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supercharger

Old 03-29-2005, 06:43 PM
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crankshaft
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Default supercharger

anybody seen the rbinnovations superchargers? has anybody tried it or know if they run good? I was looking at one for the .25. i noticed that they are compressing the air before it goes through the carburetor. a carburetor relies on a vacuum to draw fuel from the needles, so wouldn't that screw up the fuel delivery? also, the compressed fuel/air has to go through the crankcase, which seems to have problems sealing at one atmosphere of pressure. the other problem i have with it is that the intake and exhaust ports on a 2stroke engine are open at the same time. the incoming fuel/air is forced in through the ports by the pressure created in the crankcase by the downward motion of the piston. it is also drawn into the cylinder by the vacuum created by the exhaust gases leaving the cylinder, called a scavenging effect. it is important to the performance of the engine to have this correct, as well as the angle of the ports and even the shape of the combustion chamber. its all relative, and pressurizing the intake charge would affect this. it is possible, and seems to me fairly likely that you would loose a lot of your incoming fuel/air through the exhaust port if you increased the pressure of the intake charge. based on this, their claims sound like bull**** to me. i could be completely wrong as these are only my theories based on what knowledge I have. i was just wondering if anybody had run one of their superchargers and if they had any luck with it.

thanks
Old 03-29-2005, 09:10 PM
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dan6362001
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Default RE: supercharger

Im not an expert on nitro engines but what you said makes sense to me. All I know is that a supercharger,turbo or anything of the sorts just leans out your engine. They require you to richen significantly to make up for it and in turn you end up with basically the same performance and a big hunk of expensive worthless metal.

Old 03-29-2005, 10:34 PM
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46u
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Default RE: supercharger

If you do a search you will this topic has all ready been covered! These are nothing more then a waste of money.
Old 03-30-2005, 12:22 AM
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tndiverdown
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Default RE: supercharger

ORIGINAL: 46u

If you do a search you will this topic has all ready been covered! These are nothing more then a waste of money.
I wish I had a quarter for every time that someone comes on here asking about superchargers. Total gimick and a waste of money. A good tuned pipe will far outperform a supercharger on a glow engine for lots less money.
Old 03-30-2005, 01:49 AM
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claccytim
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Default RE: supercharger

I can fully unerstand what you guys are saying but it should have a reasonable effect, this comment is based on practice.

I have a savage 21 and also a hyper 21, which is running with the hyper 8 port, now if you look at the specs you will see the hyper 8 port outperforms the savages standard .21 BB. now look at the engines themselves, and you will see one major difference, the hyper 8 port has a form of supercharger built in to it on the back plate. after swoping engines i have found that the savage keeps up with other savages using the standard .25...

I cant help nut wonder if a supercharged .21 can keep up with a .25, then what would a supercharged .25 do???

also a supercharged .25 would have a much better power curve than a standard .28 so you wouldnt have the same "I cant stop it from wheelie'ing" problems as you would have with a .28, but i should imagine the mid and top end would be similar.

I dont fully understand it myself but it could be something to do with the fact that a standard 2 stroke doesn't expell all of the exhaust during a piston cycle, but with a supercharger the increased intake pressure would force the exhaust gases out of the cyclinder, thus freeing up more space for fuel/are mix on the next cycle.
Old 03-30-2005, 08:29 AM
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Default RE: supercharger

You are dreaming.



REAL (1:1) bolt on street-chargers make 40-50% more horsepower.

The magazine dynos showed a 3% gain with an externally powered (doesn't drag it's 3% gain from the crank like the RBi charger) unit. So for something that is nearly the cost of my engine to give me 3% is just crap. A good tuned pipe will make a bigger difference, as was noted above.
Old 03-30-2005, 08:30 AM
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ed260z
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Default RE: supercharger

The impeller on the back of the Hyper .21 is not a turbo or a supercharger of any kind. It's purpose is to atomize the fuel for a better burn, which gives it a bit more power. Because of the way these things make power, a supercharger or turbo, just won't work on a 2 stroke motor.
OS is coming out with a 4 stroke .21 car engine. A supercharger can in theory work with that engine.
Old 03-30-2005, 06:42 PM
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crankshaft
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Default RE: supercharger

a 4stroke car engine? that's awesome. where did you here that? .21 is pretty small for a 4stroke, they make less power and turn less rpm than 2strokes. that would still be cool though. its been a while since anybody put a 4stroke in a car, at least that i know of.
Old 03-30-2005, 09:43 PM
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Default RE: supercharger

i have read in other posts about this supercharger and everyone says the same thing "they dont work on a 2-cycle engine" well some friends of mine are into snowmobile hillclimbing and one of thier sleds has a turbo, another guy has nitros and my other friend is running a supercharger on his. i think the sled running the nitros has like 200 hp or so and the supercharged one is around 250, im not sure what the turbo sled has for power. im just trying to figure out why superchargers and such work on a 2stroke snowmobile but not a 2 stroke r/c car engine.....anyone have an idea?
Old 03-30-2005, 10:22 PM
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Default RE: supercharger

...... our glo engines share little to nothing with the type of engines you are referring to. It's apples and oranges really.

This is the deal, you can't create boost in the cylinder because when the intake port is opened so is the exhaust. The positive pressure is bled off through the exhaust port.
Old 03-30-2005, 10:22 PM
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Default RE: supercharger

OS and others have been making 4-stroke car and truck engines for quite a few years. You are right they will be much slower then the 2 strokes as 2 strokes are the cheapest way to make HP. Just hope they do not do them like they are on motor cross bikes. Will not be much longer before 2 cycle race bikes are outlawed do to pollution. They outlawed 2 stokes on road use in the US in the seventies.
Old 03-30-2005, 10:32 PM
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gasoline hpi
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Default RE: supercharger

yeah it sucks, 2cycles make more pollution because they burn oil. i dont know that they even necessarily outlawed 2strokes, they just couldnt pass emissions. only some diesel engines now use 2stroke and can still pass emissions, i guess because diesel fuel naturally acts as a lubricant so maybe they dont need oil. even that was a few years back, so they may not even be around anymore.
Old 03-30-2005, 10:41 PM
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CR500rider
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Default RE: supercharger

frost....this is the first time i have disagreed with what you are saying... my 2 stroke dirtbike and my friends snowmobiles engines operate the exact same way as 2 stroke r/c car engines except for they have spark plugs and not glow plugs. all 2 stroke engines need the incoming fuel charge to push out the exhaust gasses, therefore on all 2 strokes the intake and exhaust ports will allways be open at the same time for a brief moment. I am not saying that the super charger will work on an r/c car engine, i believe that is just a sales gimmick and bling factor. But i do know for a fact that they do work on snowmobiles.
Old 03-30-2005, 10:43 PM
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Default RE: supercharger

Emissions have to do with pollution about the same thing. It is what is being put in the air either way you say it. If you look you will see that there are more 4-cycle motocross bikes then there ever has been because 2 cycles are on their way out do to emissions or what ever you want to call it. I agree with Frost how can you force more air and fuel in a motor like we run when both the exhaust and intake port are open at the same time. All you would be doing is wasting more fuel as it would go straight throw an out the pipe.
Old 03-30-2005, 10:52 PM
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tndiverdown
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Default RE: supercharger

ORIGINAL: CR500rider

frost....this is the first time i have disagreed with what you are saying... my 2 stroke dirtbike and my friends snowmobiles engines operate the exact same way as 2 stroke r/c car engines except for they have spark plugs and not glow plugs. all 2 stroke engines need the incoming fuel charge to push out the exhaust gasses, therefore on all 2 strokes the intake and exhaust ports will allways be open at the same time for a brief moment. I am not saying that the super charger will work on an r/c car engine, i believe that is just a sales gimmick and bling factor. But i do know for a fact that they do work on snowmobiles.
Hey, finally another person than knows how a 2-cycle works whether it be glow or ignition.
Old 03-30-2005, 11:01 PM
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Default RE: supercharger

yeah i know how they work, been riding and wrenching on dirtbikes and snowmobiles since i was a youngin, i also hate the fact that they are replacing them with thumpers. On the brighter side the thumpers go longer between rebuilds
Old 03-30-2005, 11:01 PM
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Default RE: supercharger

I do not know about snow mobiles as there is not much snow where I live in Georgia but I do know from working on motorcycles for over 30 years that a lot of high performance 2 cycle dirt bikes have what is called a power valve that changes the size and shape of the exhaust port. Which in turn make it where the ports are a little more off set at low RPM’s.

Please list a manufactures web site on snowmobiles that sell them with a super or turbo charger on them. If they are running them there is more to it then just a normal 2 stoke motor and they are much more complex then just a normal 2 stroke. Or may be they are like some old 2 stokes that use to have a rotor valve on the crank where the in take port was not open all the time. All so most all-2 stroke motorcycles have reed valves on the intake.

So you might be right but once again you are comparing oranges with apples.
Old 03-30-2005, 11:05 PM
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gasoline hpi
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Default RE: supercharger

that is correct, I believe. the intake charge is not only forced in by the pressure created in the ports, but is also drawn in by the pulse created by the exiting fuel/air, and to get this right, so you get out as much burnt air/fuel while losing the least possible amount of unburnt fuel/air, is important, thus we run tuned pipes not open exhaust. by forcing the air into the ports, you increase its velocity and cause more fuel/air to be let out the exhaust than is supposed to be, and you end up losing uburnt fuel/air from the exhaust. i guess with different valve timing, or even just with a different tuned pipe to change the scavenging effect, it may be possible to create pressure in the cylinder without losing it all out the exhaust. but I dont think it can be made to work with one of these little rc engines. at that, compressing the air causes it to be heated up, resulting in a less dense in take charge and a loss of power.
Old 03-30-2005, 11:17 PM
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Default RE: supercharger

ORIGINAL: CR500rider

yeah i know how they work, been riding and wrenching on dirtbikes and snowmobiles since i was a youngin, i also hate the fact that they are replacing them with thumpers. On the brighter side the thumpers go longer between rebuilds
Me too on the yougin part. I have to admit thumpers have come a long way in the last 10 years or so. I still love the light swicth power of my banshee.
Old 03-30-2005, 11:32 PM
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gasoline hpi
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Default RE: supercharger

i grew up with the thumpers. I drove gokarts we ran briggs engines. they were just one cylinder 4strokes (basically lawnmower engines) set up to run on methanol. go to admit though, theres nothing quite like a 2stroke once it gets on the pipe.
Old 03-30-2005, 11:42 PM
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Default RE: supercharger

I know what you mean as I had a briggs 5 HP that when I got done with it, it was putting out over 30 HP running on methanol.

I was all so thinking the crank valve we run in the RC engines would be a lot like the old rotor valve in the old 2 cycle motorcycles. I have been fulling with motors for over 40 years. Got my first motorcycle in 1969 and never stopped riding since.
Old 03-30-2005, 11:44 PM
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Default RE: supercharger

i agree with some of that except the power valves used on modern dirtbikes and snowmobiles only change the top of the exhaust port. its the very top of the intake ports and the entire exhaust port that are open at the same time, remeber that on a 2 stroke the piston is the valve that allows the intake charge to enter the combustion chamber. the reed valves keep the charge from escaping just like the crank on a crank port engine keeps the charge from escaping on a crank port engine. But once it enters the combustion chamber it is all the same regardless if they have the exhaust power valve. as far as i know there isnt a snowmobile manufacterers that put a supercharger or turbo on a snowmobile...it is all in the aftermarket. do a web search and i am sure will find some. also i would like to add that even on high performance 4 cycle engines (cars and bikes) the intake and exhaust valves are open at the same time, just not as long as on a 2 cycle, it is called valve overlap and it helps scavenge exhaust gasses out but in return you lose some vacuum
Old 03-31-2005, 12:19 AM
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Default RE: supercharger


ORIGINAL: CR500rider

i agree with some of that except the power valves used on modern dirtbikes and snowmobiles only change the top of the exhaust port. its the very top of the intake ports and the entire exhaust port that are open at the same time, remeber that on a 2 stroke the piston is the valve that allows the intake charge to enter the combustion chamber. the reed valves keep the charge from escaping just like the crank on a crank port engine keeps the charge from escaping on a crank port engine. But once it enters the combustion chamber it is all the same regardless if they have the exhaust power valve. as far as i know there isnt a snowmobile manufacterers that put a supercharger or turbo on a snowmobile...it is all in the aftermarket. do a web search and i am sure will find some. also i would like to add that even on high performance 4 cycle engines (cars and bikes) the intake and exhaust valves are open at the same time, just not as long as on a 2 cycle, it is called valve overlap and it helps scavenge exhaust gasses out but in return you lose some vacuum

I agree with most of what you say but you say you know for fact that super or turbo charger works on snowmobile 2 strokes. Do you have one or are the companies that sell them all hype like on the RC engines. I still do not think either are worth it and there are better ways to increases performance then turbo or supercharge on a 2 cycle. I am all most 51 and I am still learning every day and I like to be proven wrong because that is one way of learning.
Old 03-31-2005, 12:29 AM
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Default RE: supercharger


ORIGINAL: CR500rider

i have read in other posts about this supercharger and everyone says the same thing "they dont work on a 2-cycle engine" well some friends of mine are into snowmobile hillclimbing and one of thier sleds has a turbo, another guy has nitros and my other friend is running a supercharger on his. i think the sled running the nitros has like 200 hp or so and the supercharged one is around 250, im not sure what the turbo sled has for power. im just trying to figure out why superchargers and such work on a 2stroke snowmobile but not a 2 stroke r/c car engine.....anyone have an idea?
If he has a turbo on his snowmobile, than the engine is a 4 stroke.
Old 03-31-2005, 12:29 AM
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Default RE: supercharger

yeah, i know for a fact. i am friends with some snowmobile hillclimbers that have forced induction of some sort (one has a supercharger and the other has turbo) and they let me ride thier machines...very impressive actually

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