OS MAX .10 FP tricked out
04-29-2007, 09:56 PM
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OS MAX .10 FP tricked out
Pictured is a stock, OS Max .10 FP that was picked up on Ebay. Typical of OS, the quality is immaculate. This engine is of the ABN variety with some unique cylinder porting.
Here, http://www.youtube.com/watch?v=tYRzGzQAuuQ we have some break in runs to limber it up. The prop is an 8 X 4 black Tornado. I made no attempt at getting a low idle, I just wanted to see what the top end would be on that prop and 25% Cool Power. (Correction,, OMEGA fuel)
From here, I'm going to detail some hop up tricks, the first few of which anyone can do with hand tools. Today, the crankshaft gets all the attention.
First we grind an off center groove at the back of the crankweb. As you might visualize, this delivers fuel to the case in a more efficient manner. Thanks to Larry Driskill for this tip. The next one, Larry has also detailed elsewhere but I've been doing this bit for years. That includes grinding the crank's intake port to a knife edge. This has to be done carefully so as to not alter the intake timing. Unless you want to but we're going to save that for later. Finally, we use JB Weld to fill in the dead zone inside the front of the crank's bore. As you can also visualize, this allows for much more efficient delivery of fuel to the case.
These tricks have been used on Norvel .061s to good effect giving us a decent, "free" 500 RPM increase.
These modifications will be tested just as soon as it stops snowing.
From there, we'll modify the head to take a button cut to take a turbo plug. As we know, stock plugs on 1/2A reward us with a loss of up to 1.5K. Not good and it occurred to me that perhaps even a .10 might benefit from the use of a turbo. As illustrated, the combustion chamber of the .10 is quite small and the threads of the plug are a major factor in the head's internal shape. A stock, Norvel .074 glow button is shown for comparison.
Finally, we're going to stuff in, the innards of an aftermarket cylinder and piston for a .15. This won't make it a .15 as we'd need more crank throw as well but Detroit has never been contradicted in it's assertion that there's no substitute for cubes. We are upping the cubes here and past experience on another OS .10 has given us a healthy 1,000 RPM increase. That one didn't have a turbo plug so on this engine, we might see a good 2K increase with virtually no increase in weight.
Not pictured is the crank out of an old, OS .15 that looks like it can be shoehorned to fit. Just a bit of the crankweb will be turned off on the lathe and a new, compact rod will be made to suit. We're also thinking of finding a way to "stuff" the crank. The gasser, RC car guys claim much benefit from such a device. The idea there is to reduce crankcase volume as much as possible to increase the velocity of the fuel as it's delivered to the cylinders.
That can be seen here. http://www.oneillbrothersracing.com/...it_stuffed.htm
As you can see, the crank web is full circle with the cutouts filled in with some kind of lightweight material. My dirtbike racing nephew, says the bike guys do this with cork.
Yesterday we went to the beach. Tonight we have snow flurries. Go figure. More later.
Here, http://www.youtube.com/watch?v=tYRzGzQAuuQ we have some break in runs to limber it up. The prop is an 8 X 4 black Tornado. I made no attempt at getting a low idle, I just wanted to see what the top end would be on that prop and 25% Cool Power. (Correction,, OMEGA fuel)
From here, I'm going to detail some hop up tricks, the first few of which anyone can do with hand tools. Today, the crankshaft gets all the attention.
First we grind an off center groove at the back of the crankweb. As you might visualize, this delivers fuel to the case in a more efficient manner. Thanks to Larry Driskill for this tip. The next one, Larry has also detailed elsewhere but I've been doing this bit for years. That includes grinding the crank's intake port to a knife edge. This has to be done carefully so as to not alter the intake timing. Unless you want to but we're going to save that for later. Finally, we use JB Weld to fill in the dead zone inside the front of the crank's bore. As you can also visualize, this allows for much more efficient delivery of fuel to the case.
These tricks have been used on Norvel .061s to good effect giving us a decent, "free" 500 RPM increase.
These modifications will be tested just as soon as it stops snowing.
From there, we'll modify the head to take a button cut to take a turbo plug. As we know, stock plugs on 1/2A reward us with a loss of up to 1.5K. Not good and it occurred to me that perhaps even a .10 might benefit from the use of a turbo. As illustrated, the combustion chamber of the .10 is quite small and the threads of the plug are a major factor in the head's internal shape. A stock, Norvel .074 glow button is shown for comparison.
Finally, we're going to stuff in, the innards of an aftermarket cylinder and piston for a .15. This won't make it a .15 as we'd need more crank throw as well but Detroit has never been contradicted in it's assertion that there's no substitute for cubes. We are upping the cubes here and past experience on another OS .10 has given us a healthy 1,000 RPM increase. That one didn't have a turbo plug so on this engine, we might see a good 2K increase with virtually no increase in weight.
Not pictured is the crank out of an old, OS .15 that looks like it can be shoehorned to fit. Just a bit of the crankweb will be turned off on the lathe and a new, compact rod will be made to suit. We're also thinking of finding a way to "stuff" the crank. The gasser, RC car guys claim much benefit from such a device. The idea there is to reduce crankcase volume as much as possible to increase the velocity of the fuel as it's delivered to the cylinders.
That can be seen here. http://www.oneillbrothersracing.com/...it_stuffed.htm
As you can see, the crank web is full circle with the cutouts filled in with some kind of lightweight material. My dirtbike racing nephew, says the bike guys do this with cork.
Yesterday we went to the beach. Tonight we have snow flurries. Go figure. More later.
04-29-2007, 11:05 PM
#2
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RE: OS MAX .10 FP tricked out
Cool stuff! I am supposing the .15 piston and sleeve will slide right in replacing the original unit? Anyone done the math to see what the diplacement will acually be afterward? Not that this info is critical.
As to the stuffing the crank idea, how about taking a bit of cork or cork/neoprene gasket material (a square foot of this would be pretty cheap from the local auto parts store and would make scores of the appropriate shape) glued to the edges with permatex #1 or #2 (sorry can't remember which).
The gasket material should of course be the appropriate thickness. This would round out the flats shown.
Surely this may not be the best idea as there would be no metal all the way around the disc and I suppose the gasket material could easily come apart making a terrible mess of things internally. Just tossing it out there. Maybe some really light plastic instead? Not too serious here, just hoping my suggestions may spark someone else to the holy grail for which we seek.
Robert
As to the stuffing the crank idea, how about taking a bit of cork or cork/neoprene gasket material (a square foot of this would be pretty cheap from the local auto parts store and would make scores of the appropriate shape) glued to the edges with permatex #1 or #2 (sorry can't remember which).
The gasket material should of course be the appropriate thickness. This would round out the flats shown.
Surely this may not be the best idea as there would be no metal all the way around the disc and I suppose the gasket material could easily come apart making a terrible mess of things internally. Just tossing it out there. Maybe some really light plastic instead? Not too serious here, just hoping my suggestions may spark someone else to the holy grail for which we seek.
Robert
04-29-2007, 11:32 PM
#3
RE: OS MAX .10 FP tricked out
I'm rooting for you Andy, you're leading the way to what many of us might find ourselves doing in the future, which will be playing with hot .10 sized engines and planes instead of flying mostly 1/2A. I've neglected .10s for the most part due to their wimpyness, but did have some fun with a FP .10 on my first delta. A 2000 rpm increase from internal mods would be great and could also see more from a mousse can pipe.
04-30-2007, 12:16 AM
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RE: OS MAX .10 FP tricked out
Robert,
Actually, the cylinder needs to be turned down a bit on the OD and the case will be bored out a bit. The top and bottom of the piston needs to be trimmed some also, to maintain timing and compression ratio and the like. The neat thing is that the wrist pin diameter is the same on both so no messing with that is required. Neat.
Stuffing the crank with cork or neoprene/cork might work OK but concern over the stuff shedding is a possibility at high revs. Gassers and dirt bikes go to 8 or 9K. I'm considering making a form or mold that the crank web will sit in and apply epoxy with microballons mixed in. Should hold strong and be quite light. If it doesn't hold, though, them glass bubbles will be real hard on the fit, unlike cork. But we'll see. That mod will be the last to try. Apparently on the gassers, it also improves throttling .
In all of this, I'll be sure to do the math to determine what new, crazy size, we've created.
Thanks CP,
You may be right in that we'll not be seeing anything new below a .10 in the not so distant future. But wouldn't you know it, drawings for tricking up the Norvel .074 to an ABC .10 is in the book. One of my Norvel .15s also has an OS .25 piston and liner bagged together just waiting for some free time. [>:] Geez, I hope the cranks hold up. [X(]
I've got a little program that determines HP and static thrust based on RPM and prop.
The original engine, on an 8 X 4 at 11.5K,
HP Static Thrust
.178 24 ounces
With the mods at 13.5K
.288 33 ounces
Could we get another 1000 with a piped muffler?
.357 40 ounces
Wow, a 66% increase. Neat.
Actually, the cylinder needs to be turned down a bit on the OD and the case will be bored out a bit. The top and bottom of the piston needs to be trimmed some also, to maintain timing and compression ratio and the like. The neat thing is that the wrist pin diameter is the same on both so no messing with that is required. Neat.
Stuffing the crank with cork or neoprene/cork might work OK but concern over the stuff shedding is a possibility at high revs. Gassers and dirt bikes go to 8 or 9K. I'm considering making a form or mold that the crank web will sit in and apply epoxy with microballons mixed in. Should hold strong and be quite light. If it doesn't hold, though, them glass bubbles will be real hard on the fit, unlike cork. But we'll see. That mod will be the last to try. Apparently on the gassers, it also improves throttling .
In all of this, I'll be sure to do the math to determine what new, crazy size, we've created.
Thanks CP,
You may be right in that we'll not be seeing anything new below a .10 in the not so distant future. But wouldn't you know it, drawings for tricking up the Norvel .074 to an ABC .10 is in the book. One of my Norvel .15s also has an OS .25 piston and liner bagged together just waiting for some free time. [>:] Geez, I hope the cranks hold up. [X(]
I've got a little program that determines HP and static thrust based on RPM and prop.
The original engine, on an 8 X 4 at 11.5K,
HP Static Thrust
.178 24 ounces
With the mods at 13.5K
.288 33 ounces
Could we get another 1000 with a piped muffler?
.357 40 ounces
Wow, a 66% increase. Neat.
04-30-2007, 12:19 AM
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RE: OS MAX .10 FP tricked out
Nicely done. Keep on it.
I've got a .10 that's still in the box. Not sure if it'll see this sort of attention at any time but it's wonderful to have the option.
I've got a .10 that's still in the box. Not sure if it'll see this sort of attention at any time but it's wonderful to have the option.
04-30-2007, 12:49 AM
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RE: OS MAX .10 FP tricked out
I dunno.... You think they'll recoup their tooling and other costs from selling engines to the 30 or 40 of us here on RCU that worship this sort of thing?
I hate to say it but the writing is on the wall and all the paint removal that we're trying to do isn't going to change it. Small glow is an oddity these days. Brushless electics that supply these sorts of power levels are just so much more available and about the same price and weight thanks to cheap Lipos. For those of us that enjoy small glow let's not give up but the idea of converting legions of those "others" to small glow is just a will o' the whisp these days.
Oh Oh.... QUICK! SOMEONE START UP A FORA FOR CP BEFORE HE BLOWS A GASKET! I guess the reality was just too much for him...
I hate to say it but the writing is on the wall and all the paint removal that we're trying to do isn't going to change it. Small glow is an oddity these days. Brushless electics that supply these sorts of power levels are just so much more available and about the same price and weight thanks to cheap Lipos. For those of us that enjoy small glow let's not give up but the idea of converting legions of those "others" to small glow is just a will o' the whisp these days.
Oh Oh.... QUICK! SOMEONE START UP A FORA FOR CP BEFORE HE BLOWS A GASKET! I guess the reality was just too much for him...
04-30-2007, 01:05 AM
#8
RE: OS MAX .10 FP tricked out
Bruce, I have a FORA CD that I can play to soothe me when I read comments like that.......[>:]
Too bad what you say is true. Thankfully there is still enough interest in 1/2A competition engines to keep things going and enough open land to have that kind of fun.
Too bad what you say is true. Thankfully there is still enough interest in 1/2A competition engines to keep things going and enough open land to have that kind of fun.
04-30-2007, 07:02 AM
#9
RE: OS MAX .10 FP tricked out
Andy, thanks for posting that picture of the duratrax O.S15 replacement cylinder. I have a CV15 that I was thinking about putting in a newer cylinder in as the later models put out a bit more power. A trued hard chrome job is just what the doctor ordered[8D]
I look forward to seeing how this turns out.
Stefan
I look forward to seeing how this turns out.
Stefan
04-30-2007, 09:35 AM
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RE: OS MAX .10 FP tricked out
Stefan,
I like chrome a lot. The bonus too here, is that Duratrax gives you a healthy pinch at TDC. I like that a lot too.
I like chrome a lot. The bonus too here, is that Duratrax gives you a healthy pinch at TDC. I like that a lot too.
04-30-2007, 03:13 PM
#11
RE: OS MAX .10 FP tricked out
As far as filling in the cranks' counterweight with a light weight filler, I would dowel the flat spots on the counterweight with aluminum pegs and use aluminum plate for the filler pieces. Like the way a dentist would anchor a tooth implant. The heavy end of the crank might need Mallory metal added to offset the weight gain on the pin side of the disc. A Cyclon style stuffer plate would then finish the job on the back plate, as well as removing the piston skirt like they do. It is good to know about those high performance replacement parts from Duratrax.
04-30-2007, 05:37 PM
#12
RE: OS MAX .10 FP tricked out
On tower hobbies it was $17. Not bad. But then there is international shipping [:'(]
How do you get around that Andy? I am such a penny pincher I`ll do anything to avoid paying the big shipping fees. It just offends me to pay $12 shipping on a part that can be sent via USPS Airmail to Japan for $3
After playing with the Fora020 I REALLY like chrome too. It would be nice to find somewhere where we could get our norvel cylinders hard chromed after chucking them in the caustic soda to take off the hard anodise.
Then those of us with lathes could have engines that are almost perpetual- make a new piston when the old one wears out.
I like your idea of hard anodise vs hard chrome. That would be durable!
How do you get around that Andy? I am such a penny pincher I`ll do anything to avoid paying the big shipping fees. It just offends me to pay $12 shipping on a part that can be sent via USPS Airmail to Japan for $3
After playing with the Fora020 I REALLY like chrome too. It would be nice to find somewhere where we could get our norvel cylinders hard chromed after chucking them in the caustic soda to take off the hard anodise.
Then those of us with lathes could have engines that are almost perpetual- make a new piston when the old one wears out.
I like your idea of hard anodise vs hard chrome. That would be durable!
04-30-2007, 10:56 PM
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RE: OS MAX .10 FP tricked out
CP,
Those are some interesting ideas. Might try some of them on my .25 or .40,,, but wait,, they're not making these things anymore so,,,
Maybe I'll pick up a Magnum cheap on Ebay. Going to look into your references to the Cyclon. Reminds me I still have to run that rebuilt CS with the new Nelson plug.
Stefan,
I feel your dilema about shipping. We have similar problems, maybe not so bad.
I think that an AAC version of the Norvels would be an outstanding idea. I really liked the unique, anodized technology but it did have its idiosyncrasies. I marvelled at the ease of starting of the ABC VAs. They even hand start with just a few flips on diesel.
Those are some interesting ideas. Might try some of them on my .25 or .40,,, but wait,, they're not making these things anymore so,,,
Maybe I'll pick up a Magnum cheap on Ebay. Going to look into your references to the Cyclon. Reminds me I still have to run that rebuilt CS with the new Nelson plug.
Stefan,
I feel your dilema about shipping. We have similar problems, maybe not so bad.
I think that an AAC version of the Norvels would be an outstanding idea. I really liked the unique, anodized technology but it did have its idiosyncrasies. I marvelled at the ease of starting of the ABC VAs. They even hand start with just a few flips on diesel.
05-01-2007, 10:26 AM
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RE: OS MAX .10 FP tricked out
Got to run the modified .10 late last night and came away not too disappointed. The mods to the crank only yielded 200 RPM gain. The upside is that we got improved idle and pickup.
The latest run is here, http://www.youtube.com/watch?v=26aG0d89KRg
Last year I did up a glow head that could be adjusted for compression on the fly for the Norvel .15 here, http://www.youtube.com/watch?v=_pN6-rgXEFk
This indicated that the CR on the Norvels might be a little on the conservative side. So, on all the Norvels over a space of a week or so, I ran the .06 up to the .40 with the gasket in place and also with the gasket removed. A good seal sans gasket can be assured if you dress the bottom of the plug/carrier with 600 grit paper against a piece of glass. The anodized base holds oil in the pores. This helps to seal and I had no leakage problems. The result was a gain in RPMs with no losses anywhere. On the .15, I even shaved down the button for more gains. We're talking about 2 to 300 RPM.
So with the .10 in question here, I took out the .22mm head gasket and lapped the cylinder top to the underside of the head. This gave me an additional 300 RPM for a top end of just over 12K. Taking that further, I then shaved down the top of the cylinder another .15mm and had the piston bump the head a bit. This was dressed down for a clearance fit and I was hoping that we'd get some gains from the squishband effect. That didn't happen as despite the additional compression, I got no more gains. The only negative was that if you overprimed, you'd get the prop kicking back and forth till the prime cleared. Just the right prime allowed an easy hand start.
Seen here, http://www.youtube.com/watch?v=HcHD8ufCw8o
At this point I need to correct an error in the first post on this thread. The fuel used all along is/was, 25% OMEGA, not Cool Power. What I'll do today is to run the engine with 10% CP and see if the extra compression will still give us good results with a cheaper fuel.
Having achieved 12K, hopefully the turbo head will give us at least another 1,000 RPM.
Hope to do up the turbo head today and get a run in before nightfall.
The latest run is here, http://www.youtube.com/watch?v=26aG0d89KRg
Last year I did up a glow head that could be adjusted for compression on the fly for the Norvel .15 here, http://www.youtube.com/watch?v=_pN6-rgXEFk
This indicated that the CR on the Norvels might be a little on the conservative side. So, on all the Norvels over a space of a week or so, I ran the .06 up to the .40 with the gasket in place and also with the gasket removed. A good seal sans gasket can be assured if you dress the bottom of the plug/carrier with 600 grit paper against a piece of glass. The anodized base holds oil in the pores. This helps to seal and I had no leakage problems. The result was a gain in RPMs with no losses anywhere. On the .15, I even shaved down the button for more gains. We're talking about 2 to 300 RPM.
So with the .10 in question here, I took out the .22mm head gasket and lapped the cylinder top to the underside of the head. This gave me an additional 300 RPM for a top end of just over 12K. Taking that further, I then shaved down the top of the cylinder another .15mm and had the piston bump the head a bit. This was dressed down for a clearance fit and I was hoping that we'd get some gains from the squishband effect. That didn't happen as despite the additional compression, I got no more gains. The only negative was that if you overprimed, you'd get the prop kicking back and forth till the prime cleared. Just the right prime allowed an easy hand start.
Seen here, http://www.youtube.com/watch?v=HcHD8ufCw8o
At this point I need to correct an error in the first post on this thread. The fuel used all along is/was, 25% OMEGA, not Cool Power. What I'll do today is to run the engine with 10% CP and see if the extra compression will still give us good results with a cheaper fuel.
Having achieved 12K, hopefully the turbo head will give us at least another 1,000 RPM.
Hope to do up the turbo head today and get a run in before nightfall.
05-13-2007, 03:07 AM
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RE: OS MAX .10 FP tricked out
It's taken a while to get back to the .10 FP for various reasons. Finally, we have something to report. Pictured is the turbo head made to fit the stock, .10 cylinder. At the same time, a turbo head was made to suit the anticipated, .15 retrofit. (not shown)
The results were not as encouraging as we had hoped.
At issue is the prop I used for these tests. I went a bit bigger than usual, (8 x 4) because I'm anticipating converting this one to diesel and I wanted to work all along with the same prop to do that revealing, apples to apples comparison, between glow and diesel.
I changed my mind and went to the usual .10 sized prop, a 7 X 4 black Tornado. Good thing I did as we learned something.
Last week we were running the engine in 80 degree F temperatures. Unusual for this part of the planet at this time of year but don't worry, that didn't last. Today, (Friday) it was rather cold, only 40 F. Again, Global Warming lets us down.
But this allowed us to run this engine without any concerns about overheating. Along with the standard prop, we also tested some 10% Cool Power fuel.
On this day, we got the following results which can be seen below. In brackets is lowest and best idle. No attempt was made to adjust the idle mixture, we just took what we got for the time being.
As can be noted, and as posted on YouTube, our original run on the stock engine, with no modifications and 25% Omega on an 8 X 4 black Tornado, we got 11.5K
All our tricks and the Turbo Head only delivered another 500 RPMs on the 8 X 4 and 25% fuel. As shown here, http://www.youtube.com/watch?v=8m5McsHRh3E
However, on 10% fuel, we saw the best gains with the Turbo plug at a 700 RPM gain.
Notice too, that with the larger, 8 X 4 prop, there was only a small, 200 RPM gain, with the higher nitro fuel, on the stock head.
With the larger prop and the Turbo Head, we saw NO gain when going to the high nitro fuel.
To test whether this meant that both heads were overcompressed for the extra nitro, we added the head gasket to the turbo head and predictably, we saw a drop of 700 to 1000 RPM. It appears that we got the compression ratio about right in all of these tests. It was higher than stock but in all cases was not overcompressed.
The conclusion that we have arrived at in this experiment, is that on this small engine, the OS Max .10, Turbo plugs offer only a small boost in performance. I'm inclined to think that OS did similar research and came to the same conclusion. A stock plug works, and works well, no need for turbo plugs.
BUT, why are they used on car engines?
In any event, next up is stuffing an ABC piston and liner into our OS Max .10 FP
The results were not as encouraging as we had hoped.
At issue is the prop I used for these tests. I went a bit bigger than usual, (8 x 4) because I'm anticipating converting this one to diesel and I wanted to work all along with the same prop to do that revealing, apples to apples comparison, between glow and diesel.
I changed my mind and went to the usual .10 sized prop, a 7 X 4 black Tornado. Good thing I did as we learned something.
Last week we were running the engine in 80 degree F temperatures. Unusual for this part of the planet at this time of year but don't worry, that didn't last. Today, (Friday) it was rather cold, only 40 F. Again, Global Warming lets us down.
But this allowed us to run this engine without any concerns about overheating. Along with the standard prop, we also tested some 10% Cool Power fuel.
On this day, we got the following results which can be seen below. In brackets is lowest and best idle. No attempt was made to adjust the idle mixture, we just took what we got for the time being.
As can be noted, and as posted on YouTube, our original run on the stock engine, with no modifications and 25% Omega on an 8 X 4 black Tornado, we got 11.5K
All our tricks and the Turbo Head only delivered another 500 RPMs on the 8 X 4 and 25% fuel. As shown here, http://www.youtube.com/watch?v=8m5McsHRh3E
However, on 10% fuel, we saw the best gains with the Turbo plug at a 700 RPM gain.
Notice too, that with the larger, 8 X 4 prop, there was only a small, 200 RPM gain, with the higher nitro fuel, on the stock head.
With the larger prop and the Turbo Head, we saw NO gain when going to the high nitro fuel.
To test whether this meant that both heads were overcompressed for the extra nitro, we added the head gasket to the turbo head and predictably, we saw a drop of 700 to 1000 RPM. It appears that we got the compression ratio about right in all of these tests. It was higher than stock but in all cases was not overcompressed.
The conclusion that we have arrived at in this experiment, is that on this small engine, the OS Max .10, Turbo plugs offer only a small boost in performance. I'm inclined to think that OS did similar research and came to the same conclusion. A stock plug works, and works well, no need for turbo plugs.
BUT, why are they used on car engines?
In any event, next up is stuffing an ABC piston and liner into our OS Max .10 FP
05-14-2007, 09:50 AM
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RE: OS MAX .10 FP tricked out
ORIGINAL: 1705493-AndyW
The conclusion that we have arrived at in this experiment, is that on this small engine, the OS Max .10, Turbo plugs offer only a small boost in performance. I'm inclined to think that OS did similar research and came to the same conclusion. A stock plug works, and works well, no need for turbo plugs.
The conclusion that we have arrived at in this experiment, is that on this small engine, the OS Max .10, Turbo plugs offer only a small boost in performance. I'm inclined to think that OS did similar research and came to the same conclusion. A stock plug works, and works well, no need for turbo plugs.
It would be interesting to see the gains on a lighter load yet. I wonder what would happen if you did comparisons in the 17-18k regime. Mebbe a 7-3 or 6-4? Not the direction you were headed I know but while you're at it...?
MJD
05-14-2007, 04:51 PM
#17
RE: OS MAX .10 FP tricked out
That's what I think, too. This oversized prop stuff is like doing performance mods to a 454 that is mounted in a dump truck. The gains will be muted by the load. If anything, try a MAS 8x3, then snip the tips to see if you're working in the right direction compared with what Thrust HP has to say. I think anything short of dieseling will make a 7x3 the best choice for pure power. Look at the bore, stroke and rod ratio, then ask yourself is this a HP motor or a torque motor. I couldn't tell you. To me, a 8x4 is on the upper limit of what to run on .15s.
05-14-2007, 06:49 PM
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RE: OS MAX .10 FP tricked out
cp:
Years ago I ran a stock .10fp with a 7-3 prop and 15% fuel, I got 18,500 RPM. I had a MAX .099 that I was curious about. It did 17,500 with the same stuff.
regards - Steve B.
Years ago I ran a stock .10fp with a 7-3 prop and 15% fuel, I got 18,500 RPM. I had a MAX .099 that I was curious about. It did 17,500 with the same stuff.
regards - Steve B.
05-14-2007, 09:13 PM
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RE: OS MAX .10 FP tricked out
I dunno, 15,300 versus 14,600 rpm is a 9.8% horsepower increase. That's not insignificant.
It would be interesting to see the gains on a lighter load yet. I wonder what would happen if you did comparisons in the 17-18k regime. Mebbe a 7-3 or 6-4? Not the direction you were headed I know but while you're at it...?
MJD
[/quote]
Actually more like 15% horsepower increase. ..... Compared to .10 size engines that I'm accustomed to. (old baffle piston Enyas) this engine doesn't seem to like the 8x4 prop size. "Wants" to be more of a "rever". I'm aware, though, that the end result is not gonna be a .10 size engine. ................... George K.
It would be interesting to see the gains on a lighter load yet. I wonder what would happen if you did comparisons in the 17-18k regime. Mebbe a 7-3 or 6-4? Not the direction you were headed I know but while you're at it...?
MJD
[/quote]
Actually more like 15% horsepower increase. ..... Compared to .10 size engines that I'm accustomed to. (old baffle piston Enyas) this engine doesn't seem to like the 8x4 prop size. "Wants" to be more of a "rever". I'm aware, though, that the end result is not gonna be a .10 size engine. ................... George K.
05-15-2007, 12:09 AM
#21
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RE: OS MAX .10 FP tricked out
ORIGINAL: burtcs
cp:
Years ago I ran a stock .10fp with a 7-3 prop and 15% fuel, I got 18,500 RPM. I had a MAX .099 that I was curious about. It did 17,500 with the same stuff.
regards - Steve B.
cp:
Years ago I ran a stock .10fp with a 7-3 prop and 15% fuel, I got 18,500 RPM. I had a MAX .099 that I was curious about. It did 17,500 with the same stuff.
regards - Steve B.
The OS I got was not new, but virtually new. Evidence from the mounting lugs shows that it wasn't bolted in place, as in an airplane but just run on the stand. Inside it was impeccable when I tore it down. BUT, and this is a problem in my opinion, with a lot of engines coming to the mass market, the piston fit is very light. NO pinch at the top. It snaps over when cool with fresh prime but after shut down, when hot, there's no snap at all. Till it cools off. ABN type engines are supposed to come up to a just right fit at temperature, aren't they? Here, we're getting poor compression seal when hot. I guess that's why I'm not really getting the power you did. What brand of prop did you use?
But initial power wasn't the game here. I wanted to see what a turbo might do for us in a still relatively small engine. From there, I wanted to bore and stroke it to see how far we could take a .10 platform.
About the increase I did get, I was hoping to see the same kind you get with 1/2A. That is, a stock plug robs 1.5K and I was thinking that a similar situation existed here.
CP,
You're right as the chart shows, no real gain with the 8 X 4 but decent gain with the 7 X 4. And I'm now convinced that I should now go to a 7 X 3 and then, a 6 X 4, just to see.
George,
I went to an 8" prop initially in anticipation of re-building this engine as a bored out diesel. So I wanted to see, on the fly, how it would compare in both modes. The turbo idea was secondary but has now become a primary element of this project.
It rained all day today, and tomorrow they're calling for snow flurries. That'll give me a chance to build a new, proper test stand and do some more testing.
I have a creeping suspicion that I've overlooked something.
05-15-2007, 01:44 AM
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RE: OS MAX .10 FP tricked out
Andy:
I had been using the .10fp on a Clancy Lazy Bee, hand started, 10% nitro and a 7-3 APC ( it's been a few years ago). It does have the ABN fit at tdc. The Lazy Bee died when I did a three point 18 inches off the deck (mybad) so I did wondered whether it would make a good freeflight engine (not uncommon). This would require a change of venturi, prop (maybe) and maybe fuel. The RC carb was not checked for function, just WOT.
I may have run the engine on the bench with the muffler off since I was comparing with a Max .099. Both engines would have been legal for something but I was curious how the .099 stacked up against a .10
The 7-3 never seemed like it was loading the .10, it just ran well and hand started.
regards - Steve B.
I had been using the .10fp on a Clancy Lazy Bee, hand started, 10% nitro and a 7-3 APC ( it's been a few years ago). It does have the ABN fit at tdc. The Lazy Bee died when I did a three point 18 inches off the deck (mybad) so I did wondered whether it would make a good freeflight engine (not uncommon). This would require a change of venturi, prop (maybe) and maybe fuel. The RC carb was not checked for function, just WOT.
I may have run the engine on the bench with the muffler off since I was comparing with a Max .099. Both engines would have been legal for something but I was curious how the .099 stacked up against a .10
The 7-3 never seemed like it was loading the .10, it just ran well and hand started.
regards - Steve B.
05-15-2007, 04:31 AM
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RE: OS MAX .10 FP tricked out
Thanks Steve,
Those details give me an opportunity to see how mine compares. If you had pinch at TDC, then I have a plan to get that in mine by making up a new piston and see how much difference it makes. Looks like I got a bit of a dud in mine, but we'll see.
Those details give me an opportunity to see how mine compares. If you had pinch at TDC, then I have a plan to get that in mine by making up a new piston and see how much difference it makes. Looks like I got a bit of a dud in mine, but we'll see.
05-15-2007, 04:37 AM
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RE: OS MAX .10 FP tricked out
I tweeked my .10 OS by installing enya .10 muffler on it..it almost half sized compared to OS muffler...less drag and weight at least.
05-15-2007, 09:06 AM
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RE: OS MAX .10 FP tricked out
ORIGINAL: mtntopgeo
I dunno, 15,300 versus 14,600 rpm is a 9.8% horsepower increase. That's not insignificant.
It would be interesting to see the gains on a lighter load yet. I wonder what would happen if you did comparisons in the 17-18k regime. Mebbe a 7-3 or 6-4? Not the direction you were headed I know but while you're at it...?
MJD
I dunno, 15,300 versus 14,600 rpm is a 9.8% horsepower increase. That's not insignificant.
It would be interesting to see the gains on a lighter load yet. I wonder what would happen if you did comparisons in the 17-18k regime. Mebbe a 7-3 or 6-4? Not the direction you were headed I know but while you're at it...?
MJD
[/quote]
What is the relationship actually, I forget. I just took the square of the rpm change based on drag increase, but is it a cubic relationship?
MJD