You could just run a really steep pipe expansion chamber and get residual backflow waves to boost it.
How would one go about doing this? Lol
Boosted 2 Stoke
- Thread starter FearTheH
- Start date
How would one go about doing this? Lol
People have put forced induction on 2 strokes in the past.....but it's kind of silly.
4 strokes can benefit from forced induction due to the fact they rely on valves and valve duration for intake. A force induction engine can force more air(and fuel with control) into the motor while the valve is open. This philosophy doesn't quite work as well on 2 strokes. Why?......The beauty of 2 strokes their simplicity. The vacuum of the cylinder moving is going to draw air in regardless to more or less it's max volume required for an efficient combustion stroke.....forcing more air doesn't do a WHOLE lot as ULTIMATELY, the air flow is limited or unlimited by:
Intake/Exhaust port size
Transfer port size
Pipe Expansion size
The 2 stroke engine ultimately controls it's own income air charge. Due to this uniqueness, this is why you see the pipes with expansion chambers for 2 strokes and not 4strokes....and ultimately the closest thing to "forced induction" on a 2 stroke is actually the powervalves on the exhaust ports of some 2 stroke bikes which can perform a chorus of tasks but routinely modifies the frequency of waves exiting into the pipe and reverse pressure of air/fuel mixtures back into the cylinder to provide "large charges" at low RPMs to provide more power at lower RPMs.
4 strokes can benefit from forced induction due to the fact they rely on valves and valve duration for intake. A force induction engine can force more air(and fuel with control) into the motor while the valve is open. This philosophy doesn't quite work as well on 2 strokes. Why?......The beauty of 2 strokes their simplicity. The vacuum of the cylinder moving is going to draw air in regardless to more or less it's max volume required for an efficient combustion stroke.....forcing more air doesn't do a WHOLE lot as ULTIMATELY, the air flow is limited or unlimited by:
Intake/Exhaust port size
Transfer port size
Pipe Expansion size
The 2 stroke engine ultimately controls it's own income air charge. Due to this uniqueness, this is why you see the pipes with expansion chambers for 2 strokes and not 4strokes....and ultimately the closest thing to "forced induction" on a 2 stroke is actually the powervalves on the exhaust ports of some 2 stroke bikes which can perform a chorus of tasks but routinely modifies the frequency of waves exiting into the pipe and reverse pressure of air/fuel mixtures back into the cylinder to provide "large charges" at low RPMs to provide more power at lower RPMs.
Awesome, thanks man...that answered my question(and confusion) perfectly! Like I said, im new to modifying 2 strokes. And was quite mislead previously about how it is they work. Thanks a bunch!
Just stick to the "usual" mods like porting, stroking, and intake/exhaust mods and all will be good.
OHHHHH! the holy grail.... you cut straight to the point huh?
For starters, it's a power valve (singular) which is a small flapper valve that sits at the top of the exhaust port which, when activated, flips up and out of the way to change the exhaust port timing (advance the opening and increase duration).
It gives you the decreased timing advance and port duration for torque at low RPM's and then the increased blowdown time needed at high RPM's for high HP running.
The trick to building a high output blaster motor is to start the build with a goal in mind and then stick to it. If you go around adding every "go fast" part you run across in this forum you'll end up with a cobbled together piece of junk that won't hardly get out of it's own way. Getting the chorus to sing together is WAY more important on a 2 stroke than a 4 stroke (where it's nothing to sneeze at) because EVERYTHING in a 2 stroke affects everything else.
Start with a plan, budget, and goal. Double the budget first thing to get a real idea of what this is going to cost you and then reduce your goals just a bit for the "real world" tax.
The problem with a turbo charger on a blaster is HEAT. Blaster top ends are subject (if jetted incorrectly) to overheating as it is. If you go backing up that hot exhaust into the cylinder because of the backpressure of a turbo, you're going to burn the piston crown at the exhaust port in a hurry.
What 99LRD is talking about is getting a differently tuned head pipe. Almost all aftermarket head pipes are a HUGE difference in power on the blaster. The possible exception being a DG (which is still an improvement over stock just pricy for as little as you net). Different pipes have different power characteristics, FMF, procircuit, and DG are "torque pipes", they don't sacrifice all of the bottom end but don't gain as much at max RPM. Trinity, F7, power pros, CPI, Vito's FB are all "top end pipes" which give away some torque but see gains at the top of the RPM range. They are better suited for a larger bore screamer engine, not a trail bike. Not to say that those descriptions are mutually exclusive, either can be used for either but we get back to goals and expectations, you want to choose parts and build your bike around your goals and what you need out of your bike. If you're riding through tight trails out in the woods, you don't need a pipe that puts out power only at 9K RPM and loses all the bottom end torque to do it.
Thanks for the sarcasm, like I said im learning. I've spent my time building real power in my em1 to plat with little toys like a blaster. I got my gf a blaster for christmas and I got very interested so excuse me for not knowing everything about a 2 stroke right out of the box, im sure you didn't either. As far as a budget to double, I have none as I have spoke with multiple builders about maxing out the build and looked at all of the very inexpensive parts for these things. I ask questions so ill know, anyway thanks for the explanation
With a ton of fabrication a turbo works on a smoker just like a 4 stroke.
How about a stock bore, stoke stroke, unported Banshee that makes 146hp?
Turbocharged banshee powered 250R video by terboed - Photobucket
How about a stock bore, stoke stroke, unported Banshee that makes 146hp?
Turbocharged banshee powered 250R video by terboed - Photobucket
What's possible and what's practical are two different things 
. I don't think he was being sarcastic, he was being blunt .I:I We all started at zero with two stroke knowledge. Best thing to do is educate ones self. Read Gorden Jennings, H. Gram Bell, read all you can(want) here,Banshee H.Q. ,E2S, Planet Sand , and infinity. At the end of the day a 2 stroke just doesn't lend it'sself to turbo charging well .
. I don't think he was being sarcastic, he was being blunt .I:I We all started at zero with two stroke knowledge. Best thing to do is educate ones self. Read Gorden Jennings, H. Gram Bell, read all you can(want) here,Banshee H.Q. ,E2S, Planet Sand , and infinity. At the end of the day a 2 stroke just doesn't lend it'sself to turbo charging well .
So I've heard. And im trying that's why im on here...I've built many a four strokes. I just got her blaster and it has some work done to it and surprised me how quick it was so I bought myself one(2002 with blown piston for 150 bucks) couldn't pass that up!
I'm sorry for coming off incorrectly, I wasn't being sarcastic simply stating the facts.
Paulie, incredible but out the reach of most mere mortals (and blaster owners) there simply isn't the capacity to carry away that much heat out of the air cooled head and cylinder without using some even more exotic fuel than mentioned below
If you want to put down SERIOUS power and your budget isn't in question, design the system around using exotic fuel. Either 110LL or pure alcohol will do it.
Conquest 86 has an engine built around 111 octane zip fuel and it really hauls.
The higher octance fuels resist detonation at higher compression ratios and the alcohols have more latent heat absorbtion during their phase change. Both are a fine choice for getting maximum power out of a blaster even if they are unfriendly to your wallet.... again to the budget problem....
Paulie, incredible but out the reach of most mere mortals (and blaster owners) there simply isn't the capacity to carry away that much heat out of the air cooled head and cylinder without using some even more exotic fuel than mentioned below
If you want to put down SERIOUS power and your budget isn't in question, design the system around using exotic fuel. Either 110LL or pure alcohol will do it.
Conquest 86 has an engine built around 111 octane zip fuel and it really hauls.
The higher octance fuels resist detonation at higher compression ratios and the alcohols have more latent heat absorbtion during their phase change. Both are a fine choice for getting maximum power out of a blaster even if they are unfriendly to your wallet.... again to the budget problem....
a huge problem with turbo is the reeds. they tend to break.
people have turbo banshee a few times. like paulie showed a 146hp 350cc engine. there is another that was a 421 cub make 200hp on a turbo.
to the guy saying a 2-stroke doesn't like boost, i think this numbers speak for themselves.
people have turbo banshee a few times. like paulie showed a 146hp 350cc engine. there is another that was a 421 cub make 200hp on a turbo.
to the guy saying a 2-stroke doesn't like boost, i think this numbers speak for themselves.
The main idea behind this topic is that happen to have an extra blaster frame laying around and most of the parts to get her rolling like banshee hubs, banshee hydros, mixed set of banshee and raptor wheels...just need an axle and extended swinger an lots of research. I've boosted a lot of things including an 18hp john deere, yes i'm country as hell lmao. I just never really fully understood the workings and principles of a 2 stroke engine although I've rode kx250s for years I've never had to rebuild and the extent of modding them was reeds and exhaust. Never tried to bore one since I have heard the kx250 guts are nickel plated. Just looking for a toy project that I can take to the strip a few times and show off...methanol isn't out of the question... I've got a tank of it in my garage from racing karts lol
If you really wanted to build a drag blaster (sheeblast sometimes the idea is do it with what you've already got, working inside the limitations of what's available) and methanol is available, you could turbocharge a blast engine. The only thing it would be good for is drag racing because the enormous amount of heat generated will need to be let out once in a while so it would be do a drag run and then sit in front of a fan to cool the cylinder off for a few minutes...
Use an expansion chamber for the RPM you'll be running (usually maximum piston speed which, for the blaster, is about 10.5K rpm) and weld a plate on the end of the stinger where the silencer would normally go.
For ease of use, a draw through carburetor is simplest.
For fuel atomization, a blow through carburetor is better
For peak performance, a mini EFI system is best.
Each system has their drawbacks and advantages.
Draw through carb leaves a lot of fuel stuck inside the turbo housing and the throttle response isn't as quick as the other systems.
Blow through carburetor has to be externally pressurized with boost reference pressure to work properly and they are difficult to tune and work on. Jetting changes require cracking the induction system open and working on it. Also, with a blow through carburetor, engines have a tendency to load up on idle. The carburetor is DESIGNED to operate under a vacuum referenced to atmosphere not under a relative vacuum referenced to boost pressure sometimes and atmosphere sometimes. The transition is difficult and most times leads to rich or lean conditions (normally rich for some reason).
EFI has all of the aforementioned problems; power consumption, complexity, and tuning requirements but has the most potential for power output and the least amount of "running" problems as long it's tuned properly.
If you don't mind dumping untold amounts of time and parts into the project... go for it! Take really good pictures and notes so we can all enjoy it and have fun.
Use an expansion chamber for the RPM you'll be running (usually maximum piston speed which, for the blaster, is about 10.5K rpm) and weld a plate on the end of the stinger where the silencer would normally go.
For ease of use, a draw through carburetor is simplest.
For fuel atomization, a blow through carburetor is better
For peak performance, a mini EFI system is best.
Each system has their drawbacks and advantages.
Draw through carb leaves a lot of fuel stuck inside the turbo housing and the throttle response isn't as quick as the other systems.
Blow through carburetor has to be externally pressurized with boost reference pressure to work properly and they are difficult to tune and work on. Jetting changes require cracking the induction system open and working on it. Also, with a blow through carburetor, engines have a tendency to load up on idle. The carburetor is DESIGNED to operate under a vacuum referenced to atmosphere not under a relative vacuum referenced to boost pressure sometimes and atmosphere sometimes. The transition is difficult and most times leads to rich or lean conditions (normally rich for some reason).
EFI has all of the aforementioned problems; power consumption, complexity, and tuning requirements but has the most potential for power output and the least amount of "running" problems as long it's tuned properly.
If you don't mind dumping untold amounts of time and parts into the project... go for it! Take really good pictures and notes so we can all enjoy it and have fun.
Thanks. Im wondering if it may be easier to make the supercharger I spoke of before that was used in kart racing work for this. Im going to continue doing research into this and see what I can come up with. And will definitely do a good build thread with lots and lots of pictures.
Sheeblast...little off topic but what kind of lights are you running in you avatar/signature?
Sheeblast...little off topic but what kind of lights are you running in you avatar/signature?
I'm presuming you are dragging this bike right? Or is this just a fun build? Hell, for the ambition on the project you might as well just spec the top and bottom end for that matter and recast a cylinder with a cooling jacket. Crank will need to be beefed up and trued beyond belief and the crank seals will have to be custom made to withstand the forced induction.
