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forced induction cr125?

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Hey guys, I've been reading around about the cr125, and everyone seems to agree on the major problem of the pre-05' bike, of which mine is counted. (2003)

Is forced induction possible? please no bashing on "turbos aren't feasible" or "superchargers have no place to mount" because those are not my intention. I simply want to know if anyone thinks that any type of forced induction would drastically help the bike.

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Would it help? Sure.

Is it possible? Sure, how much money can you spend? $5 to $10K might get it working.

Is it worth doing to increase the performance? No.

Smart money says sell your bike and buty a more powerful one.

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Well, you're forgetting what I said. A super or a turbo isn't what I was thinking. What I had in mind was like a fan in the air boot hooked up to a rotary magnetic potentiometer in the throttle, so no turbo lag. If it had any amount of air moving power at all, that could really put out some boost. Next issue; controlling boost pressure.

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Any more input guys? C'mon, it sounds like a good idea. Way more airflow for cheap? It sounds like a winner.

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I remember there used to be a company that made a kit for atc250r and trx250r, or it may have been universal. I think it was called "super stratocharger." I think it was some sort of fan that may have been powered by a r/c battery pack.

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I've designed and built a custom twin turbo system for the car in my avatar and having done major research on the subject, I'll offer this.

Any type of supercharger requires a lot of power to drive it. This is why they typically use a belt drive direct from the engine's crankshaft or use the large source of heat energy of the exhaust in the case of the turbo. Any type of fan able to make positive pressure on even a 125cc engine would require a ton of power to drive it and if using batteries, it would be short lived at best. There's many reasons fans aren't used for supercharging purposes, poor efficiency being at the top.

IMO, don't waste your time:bonk:

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Well, if you need power, thats NO problem. I'm a member of the RC community, and batteries have come a very long way from old ni-mh and ni-cd batteries. Nowadays we have Lipos and brushless motors, hooked up to a propeller for a park flyer, and I could move quite a large amount of air. Power is no object.

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I would guess you would need around 50 amps at 14v to drive a fan capable of showing any pressure in a 125s intake at 8000rpm. Even at that, 1 psi boost on a 30hp engine would be worth maybe 1 hp taking thermal losses into acct. These are very rough estimates based on my experience to give you an idea of the challenges you'd be facing. I'm sure your not looking for a lecture on supercharging but you must also remember that there's much more to it than just shoving air down the intake. Excess heat and incorrect A/F ratios can melt pistons in a flash while under boost.

Irregardless, experimenting can be fun and I'd love to here of the results of a project like this. Good luck.

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OK, with that in mid, I can get a 100A esc, hooked up to a 6s lipo, for under 300$. For the lipo talk, 14v as about a 4s lipo, 14.4v. 3.3v per cell. 6s is like 22v or something. And about a supercharging lecture, if I could get some info on that supercharging subject, that would be greatly appreciated.

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50 amps though, the biggest single battery I can get is a 5000 mAh. So, I need 10 of those batteries. Interesting issue. How to get around this?

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LOL, you are lookinmg for perpetual motion. Not going to happen. To run a fan to force induction, you will need a lot of electrical power. To get a lot of electrical power you need a huge stator. A huge stator will suck up all your power.

Generating electricity and using it to power a motor is terribly inefficient compared to a turbo or spercharger. Both cut out the waste of converting the rotating (or blowing of the exhaust) into electricity and back into rotary motion.

The 'air box fans' you see advertised are a total joke. Do a little googling, you'll find hindreds of comments regarding this folly.

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honestly a waste of time mate

a fan just wont supply enough pressure to make a differance

have seen them all fail my self on dyno's!

u can buy elect superchargers and mate they are shit they actualy cause more of a restriction

think it was between 3000 to 4000 rpm they actualy made a improvement to performance slightly but after that it would restrict the engine and lose power

mind you thsi was all tested on my mates ke ford laser 1.8ltr

honestly even on a bike it would not make a appceptible differance

but hey if you can make it work and have dyno proven results i would be very very intressted and you would have a market to sell your set up providing the dyno results were practicle

was a good idea mate just taht the technology is not there yet

as for having enough power to run it i dont see this being that much of a issue you would have have to use capacitors to hold the current and have some good battery's witch would not come cheap

would alos be really hard to tune being 2 stroke as well it would want to run lean on full throttle and to rich while out of the band

because with any forced induction if you force more air into the chamber you need to counter it and add more fuel = more combustion = compression

trust me ive built a 92 subaru ej20-g stroked and sleved and bored to a 2.8ltr turbo engine with a g35r turbo set up and dyno'd at 407akw at the wheels thats daily driven 407kw btw have pushed it to around 512kw before my bottom end bearing went pop

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Just a few numbers from an online calculator site to give a rough idea of the fan motor/power needed on a small 2t motor (hp and wattage numbers are ideal, multiply by @ 1.2 for real-world):

80 cfm, 1 psi: .54 hp, @ 403 watts

80 cfm, 2 psi: .84 hp, @ 626 watts

100 cfm, 1 psi: .67 hp, @ 500 watts

100 cfm, 2 psi: 1.07 hp, @ 798 watts

By my calculations, a 250cc 2t motor pulls at least 81 cfm @ 9,000 rpm.

There's a device called an e-RAM (12 VDC, 1.2 hp motor, 833 watts) that may be able to provide 160 cfm @ 1 psi boost at full power input, and surely less at reduced power. It's roughly 5" in diameter by 5" long. It would be interesting to simply switch it in and out at WOT using the TPS.

One of these days I hope to try this idea out. Yes, it would take some work and money, but worthwhile endeavors often do.

Ray

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You aren't realizing that fans cannot build pressure. Fan blades and compressor blades are very different by design. Putting a fan in your intake will do nothing other than restrict it and cause a loss of power.

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You aren't realizing that fans cannot build pressure. Fan blades and compressor blades are very different by design. Putting a fan in your intake will do nothing other than restrict it and cause a loss of power.

Was to be my next point.

A fan is not a positive displacement device like a turbo/centrifugal compressor or roots/screw type supercharger. Although I believe it could make minor above atmospheric pressure, I don't think it would be worth the effort.

A better idea would be to drive a small correctly sized turbo compressor with a motor/gear system. This could raise the efficiency enough to make some power. Then you just need to overcome the many fueling issues. Mainly, correct jetting both on and off boost, sealing the carb against blow-thru boost pressure, blow off valve issues of course fuel delivery to the carb which will be non-existant as soon as it sees any positive boost because it is gravity fed and has no pressure.

Edited by Kroynon
sp.

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Putting a fan in your intake will do nothing other than restrict it and cause a loss of power.

This isn't a computer cooling fan; it's a 1.2 hp, 25,000 rpm, 3"-output blower capable of lifting its own weight, working into the partial vacuum of a 125cc 2t motor's crankcase. When its switch is thrown with the throttle pinned, I guarantee that "nothing" is not what will happen, regardless of fan theory. 👍 I also doubt very much that a 3" intake will restrict a 125cc-size carb's flow at all at partial or even full throttle, despite the presence of fan blades.

Ray

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seen leaf blowers blown into intakes on cars sitting on a dyno and the power picks up, youtube

this is what I was thinking...... mounting a leaf blower in the air box....won't be substancial gains , but the fuel the premix in your bike tank and it being its own power source would be two hurdles eliminated.

although not a true compressor I am sure it would help eliminate any fluid drag losses of a normally aspirated engine.

at the risk of the engine getting too pipey you can always stuff the crankcases to raise primary compression.

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This isn't a computer cooling fan; it's a 1.2 hp, 25,000 rpm, 3"-output blower capable of lifting its own weight, working into the partial vacuum of a 125cc 2t motor's crankcase. When its switch is thrown with the throttle pinned, I guarantee that "nothing" is not what will happen, regardless of fan theory. 👍 I also doubt very much that a 3" intake will restrict a 125cc-size carb's flow at all at partial or even full throttle, despite the presence of fan blades.

Ray

It doesn't matter how much hp is behind the fan, fan blades by design lack the ability to build positive pressure within an enclosure. You could put a 400 hp motor behind a fan blade and spin it at 1,000,000 RPM, the result will be the same. Put some blades of proper design on it and you might see some sort of a difference.

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