Rear exhaust Norvels.
02-23-2004, 11:08 PM
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Rear exhaust Norvels.
Having acquired several CS tuned pipes, adapting them to Norvels, with side exhaust became an issue. The pipes were first tried on VAs with their rear exhaust and power boost was a full 3K over the muffled version.
The Norvels were successfully converted to rear exhaust and the pics illustrate how that was done. The exhaust nipple was made from silver soldered brass and was nickle plated. As with the VA, performance was boosted a full 3K.
JB Weld was used to fill the rear bypass and was also used, along with a small plate, to fill the exhaust side allowing a new bypass to be cut in that location. Despite the crude appearance of the new bypasses, this didn't affect the operation of the engine.
The last pic shows an exhaust header that was intended to be used with FlyQuiet tubing as a really, really large, long, muffler. The intent was to have this run straight back into the fuse of the Tsunami and, along with a small tail pipe, have the exhaust exit behind the tail wheel. The entire radio installation was carefully arranged to avoid the hot exhaust pipe. However, despite my best efforts, it just wouldn't all fit in the same fuse. Maybe a crazy notion, heat certainly being an issue but you never know till you try. Yes, nearly half of the entire rear bottom section of the fuse was left open for extracting hot air. In the end, a side exhaust arrangement along with the FlyQuiet tubing worked just fine giving a very quiet engine along with a 500K boost in power due to the use of a tuning baffle.
The Norvels were successfully converted to rear exhaust and the pics illustrate how that was done. The exhaust nipple was made from silver soldered brass and was nickle plated. As with the VA, performance was boosted a full 3K.
JB Weld was used to fill the rear bypass and was also used, along with a small plate, to fill the exhaust side allowing a new bypass to be cut in that location. Despite the crude appearance of the new bypasses, this didn't affect the operation of the engine.
The last pic shows an exhaust header that was intended to be used with FlyQuiet tubing as a really, really large, long, muffler. The intent was to have this run straight back into the fuse of the Tsunami and, along with a small tail pipe, have the exhaust exit behind the tail wheel. The entire radio installation was carefully arranged to avoid the hot exhaust pipe. However, despite my best efforts, it just wouldn't all fit in the same fuse. Maybe a crazy notion, heat certainly being an issue but you never know till you try. Yes, nearly half of the entire rear bottom section of the fuse was left open for extracting hot air. In the end, a side exhaust arrangement along with the FlyQuiet tubing worked just fine giving a very quiet engine along with a 500K boost in power due to the use of a tuning baffle.
02-24-2004, 01:13 AM
#2
RE: Rear exhaust Norvels.
HI ANDY! That's amazing work! The JB WELD flowed out real nice on the outside of the case, neat work. The open tunnel on the bottom of the fuse works pretty well for the pattern flyers, but I'm not sure what kind of heat shield they use. That self adhesive foil tape might work. If you can get a 3 grand boost with a standard prop, that's impressive! It's a good thing guys like you are interested in model engines, and not bombs[X(]!!
02-24-2004, 01:25 AM
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RE: Rear exhaust Norvels.
Thanks Combat,
Yes, next time I'll consider a tunnel with an inverted engine. Been thinking of a delta for insane speed,,, just for the 'ell of it.
Yes, next time I'll consider a tunnel with an inverted engine. Been thinking of a delta for insane speed,,, just for the 'ell of it.
02-25-2004, 07:56 AM
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RE: Rear exhaust Norvels.
Wow,
This is timely.
I have just got some cool diamant aluminium glue for another project, and I once thats out of the way i have been thinking about doing this very same mod to my norvys- it makes a lot more sense for D.F.
one thing i have been wondering about- did you re-drill the piston pin hole 90deg off set to stop the grind out in the piston skirt making for `super` sub piston induction? or is it o.k just to "have fun and run"?
Kudos for posting this trick.
who knows, maybe i will post my recepie for a high rpm 0.074?[8D]
J.M
This is timely.
I have just got some cool diamant aluminium glue for another project, and I once thats out of the way i have been thinking about doing this very same mod to my norvys- it makes a lot more sense for D.F.
one thing i have been wondering about- did you re-drill the piston pin hole 90deg off set to stop the grind out in the piston skirt making for `super` sub piston induction? or is it o.k just to "have fun and run"?
Kudos for posting this trick.
who knows, maybe i will post my recepie for a high rpm 0.074?[8D]
J.M
02-25-2004, 08:24 PM
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RE: Rear exhaust Norvels.
J Man,
No, the piston wasn't altered in any way. Yes, you get a big bunch of sub-piston induction. Doesn't hurt operation in any way,,, including throttling. Another illustration that SPI has no detrimental effect on throttling. The only time it does, is with a Cox engine using an exhaust sleeve. And that's a whole different animal.
If and when the need arises, I'll be doing up an .074 for one of my pipes. Just to see how fast that great little engine can go. Might make a new rod for it though, with brass bushings.
No, the piston wasn't altered in any way. Yes, you get a big bunch of sub-piston induction. Doesn't hurt operation in any way,,, including throttling. Another illustration that SPI has no detrimental effect on throttling. The only time it does, is with a Cox engine using an exhaust sleeve. And that's a whole different animal.
If and when the need arises, I'll be doing up an .074 for one of my pipes. Just to see how fast that great little engine can go. Might make a new rod for it though, with brass bushings.
02-25-2004, 09:52 PM
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RE: Rear exhaust Norvels.
Nice work. Makes me envious, a little... 
I'm usually too lazy to pour that much labor into something like this...
As a By-the-way, most pattern ships don't use any heat shielding besides a 'glass or carbon tunnel. I've seen many with just sealed balsa. Airflow and exit ports had much to do with keeping the pipe cooled down. Mine never had any troubles.
phil in austin
I'm usually too lazy to pour that much labor into something like this...As a By-the-way, most pattern ships don't use any heat shielding besides a 'glass or carbon tunnel. I've seen many with just sealed balsa. Airflow and exit ports had much to do with keeping the pipe cooled down. Mine never had any troubles.
phil in austin
02-25-2004, 10:25 PM
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RE: Rear exhaust Norvels.
Phil,
Believe me, when you get a lathe, it becomes fun,,, not work.
I like your quote from Goethe. Who was it that said, "Sieze the day" ?
Believe me, when you get a lathe, it becomes fun,,, not work.
I like your quote from Goethe. Who was it that said, "Sieze the day" ?
02-26-2004, 07:13 AM
#8
RE: Rear exhaust Norvels.
And when you are separated from your lathe, your love grow`th stronger!
I have managed to track down a supplier of aluminium here... and they stock 2024!! (right down to .5mm too)
I am seriosly considering a new rod for both my norvels. Actually I want to reduce aluminium bearing surfaces to a minimum- A main bronze bushing and a conrod bushed at each end. That way I won`t aluminium plate my plugs when i get those babys revving. but its all a dream right now. (= no lathe[&o])
J.M
I have managed to track down a supplier of aluminium here... and they stock 2024!! (right down to .5mm too)
I am seriosly considering a new rod for both my norvels. Actually I want to reduce aluminium bearing surfaces to a minimum- A main bronze bushing and a conrod bushed at each end. That way I won`t aluminium plate my plugs when i get those babys revving. but its all a dream right now. (= no lathe[&o])
J.M
