can you tell me more about this?
How should you break in the 3.3 if not the traxxas way?

1QwkSport2.5r

Preheat the head to 200F, start engine, and drive it. Adjust the low speed needle so it will idle and clean out easily but not a full on tuned/lean setting. Set your high speed so on a good 2-3 second WOT pass the engine temp cools off. Basically you want it to build some heat and hold it at the lower throttle settings and cool off on a WOT pass. This is keeping the temp within check and providing extra lubrication.

My break-in fuel consists of 4 quarts of fuel (1 US Gallon).
Quart 1 is 14% oil - 12% castor 2% synthetic
Quart 2 is 13% oil - 11% castor 2% synthetic
Quart 3 is 12% oil - 10% castor 2% synthetic
Quart 4 and beyond is 11% oil - 9% castor 2% synthetic

Use a fuel with a castor synthetic blend - starting with a race fuel with 8-10% oil works best - add castor oil only to the fuel. As you add oil, you reduce the nitro by a little bit. Not a big deal. Simple math formulas will tell you how much oil to add for a given step. I run extra oil and a leaner needle setting. This keeps the engine hot enough while still adequately lubricated. Here’s a video of how I break engines in. Note, this is the end of the first quart. This engine has a gallon and a quarter through it and the pinch is still exactly like it was from new. (I built this 3.3 completely from spares and modified it.). Break the engine in with purpose - not paranoia. Too cold and too rich isn’t good just like too lean and hot isn’t good. You may need a wider idle gap and hotter glow plug for the first half gallon, but afterward, go to a medium get plug and run a 0.5-0.7mm idle gap. Modifying an 1/8 scale carb is a good way to get a better operating carb than the Traxxas carb, but that requires some finesse.