bbntc3

This is interesting, I have built Detroit Diesel 2 stroke engines for 25 years. They use superchargers, (blowers) to force air into the systems. On the higher HP engines they use both, blowers and turbos. But they also use exhaust valves.
I would think it could be possible, but would'nt there be alot of turbo lag?? It seems to me it would be kinda hard to keep the system charged with air, without some sort of exhaust valve, or trick porting to close the system, when charging it with air/fuel. Can you explain how this is done???? I cant see where it would be very effecient, once or if you did get a good charge of air it would be lost, due to the exhaust being opened.
Explain how you keep it boosted, we're listening!!
No offence intend here!! I'm interested!

orangbaligila

good one,... but I'd go lean and mean, while watch you scream and pit-in,...


dumm,.. cha,... duduummm,..dumm,..chaa..... (music by revving and venting t-charged engine)

so as ya pit-in and wrenchin',... i keep my wheels spinnin and screechin',...
smoke flows as it goes,... rev hard and it roars,... yo,...

duumm,.. cha,...duduumm,...dumm,..chaa....

hehehe...

AMGRacer

This is my biggest query too. I have seen rotary motors with blowers and turbos which have been "peripheral ported" work, but only in the extreme top end of their power bands. A rotary in many ways is similar to our motors in that the "piston" (or rotor) is covering and uncovering ports to control the intake and exhaust timing events. These motors all worked above 8000 rpm where the timing overlap became so small that the boost did not have time to escape in significant amounts. I am assuming this is why this system is working.

Bishop

iTrader: (5)

Good point AMG, you been doing some tech reading?
It's one of the things forced induction has to make up for when turbocharging a two stroke, take away one pressure source and you have replace it with another, yet another reason why turbocharging a two stroke is not practical.
I should add that there are various two stroke porting methods to help get around various problems, but then you start getting into redesigning most of the engine, which takes away the whole bolt on benefit, and comes back to the reasons why it's not really practical, or worth it to begin with.

Oh, and usually you can only work with limited or small port engines to begin with when dealing with turbos, more ports create even more issues (there are some simular issues on 4 strokes, but it gets even more complex), which rules out a whole heap of higher end Nitro RC engines anyway, and of course the irony is that lower spec engines don't have the engine strength to tolerate most of what he is doing...

And really, I am not now, or ever have been hostile, if this guy wants to keep doing this, good for him, I'm just glad it's not my money he's playing with.

Bishop

iTrader: (5)

None taken, but I think some can't tell the diffrence between a debate or discussion and an argument or flame war...


Nice questions being asked now though in general, which is what I wanted to see happen, some people are obviously going out and seeking some real info now.

AMGRacer

I have been into MotoGP (500cc back then) for a long time and have followed the technical developments of tuned pipes and expansion chambers. Also I used to ride 2 stroke bikes a long time ago and we used to remove the exhaust systems to make them loud, and then wonder where the "powerband" (as we called it) went

For those people who want to see a graphic example of what we are talking about, run your motor without a tuned pipe. You will soon see what the loss of the return pressure waves adds up to

popsracer

Guys;

You cannot put a Turbocharger on a R/C type 2 stroke Engine for the simple reason of the large amount lubricating Oil that is normally being passed out the exhaust of these engines.

The oil mist would seriously effect the spinning Turbine blades and most likely be whipped into a froth that would negate any possible performance benefit.

You would also lose the scavenging effect of the tuned pipe which significantly improves performance.

2 stroke Diesel engines have pressurized oiling systems and do NOT pass large amounts of unburned lubricants through the exhaust system.

orangbaligila

a message from me to 1BadTransam : no matter what happened,.. at least I'd get two of your finished project,... I'd find use of it somehow and it'd be bad,.. real bad,...

btw,.. what's your comments if we use it for 4 strokers and rotaries,... you guys seem to always point your fingers at the 2 strokers,...

will the result be the same?! we'll find out what others think, in a few posts,... (TV reality-show background music playing)

AMGRacer

With a 4 stroke it is a different story. Exhaust valves make all the difference.

See here:



1990

A special high-performance version of the 20cc single cylinder FS-120S four-stroke, this engine has the addition of an O.S. designed Roots type supercharger: the very first time that a genuine supercharger has been fitted to a production model engine. Mr. Giichi Naruke won the 1995 FAI F3A (aerobatics) World Championship using one of these engines.

rjl

I know that forced induction for itty bitty little two strokes will not work for a variety of reasons but I'd like to be forced to change my opinion. The problem I have is that both my 1/8th cars very much need throttle control as they both have too much power to just grab a fist full. My tourer is also close to its limits power wise.
I also have some dinged pipes you can have for testing if you like, can someone explain why new pipes are more prone to damage than old ones?

rjl

I think he was the only one ever to do any good with this engine, it's not very pleasant to tune and made little if any difference to the performance of the aircraft.

orangbaligila

some of the newer pipes are made to be lightweight, plus according to some manufacturers, thinner alloy dissipates heat faster, and lastly,... the mass production effect,... need to gain more profit, so lower quality or less hardening treatment is used,... just my thoughts on the last one,...

I make my pipes using thin sheet-metal,... strong, and still light enough for a 1/10,.. and the best part, I can weld it in any configurations I like

Sow&Steady

Amazing!

1BadTransam

All good questions, the oil thing is something i was concerned with. It doesnt effect the turbine when the engine is up to temp. my only guess is the turbine is hot enough to burn it off. another thing to remember, is the bearings in this are not exposed to gasses in any way. there are 2 seals before the oil would get to the bearing.

On throttle control, i know what you mean. My Tc3 with the 5 port sirio, 5 port rody, or the novarossi with the microcasted piston is too much motor for a small track, and almost too much for a big track. Running on a track is no the intended purpose of this, it is just to much power and rpm. I intend for this to be used on cars for speed runs, running parking lot BS races, and bashing around in the dirt with a truck. also on bigger motors on boats and airplanes.

you guys keep talking about loss of backpressure, there is none, remember the "bad" thing about a turbo on a 4-stroke is adding an exhaust restriction, well on a 2 stroke it works to the turbochargers advantage.

AMG, yes you are right about the boost needed to get 100% gain in full scale. Maybe the load i am putting on the car when i run it on the bench is not enough? It might be because i am not simulating the wind resistance of the body. If the load increases, the boost does also, that is why i run such a tall gear on my car, and i do not run a 2 speed. a 2 speed is not needed, beside the fact that 1st gear would just be to smoke the tires, its easier and faster to put the 2nd gear ratio on it and run, it makes more boost that way anyhow. I have not been able to blow the motor up in the car on my test bench, even running it WFO under "load". the minute i wind it up running wide open more than about 600 feet at a time, it splits the con-rod. no piston sieze, no lean burned plug, But that good ole rod will go boom. Hmmm, maybe i should make one out of ti? The whole motor except for that seems to be fine. i have run 5 gallons of fuel through the motor total, 4 gallons were ran when it was in my GT, changed the piston and sleeve twice, and the con rod once. the last gallon has been in the tc3, some with boost, some without. when i started the last gallon i planned on using the turbo, so the motor came out of retirement, got a 3rd piston and sleeve, and a new connecting rod. so far i have popped 4 con-rods, and the piston and sleeve are still going strong. my opinion is the OS has a weak rod, but thats just me. the Rod bearing surface on this old crank could be loose causing the rod to moove around, and that could also cause it to fail. i should get a new rossi, knock down the compression a bit and try that.

I dont want to release pics of it right now. besides the air induction, there is also a boost to the fuel tank to make the system work, and i have not decided if that is my final or not. the whole system is not complete, and it will not be ready to be seen or sold for another 4 to 6 weeks... winter is a time i take to work on my fullsize Drag boat, and that is my #1 priority. Besides, I shouldnt have to answer to people about why it has been so long, everything that is right takes time to engineer and machine properly, and when the project is only worked on 2 days a week, it takes even longer.

Either way, believe it or not, but i do see why you guys are skeptical. it seems like something that is too simple (which it isn't, i just leave alot of details out) is giving a big increase. If someone told me i could bolt on a do-dad to my real car and get 100mpg, or 400 more HP, i would be skeptical too.

1BadTransam

as for the new pips, i think he is right, they are made cheaper. It is actually a bad thing for a pipe to dissipate heat. The hotter you keep the exhaust gas, the faster it can flow- same reason a turbo needs to be close to the exhaust port. I have seen plenty of guys who go as far as having their expansion chambers on bikes and such ceramic coated- it holds the heat in better and lets the exhaust flow faster.

sometimes with various things it isn't the quantity of flow, But the smoothness and velocity of the flow that makes the power...