hello i am student and taking up a project to supercharge a 2 stroke engine, im experimenting it with a nitro engine first, the basic principle is explained in here http://en.wikibooks.org/wiki/Engineering_Acoustics/Sonic_Supercharging_of_2_Stroke_Engines and so we are building a tuned pipe according to this http://www.mh-aerotools.de/airfoils/javapipe_en.htm . all the necessary parameters required for the tuned pipe will be found out and thus getting the dimensions of the pipe and we will build it and we will have a compressor built up which will be powered by the energy from the crankshaft. we will be using this car for a inter-college competition, we have to actually fabricate the entire car like chassis and the suspension mounts etc. so we already have a car which we fabricated last year, we used a lot of plastic in fabricating the members but they did not hold up well so this time we will be using all metal components to make the car durable and withstand stress, and also our car is a hpi nitro monster king it has a very large turning radius, so we will be trying to implement a 4 wheel steering on it so as to have better maneuverability,( there are tests which check our cars maneuverability so it is helpful to have a 4 wheel steering) the mechanical aspect of 4 wheel steering has been figured out, all we need is to install another servo to power the rear steering system. we currently have a 2 channel AM radio controlling the car. so this is what we are doing and we need some help/guidance in

1. Any suggestions/advice of improving our supercharging system.(we ruled out turbo charging because the exhaust pressure is too less to power a compressor and there would lot of losses involved as well)

2. we are okay with the design aspect of 4 wheel steering but the problem is we dont know how to power the installed servo for the rear wheel servo, is it okay if we just parallelly connect the rear steering servo with the front one? or will the power be too less?? or do we have to install a 3 channel radio? if so where we could find one? and how do we actually control it?

3. we have lost the clutch bell for this engine ( 11T one ) and also the spur gear ( 54 tooth one) and also some engine mount screws and also might need new shock absorbers. so please let me know where i can find the parts we need?

we will keep updated of our progress and get some pics as we get along, but really need help in the above matters, any advice will be really helpful!

thanks in advance

looks like u are Gearing up for SAE BAJA....??

to your questions:

1> as far as i know ... turbo chargers are more efficient than superchargers.. as super chargers suck up power from the engine turbos dont.. so u get more power from turbos...

2> if i am getting this question right.... u want to steer both the front and the back wheels the same time.... just go in for simple Y connector to get the servos in parallel... will work all out

3> try Hobbyking, Model art, Or adventure hobbies.... ( i am not a car guy... so some one from the cars section will he helpful here..)

thanks for the reply first of all
no in baja we use 4 stroke engines, not 2 stroke, we are doing this project out of interest and curiosity and may be take it up as our finial year project.

1. turbo chargers are better but in case of a rc car the pressure is too less and the frictional losses involved is pretty high as the scale is small. and supercharging takes very small energy from the engine and is much more simpler and efficient and has less losses compared to turbo, that is why we selected supercharging over the other after good amount of research.

2.yes we want to steer both front and rear wheels at the same time, the only concern we had in using a Y connector was will the power transferred to both servos be enough? i mean we dont want to end up having a system which has insufficient power to turn the wheels.does using a Y connector distribute the same voltage and current to both servos? i mean will the power output from both the servos be the same?

3.thanks for the contacts will try giving them a buzz tomorrow.

as a suggestion... for a final yr project... look at some thing big....

but out of interest and me being a mechanical guy myself... will be subscribed to this thread...

for
1> u may be right there... but again give it a second thought....

2> yes u can use y lead... If we can risk our expensive planes to the Y-leads  so can u for the car...

Which model are you using?

I'm no nitro guy but trust me when I say this, supercharging a nitro engine is not worth the effort. The gains will be minimal at best or none.





Monster trucks used to have 4 wheel steering. Take a look at how they tackled the problem. Some rock crawlers also use 4-wheel steering.

You can use a Y cable but make sure you power the Rx with a high power BEC. When both the servos are at full draw, you should be able to feed them and have enough power to supply the Rx. If not, you will face a 'brown out'. The Rx will re-boot itself and all control will be lost for that moment.

We need to know all the equipment you're looking at.

@aeroshiva we are not doing this as our major project for final year, its just out of curiosity

@iamhuman i saw the videos but the tuned pipe which he has is ready made which is not designed for a supercharger, we are fabricating a tuned pipe taking into consideration the exhaust gas temperatures after supercharging so let us see if it works, its just a try.

also need more info on the the use of y cable, i dunno what Rx and BEC means? can you please elaborate on it, also what all equipment we need? please help us out here.
thanks in advance 

Rx= (Radio) Receiver

BEC= Battery Eliminator Circuit

I do not think you have thought this through - what size engine are you
trying to supercharge ? Assuming an average .40 size - what will the physical
size of the supercharger ? and how will you make the housing ?

Think off the following - PTO for the supercharger - belt or gears - if gears then where
will you source them from ?
How will you make the impeller ? this  should rotate upwards of 35k rpm to have
any appreciable compressibility. For making this you will need specialised CNC machinery
like those used for making swiss watches . what about creamic bearings in those micro sizes?
how will you make the housing for the impeller ? casting or billet machining ?? what about
the ducting ? and then you will have to change the timing of the engine itself.

Do you have the skills and access to this kind of design and machining capability ?

rx means receiver and bec is batry eliminating circuit. what it does is in mostly electric vehicles people use bec to power their servos as the normal esc becs are not powerful enough to supply the required current . but in nitro some times it is required when running lots of servos .

trying to supercharge a nitro 2 stroke was tried around 7-8 years back. IMO is not very yielding or worth it , as when u supercharge it of the flywheel, it pushes air into the engine while fuel is flowing normally therefore leaning(damage alert) it out and if u richen it, it bogs down and is hard to tune . maybe having a tuned pipe that changes its internal length will help a little in scavenging but overall not worth.
basically 2 strokes dont have valves so u cant force air into the chamber like 4 strokes, if u do it will come out from the other ports.
forced induction doesnt work in rcs
why not try with a 4 stroke rc engine? or try modding the 2 stoke with better timing, balanced crank, port work. ul have better results. do watch the videos iamhuman posted. a supercharger requires skils and ready made ones were sold for 150 $.

a good servo will help almost as much as 4ws setup in a fast vehicle .

y channel is a paralel splitter so u can run without problem

4 Wheel Steering in Crawling terms is generally reffered to as Crab Steering.
Many ways to configure the steering function on your transmitter.
First as said u could use a simple 'Y' Cable.
Secondly and the more complex as well as precise way to do it is via a seperate 'Aux' channel and then mixing it with your steering channel. The futaba 4pks has lots of mixes for four way steering/crab steering. The spektrum Dx3r also has the mixing option, you could also assign a 3 position switch to define when you want the steering to be four wheels and when only front or only back. kind of a 'DIG' function for steering.