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Old 06-16-2011, 12:55 PM   #1
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Default Exhaust Help

Hello, I am looking for advice on building a custom exhaust setup for my Redcat Racing Lightning STR. I am fine with the current mufler but I do not like the exit location and want to build a rear exit system. I was wondering if anyone knew what material I should use to pipe the exhaust to the back. Thank-you for any help.
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Old 06-16-2011, 01:23 PM   #2
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Get a Tsai rear exhaust pipe.
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Old 06-16-2011, 01:29 PM   #3
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I think you misunderstood my post, I am looking for some kind of tubing to reroute the exhaust, I don't want to have to get a new muffler, and it possibly not fit under the body correctly.
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Old 06-16-2011, 03:16 PM   #4
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Attempting to do what you want, by using tubing to re-rout the exhaust is fraught with danger. The dimensions of the exhaust system in 2 stroke engines and how an engine runs and performs are invariably linked.

Change the dimensions of an expansion chamber by a millimeter or 2 and the entire dynamic of the engine will change, the same goes for the length of the stinger or even the amount or type of packing that is used around it.

Now, currently i am talking mostly from my experience with 2stroke race bike and the amount of effort we put into building one off pipes to give us a competitive advantage, as well as the 1000's of dollars spend on software that would aid us in determining the outcome of various chamber modifications.

2stroke gas engines are much less forgiving IMO, to changes outside the norm. So the only real options you have, are to get a pipe that is designed to give you rear exhaust, or to take to your current one with saw and tig welder to turn it around and make it face backwards.

Anything other than this, and you will find the performance of the car to be totally crap, if it runs well at all.

EDIT: Oh and you would also need to consider the fuel pressure pipe, changing the flow dynamics of the exhaust will also change the amount of pressure supplied to the fuel tank, it does not take much change here to totally wreck the tune of a car.
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Old 06-17-2011, 08:44 AM   #5
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I dont understand what could go wrong by extending the length of the exhaust, automakers have no problem making the exhaust travel all the way from the front to the back. I certainly think it would be alot safer than having the exhaust exit before the air intake with no ventalation, to where the engine is breathing its own exhaust. Can someone help me understand why the stock exhaust is like that if It isn't practical to stretch it?
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Old 06-17-2011, 09:01 AM   #6
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Quote:
Originally Posted by Alfa Romeo 159 View Post
I dont understand what could go wrong by extending the length of the exhaust, automakers have no problem making the exhaust travel all the way from the front to the back. I certainly think it would be alot safer than having the exhaust exit before the air intake with no ventalation, to where the engine is breathing its own exhaust. Can someone help me understand why the stock exhaust is like that if It isn't practical to stretch it?

Be careful not to compare these engines and exhausts to much to real vehicles. these nitro motors are much more suseptable to any change you make. I am not sure exactly how your motor and exhaust are mounted, but I know that it being in front is not unsafe. The point above yours is that trying to modify your exhaust by addind more header and pipe length will throw the motor tuning off. The design of "one piece" header and pipe combinations are very exact. Adding length can create uneven pressure in the system causing the tuning to be off.

As for the Ventilation, Have you cut holes for ventilation in your body's windshield?
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Old 06-17-2011, 11:29 AM   #7
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The shockwave in the exhaust is comming back to the exhaust port of the engine. At the moment when fresh fuel is hitting the cilinder it could flush through the exhaust. When the shockwave is on time it will act as a wall so it holds fresh feul inside the cilinder. The length is set to a certain rpm range. If you are going to extend or shorten the pipe you will change the resonance of the shockwave and it will affect the performance of the engine.

Take a look on the site of Buku exhaust where they have made nice explained animations.

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Originally Posted by Alfa Romeo 159 View Post
I dont understand what could go wrong by extending the length of the exhaust, automakers have no problem making the exhaust travel all the way from the front to the back. I certainly think it would be alot safer than having the exhaust exit before the air intake with no ventalation, to where the engine is breathing its own exhaust. Can someone help me understand why the stock exhaust is like that if It isn't practical to stretch it?
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Old 06-17-2011, 05:06 PM   #8
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Roelof is correct, the length and shape of a pipe is designed to give a certain amount of back pressure which stops the fuel from flowing straight through the engine. There are no valves on a 2stroke engine, so fuel input and exhaust output is all done through ports in the cylinder sleeve as well as the crankcase.

Nitro gas engines are nothing like your everyday car engine, car engines are designed to be very forgiving to dealing with parameters outside its optimal range, a nitro gas engine is not, its is more like an F1 car engine, in that it is designed to very high tolerances and will not like to work much outside its optimal range.

There is possibly one thing you could do that would not upset the engines balance too much, you could cut the manifold so you can rotate the output by the required amount, sealing with silicon tube and zippy ties, if done correctly you would neither lengthen or shorten the manifolds length or dimensions. This would change a forward facing pipe to one that sits at 90deg to its current position. You would also need to manufacture new mounts etc to support it, assuming that there is room to do this to begin with.

Your next problem will be car handling, as you have just upset the weight balance of the car, by moving weight from the side to the rear, so how it drives and turns will be different, you might need to add weight blocks to the side that had the exhaust previously to fix the left right balance of the car and maybe move some weight forward as well to help with turning if thats a problem.
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Old 06-17-2011, 05:23 PM   #9
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I think you guys are getting too technical...
To the OP, did you cut a hole on the body to match the where the stinger is on the pipe? You HAVE to cut that hole, otherwise the exhaust is hitting the body and hurting the performance of your engine. Also, by adding a piece of tubing to the stinger you will HURT the performance of the engine. Just cut the hole in the body and leave as is, theres decades of people running the exhaust on the side, we all know what we're doing.
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Old 06-17-2011, 05:46 PM   #10
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Originally Posted by nitrodude View Post
I think you guys are getting too technical...
To the OP, did you cut a hole on the body to match the where the stinger is on the pipe? You HAVE to cut that hole, otherwise the exhaust is hitting the body and hurting the performance of your engine. Also, by adding a piece of tubing to the stinger you will HURT the performance of the engine. Just cut the hole in the body and leave as is, theres decades of people running the exhaust on the side, we all know what we're doing.
You know, it never occurred to me that this might have actually been his problem. You kind of take it for granted that you cut a hole in the side of the body so the stinger can protrude through it to vent exhaust gasses. KUDOS nitrodude.
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Old 06-17-2011, 07:46 PM   #11
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I happen to know Alfa Romeo 159 personally and the car already has the exhaust hole cut out but the wants to re route it because the exhaust gases escapes and goes into the Air Filter. He also does not want to cut oles in the windscreen because he and I am trying to avoid that not to ruin the bodies. We were wondering if there is anyway to create a cooling system, like a radiator or intercooler.

Thanks,
Mercedes 190 E
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Old 06-17-2011, 08:42 PM   #12
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http://www.buycheapr.com/us/result.j...exhaust+header

check these guys out. they have a big assortment of oddball exhaust systems.
their phone number is 888-393 5000
they have rc headers/pipes and also full size exhaust systems.
dont know why they have such a strange inventory <rc and full size> but they do
let us know what you find
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Old 06-17-2011, 09:00 PM   #13
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Quote:
Originally Posted by Mercedes 190 E View Post
I happen to know Alfa Romeo 159 personally and the car already has the exhaust hole cut out but the wants to re route it because the exhaust gases escapes and goes into the Air Filter. He also does not want to cut oles in the windscreen because he and I am trying to avoid that not to ruin the bodies. We were wondering if there is anyway to create a cooling system, like a radiator or intercooler.

Thanks,
Mercedes 190 E
There is a company that makes a liquid cooled rc engine, cannot think of the name off the top of my head, they have an advert in one of the magazines i read, have no idea what they cost tho. I will post back with a name soon.

EDIT: Grossi Engines, make a .21 buggy engine liquid cooled, about 600 bucks US tho, so she aint cheep.
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Old 06-18-2011, 05:25 AM   #14
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Thanks for all of the assistance. This should help the cooling considerably. Also if anyone has a body with a intake on the roof, to improve performance and reliability cut the hole open and inside of the body stick a small pen fan upside down so the fan sucks in air from the intake, this improves aerodynamics and the cooling system of the car.

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