Some help here for a fellow member please poll

On what trx engine is the most Reliable?
1) 3.3
2) 2.5R
3) Pro .15
How many gallons per each with proper tuning done?

Please vote for 1, 2, 3 for the selected engine.

Hoping to start nitro soon. This thread is for a friend. Thanks everyone.

I have had 2.5's last up to ten gallons. They just seem to be a little more reliable. The 3.3 uses the same crank, con rod, and carb, which I think is a little under sized for the larger bore. I had one I bought used split a con rod shortly after I bought it. The piston showed signs of running severly lean. I know the damage was done before me on that one. I have had a 3.3 last to about 7 gallons, which is still not to bad. The 3.3 seems a little more tighter to tune, and less forgiving. Just a small change can go from rich to too lean. A 2.5 I dont seem to ever hardly have to adjust. That is my opinion. I am not however in any way putting the 3.3 down. I can't I own too many of them. LOL

Thanks alot Mike^^^

Thanks to all those who give information aswel :)

[QUOTE=westoakmech;5404885]I have had 2.5's last up to ten gallons. They just seem to be a little more reliable. The 3.3 uses the same crank, con rod, and carb, which I think is a little under sized for the larger bore. I had one I bought used split a con rod shortly after I bought it. The piston showed signs of running severly lean. I know the damage was done before me on that one. I have had a 3.3 last to about 7 gallons, which is still not to bad. The 3.3 seems a little more tighter to tune, and less forgiving. Just a small change can go from rich to too lean. A 2.5 I dont seem to ever hardly have to adjust. That is my opinion. I am not however in any way putting the 3.3 down. I can't I own too many of them. LOL[/QUOTE]

How many times have you had to rebuild your engine?
What about fuel?
20%

I've had the 2.5, rebuilt it to a 2.5r, had 1 3.3 went 6 gallons it's now rebuilt, ported and polished myself and dropped ceramics in it... Runs great and it's on gallon 2. Then I have another 3.3 it's on it's 7th gallon.

All performed and raced well.... I have no hands on experience with the Pro 15's, but I've had a lot of hands on with the 2.5's 2.5r's and 3.3's... They perform like they should and I have not had any issues with reliability.

What affects engine life?
Temps it has been ran at (many failure happen after it's been overheated too much, not as much during)
Proper break in.
Using after run.
Type of fuel makes a huge difference in tuning and performance in many cases.

For me I find it hard to put this into a poll. :cool:

I ran 10 gals before I had to rebuild. One 2.5, now built as 2.5r has been rebuilt 5 times. As long as you don't damage the crank case, they can be rebuilt many times. If you can last to 7 gallons, that is doing pretty good. I requires not putting away with out doing after run. Unless I know I am gonna run again the same day, I do after run when finished. Keep air filters clean, I carry 3 or 4 spares, in a ziplok baggie and change out as the day goes along, depending on where I am running. I run traxxas 20%, traxxas 33%, have ran morgan fuels back yard basher in 30%, and there worlds in 30%. It has lower oil, have to be careful with it. I am getting ready to try some vp power master, I have never used it before.

Hey NN did you run a losi 3.4 carb on your modded 3.3? I just modded a 3.3 crank and sleeve, getting ready to try the 3.4 carb. It works good on my other 3.3

[QUOTE=kdvanb;5404888]Thanks alot Mike^^^

Thanks to all those who give information aswel :)[/QUOTE]
no problem at all glad i could help a fellow member out.

[QUOTE=westoakmech;5405043]I ran 10 gals before I had to rebuild. One 2.5, now built as 2.5r has been rebuilt 5 times. As long as you don't damage the crank case, they can be rebuilt many times. If you can last to 7 gallons, that is doing pretty good. I requires not putting away with out doing after run. Unless I know I am gonna run again the same day, I do after run when finished. Keep air filters clean, I carry 3 or 4 spares, in a ziplok baggie and change out as the day goes along, depending on where I am running. I run traxxas 20%, traxxas 33%, have ran morgan fuels back yard basher in 30%, and there worlds in 30%. It has lower oil, have to be careful with it. I am getting ready to try some vp power master, I have never used it before.

Hey NN did you run a losi 3.4 carb on your modded 3.3? I just modded a 3.3 crank and sleeve, getting ready to try the 3.4 carb. It works good on my other 3.3[/QUOTE]
Nope just did the 3.3 sleeve and crank, porting and polishing... The RPM's are definitely higher now and the engine is actually performing cooler would you believe......

I've not gone messing with the carb... Haven't had any reason to. :cool:

NN what's porting? I hear it all the time...

The 2.5 is pretty reliable, but the 3.3 can also be very reliable, it's just easier to break the conrod on a 3.3.

I did the crank, the hole in the middle between the bearings, and then the sleeve, like you had posted in your thread. I did not mess with the exhaust side, just the intake side. It for sure sounds different, the tune window so far seems pretty tight, but holds good. It just takes very small adjustments now. I got to do the crank twice, since the first one broke. ugh!

[QUOTE=kdvanb;5405139]NN what's porting? I hear it all the time...[/QUOTE] Porting is basincally opening op the passages in the engine to allow more efficient fuel flow. Polishing also increases efficiency i fuel flow... Overall better performance,,, but you better know how to tune by than reading a sticky or following a tuning flow chart I can tell you that much.. It's not for beginners and you need to be prepared that if you mess up it's going to cost you...
Here's a link to my first porting job, I've done a few more that were more aggressive on the crank as far as cutting away material from it and working the piston a little.... Not had enough test time on that one to say anything as of yet.. Building a sleeper 3.3 is in my dreams... :cool:

[url]http://traxxas.com/forums/showthread.php?8948867-As-promised-my-porting-job...&highlight=Porting[/url]

[QUOTE=Nitronaught;5405950]Porting is basincally opening op the passages in the engine to allow more efficient fuel flow. Polishing also increases efficiency i fuel flow... Overall better performance,,, but you better know how to tune by than reading a sticky or following a tuning flow chart I can tell you that much.. It's not for beginners and you need to be prepared that if you mess up it's going to cost you...
Here's a link to my first porting job, I've done a few more that were more aggressive on the crank as far as cutting away material from it and working the piston a little.... Not had enough test time on that one to say anything as of yet.. Building a sleeper 3.3 is in my dreams... :cool:

[url]http://traxxas.com/forums/showthread.php?8948867-As-promised-my-porting-job...&highlight=Porting[/url][/QUOTE]

Sweet thanks

[QUOTE=Nitronaught;5405014]I've had the 2.5, rebuilt it to a 2.5r, had 1 3.3 went 6 gallons it's now rebuilt, ported and polished myself and dropped ceramics in it... Runs great and it's on gallon 2. Then I have another 3.3 it's on it's 7th gallon.

All performed and raced well.... I have no hands on experience with the Pro 15's, but I've had a lot of hands on with the 2.5's 2.5r's and 3.3's... They perform like they should and I have not had any issues with reliability.

What affects engine life?
Temps it has been ran at (many failure happen after it's been overheated too much, not as much during)
Proper break in.
Using after run.
Type of fuel makes a huge difference in tuning and performance in many cases.

For me I find it hard to put this into a poll. :cool:[/QUOTE]
Well I would have to argue that Traxxas didn't upgrade the 3.3's connecting rod. Sure it works fine, but you have to agree that it has a greater chance of breaking under the stress of the larger piston.

No more votes?
Not since awile ago..
(15+ days)
Only 10 votes..

Who else has there opinion...

[QUOTE=1979chevy.;5417115]Well I would have to argue that Traxxas didn't upgrade the 3.3's connecting rod. Sure it works fine, but you have to agree that it has a greater chance of breaking under the stress of the larger piston.[/QUOTE]

Then again, using the same conrod in different sized engines/pistons is a common thing, even in the auto world they will use the same conrod in a Chevy 305 CI engine as they do a Chevy 350 CI engine... So far every TRX engine I've seen with a broken conrod has had circumstances leading to the secondary damage of the conrod.... I've opened up a lot of TRX engines, rebuilt over 20 of them at this point...

I don't think a conrod is going to fix being ran way out of tune issue or the lean settings of a leak somewhere. :cool: