JRexA

The thing I was commenting is that You CAN get superchargers to work on other than 4 stroke Engines.

And Yes, there is several things that is needed for that, but the statement was that Superchargers was for 4 stroke only, which is not correct.

And Yes I do know, that in order to get it to give a drastic increase in power of a supercharged two stroke engine, it needs to have the exhaust contolled by a valve, so that the exhaust opens first and also closes first.

And since you can get small 4 strokes, it shouldn't be to impossible to make a valve controlled 2 stroke.

Direct Fuel Injection, like you have on modern Outboard Engines would also be nice.. But I would never expect to see that on engines below 100cc. But it might happen if Emission control regulations also gets to be valid for R/C Engines.

Happy Modelling from Greenland
Jesper Rex

cossie

SUPERCHARGERS DONT WORK

smokingcrater

isn't it great to have lots of informative 'facts' like this one!!!! I was almost going to post a couple links to supercharged vs the same engine stock so you can see the specs for yourself, but why bother...

as the above 10 posts mentioned, without valving there isn't going to be much use to it, although there technically could be a SLIGHT power increase, .1hp is a pretty good guess as someone else had.

cossie

how about .0000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000 0000000001 hp decrease

dalolyn

My Feedback: (7)

I would think raising the pressure in the crankcase would result in a greater amount of air fuel mixture. Then here lyes the problem, how would you get an increase into the cylinder with out blowing it all out of the exhaust. where a 4 stroke sucks in the air,through a valve, a two stroke blows it into the cylinder through ports. And both ports are open at the same time. You could go with a backplate mounted carb that would let the intake start as soon as the exhaust port is open and close its port at tdc and have the top of the intake port higher then the top of the exhaust port and the bottoms would be the same. I might just be squawking here but wouldn't that last bit of forced intake raise the combustion mixture?

JRexA

dalolyn:
I was thinking a little about a valve like the Yamaha YPVS system, where the engine regulate the hight of the exhaust port, depending on the RPM. The problem would be to get it to move fast enough, so that the Exhaust can both open and close first...
And Also.. how to get it small enough for an .21 Engine. Would be easier on a Zenoah.

As for the SuperCharged/Turbocharged discussion. The basic problem with the 2 stroke engine will be the same, except that for a small engine a Supercharger will likely be a lot easier to make, also, you don't get the Turbo lag with a Supercharger. The purpose of both systems is to forcefeed the engine.

classic-trial

Hi Folks!

Very nice discussion - I have to mention the fallowing thougts:
1. Supercharging on a conventional 2T engine can bring extra horsepower with the exact pipe, that works with the resonce. That provides a back running wave, "supercharging" the engine before closing the exhaust by the piston!
2. The electric charger on the buggy has exactly the problem that micropuller is avoiding placing the carbs BEFORE the compressor device. That the main needle had to be turned to make the mix richer (in comparison to the original position) is only logic. Instead of athmospheric pressure or sub-pressure around the needle-holes in the carb, we have compressed air, that has the tendance to push also back the fuel - a "richer" setting is needed to compensate this "barrier" for the fuel and alow that at least the same amount will come as before!
3. ALWAYS think of volume! How much air has to be provided by an "compressor" that it is capable of charging? Dos ist has the power to deliver this amount? I guess the electro charger does not have!

I'd make the fallowing experiments/changes to the electro charger:
1. measure the max flow by filling an empty plstic bag with the charger (eg for a minute), look then how much water this bag can push away (not at the ground of the pool ;-) ), then compare with the engine - it's size and rpm... enough air???
2. I'd change the setup that the carb is BEFORE the charger an the Charger directly on the engine...

regards
Phil

PS: I'd love to have such a charger for my tuned FS48 Surpass (now going 15'000rpm in my experimental Buggy)

craigb

Great work Micropuller!

people you need to remember that 2stroke ain't that efficient... there will always be quite abit of unusable (burnt) gasses left in the combustion chamber from the last stroke! so even if the extra fuel/air been pushed into the combustion chamber just push out the exhaust port it will Cary more of the burnt fuel out with it leaving a more pure mix in the combustion chamber for the next stroke.... meaning more power

plus i cant see all the extra fuel getting pushed out the exause port as long as the exhaust is well tuned... maybe adding a BIT of back pressure in the exhaust will help keep some more of the fuel in?

anyway i think you will have a pretty big increase in power as long as ita all tuned good! lots more then the .1hp that people are saying. these are two .91 engines (almost 30ccm) i think its likely to have more of a effect on this engine over a single .21 - .26 engine

Cheers Craig

Frost_

My Feedback: (1)

Dude, I don't care what you think... As I said, those were dyno results of the electric s-charger on a small-block... I'm sorry, but I'm gonna have to go with the measured difference over your thought.

craigb

yes but thats electric... it looks like its more for "looks" then anything (and yes it looks nice) but i really cant see it doing much compressing ... if any!

this one is going to be crank driven (right?) its going to have some power going through it and its going to be doing some insane compressing over a electric one!

Frost_

My Feedback: (1)

Any minimal gains achieved could be quite easily offset by the drag on the engine... This is the sole-saver of the electric unit.

stncld69

My Feedback: (2)

hey i just read how u mix and match and tune carbs alot..im having probs tunning my xtm24.7. also i have a picco.21 that is almost new..they guy i got this stuff off said he didnt like using the picco cuz the carb was hard to tune so i was wondering if the carb off the xtm would work on the picco 21 and if so what benefits would i get from it.also any ideas for a good replacement pullstart cord?

randk97

check out RB Innovations, they build superchargers for 2 strokes

dlklamfo

There was an article in the December issue of RC Driver Magazine reviewing the MPPA Electric Super Charger (the one pictured on the buggy earlier in the thread). They said the engine stock had a base horsepower of 2.522@ 32,851 rpm and super charged it had 2.598 @ 33,178 rpm, torque stock was 77.416 @ 32,851 and super charged was 78.965 @ 33,178 rpm. Looking at the dyno graph it also flatened it out and made it a smoother power band.

Looking at these numbers may not seem like much of an improvement. But remember that on real cars super chargers only add around 20% HP. Obviously this super charger is working. Just have to ask yourself if it is worth it.

Frost_

My Feedback: (1)

20%? A 'street' charger running manageable pressure/boost can make 40-45%... Either way, the gains computed from what is listed above (I have the article too) show only a 3% increase in power.... Given the amount of money it costs......... well....

46u

My Feedback: (3)

There is a company making super chargers for the engines we run. Most opinions is they are a waste of money. Here is the link.
http://rbinnovations.com/catalog/index.php/cPath/21

supertib

a 3% increase could be inconsistancies in the dyno, if you look at how small the forces being calculated when your spinning 28K 3% difference could be the weight of a few hairs stuck to the rotating weight of the dyno, as they do test with inertial dynoes and at 28K the actual force is very minute, as well they do not use any SAE or STP correction factors, so to me that SC did nothing......but i still beleive a 2 stroke could be supercharged if the tuned pipe would still have a return pulse that worked with the setup.....