My Turbocharged MDS .68
12-19-2005, 06:18 PM
#27
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RE: My Turbocharged MDS .68
If you don't mind me asking, where do you go to school and for what? I know a lot of younger guys on the forum like this hands on kind of thing when they are looking at college. What classes have you taken that give you the information needed to build a small turbo charger? All my classes in college ( I.C. Engines, Heat Transfer, Fluid Dynamics, Thermo Dynamics, Design and Manufacturing) none of them made a small turbo charger seem efficent for our small sized models. A larger engine would be better. Or are you just building it for fun?
One thing that concerns me is you state an inter cooler cools air before the turbo... You might want to check but a inter cooler cools air after it goes through the turbo, which increases the density, therefore raising the temperature (law of thermodynamics) and the inter cooler is a heat exchanger lowering the intake air temperature. A inter cooler would be extremely easy for you to make seeings how you have already done all the hard work. Take the pipe after the turbo and add fins to it... Yes it is very "raw" but it will help you somewhat.
If it does work, I don't think it is even the slightest bit practical unless you re-design the engine to work with the turbo. Moving intake and exhaust ports, and changing the angle that they are at from the factory. If you have went to all this work I would like to see someone do a project like this in a program like GT-Power or another developing software designed for engines.
Steve
One thing that concerns me is you state an inter cooler cools air before the turbo... You might want to check but a inter cooler cools air after it goes through the turbo, which increases the density, therefore raising the temperature (law of thermodynamics) and the inter cooler is a heat exchanger lowering the intake air temperature. A inter cooler would be extremely easy for you to make seeings how you have already done all the hard work. Take the pipe after the turbo and add fins to it... Yes it is very "raw" but it will help you somewhat.
If it does work, I don't think it is even the slightest bit practical unless you re-design the engine to work with the turbo. Moving intake and exhaust ports, and changing the angle that they are at from the factory. If you have went to all this work I would like to see someone do a project like this in a program like GT-Power or another developing software designed for engines.
Steve
12-20-2005, 07:14 AM
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RE: My Turbocharged MDS .68
This is an extremely interesting project that I hope is successful. Following are a few random comments regarding a few of the earlier posts by others, including the original poster.
"Intercooler" is called 'inter...' because it is between the turbo and the engine (intermediate) to cool the compressed air that gets hot due to the compression, it is not upstream/before the turbo.
Turbo lag may well be a problem, but then again it may not be given the normal high RPM that we run the RC engines. It may, however, be a significant problem for transition from idle to power, but experimentation is probably the only way to find out. This is one of the main problems with the turbine engines (with them it's 'spool up' time) but the RC turbine folks seem to have made this much more manageable in today's engines.
The issue of oiling of the turbo bearings is a large one that has been a serious problem for many of the commercial turbo manufacturers such as Garrett. A couple of examples: The Nissan NSX turbos were plagued by this problem so much that they discontinued the option. The Nissan 280ZX Turbo had a 120% turbo failure rate, meaning that on average each 280ZX (I believe that was the current designation at the time - mid-1980s) had had the turbo replaced at east once, and - again on average - 20% were on their third turbo. A similar situation existed with Chrysler's turbos, causing them to discontinue these.
The oiling problem is not simply getting enough oil to the bearings, but is most heavily due to 'heat soak'. It is during heat soak - after the engine is shut down and therefore there's no further coolant or air or oil flow - that the bearings reach their peak temperature. Chrysler even tried to solve this problem – after simply increasing the size of the oil supply passages failed - by having an electric oil recirculation system that ran for a period of time after the engine was shut down until the temperature was reduced enough not have problems. The most serious situation was when the cars - especially the Nissan 280ZX Turbos - were driven hard (think high performance sports cars being driven ‘assertively’ in Texas in the summer on an open highway) and the driver then pulled directly into a gas station/cafe and had lunch. While the engine was 'cooling' the turbo bearings were heating up, and the oil was forming a hard coke-like substance that's almost as hard as diamonds. After a few times of this the hard deposits would act like a lathe tool to cut grooves in the bearings and then all sorts of ugly things happened. The only 280ZXs that didn't have the problem seemed to be those that were where the owners lived on residential streets, where whenever they drove the car hard they were also then driving quite easily for a period of time (on surface streets) before shutting the engine down. This allowed the bearing temperatures to moderate before shut down and therefore reduced the negative effects of the heat soak.
Unfortunately for this project, we normally fly our models, land and shut the engine down immediately – or it shuts off by itself if we don’t have the idle well set. This could be a real problem, but could potentially be avoided by going through a programmed shutdown procedure such as is done for turbines today.
The comment that “in reply to APIA: if my bearings do burn out which i doubt they will i can just go down to radioshack and buy another pack for $20.00†seems reasonable, but in fact is likely to be a bad planning basis. If/when the bearings fail they are most likely going to take the turbo shaft with them and completely destroy all the fine and time-consuming machining with it.
Again, I’m very supportive of the project, but wanted to share some of the earlier learnings of others to hopefully ease the teething pains of this project. Good luck.
"Intercooler" is called 'inter...' because it is between the turbo and the engine (intermediate) to cool the compressed air that gets hot due to the compression, it is not upstream/before the turbo.
Turbo lag may well be a problem, but then again it may not be given the normal high RPM that we run the RC engines. It may, however, be a significant problem for transition from idle to power, but experimentation is probably the only way to find out. This is one of the main problems with the turbine engines (with them it's 'spool up' time) but the RC turbine folks seem to have made this much more manageable in today's engines.
The issue of oiling of the turbo bearings is a large one that has been a serious problem for many of the commercial turbo manufacturers such as Garrett. A couple of examples: The Nissan NSX turbos were plagued by this problem so much that they discontinued the option. The Nissan 280ZX Turbo had a 120% turbo failure rate, meaning that on average each 280ZX (I believe that was the current designation at the time - mid-1980s) had had the turbo replaced at east once, and - again on average - 20% were on their third turbo. A similar situation existed with Chrysler's turbos, causing them to discontinue these.
The oiling problem is not simply getting enough oil to the bearings, but is most heavily due to 'heat soak'. It is during heat soak - after the engine is shut down and therefore there's no further coolant or air or oil flow - that the bearings reach their peak temperature. Chrysler even tried to solve this problem – after simply increasing the size of the oil supply passages failed - by having an electric oil recirculation system that ran for a period of time after the engine was shut down until the temperature was reduced enough not have problems. The most serious situation was when the cars - especially the Nissan 280ZX Turbos - were driven hard (think high performance sports cars being driven ‘assertively’ in Texas in the summer on an open highway) and the driver then pulled directly into a gas station/cafe and had lunch. While the engine was 'cooling' the turbo bearings were heating up, and the oil was forming a hard coke-like substance that's almost as hard as diamonds. After a few times of this the hard deposits would act like a lathe tool to cut grooves in the bearings and then all sorts of ugly things happened. The only 280ZXs that didn't have the problem seemed to be those that were where the owners lived on residential streets, where whenever they drove the car hard they were also then driving quite easily for a period of time (on surface streets) before shutting the engine down. This allowed the bearing temperatures to moderate before shut down and therefore reduced the negative effects of the heat soak.
Unfortunately for this project, we normally fly our models, land and shut the engine down immediately – or it shuts off by itself if we don’t have the idle well set. This could be a real problem, but could potentially be avoided by going through a programmed shutdown procedure such as is done for turbines today.
The comment that “in reply to APIA: if my bearings do burn out which i doubt they will i can just go down to radioshack and buy another pack for $20.00†seems reasonable, but in fact is likely to be a bad planning basis. If/when the bearings fail they are most likely going to take the turbo shaft with them and completely destroy all the fine and time-consuming machining with it.
Again, I’m very supportive of the project, but wanted to share some of the earlier learnings of others to hopefully ease the teething pains of this project. Good luck.
12-20-2005, 08:56 AM
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RE: My Turbocharged MDS .68
fly nitro rc and others....To post photos resize them to about 1200 pixels max, click on Post Reply in lower left corner, type in a message, then click at lower left of message box on"click to upload". Locate your file and go with it. On 2 or 3 occasions it did not work for me. Just try and try again.
To you and others, Whats the max turbo RPM on a typical car equipt with same? I don't seem to recall. About 40 years ago we tested 4-5 inch diameter compressor turbos to 100,000 RPM for acceptance (my memory may be off). Running RPM was probably around 70,000 RPM. I'm probably wrong but something tells me that tip speed would be similar between different rotor diameters in order to control leakage between the rotor and the housing. Since tip speed is proportional to diameter (lets assume yours is one inch diameter) your needed RPM might be up around 300,000 RPM. What is your rotor diameter?
To you and others, Whats the max turbo RPM on a typical car equipt with same? I don't seem to recall. About 40 years ago we tested 4-5 inch diameter compressor turbos to 100,000 RPM for acceptance (my memory may be off). Running RPM was probably around 70,000 RPM. I'm probably wrong but something tells me that tip speed would be similar between different rotor diameters in order to control leakage between the rotor and the housing. Since tip speed is proportional to diameter (lets assume yours is one inch diameter) your needed RPM might be up around 300,000 RPM. What is your rotor diameter?
12-20-2005, 09:43 AM
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RE: My Turbocharged MDS .68
Sounds like you just need to buy a bigger engine. The turbo idea sounds intriging but with the extra weight and now you need a lot bigger fuel tank what will you gain. unless you inject fuel as the piston comes up sealing off ports your way too inefficent.
12-20-2005, 11:26 AM
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RE: My Turbocharged MDS .68
Villa, I seem to recall that the 'typical' max. RPM for turbos in automotive application is around 120,000. Could be that I'm having a senior moment, but that's my recollection.
Speedster; That one could get a larger engine and that this would be more practical than a turbo I don't think is the point here. I believe that the objective is to stretch the envelope and have fun with a hobby. Virtually nothing about our hobby fits a logical test of reason, and that's one of the major beauties and attractiveness of it as far as I'm concerned. I like to try new things and I think that this is the objective here - in addition to perhaps doing it for some sotrt of school course. Without the innovativeness being shown by this project there would be no inventions, most of which aren't practical in their first versions or attempts.
Speedster; That one could get a larger engine and that this would be more practical than a turbo I don't think is the point here. I believe that the objective is to stretch the envelope and have fun with a hobby. Virtually nothing about our hobby fits a logical test of reason, and that's one of the major beauties and attractiveness of it as far as I'm concerned. I like to try new things and I think that this is the objective here - in addition to perhaps doing it for some sotrt of school course. Without the innovativeness being shown by this project there would be no inventions, most of which aren't practical in their first versions or attempts.
12-20-2005, 01:27 PM
#32
RE: My Turbocharged MDS .68
Quite the project. I just read the whole thread, lots of good comments. First post December 7, and you have made a lot of progress and pulled a lot of interest.
One comment I was interested in was about compression ratio. The whole idea of putting a compressor in the intake system is to increase your effective compression ratio. The manufacturer is allowed to reduce the geometric compression ratio, which allows for easier cranking & makes for a smoother idling in gasoline automobiles. The effective compression ratio can still equal or exceed the geometric ratio.
At high compressor speed, presuming your MDS .68 will benefit from this increased compression, you'll be running a lot higher effective compression than the engine was designed for. I believe the guy who posted about that inquired what you would do with your compression ratio, and I suspect it would be good to add gaskets to raise the head, or something of that nature.
I'm one of the skeptics, since the inlet and outlet ports are both at the bottom of the cylinder, and thus close about the same time. Seems unlikely to me that there will be complete exchange of exhaust gas for fresh air & fuel. Fourstrokes, and the aforementioned Detroit Diesel 2strokes, just close the exhaust valves after the cylinder is filled with a fresh charge, and before the intake ports or valves close.
However, I'll be eager to see your results, and hoping for your success.
Best wishes,
Dave Olson
One comment I was interested in was about compression ratio. The whole idea of putting a compressor in the intake system is to increase your effective compression ratio. The manufacturer is allowed to reduce the geometric compression ratio, which allows for easier cranking & makes for a smoother idling in gasoline automobiles. The effective compression ratio can still equal or exceed the geometric ratio.
At high compressor speed, presuming your MDS .68 will benefit from this increased compression, you'll be running a lot higher effective compression than the engine was designed for. I believe the guy who posted about that inquired what you would do with your compression ratio, and I suspect it would be good to add gaskets to raise the head, or something of that nature.
I'm one of the skeptics, since the inlet and outlet ports are both at the bottom of the cylinder, and thus close about the same time. Seems unlikely to me that there will be complete exchange of exhaust gas for fresh air & fuel. Fourstrokes, and the aforementioned Detroit Diesel 2strokes, just close the exhaust valves after the cylinder is filled with a fresh charge, and before the intake ports or valves close.
However, I'll be eager to see your results, and hoping for your success.
Best wishes,
Dave Olson
12-22-2005, 12:47 AM
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RE: My Turbocharged MDS .68
I hate to say it but I too am a skeptic....
Do not give up...
This has been tried before and every time people say they are skeptic, people stop posting and give up... or it was never a project in the beginning. I would like to see what you have acomplished so far, just for the sake of curosity.
Steve
Do not give up...
This has been tried before and every time people say they are skeptic, people stop posting and give up... or it was never a project in the beginning. I would like to see what you have acomplished so far, just for the sake of curosity.
Steve
12-23-2005, 03:12 PM
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RE: My Turbocharged MDS .68
I am in high school, and have taken many auto classes and machining classes, and engine classes etc., and i just get my knowledge from what i know. I didnt make this project as a last resort to more power, i simply felt like making a turbocharger for a small engine. Its not a question of why, its "why not???". And I also dont know "fluid-dynamics" and this and that, and i never intended for this project to be the most efficient, powerful turbo ever, but just as a fun project. ---The rotor size for both turbines are 1".
As for the first test run that lasted more than a few seconds-
After the engine started the turbines immediatly spooled up, and seemed to have a pretty high rpm. The engine ran fine with it on, but it took a little while to get the mixtures right. Something interesting happened though, when i disconected the air line that went to the carburetor. The engine ran very fast for a few seconds and then died very quickly (about 1 second from the time i disconnected the line, the engine died --much faster than usual if i cut the fuel, and even the air as well). Im hoping this is a clue to what effect the turbocharging had on the engine, but it isnt any really good info because i didnt have time to play with the engine settings. Also a little after i took the intake tube off the custom header cracked and broke off (this is all that holds the turbo to the engine). So, I am thinking of adding an aluminum brace, and I will machine a thicker fitting to fix the cracked header. So my results were rather confusing, but i also didnt have time to really tweak the engine at all. I will try again when the header is fixed (a week from now, since we are off for christmas break), and i will also try to post my pictures again.
Any ideas on what effect the turbo had on the engine, and why it died so abnormally quickly?
Here also are some specs on the engine and turbo:
MDS .68 two stroke, stock everything. Medium heat glow plug.
CNC machined steel exhaust turbine 1"
CNC machined aluminum intake turbine 1"
1/8" steel shaft to support turbines.
2 Ball bearings for shaft.
3/8" internal porting for exhaust and intake passages.
fuel used: Byron originals 15% nitromethane
As for the first test run that lasted more than a few seconds-
After the engine started the turbines immediatly spooled up, and seemed to have a pretty high rpm. The engine ran fine with it on, but it took a little while to get the mixtures right. Something interesting happened though, when i disconected the air line that went to the carburetor. The engine ran very fast for a few seconds and then died very quickly (about 1 second from the time i disconnected the line, the engine died --much faster than usual if i cut the fuel, and even the air as well). Im hoping this is a clue to what effect the turbocharging had on the engine, but it isnt any really good info because i didnt have time to play with the engine settings. Also a little after i took the intake tube off the custom header cracked and broke off (this is all that holds the turbo to the engine). So, I am thinking of adding an aluminum brace, and I will machine a thicker fitting to fix the cracked header. So my results were rather confusing, but i also didnt have time to really tweak the engine at all. I will try again when the header is fixed (a week from now, since we are off for christmas break), and i will also try to post my pictures again.
Any ideas on what effect the turbo had on the engine, and why it died so abnormally quickly?
Here also are some specs on the engine and turbo:
MDS .68 two stroke, stock everything. Medium heat glow plug.
CNC machined steel exhaust turbine 1"
CNC machined aluminum intake turbine 1"
1/8" steel shaft to support turbines.
2 Ball bearings for shaft.
3/8" internal porting for exhaust and intake passages.
fuel used: Byron originals 15% nitromethane
12-23-2005, 05:37 PM
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RE: My Turbocharged MDS .68
I have been following this thread as have others. When are we going to see some pics as others have asked?? Seems to me if we don't see some soon, FWIW and IMHO this may be a bunch of BS 
!!
!!
12-23-2005, 06:07 PM
#37
RE: My Turbocharged MDS .68
Fly_Nitro_rc said:
<<snip>>As for the first test run that lasted more than a few seconds-
After the engine started the turbines immediatly spooled up, and seemed to have a pretty high rpm. The engine ran fine with it on, but it took a little while to get the mixtures right. Something interesting happened though, when i disconected the air line that went to the carburetor. The engine ran very fast for a few seconds and then died very quickly (about 1 second from the time i disconnected the line, the engine died --much faster than usual if i cut the fuel, and even the air as well). Im hoping this is a clue to what effect the turbocharging had on the engine, but it isnt any really good info because i didnt have time to play with the engine settings. Also a little after i took the intake tube off the custom header cracked and broke off (this is all that holds the turbo to the engine). So, I am thinking of adding an aluminum brace, and I will machine a thicker fitting to fix the cracked header. So my results were rather confusing, but i also didnt have time to really tweak the engine at all. I will try again when the header is fixed (a week from now, since we are off for christmas break), and i will also try to post my pictures again.
Any ideas on what effect the turbo had on the engine, and why it died so abnormally quickly? <<snip>>
<<snip>>As for the first test run that lasted more than a few seconds-
After the engine started the turbines immediatly spooled up, and seemed to have a pretty high rpm. The engine ran fine with it on, but it took a little while to get the mixtures right. Something interesting happened though, when i disconected the air line that went to the carburetor. The engine ran very fast for a few seconds and then died very quickly (about 1 second from the time i disconnected the line, the engine died --much faster than usual if i cut the fuel, and even the air as well). Im hoping this is a clue to what effect the turbocharging had on the engine, but it isnt any really good info because i didnt have time to play with the engine settings. Also a little after i took the intake tube off the custom header cracked and broke off (this is all that holds the turbo to the engine). So, I am thinking of adding an aluminum brace, and I will machine a thicker fitting to fix the cracked header. So my results were rather confusing, but i also didnt have time to really tweak the engine at all. I will try again when the header is fixed (a week from now, since we are off for christmas break), and i will also try to post my pictures again.
Any ideas on what effect the turbo had on the engine, and why it died so abnormally quickly? <<snip>>
I would venture to guess that, in order to operate, you had to richen the mixture up for the extra air supplied to the engine. Then when you pulled off the compressor pipe to the carburetor, the mixture was quite rich and cooled the glow plug. The extra liquid in the cylinder and the backpressure from the turbine at that point would apply a lot of load to the piston, making it stop the prop shaft in a hurry. At least that all sounds reasonable to me. That doesn't explain the rev up when you removed the boost line, though.
How did you keep the boost pressure from blowing the fuel back out of the carburetor into the tank? Did you pressurize the tank, too? I had assumed you would move the carburetor to the compressor inlet, but it sounds like you had the compressor piped to the carburetor inlet.
Best wishes,
Dave Olson
12-23-2005, 11:17 PM
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RE: My Turbocharged MDS .68
The fuel stays in the engine for two reasons:
One, because my fuel pressure tap is directly on the header - not on the muffler like normal engines, and
Two, because in the carburetor, the fuel tap is locatied in the center of the venturi. The venturi is used to create a low pressure because of the air having to travel faster (like the lift created by a wings airfoil), so this always provides a little "vacuum" within the boost if you will.... either way it works so beside all the mumbo jumbo thats all i need to know is that it does work.
in reply to "olstoney"- no this isnt a bunch of BS. I actually started this project because i was sick of all the arguments about small turbos, in which no-one had proof to back them up. I wouldnt think about posting this many times for something i didnt do-that would be a big waste of my time. Also i have tried to post pics, but when it loads and says that the pic has been saved or whatever it never shows up-- i think i need to downsize the pic tho. I will try after i am finished posting this. Oh yeah and a turbo is not the hardest thing to make in the world. Im only 18, and have access to a machine shop, and just wanted to do something different.... No BS, just having a good time.
One, because my fuel pressure tap is directly on the header - not on the muffler like normal engines, and
Two, because in the carburetor, the fuel tap is locatied in the center of the venturi. The venturi is used to create a low pressure because of the air having to travel faster (like the lift created by a wings airfoil), so this always provides a little "vacuum" within the boost if you will.... either way it works so beside all the mumbo jumbo thats all i need to know is that it does work.
in reply to "olstoney"- no this isnt a bunch of BS. I actually started this project because i was sick of all the arguments about small turbos, in which no-one had proof to back them up. I wouldnt think about posting this many times for something i didnt do-that would be a big waste of my time. Also i have tried to post pics, but when it loads and says that the pic has been saved or whatever it never shows up-- i think i need to downsize the pic tho. I will try after i am finished posting this. Oh yeah and a turbo is not the hardest thing to make in the world. Im only 18, and have access to a machine shop, and just wanted to do something different.... No BS, just having a good time.
12-23-2005, 11:34 PM
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RE: My Turbocharged MDS .68
I finally have some pics to show all of you: I cant get them directly to this page- i dont know why. But just click on my profile gallery and you can see all of them!!
12-24-2005, 12:14 AM
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RE: My Turbocharged MDS .68
to run an outer cooler you need a cooling chamber,there is no place to run an intercooler on rc engines they don't have any fluid system to cool the air down.having too much tolerance between the compressor shaft would lead to oil scavenging and burned out bearings every time,the heat generated from the compressor;s turning so fast would fry them with no adequate oil supply.i am curious as to how you are balancing these turbines?i don't think you are going to get the rpm's out of this thing that you expect.i have overhauled plenty of turbochargers and blowers in my time,the bearings are specially designed to take heat and high rpm's.are you going to design and build the steel rings for the seal on the intake side bearings,also the exhaust seal and diffuser?i have had exhaust side seals leak on turbo's and it Burns the shaft and compressor sometimes to a meltdown.a supercharges is more piratical on these engines.if this works i will be amazed.im not trying to be discouraging because all through the ages someone has always told the other that it cant be done.just trying to raise some concerns on your design,maybe you have this all figured already if so keep on trucking.i would love to see your photos,good luck on your project
12-24-2005, 12:31 AM
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RE: My Turbocharged MDS .68
w8ye- thanks for properly posting my pics... and for the compliment.
in reply to horace315: I do not have to balance my turbines because they have been so accuratly machined. I machined both of them on a Bridgeport mill fitted with Acu-Rite servo's and software, and machined them to size on a Supermax lathe.
I hope to take more pics tommorow now that the aluminum turbine has been completely machined, and the turbo has actually been ran and completed.
I didnt get time to fix the header at school today so it may be a while till the next test run... But make sure to check often because i WILL make sure to post again soon.
Enjoy the pics, -Preston
in reply to horace315: I do not have to balance my turbines because they have been so accuratly machined. I machined both of them on a Bridgeport mill fitted with Acu-Rite servo's and software, and machined them to size on a Supermax lathe.
I hope to take more pics tommorow now that the aluminum turbine has been completely machined, and the turbo has actually been ran and completed.
I didnt get time to fix the header at school today so it may be a while till the next test run... But make sure to check often because i WILL make sure to post again soon.
Enjoy the pics, -Preston
12-24-2005, 12:31 AM
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RE: My Turbocharged MDS .68
The article I remember on turboing a model engine was in Flying Models in the boat section. The housing was square aluminum with a 3/8" hole bored through and then each end counter bored 3/4" dia. by 1 or 2 inches deep for the rotors. The compressor was milled bar stock in a spiral pattern with the carb at one end and inlet tube at the other. The exhaust rotor was bar with straight milled slots with the housing slotted above center on both sides to pass the gasses across the top of the rotor. bearings were sealed types with both seals removed on the exhaust side and one seal removed on the intake with the open side mounted toward the exhaust. The shaft was 5/16" turned to 1/4" for the rotors and bearings to press on. Boost was controlled by leaving enough clearance between compressor and housing to allow blow by with the bearings oiled with exhaust residue and oil stopped by the one seal in the intake side. The author tried it with brass rotors ( large lag in response with slow spool down) and aluminum ones ( almost no lag ). No nitro and extra head gaskets to lower compression made it run good. I milled the head to lower compression and ran no nitro on a Veco 61, it ran great at sea level and at 5,000' without major adjustment but I did have to tinker with it to find the right adjustments of compression and mixture the first couple times I tested it.
12-24-2005, 05:37 AM
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RE: My Turbocharged MDS .68
Great work, nitro! Keep it up despite the naysayers.
Horace315 - Don't believe that I've ever heard of an 'outer' cooler, since the objective is to cool the compressed air, not to cool the air before it's compressed (and therefore gets hotter), but intercoolers don't need any 'fluid' (assuming that you are referring to liquid fluids, since air is a fluid) for their operation. Most all turbocharger intercoolers are air-to-air, whether the engine is land-based or in the air.
Horace315 - Don't believe that I've ever heard of an 'outer' cooler, since the objective is to cool the compressed air, not to cool the air before it's compressed (and therefore gets hotter), but intercoolers don't need any 'fluid' (assuming that you are referring to liquid fluids, since air is a fluid) for their operation. Most all turbocharger intercoolers are air-to-air, whether the engine is land-based or in the air.
12-24-2005, 06:50 AM
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RE: My Turbocharged MDS .68
From the pic, it wouldn't be hard to put the carb on the inlet side of the compressor where it would be more efficient. Idea is to have it put out more power with charger than without.
12-25-2005, 12:25 PM
#48
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RE: My Turbocharged MDS .68
I never thought about putting the carb before the turbo when I was first designing it. However.. you cant see from the pics that well... but the clearance between the turbo inlet and the propeller spinning around is only around a half an inch- imagine trying to adjust that with the engine running! But, maybe i can always machine an adapter later for it.
I did see another forum where a guy had a supercharged airplane engine, with the carburetor before the turbo inlet and it seemed to work out quite well for him.
I did see another forum where a guy had a supercharged airplane engine, with the carburetor before the turbo inlet and it seemed to work out quite well for him.
12-25-2005, 06:53 PM
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RE: My Turbocharged MDS .68
Does anyone have any pictures of any other RC turbochargers for airplanes that have been made? I am curious to see their designs. I have seen a few turbochargers made for cars before, but not for airplanes.