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Teh SPIK
or an emissions pump off a small car!
Homemade supercharger
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Teh SPIK
Dear god.. Please tell me no one has bought one...
as stupid as it sounds and looks for a real car that might work on a small engine
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Teh SPIK
thats why i mentioned the emissions pump it sucks in a good amount of air and is belt driven so as your engine revs higher more air is being sucked in and is simpler then a electirc fan with a fixed air flow speed
This is more like, more ideas. If people really want a supercharger or such we need ideas to help. And to the ones who have more technical information when you put in your input try to help us (the less educated in this specific part of engines in general) understand how we can make this work...
So anyone got a few bucks to spend =P
So anyone got a few bucks to spend =P
some one should make a supercharger like the ones on older carby cars. where the carb sits on the super charger and it sucks more air and fuel in it. mabey have it belt driven and im gettin a idea here. my engine the intake is like right over the jack shaft extend the jack shaft have it belt driven and then it goes with what the tav speed is.
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Teh SPIK
here u guys go: http://karting.4cycle.com/showthread.php?t=199318&highlight=smog+pump
heres what i ment about the emissions pump and theres a link to it
heres what i ment about the emissions pump and theres a link to it
frederic
The Junk Man
There are two defects with this configuration. First, the back of the belt is not exactly a traction surface like the ribbed side, therefore it will be prone to slip. Second, only about 15% of the pulley is covered by the belt, meaning it will be prone to slip.
Emissions injector pumps are of the vane style which is okay for higher flow, low pressure applications and this is exactly what they are for on a vehicle. They do not produce pressure, and if you were to remove the tube from your vehicle's injector pump, cork it, and thread in a pressure gauge you'd be lucky to find 1psi: http://www.pumpschool.com/principles/vane.htm
The emissions pump's sole purpose is to pump fresh air into the exhaust manifold(s) so the catalytic converter can use the pumped in oxygen (found in fresh air) to burn unspent fuel vapor and flammable gasses that left the engine instead of burning in the engine.
Ford units (which I am familiar with) take a hair under one HP to turn if the exhaust side is plugged and you'll get less than 1 psi. Lets round both to "1" to make the example easier to grasp:
A 5 HP briggs will give you 5 HP naturally aspirated, peak.
A 5 HP briggs with 1 psi of boost will give you 5.38 HP peak, but you're losing 1HP to drive the injector pump - so you're down to 4.38 peak HP.
You either need to find, buy or make a pint-sized supercharger or turbocharger based at least loosely on say, the Garrett design. Anything short of that will be an amusing adventure to learn something, but with fruitless results.
Thinking about it some more, a "wipple" design is probably easier to machine, but again the clearances must be real tight or you won't get any real pressure. Forced induction requires pressure, AND flow, not one or the other.
You cannot make power out of nothing.
Raywelder
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BradenM
Etre Et Durer.
A tiny tubo would work on your opposed twin. Whats the displacement?
sideways
Unfinished projects king.
i might acctually get one, thier worth an experiment i think. you've got to remember that we are dealing with engines less than a tenth of the size here, you could even butcher one so that it ran off a pulley instead of electricity BUT we have to make some kind of governer system to keep the supercharger spining at the same revs contantly other wise as revs go up so does pressure produced wich could cuase all kind of problems, even on a briggs thats still limited to 3600rpm the pressue is going to double for idel to flat out, a centrifugal type governer mounted on the pulley could be made fiarly easily but adds compexity
Raywelder see the tubos i posted before, they will get you your boost, reliably
frederic
The Junk Man
That looks to be sized appropriately!
Let's say the 1-2psi rating is not bogus (I've seen these fans before and know several who got nothing out of them).
You will need to provide 10 amps to drive the fan for a 2psi gain. That 2psi gain will make a 5HP peak engine give 5.66 HP, for a .66 HP gain.
Watts = HP * 746
492.36 watts
It's a 12V fan motor that draws 20 Amps so 12V * 20 A = 240W of power necessary.
You would gain 492.36 - 240 peak watts (252.36)
Or, 0.338 peak horsepower gain.
That's assuming the non-sealing fan actually can deliver 2psi, which it cannot.
This is assuming the engine is operating at peak HP RPM all the time and the engine's ability to turn an alternator to provide the necessary electricity is 100% efficient and has no friction.
A free spinning new alternator without any electrical load whatsoever requires 0.21 HP to spin at the necessary speed where it could produce useful electricity.
To your kart you've added a 25 lb alternator plus the additional weight of the fan, belt and pulleys and new intake tract which lowers the usefulness of the additional 0.338 peak horsepower.
Alternators are barely 75-80% efficient, reducing the usefulness of that gain even further.
By all means, buy one and play with it. It's an excelent learning experience that can help you understand how turbochargers and superchargers work.
Regarding hacking a "real" turbo to make a supercharger, that's very doable, but again the power gained has to exceed the power drawn otherwise it's not a useful system. For a turbo intake housing (scroll) to be efficient, you need to spin the thing above what the boundary layer of air in the housing will shear at, as that's how it seals. Typically this is in the 50,000 RPM and up range. So you will need to devise a device or mechanism that takes the 3600 RPM off the crankshaft and "steps it up" to at least 50,000 RPM. That adds weight, cost, packaging issues, and so on as well.
Anyway, here is a "monkey way" to size a turbo from donor vehicles, and while not precise mathematics it at least puts you in the ballpark.
Destination displacement x destination engine RPM
--------------------------------------------------------- = destination turbo quantity
Donor displacement x donor engine RPM x donor turbo qty
Lets say you have pull a Chrysler turbo out of the junkyard, off a Dodge Daytona. The donor part of the equasion would work like this:
Donor (2.5L * 6500 * 1) = 16250
And lets say you're going to put that turbo onto a 351W Ford engine (5.8L), the math works out like so:
5.8L * 5500
------------ = destination turbos (1.96307)
16250
This means to turbocharge a Ford 351W small block V8, you would need approximately 1.96 Dodge Daytona factory turbos, meaning two.
Regarding a motorcycle turbocharger... what is the displacement of a 5 HP lawnmower? 125 cc? What is the displacement of a turbocharged motorcycle? 750 cc? Do you think there could possibly be enough hot, expanding exhaust to drive that turbo? Probably not. It will spin, sure, but it won't have enough power to generate any boost and it adds weight which reduces your overal kart's performance. Adding 50 lbs of "stuff" to a small go-kart that probably weighs 250 lbs total is a massive performance hit as compared to adding that same 50 lbs to say, my 6997-lb F350 crewcab.
While the math is the same for philosophical discussions, things that are "tiny" (like a kart) are more heavily influenced by minor adjustments in the parameters.
frederic
The Junk Man
I am not trying to discourage anyone from experimenting, if that's their thing. By all means. Certainly, experimenting and brainstorming is a great way to learn. I've done many things along these lines myself.
Unfortunately, the automotive aftermarket crowd has tried all of these ideas and the rear-world success rate (despite the claims) is zero, and I'm sharing this as well as some of the simpler math because I'm trying to save people the effort involved in building such things only to be disappointed...
To fabricate your own supercharger or turbocharger you need to be able to provide much more CFM than the naturally aspirated engine would normally take in, at a given pressure.
To achieve this you need flow, and pressure, and you can't do that without a seal of some kind, and that's why I keep harping on this.
Here is a "ballpark truth". If you have a 5 HP engine, and you want it to produce 10 HP at the same RPM, you need to double the airflow (cfm and pressure) and fuel.
You can easily figure this out as well.
CFM = bore x stroke x RPM/1728
Double that figure for the minimum CFM requirements of your forced induction device, then find a forced induction device that can maintain that CFM well above atmospheric pressure?
That will give you 10 HP out of a 5 hp engine.
Can your little fan provide 150 cfm at 10 psi?
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Teh SPIK
i'll give that supercharger plan a try but frederic you just really killed my inspiration dude.... lol
Kaptain Krunch
Pro Junk Collector
why dont we all get sled and mc engines, that way we dont need to supercharge. Besides, a supercharged lawnmower engine wouldnt last very long.
frederic
The Junk Man
Right! Or, if you guys are using a 5HP engine and want 10HP, get a used 10HP lawnmower engine. It's likely to be a lot easier to install than a homemade supercharger system on a 5 HP
The cheapest way to make "more" power with gasoline is to increase physical displacement, generally speaking.
This is why "car guys" often swap out small blocks for big blocks. Then once they get "used" to big blocks and are again unhappy with performance, they get into forced induction and/or nitrous.
"There is no replacement for displacement". Ask any hot-rodder ;-)
Not trying to discourage, just wanting to share what little knowledge I have hoping those interested in this don't waste time and money. I've been down this road myself and after a while it got expensive for no measurable gains.
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Teh SPIK
i dont need my engine to last long dude thats why i'm willing to try it
Right! Or, if you guys are using a 5HP engine and want 10HP, get a used 10HP lawnmower engine. It's likely to be a lot easier to install than a homemade supercharger system on a 5 HP
The cheapest way to make "more" power with gasoline is to increase physical displacement, generally speaking.
This is why "car guys" often swap out small blocks for big blocks. Then once they get "used" to big blocks and are again unhappy with performance, they get into forced induction and/or nitrous.
"There is no replacement for displacement". Ask any hot-rodder ;-)
Not trying to discourage, just wanting to share what little knowledge I have hoping those interested in this don't waste time and money. I've been down this road myself and after a while it got expensive for no measurable gains.
i have to disagree with the no replacement for displacement comment lol ask anyone who owns/tunes/or races a wankel and relax dude i was just messing with you like i've said before its hard to offend/discourage me.
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