Supercharger information thread

[thunderstRuck]

zoomer46 said:

must be a pitbike,

great pic !!

Its a honda crf50...I think.

[chanito]

So we might need to do those head bolts after all

[thunderstRuck]

We're gettin closer to the truth. This is a NICE setup. I was wondering how to get around the ruck's frame just above the cover. Great job on this one!
website: www.mini-cooper1.com/my_custom.html



Okay, I just emailed the guy who owns this bike and begged him for some info on the supercharger. Hopefully he will get back to me soon. In his website he says the bike sounds like a combination of a harley and a jet. Coool. ;D

[honda919rider]

www.mini-cooper1.com/my_custom.html

[thunderstRuck]

I was discussing this issue with a friend of mine who's a mechanic. He couldn't offer much help bechuse he works on Toyotas but he said his uncle who's a mechanical engineer would look into it for me. I basically need to get him the bore and stroke and compression ratio for BOTH 49cc and 58cc (calling Chanito?). He can then run the numbers to figure out how much volume is needed in the cylinder to lower compression and the amount of boost needed. If anyone can think of any additional information I'll need to give him please speak up.

[Dandy Dan]

The stock compression ratio is 11.9:1 and the 58.1cc pistons are 12.5:1

Good luck with this awesome research

[thunderstRuck]

For anyone wh's following this thread and learning (as I am) as we go, here's the basic supercharging overview:
General Information on Supercharging


1.Introduction


If you are interested in supercharging, you probably do not need a basic course in this subject, but we could recap a little. We want more power out of our engine, and one very effective way to get that is to put more air into it. With more air goes more fuel, of course, and so there will be more energy released at each bang. This means that the temperature in the combustion chamber will go up - and as a result of that, also the pressure. It is that pressure increase in the cylinder we are after, because this is what makes the engine put out more power. In principle, this goes for all kinds of engines, but we will only discuss four-stroke cycle engines here.



When we say “more air” we mean a larger mass of air (in pounds or ounces). As the volume in the cylinder is fixed, the air taken in at the inlet stroke has to have an increased density, which we can get by increasing the pressure and lowering the temperature of the charge.



To be able to create that increased pressure (“boost pressure”) before the inlet valve, we need some sort of pump or compressor. In this case we will only deal with the types that are mechanically driven, mostly directly from the engine, and of the “positive displacement type”, meaning that they displace a certain volume in a positive way. (To be absolutely “positive”, the process should be without internal leakage, but we are not absolutely strict with that.) Thus we will not discuss the “turbo” here, which is a “dynamic” type of compressor, driven by a turbine that gets its energy from the pressure in the exhaust pipe. It is called “dynamic” because it is the aerodynamic forces inside the machine that are doing the job,



By “pump” in this context we mean a rotary device that is moving a given volume from one place to another, something like an oil pump of the gear type. In the supercharging field it is often called a “blower”. There is no “internal compression”, which means that the transported volume of air suddenly is exposed to the pressure in the discharge line when the outlet port opens. We could say that the pressure is created after the pump in this case – and it happens when the engine cannot swallow the volume of air that the pump is delivering.


A type that is used very often is the “Roots Blower”. Two rotors with identical shape are sealing (well, not quite) against each other and against the inside surfaces of the housing. For each revolution they are pumping a certain volume of air from the inlet side to the discharge side. The principle is very simple, but the basic form of the rotors is critical, as well as the clearances between the working parts.


By “compressor” we normally mean a machine that really is compressing the medium during the working cycle. Among the rotary types, we have different kinds of vane compressors, screw compressors and scroll compressors. These types have a better efficiency at higher pressure ratios, thanks to the internal compression. This also means that the discharge temperature will be lower than with a blower – a plus in several respects. They are, however, more complicated, and more difficult to make. They would not be the first choice for a hobbyist.





2.What happens in the engine?



We could also think a little more about what happens in the engine when we supercharge it. If we follow the path of the air through it, we might get an idea. For this discussion we assume that we have a Roots blower that is sucking a mixture of air and fuel from the carburetor, and is pushing it into a single cylinder engine.



First we note, that we have got a pretty steady sucking by the blower, instead of the quick gulp during the intake stroke. This means that the capacity of the standard carburetor most likely will be quite adequate, even if with supercharging we will be passing a lot more air through it in total. The steady stream of air and fuel will be well mixed by the blower, something that will be beneficial for the combustion in the cylinder. (In a multi-cylinder engine, it will also be beneficial for the fuel distribution between the cylinders.)



In the blower we are putting some power into that air-fuel mixture. The result is that it warms up quite a bit, something we do not like. But the fuel that goes through the blower has a cooling effect. If we are running on methanol, this effect will be extra good. We could also put a little oil in the fuel - unless there is a catalytic converter in the line. The oil would help to lubricate the blower, and improve the sealing between the rotors and between the rotors and the housing.



The downside of having the carburetor before the blower is that we now are creating a pressurized, inflammable mixture that can go off with a big bang, if the fire gets out of the cylinder through a leaky inlet valve, or because the mixture burns too slowly. Thus we must think of that: the chamber between the blower and the engine must be regarded as a pressure vessel, and as such it has to be reasonably strong. There should also be something like a safety valve or burst plate on it, which blows off if a backfire occurs.



With a single-cylinder engine, we can only take in the compressed air-fuel mixture during approximately 180 degrees of crankshaft rotation, while the blower is pumping steadily during the total cycle of 720 degrees – so we understand that we have to have something like a buffer between the blower and the engine. As a rule of thumb, the volume of that buffer (plenum chamber) should be at least twice the size of the displacement of the cylinder. (With more cylinders, the volume could be smaller.) We also understand that if we can lower the temperature of the charge before it enters the cylinder, we will be able to pack a larger mass of air and fuel into the engine. If we go with an aftercooler, that volume will be included in the buffer volume.



Now we come to the inlet valve. In this case, with the pressurized charge before it, there will be a force from that pressure that will tend to open it. That is a good reason for increasing the strength of the inlet valve spring.



When the inlet valve opens, the pressurized charge is rushing into the cylinder. In a naturally aspirated engine there is often a fairly long overlap between the opening of the inlet valve and the closing of the exhaust valve. In our supercharged case the full pressure is constantly acting on the inlet valve - and if both valves are open at the same time, some of our precious mixture is lost, out through the exhaust pipe. Thus we should have less overlap in a supercharged engine. A little bit could be OK, as that would help to clean out the cylinder and cool the piston and the exhaust valve. Thus, ideally, the timing should be different in a supercharged engine, but in the practical world it is possible to get quite good results just with the standard valve timing.



We are filling the cylinder much quicker now than when the engine had to suck in the charge. We are also creating a “positive” force on the piston during the down-stroke, meaning that we get something back in terms of power already here, from the power that is put into the blower to drive it. We also understand that the filling will be more complete, and with a fuel/air mixture of higher density than in the case of a naturally aspirated engine. When the intake stroke is completed, the inlet valve should close. If it stays open much longer, there will be an extra braking force created – and we certainly do not want that.



When the compression stroke begins, we have a higher pressure than in the standard case. If we have not changed the compression ratio in the engine, the air-fuel mixture will have a higher pressure and temperature at the end of the stroke. This can easily lead to knocking: the whole charge goes off at once. Not good! The remedy is to lower the compression ratio, increase the fuel-to-air ratio, and possibly retard the ignition a bit. Under all circumstances, the peak pressure will be higher than before, so there is a good reason to look after the seal between the cylinder and the head. Hotter spark plugs might also be needed.



The extra fuel we filled the cylinder with now shows up as more force on the piston during the power stroke. It also means that the pressure is higher than before when the exhaust valve is about to open. The direct result of this is that the valve has to open against a force that is trying to keep it shut. This, in turn, means that the forces in the valve mechanism will go up. We do not need a stronger spring on this side, but possibly stronger components operating the valve.


We can also think about the exhaust situation in such a way, that we now have to get rid of a larger mass of gas than before. That means, that ideally the discharge valve should be larger (and the inlet valve smaller). If not, the valve should open earlier. In any case, the heat load on the exhaust valve will be increased, so a good material and good cooling of the same will be important.


So, as always, it’s a give and take. We give away a bit of fuel economy, we have to get rid of more heat, we have to live with higher stresses in the engine – but some of us think that this is well worth it.


Make sure you re-read this twice, there will be a test on Monday.

[Dandy Dan]

Read that twice?!?! It took like 20 min the first time...

[thunderstRuck]

Here's another tidbit. I'm meeting the engineer tomorrow night to give him the numbers.

Well, I haven't personally ever tried a forced induction scheme on a 2-stroke
but it can be done. Your just have to watch out for too much overlap in the
port openings, similar to using a cam that is too long on a 4-stroke. If it is
a mild "play bike" type of engine you'll have a better chance of having mild
port timing in it. If it is highly "ported" for peak power this could be a
problem. Two strokes respond very well to porting combined with the proper
sized expansion chamber (resonator) and the result is a poor-man's supercharger
without one. Volumetric efficiencies much greater than 100% can be achieved in
narrow rpm bands. Modern day two strokes have variable port timing to widen
this band.

I you were to try to supercharge you 80cc bike, the air requirements for 100% VE
at 9000 rpm are 0.08L x 9000 rpm = 720 L/min, since it aspirates once per engine
revolution. This is about 44cfm. Assuming you want to double the volume of air
that you will aspirate, then you'll need about 88cfm capacity from your
compressor at 15-20 psi. That's not a whole lot of air. For example, I have an
800cfm compressor on my ZX-11. A general rule of thumb is that you need 160 cfm
for each 100 Hp. So, your 88cfm would be good for 55 HP. An 800 cfm compressor
is good for 500 HP.

The supercharger would be simpler than a turbo since all you need to do is
modify the intake system, rather than a complete setup with exhaust, waste gate,
etc. Of course, you still need to make a drive off the crank or clutch basket.

[chanito]

That last post confuses me, as it talks like if the ruckus was a two stroke engine (it is not), the only BIG problem i see with this supercharger project is the drive belt, since the engine revs very high, keeping the belt from flying off the pulley will be a very interesting problem to fix, also designing a plenum for a single cyl blower motor seems fun all those pulses will strain any bolts holding it together, and timing needs to be spot on, that means time with an ENGINE DYNO, not a chassis dyno. I am really looking forward to your solutions ;D ;D

[thunderstRuck]

Chan-man, is it possible to retard the timing by making the pulse generator adjustable? Also, how do you think a dynamic tensioner would work to keep the belt in check? I'm also a little worried about the crank bearings, since the pully would obviously be attched to the crank. Thanks as always for the voice of reason! . Also, by building a chamber after the supercharger and before the cylinder head (98cc's-double the volume of the cylinder) would the pulses accumulate in the camber allowing for a smooth flow into the combustion chamber?

[thunderstRuck]

I'm thinking of keeping the displacement stock, keeping the stock ECU, retard the timing, open up the exhaust port, increasing the volume in the combustion chamber (somehow) and using 92 octane gas. Maybe even a stock intake to restrict the volume of flow. Another question: How would spacing the head to cylinder affect the timing chain in terms of length? Thanks to all for your input! I'm determined to make this work.

[ZOOMER46]

i think granty should be comended for his efforts on this thread,
he really has made this his own, ;D

i think that it would be better to try and change the compression via the piston than risk
damaging the chain unless its possible to fit 2 head gaskets?

another thing i have often wondered was feasible,was to cut off the cast inlet
to the head ,and make a larger bore custom pipe,as it seems looks like it is very restrictive,
and must be a bottleneck?

as for the ignition,a plug and play cdi has to be the way to go,

restricting the intake or any outlets is not really needed if you are able to control the boost properly,it would be like un-doing all the good work of the whole idea?
open up all you can to not have to run excessive boost to get results,

as i.h.a.r has said before we operate in a fairly small powerband ,of which we rely
on the transmission to keep us in .so a broad powrband is not really needed...

[thunderstRuck]

I found this today. I'm contacting the company as we speak.

Pinnacle Group Unlimited, Inc. ("the Company")(OTC: PGPU), which recently announced that it will acquire all of the issued and outstanding shares of S-Charger Corporation, today released the results of S-Charger Corporation's first series of "Dynamometer" tests of its next-generation supercharger -- designed for engines of up to 500cc in displacement. S-Charger believes this economical product to be the smallest "production-based" "mechanical Supercharger" in the world.
At the private tests conducted in October, a 110cc motorcycle engine (the most popular engine type in the Asian marketplace) was outfitted with an S-Charger supercharger for this series of tests. Without any major adjustments or modifications, the test engine exceeded its published target of 20 percent in engine efficiency. An increase of 28.09 percent in horsepower and 27.98 percent in torque were measured with the engine running at 8000 RPM (this particular engine's "power band"). Dr. Simon Simand, Chief Technology Officer for S-Charger Corporation commented, "With focused research and customization for each particular engine type, we expect to achieve well beyond a 30 percent increase in both horsepower and torque. This is a major performance advancement for all small engine applications."

S-Charger also expects similar Dynamometer testing results when it tests its automobile version of the S-Charger supercharger in 2006. The data from the October Dynamometer test as well as video of that test will be available on the S-Charger Corporation website.

showtextures.vrx.net/product.html

[thunderstRuck]

Good link as well: Horsepower Calculator!
www.superchargersonline.com/hp_calculator.asp?submit=1

[thunderstRuck]

Here's a good in-depth article. Chanito was right about the head bolts!
victorylibrary.com/supercharger/super-c.htm

[thunderstRuck]

Supercharger designed specifically for a honda 50cc.





As you can see, I have 2 more for sale....kidding

[Dandy Dan]

So when is one going in?

[thunderstRuck]

dandydan said:

So when is one going in?

I dunno. The big bore, cam and met gears are on the way. Stock piston would last about 3 seconds. Getting my internals cryo-treated as well. I'm being a bit of a doubting Thomas lately and am starting to think this is a big can of worms. That doesn't mean I'm quitting, though!

[Dandy Dan]

Well I'm cheering for ya!