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Roots Type Supercharger

Old 09-06-2012, 03:41 PM
  #26  
glennb2006
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Default RE: Roots Type Supercharger



Glenn- I have seen simular done on nitro boats but without the water. Seen one that had a adjustable pipe, and a 3rd channel mixture control. Both the pipe and the mixture control workeed together, I am assuming as the turn would approach the pipe would lengthen and fatten the needle up for good power out of the turn then on the saw shorten the pipe and lean her down! I could see that being a nightmare to get setup and working right!
[/quote]

The best way to do it, but would need some electronics would be to have the pipe length control servo controlled by an engine rev pick up unit, as the revs rise across a range, pipe goes from long to short at max revs, hopefully following somewhat the torque curve of the motor and thus adding perfomance across a braoder spread. Need an electronics boffin, though it would not be that hard to do.
Guess the ultimate would be similar to the old two stroke bike power valve systems where revs and throttle position were measured and the power valve is adjusted to suit.
The mixture should not be too much of an issue, the carbs stay fairly consistant.

"I also realize that a 4-stroke would be easier, But that is not the "look" that I want. And I realize that RBInovations has a centifugal type supercharger but this again is not the look I want. This is more about the look than the amount of boost I will get. I do want it to boost power and by doing this I may stumble across some solutions that have been a problem with supercharging 2 stroke engines. I am sure that I will have alot of problems to overcome. "


The biggest problem to overcome is going to be the fact that you are going to be trying to pressurise the crankcase then as the transfer ports open, a lot of that pressure is going to force a disappearing act out the open exhaust port. I think that you are going to have to make some pistons to experiment with the timing to get this to work.

But all part of the fun.

Glenn
Old 09-07-2012, 03:16 PM
  #27  
Mike2735
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Default RE: Roots Type Supercharger

I have finished designing what I think is an operational exhaust power valve. The way I am understanding this is: With the boost from the super charger, the exhaust gases with escape faster because of the pressure. If I set the timing of the power valve to close for the last half of the time that the piston is still open to the exhaust port, I should have time to add some boost to the charge that is entering the chamber. The power valve will open completely when the piston is above the exhaust port. Is my understanding correct?? I am posting an exploded view of my power valve design.

Let me know what you think!!

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Old 09-07-2012, 05:40 PM
  #28  
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Default RE: Roots Type Supercharger


ORIGINAL: Mike2735

Has anyone ever built a roots type supercharger for one of our gasoline engines? I just had a thought that it would be cool to do. I don't want to push too much boost but thought it might be something that would add some horsepower.

All comments welcome!!!!

Mike Moore
Nashville NC
check this Efficiency Engineering model engine Supercharger .. just a thought [8D] http://www.ebay.com/itm/330788260922...84.m1423.l2649
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Old 09-07-2012, 05:51 PM
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Mike2735
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Default RE: Roots Type Supercharger

Specialk1 - Thanks for your reply, I know that will work but it is not the look I want. The pic I have posted is the look that I want. I want it to look like a blower and sound like a blower. I have a lot of work in front of me to get this to work, but I believe I can. I don't know how much boost I can achieve but I will do whatever I can to make this work.

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Old 09-07-2012, 06:24 PM
  #30  
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Default RE: Roots Type Supercharger


ORIGINAL: Mike2735

Specialk1 - Thanks for your reply, I know that will work but it is not the look I want. The pic I have posted is the look that I want. I want it to look like a blower and sound like a blower. I have a lot of work in front of me to get this to work, but I believe I can. I don't know how much boost I can achieve but I will do whatever I can to make this work.

well if you are good with a CNC . try this casting kit . 1/3 SCALE SUPERCHARGER made in the USA try this link http://www.google.com/url?sa=t&rct=j&q=ken's%20model%20engines%20superchargers&source=web&cd=2&cad=rja&ved=0CCUQFjAB&url=http%3A%2F%2Fwww.nvbackflow.com%2Fengines%2Fbl owers.htm&ei=x6tKUOKvDIKu8QTLr4HoCg&usg=AFQjCNG7aNTZ1Lf6otZRKUf_PW-Qhuty2g
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Old 09-07-2012, 06:30 PM
  #31  
Mike2735
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Default RE: Roots Type Supercharger

Thanks for the link. That is what I'm talking about. Look like it might be a place to start.
Old 09-07-2012, 06:35 PM
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Default RE: Roots Type Supercharger


ORIGINAL: Mike2735

Thanks for the link. That is what I'm talking about. Look like it might be a place to start.
or just buy one from Conley Precission models . Supercharger ... $1,695.00 comes with two carbs .. http://www.google.com/url?sa=t&rct=j...QUQGge1fBjPpOQ
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Old 09-07-2012, 08:45 PM
  #33  
d-lo
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Default RE: Roots Type Supercharger

i actually love this thread! i know this topic has been beaten to death, but i love the ideas popping up, and i admire the drawings and motivation popping up in here......

i am a blower man by trade, my 'drive daily as much as i can afford' car is pictured below. NOTHING beats the sound of this animal going down the road.

good luck with your path, keep us posted!
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Old 09-07-2012, 09:50 PM
  #34  
Mike2735
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Default RE: Roots Type Supercharger

d-lo - Thanks for the encouragement. And that is an awesome ride!!!!!!!!!!!!!!

As you can tell, I am still in the design/planning stage but I will keep everyone posted on the progress.

Old 09-08-2012, 02:16 AM
  #35  
Jackal1983
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Default RE: Roots Type Supercharger

here you go.

Me rebuilding an SSI 14/71 hi helix retrofit blower from the tractor puller.



Mike the power valve is mean to play around with the timing on the engine so the blade has to wrap around the piston... it works via a diapfram sensing the pressure on the exhaust port after the blade... the higher the rpm the more pressure so the diaprahm lifts the blade out to higher the exhaust port.

if you did this on the exhaust outlet of the engine you would be interupting the sonic wave goming back so could make it alot worse!
Old 09-08-2012, 02:36 PM
  #36  
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Default RE: Roots Type Supercharger


ORIGINAL: Mike2735

I have finished designing what I think is an operational exhaust power valve. The way I am understanding this is: With the boost from the super charger, the exhaust gases with escape faster because of the pressure. If I set the timing of the power valve to close for the last half of the time that the piston is still open to the exhaust port, I should have time to add some boost to the charge that is entering the chamber. The power valve will open completely when the piston is above the exhaust port. Is my understanding correct?? I am posting an exploded view of my power valve design.

Let me know what you think!!

Mike- I dont think this would be considered a power valve! A power valve on a 2 stroke changes the volume of the pipe to help in all ranges of rpms. It would be the same as if you had a straight tunde pipe and attached a sliding tube on the pipe so you could shorten and lengthen it at a moments notice. Basically a longer pipe will give you more low end and a shorter pipe would work better on the top end. So one would start off with the pipe long and as the rpms increased the pipe you would want to shorten the pipe. It's all about how long it takes the soundwave to return. A power valve just increases volume or decreases it depending on the rpms of the engine.
Also- The exhaust valve you have drawen up looks good, but I might suggest going with a butterfly valve instead as it could be moved much faster, that being said- if you are only planning on running 4-6 psi of boost, the soundwave from the tuned pipe might just be enough to hold your fresh charge where it needs to be, You might be surprised!
Old 09-08-2012, 06:08 PM
  #37  
Mike2735
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Default RE: Roots Type Supercharger

Thanks for your replies guys.

I stand corrected. It is not a power valve. It is an exhaust cutoff valve.

I did think about a barrel type valve like is in a rotary carb. I still have that design. That is similar to a butterfly valve. Your other point brings a new question. From looking at my design, can you suggest a drive ratio to accomplish 4 to 6 psi of boost. It is drawn with a 2 to 1 ratio for reference only. I think that will be a bit much but am not sure.

Old 09-08-2012, 06:33 PM
  #38  
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Default RE: Roots Type Supercharger

ORIGINAL: Mike2735

Thanks for your replies guys.

I stand corrected. It is not a power valve. It is an exhaust cutoff valve.

I did think about a barrel type valve like is in a rotary carb. I still have that design. That is similar to a butterfly valve. Your other point brings a new question. From looking at my design, can you suggest a drive ratio to accomplish 4 to 6 psi of boost. It is drawn with a 2 to 1 ratio for reference only. I think that will be a bit much but am not sure.

Mike- I apologize if I upset you with my last comment, just dont want there to be any confusion down the road. When the phrase power valve is used regarding 2 strokes most guys think of the KIPS or ATAC system (Kawasaki and Hondas power valves).
Yes I will look at your drawings and see but it might be hard to tell. It is fairly easy to adjust the boost, just change your pulley sizes. I would think running a roots style blower at normal crankshaft speed would get you pretty close to 4-6 psi but that also depends on other factors, one being blower displacement and how efficent it will be.
Old 09-08-2012, 09:50 PM
  #39  
Mike2735
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Default RE: Roots Type Supercharger

8Mills - Didn't mean to come off as upset. I was not in any way. I had just acknowledged the fact the I had it wrong.

The dimensions of my design might help: The rotors are 1 inch in diameter and 3 inches long. I have my blower pulley half the size of my crank pulley. That is why I said 2 to 1 ratio. I will change it to a 1 to 1 ratio. I also made it a twin carb setup to help with the leaning condition that will happen under boost. I plan to have an incremental throttle on the second carb that is adjustable.

Thanks everybody for all their help and keep it coming.

Old 09-08-2012, 09:59 PM
  #40  
Mike2735
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Default RE: Roots Type Supercharger

Here is a better picture of the engine assembly.

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Old 09-08-2012, 10:51 PM
  #41  
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Default RE: Roots Type Supercharger


ORIGINAL: Mike2735

Here is an exploded view of what I have planned. Let me know if you see anything wrong with my design. The rotors have a 120 degree twist like the Eaton supercharger. I don't know if this will work on such a small ap[lication.

Thanks.

Mike Moore

Mike,
I know your engine is a twin is it 50cc or 100cc? And what is the max rpm should be around 7,500- 10,000 of course you will need to either buy or make some tuned pipes for this engine which will increase it's performance and could possibly take this engine into an rpm range that could be higher than the case can handle. 10k + rpms is not really wanted for a prop driven vehicle as the prop blades are approaching or beyond the speed of sound, I suppose you would have to find the right prop that will keep your rpms down. A problem I see is the sound from the tuned pipes will easily dround out the whine from the blower. Two options, you could run some fairly restrictive mufflers on the pipes which would also give you more backpressure which would help hold your fresh charge in the cylinder as well. Option 2, you could run some type of quiet muffler maybe underwater? and put your butterfly or rotary valves in. One issue I think we are overlooking here is heat, you will be generating more heat than the original heads were designed for. The fact that it will be on an airboat is a huge plus as usally the first couple feet above water stays alot cooler than ambient air, or there is always the option of making watercooled heads for it (that would most likley be my choice). Anyways, without knowing the displacement of the blower I would guess that you would be pretty close running the blower at crankshaft speed. Once you have the blower built you can measure what rpms it's gonna take to make the boost you want, then make your pullies, maybe make a few different pullies to experiment with!
Old 09-08-2012, 11:03 PM
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Mike2735
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Default RE: Roots Type Supercharger

The engine is a 50 cc twin. The RPMs should peak out around 7000. I would like to make the heads water cooled but I am not sure I can run a water pump with the blower pressure interrupting the normal pulse from the crankcase. And that brings another question: Will the pressure from the blower affect the carb diaphragm operation?
Old 09-08-2012, 11:03 PM
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Default RE: Roots Type Supercharger


ORIGINAL: Mike2735

8Mills - Didn't mean to come off as upset. I was not in any way. I had just acknowledged the fact the I had it wrong.

The dimensions of my design might help: The rotors are 1 inch in diameter and 3 inches long. I have my blower pulley half the size of my crank pulley. That is why I said 2 to 1 ratio. I will change it to a 1 to 1 ratio. I also made it a twin carb setup to help with the leaning condition that will happen under boost. I plan to have an incremental throttle on the second carb that is adjustable.

I dont think you will have a problem with a lean condition under boost, but your carb idea is a good idea!

Thanks everybody for all their help and keep it coming.

Old 09-08-2012, 11:56 PM
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Default RE: Roots Type Supercharger

No you will still have a pulse, you dont really need a water pump to watercool the heads, you can run two water pick up lines from the rear of the boat, that would give you plenty of water flow
Old 09-09-2012, 03:41 PM
  #45  
glennb2006
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Default RE: Roots Type Supercharger

The power valve I refered to in an earlier post was based around the Yamaha system from days gone by (the 80's, some great electronic music and loads of freedom - Happy days) anyway, the Yamaha system did not effect expansion chamber volume, it altered port height, so, it was very effective in creating a docile higher torque motor below 3K RPM when the PV started to open, but the engineers were still able to have a screamer above 6K RPM when the valve was fully open. Kawsaki, Suzuki and Honda tried their versions and never beat Yamaha, only Aprilia ever got something better - and that cylinder on the RS125 is something that should be a base reference for all engine design (2 stroke) to come.

It's all relative as the materials technology now is so much better that we could have seen a whole heap more from two strokes before they were stopped.

Mark my words - they will return.

However, back onto the supercharging subject, I think it can be done if you are clever enough, but I also think that you will struggle to achieve power outputs matching the stock output.

As you seem to be looking for looks as well as functionality, is a "scale" model SC not something you could create and mount on top of your motor to look authentic?

Glenn
Old 09-09-2012, 04:00 PM
  #46  
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Default RE: Roots Type Supercharger

glennb- I am not familiar with the rs style power valve. I agree with you about the 80's- some great years for alot of things, I have a 87 YZ125 bike sitting in my garage- considered one of the best motocross engines ever built, love that bike. All of the powervalves of that era had issues with carbon build up but there are a few things you could do to the yamahas to help prevent the carbon from sticking and of course newer lubricants help in that department as well. I have owned them all currently still own a 85RM 125 and 87 CR 250 and the Yamaha power valve by far is the better one. I hope you are right about the 2 stroke making a comeback.
Old 09-24-2012, 08:54 PM
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Default RE: Roots Type Supercharger

been following this thread and am curious to see what is going on . any luck ?
Old 09-24-2012, 09:10 PM
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Mike2735
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Default RE: Roots Type Supercharger

I am still working the design. I should be able to start machining soon.

Thanks for your interest.

Mike M.

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