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Turbo or not turbo?

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Old 09-24-2008, 04:20 PM
  #1
voo2doo
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Default Turbo or not turbo?

Hi ya fellas,
just a quickie to see if a friend was telling me porkies or not,Is there such a thing as a turbo charger for SOLO,CY or ZEN engine? If so is there a big difference in HP?
Thanks
James.
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Old 09-24-2008, 04:25 PM
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Default RE: Turbo or not turbo?

No there isn't.You can't turbo a 2 stroke engine
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Old 09-24-2008, 05:40 PM
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Default RE: Turbo or not turbo?

Quote:
ORIGINAL: Giorgos_cupra

No there isn't.You can't turbo a 2 stroke engine

umm yes you can...its been done before, but you have to know what you are doing.

here is one good example of a turbo 2-stroke

http://www.youtube.com/watch?v=CjFOO...eature=related

if you want more let me know.

but the weight to power gain ratio for something a small as a 1/5 r/c cant really be that beneficial.
even a small turbo like an IHI or a T25 will weigh almost as much if not more than a 23-26cc engine, and yield a very small gain in hp/tq
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Old 09-24-2008, 07:09 PM
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Default RE: Turbo or not turbo?

turboed skidoos are DI, or have valves.
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Old 09-24-2008, 09:38 PM
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Default RE: Turbo or not turbo?

that video was just a snow mobile that cant even spool the turbo.

I would like to see something better than that
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Old 09-24-2008, 09:48 PM
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Default RE: Turbo or not turbo?

and sorry for the bad video, there used to be a whole bunch more turbo 2 stroke vids...guess they all blew up (read below)


makes no difference. turbo charging is a simple process if you understand the basics

forcing compressed air into a combustion cylinder with the correct amount of fuel to prevent detonation(running lean)..regardless if it has valves, is 2 or 4 stroke the concept is the same.

main problem with engines as small as the 1/5 scale engines is the lack of exhaust flow from the cylinder. Even with a very small td04-9B from a Stealth/3000gt TT turbo that has an .040 exhaust housing, even with a 30.5cc engine is way too much to even spool the turbo..and in some cases you can have too much exhaust flow for a turbo to handle...it would be like me taking a T-25 turbo from a 240sx (180sx) Sr20DET engine and bolting to my SC300's 2JZ-GE..the turbo is too small for the engine and cannot flow the exhaust gases properly..hence the reason I may be using an HX-35 turbo from a Cummins Diesel with a custom compressor wheel

in the end all you would get is a really crappy tune with a bunch of excess weight...and if you did manage to find a turbo small enough, getting your a/f ratios correct would be a pain in the ***...

if you want a forced induction system try a supercharger, or an no2 kit. either way, with the lack of being able to monitor exhaust temps, and a/f ratios your asking for trouble. I would say an no2 kit would be the best bet and the safest way to go.
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Old 09-24-2008, 11:55 PM
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Default RE: Turbo or not turbo?

am sorry but I dont agree with you its the same proceses on a 2stroke or a 4stroke.

on a 2 stroke the air being ramed into the cylinder all exits the engine through the exhauste port. then when the piston starts to build compresion there is no more fuel nor air going into the cylinder.

unlike the 4 stroke were 1,2 or 3 valves open and rams air and fuel into the cylinder.

I will not continue this talk about turbos on rc because its been talked about before on all the online forums and its just an ongoing battle.
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Old 09-25-2008, 12:22 AM
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Default RE: Turbo or not turbo?

there is a brief time in a NA 2strokes cycle where both inlet, tranfer and exhaust ports are all open together.... if you had forced induction, the fuel would be blowen straight out the exhaust before it gets compressed.....
back pressure in the pipe prevents this happening on the engines as they are... but forced induction would need a hell of alot of back pressure...

IMO people should be more concerned about putting the power they have to the ground rather than being obsessed about getting more power
if you want something that'll just sit there and throw dirt around, a $27 shovel from the local hardware can do that lol
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Old 09-25-2008, 03:44 AM
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Default RE: Turbo or not turbo?

yeah imagine your baja5b with a blow off valve making whistling noises lol would be a real crowd pleaser . Maybe when the chinese decide to make knockoff conley V8 engines then we might be able to turbo that and put blowoff valves making whistling noises like vacuum cleaners lol
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Old 09-25-2008, 04:11 AM
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Default RE: Turbo or not turbo?

Turbos will work on a 2stroke if done right. Have a look for clarksons extreme machines, he went to Sweden or Finland (sorry cant remember where) and had a go of a turbo charged drag racing skidoo....
There was some posts on his subject some time back... Turbo or Supercharged.


Steve
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Old 09-25-2008, 08:26 AM
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Default RE: Turbo or not turbo?


Quote:
ORIGINAL: avgas

Turbos will work on a 2stroke if done right. Have a look for clarksons extreme machines, he went to Sweden or Finland (sorry cant remember where) and had a go of a turbo charged drag racing skidoo....
There was some posts on his subject some time back... Turbo or Supercharged.


Steve

thank you..
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Old 09-25-2008, 01:15 PM
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Default RE: Turbo or not turbo?

yes, and ski doo motors with turbo's are either direct injection, or valved.
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Old 09-25-2008, 04:54 PM
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Default RE: Turbo or not turbo?

the only way you can successfully BOOST a 2 cycle is if it has an exhaust valve.

That video on youtube is a example that it simply doesn't work. A: it didn't even spin the turbo (ok maybe 100 rpm max on the turbo), B: 0 boost on the gauge.

People can try, but it wont work... snowmobile draggers on the strip dont even use turbos unless they have a 4 stroke, or as stated before, some sort of a valve.
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Old 12-13-2008, 08:43 AM
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Default RE: Turbo or not turbo?

^^^^^Spot on dude.It can be done to reed or disc valve 2 stroke engines but to no beneficial level.The piston port engines like whats in the 1/5 scales,cannot be used with forced induction,the TS reed valves could but again to no beneficial degree.This is why the Japanese M/Cycle industry never used them as its just not viable both efficiently and economically.No matter what Youtube videos are floating around,its just flogging a dead horse and the best and most effective invention for performance of a 2 stroke was the exhaust power valve introduced by Yamaha in the 70's.Turbo's and S/Chargers are best for big 4's and above,this old debate is nearly as legendry and fantastical as the boost bottle debate.....
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Old 12-13-2008, 10:35 AM
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Default RE: Turbo or not turbo?


Quote:
ORIGINAL: Kemo

the only way you can successfully BOOST a 2 cycle is if it has an exhaust valve.

That video on youtube is a example that it simply doesn't work. A: it didn't even spin the turbo (ok maybe 100 rpm max on the turbo), B: 0 boost on the gauge.

People can try, but it wont work... snowmobile draggers on the strip dont even use turbos unless they have a 4 stroke, or as stated before, some sort of a valve.
ding ding! we have a winner
The rotax snowmobile engine (or whatever manufacturer did it) had an exhaust valve to keep the turbo pressure from blowing straight through the engine like a house with the front and back doors open. Its complicated and in noway practical for rc. SO, to say it cant be done is technically not true, but practical for rc? Probally not.
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Old 12-13-2008, 11:30 AM
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Default RE: Turbo or not turbo?


Quote:
ORIGINAL: turbodremz23


Quote:
ORIGINAL: avgas

Turbos will work on a 2stroke if done right. Have a look for clarksons extreme machines, he went to Sweden or Finland (sorry cant remember where) and had a go of a turbo charged drag racing skidoo....
There was some posts on his subject some time back... Turbo or Supercharged.


Steve

thank you..
I too agree with everyone else. Our model 2stroke engines do cannot benefit significantly from forced induction. As already said, since the exhaust port stays longer than the intake ports, the boost pressure form the forced induction is wasted out the still open exhaust as that pressure, by everyday physics, seeks to equalize itself with the pressure in the exhaust pipe/can and the outside air.

As already said, valves, or some other solid mechanical obstruction at the exhaust MUST be used to keep the boosted charge in the cylinder.

Since our model gas engines are loop scavenging Schneurle) valveless/reedless engines, forced induction will not give any significant performance gains. The exhaust pipes like Jetpro or Dave's Dominators with their huge expansion chambers help scavenging, but more importantly, the return pulses they give are invaluable.
I have yet to see any production model gas engines that are not loop scavenging. There might be some cross scavenging model gas engines, but those too are valveless/reedless engines.
The big diesel train or marine engines that are turbo or supercharged are valved draw-through scavenging engines. And of course, the snowmobile and dirtbike 2-strokes have a rotating "valve" assembly to block teh exhaust valve to facilitate forced induction


Now, as avgas said, it is possible to get some appreciable performance gains from forced inducing valveless engines. BUT the engine MUST be modified. The way to do this is to make the intake and exhaust ports open and close at very near the same time. That way, you minimize the time the still open exhaust dumps out the boosted charge. The drawback to this is that too of the fresh charge will mix with too much burnt fuel-air, and just like in full sized cars with EGR, the burnt fuel-air takes some power away. Also, turning will be a pain.

When I first came into 5th scale, I thought the 5th scale gassers had a different 2-stroke engine design than nitro engines. But I was surprised to see that just like nitro engines, model gassers are also loop scavenging. I kind was hoping that they had reeds or had the rotating "valve" like larger 2-srokes. I too wanted to use forced induction.
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Old 12-13-2008, 11:53 AM
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Default RE: Turbo or not turbo?

Quote:
its just flogging a dead horse and the best and most effective invention for performance of a 2 stroke was the exhaust power valve introduced by Yamaha in the 70's.Turbo's and S/Chargers are best for big 4's and above,this old debate is nearly as legendry and fantastical as the boost bottle debate.
hear, hear...however the first huge leap in 2 stroke performance was the first invention by a CZ engineer Walter Kaaden in the 50's, the expansion chamber or tuned pipe....cz cleaned up for a few years in bike GP's until the japanese manufacturers plagarised his invention when Ernst Degner ,CZ works rider, defected from East Germany along with Kaadens blueprints which he gave to Suzuki in 1961.
In essence a tuned pipe is a supercharger for a 2 stroke...so can you supercharge a 2 stroke...yep (but not with forced air induction)
Next came the reed valve on the induction side and then the powervalve that alters exhaust port timing...so we now have a supercharged bonzi 2 stroke per se.

For all who dream of turbo this and supercharger that for port timed 2 strokes...that will actually increase performance and not just be a shiny barnacle, give it up! it doesn't have any performance benefit, zilch, nada zip.
And before any readers here digress please, please do your research...there is a mass of it online for your educational benefit...and you will then find the facts about forced air induction on a port timed 2 stroke. It don't work!
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Old 12-13-2008, 02:02 PM
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Default RE: Turbo or not turbo?

i thought about bringing up tuned pipes, but i think you said it pretty good
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