MAXXCHEVY

Sweet my t-maxx sounds. I forgot to ziptie the cupler for my exhaust and it came off after a hard landing. Ohh man it sounded awesome, really loud the low end and top end was amazing it had more power and perfomance then its ever had. Is running just a header bad for the motor? Isnt it just like running straight pipes on a hotrod? Can i just make an exhaust that comes from the header without buying a tuned pipe? IF so what could i make it out of?

Macanan

Yes its bad for the motor because its the tubing leading from the muffler to the tank that gives it, its pressure in the tank for the fuel to reach your carb the way it's suppose to, not having it will make the fuel not get there the way its ment to and your motor wont get the proper oil it needs to keep it cool.

Itsme7

And the engine needs the backpressure waves created from the exhaust to keep the fuel mixture in the combustion chamber.

slayerphonics

ya it had more power cause it started running leaner, no pressure in the tank,

125cchyperman

You guys are correct but also a little off. You can run without the pressure line leading to the fuel tank, many have done it including me. Adam drake used to(dont know if he still does) run without a pressure line going from the exhaust to the fuel tank. You just need to richen up your needles and it also creates a problem with tuning. The needles become very finicky and it becomes hard to tune. But if your good at tuning it can be done.

But in your case, you where running lean. Now if you just ran it back to you and slapped the coupler back on then no damage was probably done. But if you ran it for a while before putting the coupler back on then damage might have been done to your engine. You gotta think about those type's of things before continuing on with that type of stuff.

The engine without the pressure lines creates enough sucking pressure(from normal operation, from the crankcase pressure's) to be able to suck in enough fuel so that the engine is not lean during normal operation. You just need to have the needles rich enough to do so, but once done the needles become very finicky and is hard to fine tune. So it's not reccomneded for someone who doesnt know what there doing.

MAXXCHEVY

Well the day i tuned the truck it was set pretty rich because the weather had been cooler since the last time i ran it and that day it was nice and sunny out. So the air temp helped by not bringing such rich air to fuel mix. I was really amazed how much better it ran. Do you think my exhaust might have a clog in it, its the original 2.5 exhaust, do you have any suggestions for and aftermarket exhaust for the 2.5? I want more low end power

125cchyperman

There should be a baffle in your exhaust, you can take that out and that will give you a little more power. Just take the exhaust off the truck then look down where the exhaust coupler is. There should be a phillips head screw in there and there will be a nut at the end of the exhaust. Just Hold the nut and then turn the screw counter closkwsie, The pipe should come apart into two pieces. Then take the baffle out and then put everything back together. This should give you a little extra power, othere then that you can try a tuned pipe. A low to mid range pipe will give you what you want and shouldnt really take away form any top end as the stock exhaust on them suck. As for a pipe recomendadtio's I really dont know of may that will go good with the 2.5's

johnnyt25

125cchyperman - does removing the baffle affect the +ve pressure that is fed to the fuel tank? If so would this create the same tuning problems as you mentioned earlier in this post?

125cchyperman

If I'm thinking right the pressure line is after the baffle itself, So no real significant if any drop in pressure or gain in pressure will be seen to your fuel tank. Now you may have to retune anyways, cause there will be a lack of backpressure to the engine, like there used to be. I believe traxxas puts that baffle there so that it act's more like a tuned pipe but in all actuality it does nothing but rob power. Now dont expect this thing to do wheelies 300ft long now, it will gain some power but wont be a huge difference though. Most of the power will be seen on the top end.

johnnyt25

Ok thanks - might try and see what differant it makes as long as its not detrimental to the motor.

125cchyperman

Nah it wont hurt the motor, I did the same ething to mine when I was just getting into the rc scene.

thesouth1

The traxxas Blue tuned pipe:
http://www3.towerhobbies.com/cgi-bin...&I=LXSP47&P=ML
The MIP Stinger headerif you can happen to find one, they pop up on e-bay every now and then.
http://www3.towerhobbies.com/cgi-bin...?&I=LXFCB5&P=Z

This was the best set-up I could find for the 2.5 engine, great low end and great top end. I tried the THS pipe/header, the MIP with the stock pipe, some HPI pipe the LHS guy had lying around. Nothing compared to the combo of old blue. I had a MIP stinger that I let go with the engine when I swiched to the O.S 18. I wish I wouldve kept it[].......sigh.....