Exhaust - Stock Vs Pipe

[cathurga]

Hey All,

I have a Losi DBXL that I bought used, and when I got it, there were some basic mods done to it. These included a tuned pipe (think its a dominator,not sure). Also the mill was upgraded to 29cc, and I am not sure the engine was replaced or whether its just had the 'bore upgrade' I believe it was a Zenoah upgrade, so probably the whole thing.
Now I have run it a bit and it goes like stink, but the problem is that its VERY loud. Where I run it, there are no people to complain, its just a little LOUD for my liking. The original exhaust wasn't included.
What I want to know is whether putting a stock exhaust will quieten it down significantly, and if so, am I really going to notice a considerable drop in power. I am not racing this thing, its just something to mess with while the weather is too bad to fly my planes (I have large scale 20-50cc aerobatics & warbirds).
I also noted that the pipe on it is pretty heavy.I am all about making things lighter to help with power/weight, and of course lighter tends to handle better.

I have recently replaced the shocks and towers. I put alloy towers and 5ive-T shocks on it. Also replaced the silly plastic motor mounts/clutch carrier with alloy. Since I run mainly in sand, I also made the rear diff a little looser and tightened the center and front for more traction without losing turnability/

I know a bit about how tuned pipes influence power and running, but since this engine has been upgraded, even with a stock pipe, its still going to have more guts than a stock car. They are known for a lousy driveline, so I don't really want power that will rip everything to bits...

 

[Phill2]

Yes it will be quieter and yes you'll notice a BIG difference in performance.
If you know what brand the pipe is you may be able to get a silencer for it.
I have one on my Jetpro

 

[cathurga]

Phil, thanks for your response.
The pipe is the DDM Dominator, and it is not possible to silence it from what I can see. The outlet is in a position that wont really allow it. I put a standard exhaust on just to try and it works fine, but I have not had a chance to evaluate the power loss. As I mentioned, this is going to be bashed, not raced, and since it now has a Zenoah 29cc engine in it, I am probably in a better place than with the stock engine.
I must say that I like the fact that I have some space back and it is easier to work on this buggy since the pipe got in the way of doing anything, and removal of the pipe all the time was a PITA of the highest order! I will run it like this for a bit and see what happens...
I also put a 8Krpm clutch in it, and I am not sure if these require any 'break in' so to speak, but the clutch engages very late and its not that nice really, I would prefer it to engage quicker so that I don't have to 'scream' it to take off. I am going to put the stock clutch spring back in and hopefully I will be in a happier place. I put the turtle racing clutchbell housing on and there seems to be excessive play on the pinion, it seems to move quite a lot forward/backwards, I didn't notice it on the stock setup, but I do now, I may have to shim it up a bit.
I need to Loctite everything down a bit, I put blue Loctite on, but I don't know if it is enough on the clutch shoe holding bolts, or the pinion bolt, so I will put some better stuff on when I reassemble it.
Its a real struggle to find a decent air filter for the dbxl, I am particularly fussy about the quality of airfilter as I run this in the desert and sand gets in everywhere. At the moment I am using an alloy unit from a baja, with an outerwear, but it sticks out the side a lot, and is going to cause problems in the event of a crash, I would prefer something that sits inside the frame. The new Losi 5ive square filter is way to big, as is the original round 5ive version, so on the lookout for something decent.
I am not sold on K&N filters as they are known to let sand through. Perhaps with an outerwear it would be better, but not sure I want to take the chance....

 

[Phill2]

You're definately better off with the Zenoah.
I run the 29cc on my Dunerunner with a Jetpro rear pipe and WT 668 carb and love it.
I have never had the desire to use an 8k clutch for exactly the reason you've noted.
It would no doubt be faster on take off but a lot harder on the drive line and coming out of corners you've either in "neutral" or going flat out.
I run in sand too and use an HPI filter with an outerwear.
I lightly oil the outer filter foam.
The paper filters like K&N are useless in fine dust.
Good luck getting it all together.

 

[Rich_Morgenstein]

You can not put a scilencer on a ddm pipe. Your correct! Always way if you have the technology! Lol but pissing your neighbors off is the best part of owning a 1/5 scale to start WITH! Nothing like having a 5 foot tall 70 year old man in sc run up to you half drunk telling you to stop making NOISE!

That is the point they realize your 6foot 5inchs tall and there looking up into your face while my 280 pound pit bull sits in golf cart 5 feet away growling and they say well you have a good Day! Run home...

And no! We have a state owned rc park here. Just some people can't figure out buying a house next to it involves noise go figure?

 

[smrdmr1]

You can not put a scilencer on a ddm pipe. Your correct! Always way if you have the technology! Lol but pissing your neighbors off is the best part of owning a 1/5 scale to start WITH! Nothing like having a 5 foot tall 70 year old man in sc run up to you half drunk telling you to stop making NOISE!

That is the point they realize your 6foot 5inchs tall and there looking up into your face while my 280 pound pit bull sits in golf cart 5 feet away growling and they say well you have a good Day! Run home...

And no! We have a state owned rc park here. Just some people can't figure out buying a house next to it involves noise go figure?

Some people just can't take a joke!

 

[cathurga]

I have no intention to pee in anyone's cornflakes, and I don't need to go around annoying people for no real reason. Actually, the noise irritates ME more than anyone else. I am not racing this buggy, and the longevity of the truck is more important to me than excess power.
Without trying to sound combatative, you may be 6ft5, and have a dog, but that doesn't mean you are free to do as you want and think others will 'respect' you. Some mutual consideration goes a long way in ensuring peaceful co-existence.
If the RC park is state owned, and the neighbours knew about it when moving there, then that's their problem, its still the states responsibility to enforce the facilities allowances.

Phil, yeah, staying away from the paper filters, they aren't right for this application. Looking at the RCMK unit from DDM. Unfortunately they don't have spare foams, and would prefer to have got a second set, that is available for a quick swap while the other is being cleaned. Anyway, its only for mild use so will order it with an outerwears, and see how that goes.

Waiting on parts now....

 

[Rich_Morgenstein]

I have no intention to pee in anyone's cornflakes, and I don't need to go around annoying people for no real reason. Actually, the noise irritates ME more than anyone else. I am not racing this buggy, and the longevity of the truck is more important to me than excess power.
Without trying to sound combatative, you may be 6ft5, and have a dog, but that doesn't mean you are free to do as you want and think others will 'respect' you. Some mutual consideration goes a long way in ensuring peaceful co-existence.
If the RC park is state owned, and the neighbours knew about it when moving there, then that's their problem, its still the states responsibility to enforce the facilities allowances.

Phil, yeah, staying away from the paper filters, they aren't right for this application. Looking at the RCMK unit from DDM. Unfortunately they don't have spare foams, and would prefer to have got a second set, that is available for a quick swap while the other is being cleaned. Anyway, its only for mild use so will order it with an outerwears, and see how that goes.

Waiting on parts now....

THAT WAS THE WHOLE POINT! It's a rc track and an rc air feild. 22 acer area actually surrounded by people that built houses cause there to dumb to realize the 24/7 noise....

So there is always some old person thinking he's gid trying to make some kids life hell over it there kinda sad. But yes there loud they all are lol i wouldn't break out the 1/5 scale with tuned pipe run it up and dound road of my neighborhood to go out of my way to piss everyone off.

Sad part is its a wonderful park. Clean safe for kids for a dying hobby it seems at times. Tablet or gaming pc has replaced it now. This reason kids stay on there tablets parents don't want guys like one i describe causing crap around there kids.

But no I agree Loud! But there morons in the case I Described!

 

[Phill2]

I have no intention to pee in anyone's cornflakes, and I don't need to go around annoying people for no real reason. Actually, the noise irritates ME more than anyone else. I am not racing this buggy, and the longevity of the truck is more important to me than excess power.
Without trying to sound combatative, you may be 6ft5, and have a dog, but that doesn't mean you are free to do as you want and think others will 'respect' you. Some mutual consideration goes a long way in ensuring peaceful co-existence.
If the RC park is state owned, and the neighbours knew about it when moving there, then that's their problem, its still the states responsibility to enforce the facilities allowances.

Phil, yeah, staying away from the paper filters, they aren't right for this application. Looking at the RCMK unit from DDM. Unfortunately they don't have spare foams, and would prefer to have got a second set, that is available for a quick swap while the other is being cleaned. Anyway, its only for mild use so will order it with an outerwears, and see how that goes.

Waiting on parts now....

Couldn't agree more.
They are loud and you need to consider the neighbours that's why I put a silencer on my Jetpro.
It's still loud but a softer note if you get my meaning.
Pity you can't get one for the Dominator.
I'm pretty lucky in that my neighbours all come out to watch.
One actually came out the other day and said he'd been watching F1 but my DR sounded better.
Will an HPI filter not fit?
I use one on mine and you can buy foams.

 

[Rich_Morgenstein]

Couldn't agree more.
They are loud and you need to consider the neighbours that's why I put a silencer on my Jetpro.
It's still loud but a softer note if you get my meaning.
Pity you can't get one for the Dominator.
I'm pretty lucky in that my neighbours all come out to watch.
One actually came out the other day and said he'd been watching F1 but my DR sounded better.
Will an HPI filter not fit?
I use one on mine and you can buy foams.

Omg no one gets why even made first comment...... we live in a complex right next to a rc park. There is 3 tracks and air feild. Huge lake for boats! And drift track as well. 90% of people live here around it are rc people the othere 10% are people that like to female dog about the fact they now own a house next to a rc park...... get drunk start being jerk. There is rules^ no loud stuff before 8am or after 6pm at the track* so not like 12am people running a 4 cylinder 2 stroke in pond with wide open tuned pipes shaking every house as it goes by at 90mph in pound or at the large scale track with fully modified 1/4 scale tearing up stuff with pure alcohol 4 stroke big block in it. So guess there is this whole point missed. I live here for whole fact out of the 870 house here 800 of the owners are rc addicts and bought house her for this reason. When you own 2000+ rc models and your company you own builds and sells custom rc parts lol most of them ask me daily to built metal or print parts for them im justified in my first comment now it's explained?

 

[Rich_Morgenstein]

One other thing bugs me on this forum... you all talk about a tuned pipes as if there so awesome non really grasp while concept of why there even called tuned pipe. For one there not.. called a chambered pipe cause this two stroke motors not nitro.
Tuned pipe is designed and tuned* for a certain motor to run correctly in a nitro it puts correct amount of pressure into a fuel tank get fuel into the crank and into a piston.

Chambered pipe like on 2 stroke dirt bike. Is designed to create waves of back perfume to make fuel burn more efficient in a two stroke motor making more power.

Pure fact you all spend 200$ On a Chambered pipe or tuned now as everyone says cause no one knows this and the vendors know there called that but list them as tuned* so your Google search will find them cause whole technical aspects of the hobbyists scene took a dive with gene pool since smart phones make people stupid.

The scilencer you all speak so highly about makes it sound quiet defeats the whole point of the freaking wave chamber to start with in the pipe, freaking science not rants or raves lol i rebuild and fix this crap daily for clueless people now in hobby. It breaks everyone runs around in panic looks at it runs to hobby shop... point is the scilencer stops the waves from correctly resonating inside the pipe and is why it's quiet so you might as well of not added one to start with.

 

[Phill2]

One other thing bugs me on this forum... you all talk about a tuned pipes as if there so awesome non really grasp while concept of why there even called tuned pipe. For one there not.. called a chambered pipe cause this two stroke motors not nitro.
Tuned pipe is designed and tuned* for a certain motor to run correctly in a nitro it puts correct amount of pressure into a fuel tank get fuel into the crank and into a piston.

Chambered pipe like on 2 stroke dirt bike. Is designed to create waves of back perfume to make fuel burn more efficient in a two stroke motor making more power.

Pure fact you all spend 200$ On a Chambered pipe or tuned now as everyone says cause no one knows this and the vendors know there called that but list them as tuned* so your Google search will find them cause whole technical aspects of the hobbyists scene took a dive with gene pool since smart phones make people stupid.

The scilencer you all speak so highly about makes it sound quiet defeats the whole point of the freaking wave chamber to start with in the pipe, freaking science not rants or raves lol i rebuild and fix this crap daily for clueless people now in hobby. It breaks everyone runs around in panic looks at it runs to hobby shop... point is the scilencer stops the waves from correctly resonating inside the pipe and is why it's quiet so you might as well of not added one to start with.

Where you live puts it in a different light altogether.
Wish we had a place like that here.

As far as pipes go they used to be called expansion chambers on dirt bikes.

I get your meaning about changing the resonance but the silencer on the Jetpro hasn't changed performance at all.

 

[Rich_Morgenstein]

Where you live puts it in a different light altogether.
Wish we had a place like that here.

As far as pipes go they used to be called expansion chambers on dirt bikes.

I get your meaning about changing the resonance but the silencer on the Jetpro hasn't changed performance at all.

Well think of This! Hear me out Lol!


Jethro pipe is designed for a 26cc chambered motor no mater what one you buy. It's horrible on a 32cc motor. For the same reason a scilencer is on the 26cc motor you have with a scilencer!

Here is logical math Part! A chambered pipe such as a jet pro has an area in which gas expands and then is crush back to a smaller Area! This how some of the unburned fuel gets used more efficiently as it gets pushed back in and burned on next cycle after it was missed on first time around! If you had a 1cc motor you would need 3.5cc chamber in a pipecac and a 1mm od circle inlet and 1mm od circle cutlet to achieve one full 100% perfect burn Cycle! It's the actual math you use to create a pipe! Times it all by 26 and you get actual size of everything you have sitting in front of you. Now you can port a motor as well which is a whole new ball park. Cause now you changed the intake and outgoing exhaust ports which also needs more fuel to complete a process and more math to that but another lesson lol

Point of this is by adding a "scilencer" your changing the back pressure of the pipe created. It screws up the flow and pressure inside the chamber. Which decreases the performance. How much can't tell ya butI actually just ordered one to find out : ) it get tossed I'm my boxes of crap I'll never use after but now you have my intrest peaked! From what can tell nothing more then a pipe in a pipe inside and just has an in and out. Just like car muffler works. Where going to have to break sawzall I fear and do surgery!

 

[Phill2]

Well think of This! Hear me out Lol!


Jethro pipe is designed for a 26cc chambered motor no mater what one you buy. It's horrible on a 32cc motor. For the same reason a scilencer is on the 26cc motor you have with a scilencer!

Here is logical math Part! A chambered pipe such as a jet pro has an area in which gas expands and then is crush back to a smaller Area! This how some of the unburned fuel gets used more efficiently as it gets pushed back in and burned on next cycle after it was missed on first time around! If you had a 1cc motor you would need 3.5cc chamber in a pipecac and a 1mm od circle inlet and 1mm od circle cutlet to achieve one full 100% perfect burn Cycle! It's the actual math you use to create a pipe! Times it all by 26 and you get actual size of everything you have sitting in front of you. Now you can port a motor as well which is a whole new ball park. Cause now you changed the intake and outgoing exhaust ports which also needs more fuel to complete a process and more math to that but another lesson lol

Point of this is by adding a "scilencer" your changing the back pressure of the pipe created. It screws up the flow and pressure inside the chamber. Which decreases the performance. How much can't tell ya butI actually just ordered one to find out : ) it get tossed I'm my boxes of crap I'll never use after but now you have my intrest peaked! From what can tell nothing more then a pipe in a pipe inside and just has an in and out. Just like car muffler works. Where going to have to break sawzall I fear and do surgery!

I'm well aware of how an expansion chamber works from my 2 stroke bike days
Works just fine on my 29cc Zenoah regardless of the math.
I put the silencer on due to the noise being excessive and if there has been a change in performance it is so slight that it isn't noticeable.

 

[TODD]

Silencers do not effect performance if they are built correctly. Both dyno and running them shows no difference with ours.

 

[cathurga]

Rich, you may have an in-depth knowledge of what a 'tuned pipe' is, so I am not going to argue, but the 'tuned' part of the discussion is based on how to make the efficiency of the motor more efficient, and as you said, its different for different engines. In fact, a pipe could be tuned differently for the SAME engine. Some engines require more power at lower revs, and others higher. More torque or more power? Different pipe layout.
With regards to the nitro tank pressure issues, nitro carbs don't have a way to 'draw' fuel like walbro/gas carbs do, so the pressure from the exhaust 'pushes' the fuel to the carb. This has nothing to do with silencer/tuned pipes/exhausts.

Anyway, don't be aggressive/intimidating with the people that live in the houses near your facility, as long as you are following the guidelines and rules issued by the state, just wave them off, and point them to the rules. Simple!

A silencer on a tuned pipe will drop the noise, and to some extent, the power too. It will still produce better power than without the pipe for sure.

For me, as stated, don't need gobs of power.