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        tuned pipe on a .90 size engine

#1 MrPropJet Jan 06, 2005 04:48 AM

tuned pipe on a .90 size engine
 
Has anyone run a tuned pipe on a .90 size engine, if so , do you think it's worthwhile going to such a set up or is a waste of time, mine in particular is a G90 Supertigre with a mac's pipe, I havent fitted the pipe yet as the engine still needs to be broken in and as it is the header is to shallow for a proper fit to my plane , but if I get any favourable comments regarding this sort of set up , I will find a way to fit it together
thanks
Roger Z.

#2 Bako Jan 06, 2005 11:18 AM

btw tuned pipes, like resonator tubes give u extra 10-15% of power, depending on engine. it works better on 2stoke engines, where rpm is higher, and muffler isn't free flow, like 4 stokes have.

#3 pda4you Jan 06, 2005 01:38 PM

Quote:

Originally Posted by majic12
Has anyone run a tuned pipe on a .90 size engine, if so , do you think it's worthwhile going to such a set up or is a waste of time, mine in particular is a G90 Supertigre with a mac's pipe, I havent fitted the pipe yet as the engine still needs to be broken in and as it is the header is to shallow for a proper fit to my plane , but if I get any favourable comments regarding this sort of set up , I will find a way to fit it together
thanks
Roger Z.

It is best if you break them in with the pipe - you want the engine speed at break in to be about your top RPM on the pipe. You can also use a smaller prop to attain this.

ABC engines properly timed can benefit greatly from the use of a tuned pipe. You can easily acheive (with engines timed for their use) a great deal more power 15% is easy to get.

That is the good news. Here is the bad, they are a pain to setup and they work the engines very hard. They add weight also. You will go through plugs regularly. But they are quiet, sound great, and keep some of the mess off the front of the plane, plus the added power.

You can do one of two things - get the Ultrathrust tuned mufflers, they get you more power or do what I started to do rather than mess with pipes. Just get a larger motor with more power. With the bored out engines, you can often find a larger motor with the same weight as the smaller ones!

Mike

#4 Bako Jan 06, 2005 01:53 PM

never brake engine on top rpm. !!!
pda4you let me know any manual, where it is written to brake engine in top rpm.

#5 pda4you Jan 06, 2005 02:06 PM

Sure - Dubb Jett and Clarence Lee

Do you know how ABC engines work? You want an ABC (this is ABC we are talking about, not ringed or 4 stroke) engine to reach the same temp so the materials will expand properly. If an ABC engine is run too rich the brass cylinder will be too tight a fit, and prematurely wear the piston out.

Note that I said the RPM or speed must be up - not the work. So you use a smaller prop so that the 400 rpms that you do run it rich (in break-in only) still attains the same top run RPM's of the engine - this is the only way to do it right.

Talk to Dubb - a guy that knows engines (he makes some of the top performing 2 stroke model engines in the world).

http://www.jettengineering.com/tech/breakin.html

How about that?

#6 MrPropJet Jan 06, 2005 05:51 PM

I actually did intend to fit a larger engine, an OS 1.08 FSR 2 stroke, it has more peak rpm and it is rated at 3hp , not 2.5 like the ST, unfortunately the 1.08 was to long to fit in the nose, and I didnt want to try extensive modifications to the nose to fit it, so hence I ended up getting the Supertigre .90 2 stroke....pitty I think the OS would have made the f4 Phantom scream... might try the mod at a later date, I have a feeling the G90 will dissapoint me!

btw I omitted to mention that the g90 is a ringed engine, and I didnt think running it at max rpm was a good idea straight out of the box!.. now I have to find out if the information above would be applicable to a ringed engine , eg breaking it in with the pipe at max rpm but smaller diameter prop

#7 Bako Jan 06, 2005 06:00 PM

soo. I don't understand your method. when abc engine is too hot, piston wears the cilinder, cause due to big temperature, metal is ovesizeing.

#8 pda4you Jan 06, 2005 06:54 PM

Quote:

Originally Posted by Bako
soo. I don't understand your method. when abc engine is too hot, piston wears the cilinder, cause due to big temperature, metal is ovesizeing.

The engine is not hot - it is being run rich, but with a prop that is smaller, so it has the advantage of not working as hard, being run slightly rich, and having proper component heat to assure the engine is not wearing harshly.

ABC engines must run at temp when being broken in. It keeps them nice and tight. You would probably go nuts to watch me break in an new ABC engine -another key is getting them to temp ASAP. You start (that very first time) at idle, but advance to full throttle as soon as you can! You go to full throttle, peak the rpms (yep that is right!) and once peaked (don't let it sag for more than just a second) you richen by 300-400 rpms (tach necessary) and let it run 30 seconds. Then the motor must cool completely. You do this cycle doing longer and longer runs. Depending on how tight the engine is you may need to do this a while. Once it will hold peak without sagging, it is ready to fly. I run my ABC engines at 100-200 (max) rich rpm (from peak).

Try it on your next motor - you will be surprised how well it works. By the way the OS and TT sport engines are much less critical on break in. They are of average power anyway. The Rossi's and MVVS will take a bit more care. The Nelson and Jett really need attention to this matter. But they will turn 4-8K higher than sport engines anyway.

Refer to RCM Magazine as Clarence Lee covers the topic of ABC engine break in very regularly. I only have one issue (one where I did some photography for a model and plans featured) but he covers it again and again.

Majic12 - Please don't use the ABC method of break in for a ringed engine. They must be broken in very differently than an ABC engine. They also tend to gain less power from piping, as they are normally timed a bit more conservitavely.

Ringed must be run rich - slobbering rich, just on the verge of 4 stroke. You just want to take them to that 2 stroke, 4 stroke sound change. Then run them (they take a long time - several gallons of fuel!) But I usually only run 5-10 tanks on the stand, then do the rest in the air. Once again - it will tell you it is done, when it holds a peak setting without sagging. Then you richen the mix 200-300 rpm (ringed - half that for ABC).

Try that ST .90 you might be surprised by the power.

Mike

#9 Tony Oliver Jan 07, 2005 02:57 AM

If you have any doubt about which method to use, ask the manufacturer (it's usually in the instructions anyway).

The differences between cast iron pistons, ringed pistons and ABC setups is as Mike says and it's uselass and often damaging to use the procedure for other than the specific recommendations for type.

After all, the final outcome looked for is to get a perfect running fit at the speed the engine is to run at when in use. Most systems will respond initially to give the polishing effect but the fit is the main requirement.

#10 MrPropJet Jan 07, 2005 03:37 AM

I have got the instructions on running in the engine , so I will follow them then worry about the pipe....It would be handy to find a dyno to measure the performance, apart from that I can only gauge the performance with my tacho, but I would rather be able to graph a torque curve for it but dont know how with out a dyno!! ;)

#11 Bako Jan 07, 2005 05:09 AM

I had broke in MDS18, MDS40, OS40 LA, with succes. as i told. maby u'r right.
but i like 4 stoke brake ins :) . it's whole science.

#12 Dave Barrow Jan 09, 2005 12:48 AM

I had an Enforcer with a piped Super Tigre .90. (language removed by moderator) . It was a porker too, 12+ lbs. I would break it in on a bench with the stock muffler if it was me. There are different ways to break in ABC and ringed engines. Never get an ABC engine slobbering rich, you'll ruin it. Once you have several tanks through it, put the pipe on and tune it, then put it in your plane and go. Use your tach and you'll see the difference.

#13 MrPropJet Jan 09, 2005 05:16 AM

well this is looking better and better, hopefully this combo will make my F4 really motivate.

#14 Dave Barrow Jan 09, 2005 09:57 AM

What brand of pipe are you using? Macs pipes are the best that I have used. A 90 on a pipe is pretty loud, the muffled pipes are nice, since they reduce the volume. Make sure you follow Macs tuning instructions. You can find them on their website.
www.macspro.com

#15 Bill Glover Jan 09, 2005 11:40 AM

I ran both the Super Tigre 90 and 75 piped, using an ST pipe on the 75 and a Hattori on the 90. Neither ever blew a plug in use! As already posted, get the engine well broken in first and set the pipe up according to the instructions. If in doubt leave the manifold a little long.


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