46CC for 60 MPH

[bowljoman]

Im goina do it! I know its possible with my ride. Currently I can get 40+mph @7500RPM with 1.5 HP. This new engine Im building the mount for gets 4.2 HP at 11000 RPM stock.
GPR46 + iMotion3 + 12.5 inch rear wheel.

 

[JonnyR]

im interested in this idea and want to see how you do it and how it turns out

i wish to subscribe to your newsletter or magazine

 

[elemein]

Hrmmm let's see...

7500 * TQ / 5252 = 1.5 HP solved, is, 1.05 lb-ft of torque. <(Old engine values)
11000 * TQ / 5252 = 4.2 HP solved, is, 2.00 lb-ft of torque. <(New engine values)

Your new engine is 190% stronger than your old engine... Is 2.00 lb-ft of torque enough for 60 MPH?

Not to be a killjoy, but aerodynamic drag increases exponentially; so while you may be able to get 40 MPH now with 1.05 lb-ft of torque; double the force does not mean double the speed.

Though let me know how it goes! I'd love to see it happen!

 

[JonnyR]

some stock 49cc engines are able to do 40MPH the thing i want to see if how much more he can get out of the stock engine to drive a 48T or 44T rear sprocket effectively then 50MPH is a possibility

 

[bowljoman]

It would not be fun if it was Easy.

A goped scooter can hit 50-60 MPH without a transmission using a expansion chamber and porting. Add in the three speed and we'll see what i can get.

THe old scooter motor without the tranny was 25 MPH at peak HP, way under 8000 RPM.

Here is the new motor.

 

[JonnyR]

is that a actual set of numbers or a projected set?

 

[bowljoman]

That is factory numbers for stock motor from chung yang website.

 

[JonnyR]

elemans calculations are flawed then because the stock engine has 2.31 foot lbs of torque that was what was screwing me up so what kind of torque is projected because thats the important # to me thats the force it exerts to do work as the old racer saying goes
"horse power is for show torque is for go"

 

[bowljoman]

A couple more stats for the gear-heads out there.

For the GPR460 I will be using this.

• Rear sprocket = 20 tooth ( california excess BMX)
• Rear Wheel = 12.5" Diameter (Typical electric scooter rim)
• IGH 3-speed = 24tooth input/20 tooth output
• Engine sprocket = 12 tooth
• Crankshaft to Output-shaft ratio = 5 to 1

The setup I used with the old engine only differs in the IGH input sprocket, which is 21-tooth.

The gear calculator I use computes the 3-speed jack shaft and plots the potential speed of the combination based on RPM input values.

1. 'max torque RPM' = shift point
2. Clutch stall = lowest RPM of usable power
3. Max HP RPM = the final reliable maximum RPM you achieve
4. Max RPM with tail wind = perfect conditions RPM with a tail wind

Set all your values and then hit the start button. It is written in Flash so it will animate the power lines.

http://thebitstream.com/transcomp/

 

[bowljoman]

elemans calculations are flawed then because the stock engine has 2.31 foot lbs of torque that was what was screwing me up so what kind of torque is projected because thats the important # to me thats the force it exerts to do work as the old racer saying goes
"horse power is for show torque is for go"

If you go to this page http://thebitstream.com/transcomp/ and hit the start button, you will see my 'real world' data as collected over numerous runs. The current values the calculator are set to match real world data, so you might be able to figure it there. All told, Me and the scooter are probably 200 lbs when the data was collected.(safety pads, tools, etc

 

[JonnyR]

nice i was looking at the other engine options the 99cc predator is 3.5 ft lbs and that honda gx200 is a torque monster at 9.1 ft lbs i wonder if the 212 predator is the same curve

 

[bowljoman]

The GPR46 will likely need a higher clutch stall and of course a max RPM of 11000 and maybe a 'perfect conditions setting of 12000. Bump the input sprocket up to 24 tooth so the engine hangs in a higher rpm range than the old 52CC heshaing and sons engine which was a torque monster.

 

[JonnyR]

any links to that engine? or is it a hard one to find i cant seem to locate anything on them

 

[bowljoman]

towards the bottem of the page , just past the rmck 'twin'.

You can buy'em all day long.

http://www.davesmotors.com/s.nl/c.885035/sc.12/category.27895/.f

My old engine is no longer available, but common on a scooterX '52CC'

 

[bowljoman]

I hear this one is good for 20 hp, but dont quote me on it.

 

[JonnyR]

your talking a RC engine they produce crazy power at tiny CCs they are MAD money though and run on nitro there is someone doing a nitro carb modd on a engine here im watching he posts every now and then he ran short on the cash to finnish so we are waiting to see what he does

 

[bowljoman]

These are also the engines they put on goped scooters . The big-blocks dont usually go on the RC's, and these run on 92 octane stock. All the racers on the gopeds I associate with can hit crazy speeds with the r460 without any kind of shifting. They get speeds that my old motor could never reach without adding the three speed. And then my WOT 'top' speed is their cruising speed.

If I cant pull third gear all the way to 11000, second gear puts me at 50 MPH/11000Rpm, and from there, 3rd gear drops me to 9000 RPM/50mph where I might just have enough to get there.

If I add an expansion chamber , more...
If I go whole-hog and get porting and polishing, its a certainty in my mind.

my ride is in this thread here.


http://motorbicycling.com/showthread.php?t=40909

 

[JonnyR]

thats crazy but sounds like a fun ride

 

[elemein]

elemans calculations are flawed then because the stock engine has 2.31 foot lbs of torque that was what was screwing me up so what kind of torque is projected because thats the important # to me thats the force it exerts to do work as the old racer saying goes
"horse power is for show torque is for go"

Nope sorry, my calculations are not wrong. Period.

I'm not trying to be some bigheaded-smart aleck, but they simply aren't.

Horsepower is measured as: RPM * TQ / 5252. There are no two ways about it; that's how it is.

Maybe the engine you mentioned DOES make 2.31 lb-ft of torque, but it sure as **** doesn't do that at 7500 RPM. The laws of physics and math simply say it doesnt. So either your ratings or wrong or you're not giving me the correct figures.

 

[JonnyR]

no one said 2.31 at 7500 RPM the torque it that rpm isnt as important as the torque at clutch engage it may make 1.05 at the end of its torque band but we are interested in max torque number and where it is
you cant always get a engines torque by doing math like that the 5.5 HP honda GX200 makes 9.1 foot lbs at 2500 RPM and 5.5 HP at 3600

http://engines.honda.com/models/model-detail/gx200