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Small 2-stroke Turbocharger Answered

i was wondering if any one had heard of attaching a small turbo charger to a lawn mower or weed whacker , if anyone has heard of it could you explain how, as i am anxious to try this with my recently salvaged 2 stroke and just see as much power i can suck from it.


How about using a 60 or 70mm Electronic Ducted Fan (EDF) like the kind used on model ‘jet’ airplanes?


Now that I think about it – this idea might actually work really well.  I just bought a Ready-To-Fly (RTF), toy airplane for $120.  It came in a very nice, compact, retail box with colorful (albeit grammatically horrible) descriptive writing around it.  The plane itself is about 2 feet long, made out of Styrofoam, and has a single 70mm ducted fan.  It came fully assembled with a remote control (transmitter and receiver), a LiPo battery and charger, the servos and all the other various giblets – it flies at over 80mph.


If you haven’t played around with some of the radio controlled gadgets coming out of China lately, you probably can’t appreciate the potentially of this idea.


I’m sure there are a hundred reasons why an EDF won’t work as a supercharger - some of the pro’s would be:


1)       EDF’s really f***ing SCREAM !

2)       EDF’s spin at 10's (or 100’s) of 1000's of RPMs.

3)       You can get an EDF for under $20 – or -,

4)       You can get an entire RTF plane - complete with 1 (or 2) EDF’s; remote control and all the necessary giblets. - for around $100.

5)       EDF’s put out probably 20x the power of a shop vac.

6)       The combined weight of all the onboard components of the supercharger (the EDF, receiver, voltage controller, servo and battery) - would be less than that of a ham sandwich.

7)       You could install an EDF (or two!) onto a small engine in under 10 minutes.

8)       The EDF along with the LiPo battery they’re paired with typically run for 20 minutes – doubling, tripling, etc. the run time would be trivial.

9)       You could experiment with the boost by simply varying the fan’s speed with the remote control.

10)   EDF’s really f***ing SCREAM !

I have several boxes of wrecked r/c plane innards and four or five 31cc Ryobi engines to play with.  I’ll keep posting as Iong as anyone is interested.






P.S. – Did I mention EDF’s really f***ing SCREAM !

Hey Afrosonic,

Great idea. Electronic Ducted Fan is kind of outside of the box but might work for these ultra small displacement engines. Did you ever follow up on the idea?

this is the exact idea i had. thank you for posting your info by the way. i think this might not work but i really hope it does. the reason i doubt it is because a turbo doesnt just blow air into the engine, it compresses it to over 1 lb to 125lbs above atmosphere pressure. i mean if you can pressurize the air a lot, not just cool it down with a little fan, it would work. i know kthat those edfs scream as you said and they can possibly make this happen but i would like to see a video or proof that this works before i try it on my kx80 dirt bike

I can speak from a little experience, in my youth I modified a 120cc Kawasaki dirt bike, luckily enough with a rotary valve. I ran this unit on methanol with an injection of giggle gas (nitrous oxide). It was a powerhouse but all being said it did not last too long and if it stalled it would oft times start and run in reverse, the first time it happened it caught me unawares and scared the bejesus out of me. So in short it can be done but it certainly is not good for longevity.

I think your best bet is to keep it naturally aspirated and maximize your current setup with a simple mod like RAM Air Intake. Not only will this increase compression but it will help increase HP, you just have to make sure you adjust your carb so that the air to fuel mixture is correct.

I have thought about this problem and came to the same conclusion that if you fit a turbo chrarger, it will simply just blow all the fuel straight through the engine wasting half of it and probably setting fire to your exhaust, you could turn the exhaust into a afterburner i guess lol, or the other suggestion is using DIRECT FUEL INJECTION, this will only use the ammount needed each stroke so no wasted fuel.

The edf fan does produce a high volume of air but runs into a problem when the fan outlet has back pressure the airflow will stall @ a pound or so and then your waisting energy creating heat and turbulence. The edf motor with a centrifical supercharger is different less volume more pressure and the faster it spins at every diameter the great both volume and pressure increase there isn't a top end point.Many of the edf's have motors running 25,000 to 75,000 rpm why so high that's do to type of brushless motor used the fastest for top rpm are the type used in radio controled cars high rpm and high power and small edf units the use an inner magnet core windings that surround are switched electronically and due to no iron core it's all about switching frequency. the other type used it edf and model airplanes has a outer magnet field and both motor types your looking for need to have the best rare earth magnets and lowest number of poles for the motor so it generates it's power in the operating rpm range desired. Spinnig a centrifical supercharger low torque requirments a low rpm and this is just what motor recommended loves there are significant number of availible choices in either configuration that would satisfy small engine to engines quite large considering i can walk into a model shop and for less than 350.00 have a 6 horse power motor that the works fits in the palm of my hand would 6 hp @ max rpm of 70to 80 thousand rpm turn a 4 cylinder 2.5l engine into a 5oo hp mini brute power really light weight power plant I know so. This is not as much as top turbo engine output to size but this is not adding nitro nitrous or strangely enough CNG adding a liquified gas as fuel enrichment cools the manifold significantly and has a high octaine rating so its the way to add more to a cooler charge that's denser that does not detonate or ping. Brushless super turbo hmmm well the tuning dynamics and flexibilty turbo that's allways "spolled up" a brake to make the waist gate put on exhast side hmmm . the more enhancement that can be done to the 14psi we live in without using the power of the enigine to do it even if that power has been stored up in advance the higher the output goes for any type and every internal combustion engine any fuel used.
A small electric powered turbo type/centrifical superchargers is what I am looking for myself or just the fan unit. In this case you will want to put the motor mounted in front of the inlet to cool it and the heat transfer at wide open due to max airflow when you need it is minimal.
good luck.

i've been making small blown 2-strokes for the last 10 years and it is indeed possible but there is mutch more to care about than just finding the right blower we rebuild existing turbos to belt driven blowers this is the "best" option for small engines we got around 85 bhp from a 70cc blown scooter engine on alcohol and nitrous

I've heard that using forced induction on 2 strokes doesn't work well since the exhaust is open at the same time as the intake. Thus after a small boost it will just blow through the cylinder instead of into the cylinder.

thanks for the suggestion, mine is a only a 30cc from a weed whacker. when you say alcohol i am assuming you mean denatured alcohol?

.  Ethanol and methanol will both work.
.  Denatured is most often ethanol plus about 10% methanol, but can have other additives. Check the label.

has anyone made any progress?

how would you use a smog pump as a turbo.

Most of the time they just turn in to a big lump of metal though...

i got the engine for free so if it forges itself together i'll still be happy that i got results

Or just keep them as "Offerings to the God of Speed." Got a whole shelf of those...

i heard that you could use a smog control pump as a turbo. how would u make that work

I've offered him many chunks of flesh, left on the road... Then there's the sacrifices...

I just thought about this, a turbo is a bad idea because you'd lose the power from the tuned exhaust, a supercharger is the way to go... Good luck with the scrap dig

alright i'll try to get a super charger , thanks for all the help

That and superchargers are much easier to hook up...

As a suggestion to give a few tests out you could try with a big tank of compressed air at low pressures until you find a suitable 'charger then you only need find the smallest possible to meet requirements...

i was thinking testing it with a hair dryer but then i cant measure the pressure , looks like i need to make a trip to my dads shop for the air compressor there

You need low pressure like only a few PSI so even a shop vac or blower would be enough

apparently the junk yard gives all its turbos and superchargers to its employees so o luck there , me and my friend are going to build one when he finishes his current project (49' ford pickup)

i dont know if somebody know that a landspeed world record on motorcycle of
50cc was achieved with a turbocharged 2 stroke aprilia engine, i think it wasin bonneville.
from Argentina
had a good life

i have a racing lawnmower and i have have a 18 hp i/c briggs and stratten twin. i want to build a supercharger or a turbo so i can ge more hp. does anyone know how and where i can get the parts to make one? i would love the help and info. thanks peace

Generally it's likely to blow the thing to bits... however a small supercharger isn't unreasonable I've done worse to a little two stroke. Add extra oil to the fuel so it's about 25% more than the usual ratio, to help the engine cope, along with that de tune the exhaust before hand then retune to the new power as the extra air coming in with change the timing slightly. Before doing anything as crazy as that though try tuning the exhaust, it can double the power output of a two stroke in the right band, it only works in a small band of revs though so figure out the peak output and tune for the exhaust power band to be centred around that, to maximise output. My dad used to drive a two stroke diesel truck with a supercharger, it was pretty good, however the block and pistons were designed for the stress, start with very low pressures and observe running temperatures, there's a fine line where the engine will go to, then it'll brick itself, best bet is to run it rich, this will help control the danger of overheating, you need to account for the fact that the fuel is the lubricant in these...

any idea where i could get a small super charger or would it be a custom project

Umm kick around a junkyard, it doesn't have to be tiny, just not too much pressure...

alright i'm trying to go to crazy ray's (the junkyard) this weekend , i'll post a video if i get it running

Aye for the connection to intake manifold make a simple wastegate valve to keep pressures down and slowly close until you get a safe running pressure that's near the top of capacity, after figuring that out you can change the pulley gearing to match the pressures and airflow...

Of course, blowing the thing to bits might still be a very (de)constructive way to spend an afternoon.

I've thought about it. Of course, I have also thought about putting a turbo and nitrous on a 50cc scooter, a Baker 7-speed, hot cam, and weight reduction. In other words, it might be a very, horribly bad idea. Killerjackalope is absolutely right about mixing more oil in the fuel and erring on the side of running rich. I'm hardly an expert on messing with two-strokes, but I do know that I'd put a pyrometer on it and watch my EGT. You really don't want to have your turbo go melty.