The most beautiful O.S engines ever made
#301
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While we're at this subject, a MACs one-piece muffler is neither a tuned muffler nor a tuned pipe. I've seen people call it both, but it is neither. It is a good lightweight and might potentially give better performance than some stock mufflers however.
#303
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#304
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I think I may have to try making some headers some day for fun. Not too sure about brazing and how it will hold up, I don't want to buy a TIG welder. Bisson still makes mufflers but they seem like mostly the Pitts style. He may do custom stuff?
Last edited by aspeed; 01-13-2017 at 02:40 PM.
#305
#306
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JTEC did a custom muffler for my Mintor 38cc. Of course you will tell me I'm nuts to spend money on that dead end engine, but it has been running great since the factory rebuild.
#307
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MR cox I have been doing my own stuff for awhile now, learned and still learning from guy at the field. I can get with in 300 or so rpm of his work now. Just by raising exhaust doesnt gain much in some engines and may even kill power/torque down low. The key is the blow down measurement. Some engines have the transfer and boost ports so high you the blow down is way to much. Some engines you can fix this my lowering the sleeve in the engine but again can only go so far as you will run into sub porting. Sub port and tuned mullers(as some people call them) or tuned pipes do not mix well. The irvine has low transfers and boost ports allowing the exhaust to raised up to a good number while at the same time keeping the blow down in the good range.
By the way the Jett 1/4 wave tuned mufflers are about 200-300 down from a tuned pipe for most applications.
take the back cover off an engine shine a light into the carb and then rotate the crank and you normally see light coming in when crank pin is at the lower left corner screw and closes around the upper right corner screw
By the way the Jett 1/4 wave tuned mufflers are about 200-300 down from a tuned pipe for most applications.
take the back cover off an engine shine a light into the carb and then rotate the crank and you normally see light coming in when crank pin is at the lower left corner screw and closes around the upper right corner screw
#308
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I never messed around much with tuned pipes, I always just slapped a tower muffler on my 46ax if I wanted it to scream a little, I have at least 4 tower mufflers laying around.
I keep hearing about the Coke can pipe or CCP, I've never seen one before though, anybody have a pic?
I keep hearing about the Coke can pipe or CCP, I've never seen one before though, anybody have a pic?
#310
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I have a 46 EVO and a 52 that is the strongest 46 i own by a few hundred RPMs
i have both OS ST and ASP engines in that size
The evo has a --chrome liner --and they are very inexpesive ( actualy cheep ) and overlooked by the masses for what they offer in performance
Paid 25 dollars at a swap
I have a very excellent 75 ASP FSR ABC for sale
Turns a 12/6 APC at 12,000 RPMS
i have worn out two of these engines with about 100 hours each on them
The one for sale has less than a gallon thu it
Great high compression and bearings
You can view my Galley of the best two cycle glo engines and airframes in the last 20 years
Many have hundreds of flights on them and are 5 to 20 years old in many cases
The OS 61SF 91FX 75AX and possibly the very best glo engine EVER made the OS 1.08 FSR BX1 are my personal OS favorites
Os hands down makes the very best carbs for glo engines and i use them in any possible other engine i can to improve that engines performance ( ASP ST)
I do not understand all the issues here with wearing out engines ( liners )
Mostly not enough oil ( must use castor ) and running engines to hot and lean or you have an air leak in your engine causing excessive HEAT and burning up ( cooking ) you glo engine
I pull my engines apart when required only to find them brand new looking inside
I use 15% Morgan Omega with some extra castor oil especially for of brand engines with no wear issues at all
Cool Power is an engine distroyer as it does not control the lean heat build up thing well
Enjoy
i have both OS ST and ASP engines in that size
The evo has a --chrome liner --and they are very inexpesive ( actualy cheep ) and overlooked by the masses for what they offer in performance
Paid 25 dollars at a swap
I have a very excellent 75 ASP FSR ABC for sale
Turns a 12/6 APC at 12,000 RPMS
i have worn out two of these engines with about 100 hours each on them
The one for sale has less than a gallon thu it
Great high compression and bearings
You can view my Galley of the best two cycle glo engines and airframes in the last 20 years
Many have hundreds of flights on them and are 5 to 20 years old in many cases
The OS 61SF 91FX 75AX and possibly the very best glo engine EVER made the OS 1.08 FSR BX1 are my personal OS favorites
Os hands down makes the very best carbs for glo engines and i use them in any possible other engine i can to improve that engines performance ( ASP ST)
I do not understand all the issues here with wearing out engines ( liners )
Mostly not enough oil ( must use castor ) and running engines to hot and lean or you have an air leak in your engine causing excessive HEAT and burning up ( cooking ) you glo engine
I pull my engines apart when required only to find them brand new looking inside
I use 15% Morgan Omega with some extra castor oil especially for of brand engines with no wear issues at all
Cool Power is an engine distroyer as it does not control the lean heat build up thing well
Enjoy
#311
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I have a 46 EVO and a 52 that is the strongest 46 i own by a few hundred RPMs
i have both OS ST and ASP engines in that size
The evo has a --chrome liner --and they are very inexpesive ( actualy cheep ) and overlooked by the masses for what they offer in performance
Paid 25 dollars at a swap
I have a very excellent 75 ASP FSR ABC for sale
Turns a 12/6 APC at 12,000 RPMS
i have worn out two of these engines with about 100 hours each on them
The one for sale has less than a gallon thu it
Great high compression and bearings
You can view my Galley of the best two cycle glo engines and airframes in the last 20 years
Many have hundreds of flights on them and are 5 to 20 years old in many cases
The OS 61SF 91FX 75AX and possibly the very best glo engine EVER made the OS 1.08 FSR BX1 are my personal OS favorites
Os hands down makes the very best carbs for glo engines and i use them in any possible other engine i can to improve that engines performance ( ASP ST)
I do not understand all the issues here with wearing out engines ( liners )
Mostly not enough oil ( must use castor ) and running engines to hot and lean or you have an air leak in your engine causing excessive HEAT and burning up ( cooking ) you glo engine
I pull my engines apart when required only to find them brand new looking inside
I use 15% Morgan Omega with some extra castor oil especially for of brand engines with no wear issues at all
Cool Power is an engine distroyer as it does not control the lean heat build up thing well
Enjoy
i have both OS ST and ASP engines in that size
The evo has a --chrome liner --and they are very inexpesive ( actualy cheep ) and overlooked by the masses for what they offer in performance
Paid 25 dollars at a swap
I have a very excellent 75 ASP FSR ABC for sale
Turns a 12/6 APC at 12,000 RPMS
i have worn out two of these engines with about 100 hours each on them
The one for sale has less than a gallon thu it
Great high compression and bearings
You can view my Galley of the best two cycle glo engines and airframes in the last 20 years
Many have hundreds of flights on them and are 5 to 20 years old in many cases
The OS 61SF 91FX 75AX and possibly the very best glo engine EVER made the OS 1.08 FSR BX1 are my personal OS favorites
Os hands down makes the very best carbs for glo engines and i use them in any possible other engine i can to improve that engines performance ( ASP ST)
I do not understand all the issues here with wearing out engines ( liners )
Mostly not enough oil ( must use castor ) and running engines to hot and lean or you have an air leak in your engine causing excessive HEAT and burning up ( cooking ) you glo engine
I pull my engines apart when required only to find them brand new looking inside
I use 15% Morgan Omega with some extra castor oil especially for of brand engines with no wear issues at all
Cool Power is an engine distroyer as it does not control the lean heat build up thing well
Enjoy
#312
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With converted car engines one get much better (higher) blown down numbers without any mods needed to the liner, and tuned pipes will really make a difference there.
You only get that in airplane engine if you by the ones that are timed for tuned pipes. Novarossi will offer both types/timing for most of their engines, and they are very well priced nowadays. The build quality is also well above the OS airplane engines. It seem OS are only making an effort on their car engines...
#313
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So what mods did you do to the exhaust and what blow down numbers did you give the Irvine?
With converted car engines one get much better (higher) blown down numbers without any mods needed to the liner, and tuned pipes will really make a difference there.
You only get that in airplane engine if you by the ones that are timed for tuned pipes. Novarossi will offer both types/timing for most of their engines, and they are very well priced nowadays. The build quality is also well above the OS airplane engines. It seem OS are only making an effort on their car engines...
With converted car engines one get much better (higher) blown down numbers without any mods needed to the liner, and tuned pipes will really make a difference there.
You only get that in airplane engine if you by the ones that are timed for tuned pipes. Novarossi will offer both types/timing for most of their engines, and they are very well priced nowadays. The build quality is also well above the OS airplane engines. It seem OS are only making an effort on their car engines...
You are very right on all accounts. The car engines are timed better for tuned exhaust due to a lot of reasons - mainly because car engines tend to operate far above most aircraft engines in rpm. Typical car engines have around 195 degrees of induction timing, 120 degrees of boost and transfer port timing, and 165-170 degrees of exhaust timing. Blowdown timing often fluctuates brand to brand, but 15-20 degrees is about normal. Believe it or not, the crankshaft often has more to do with power production and delivery than the liner porting. Changing the liner porting can make a little extra power, but often it just moves the powerband. The phrase I've heard used is porting to the pipe. The magic usually happens when you change your open and closing of the inlet port to open earlier and close later giving more induction timing and the real power adder is boring the crankshaft. My last two modded engines I did for 1/8 scale monster trucks had 9mm carb's (adjustable with different carb inserts for racing) and 8.5mm crank passages. Boring the crank to a bit over 10mm wakes them up and helps them breathe (run harder). The manifold has proven to be detrimental to how the engine revs and where the power comes in. Standard tubular manifolds do okay, but the power comes on stronger across the rpm range with a conical type manifold. Of course most of this is tailored to car engines, but some of most can be extrapolated to aircraft engines however there will be trade-offs if you go too far. Airraptor is right about getting the blowdown right - an easy thing to screw up. Get the induction too high and you can get blowback from the exhaust.
#317
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Those Tower/GMS mufflers are built with a similar principle to Helmholtz resonators or 1/4 wave pipes. The Tower mufflers are shorter than the red Jett mufflers, but without any baffles. I'd think the tuned range is a bit higher in the rpm band, but would probably still add a bit more kick to a bigger prop.
My GMS .47 on the red Jett muffler really howled on a 10x6 - turned 500rpm better than my TT Pro .46. I wish I had a tower muffler to compare to the red Jett muffler. My GMS .47 didn't come with the muffler.
In case anyone has any interest, Dub Jett has some informational videos on YouTube now. Tuning tuned pipes and setting carb's. Search Jett Aerotech on YouTube.
My GMS .47 on the red Jett muffler really howled on a 10x6 - turned 500rpm better than my TT Pro .46. I wish I had a tower muffler to compare to the red Jett muffler. My GMS .47 didn't come with the muffler.
In case anyone has any interest, Dub Jett has some informational videos on YouTube now. Tuning tuned pipes and setting carb's. Search Jett Aerotech on YouTube.
#319
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I never messed around much with tuned pipes, I always just slapped a tower muffler on my 46ax if I wanted it to scream a little, I have at least 4 tower mufflers laying around.
I keep hearing about the Coke can pipe or CCP, I've never seen one before though, anybody have a pic?
I keep hearing about the Coke can pipe or CCP, I've never seen one before though, anybody have a pic?
#320
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They're castings that they machine down. The Jett muffler uses a casting for the front part and aluminum tubing for the center and the machined end cap with stinger. So yes, I'm sure the copies are heavier since they're all cast.
#321
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http://www.spadtothebone.org/Mufflers/index.html The Mousse can Mufflers. There are other variations that are taken from a header, like the car motors. MVVS has a fairly nice one too if you can find one, and convert it to a regular manifold.
Last edited by aspeed; 01-15-2017 at 06:57 AM.
#323
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Now then around Christmas time Fry's Electronics sells the small 8 ounce souvenir aluminum long neck coke bottles that work great for some engines. They do make some larger 12 ounce sizes too. But I haven't seen the larger ones much though.
In this thread they show some different beer can mufflers too. http://www.rcuniverse.com/forum/gas-...-mufflers.html They are not just for gas engines but work for glow engines too.
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Last edited by earlwb; 01-16-2017 at 06:24 PM. Reason: add more information