60 MPH...achieveable? Who cares?!? Let blueprint an engine!

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Creative Engineering

Creative Engineering

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Wind resistance becomes a "HUGE" factor at about 120mph.

At about 80 mph "air" begins to take on the characteristics of a fluid...This is why airplanes fly.

At about 100 mph...ground based vehicles are severely affected by wind resistance...the effect is nearly exponential from about 120 mph.

I can see the dilemma...at 185-190 mph!

Jim
 
Creative Engineering

Creative Engineering

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exavid said:
Bicycles have achieved some pretty impressive speeds, especially drafting. The current record for an upright bicycle drafting at Bonneville is 166.994mph. Admittedly the bike wasn't fighting much air drag but it was on it's own two wheels with a guy pedaling at that speed. The official record for an upright bike pedaled without drafting is 51.29mph. Considering that an athelete can't generate much more than 3/4 hp for a short time it shouldn't be hard for a 2hp engine to exceed 60mph. It will be interesting to see if it can be done on a dragstrip from a standing start.
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Yes...

And as always, logic will prevail...good post exavid!

Based on what I have seen...1/4 mile will be more than enough to wind the little bugger out. My shop is on a dead-end street that is almost exactly 1/4 mile, and DV gets the bike to full speed in a fraction of this distance.

Jim
 
foureasy

foureasy

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are you going to build a chamber for it? boost ports and multiple transfers seem necessary to me. im very interested in your plans for the motor.
clay
 
DVBikes

DVBikes

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No Basicly its 3 signs and then a lovely ditch. Ok thanks for the coaster brake joke. Ive been messing with small motors for about 5 years. Go peds were big where i live. and i never thought this would make 5 pages. ahahaha
 
Creative Engineering

Creative Engineering

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foureasy said:
are you going to build a chamber for it? boost ports and multiple transfers seem necessary to me. im very interested in your plans for the motor.
clay
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I will definitely make a tuned pipe for it...I have a chamber design that I tested last year...it worked great!

I'm just starting the tuning process...so honestly I really don't know where I'll go from here. It's a daily process of looking at what happens based on modifications. I will post my findings as I go along. I really don't expect that there will be anything out of the ordinary that will make these engines go.

P.S. I totally respect all of the work you have done. Most people have no clue as to the amount of hours that go into building a high performance engine.

Jim
 
skipu

skipu

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i think its possible minor stuff gets me to 39 to 41 you ony have to pick up 19 to 21 mph super light wieght and gearing is key but that motor extra rpms i see it doable on a road race bike at full tuck lol !!!!!!! cant wait to see it !!!
 
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superschwinn

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no way your going to go 60.. and at least not blow ur motor up

not enough everything unless your under 100 lbs and your wearing armstrong style spandex with a stupid helmit..

gotta hand it to you for trying tho.. have to beat the wind resistance. and you aint doin it unless ur down wind or something. need bout 70-100cc's at least
 
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exavid

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Weight matters on a drag strip but doesn't have much effect on top speed on level ground with lots of room to accelerate. Wind resistance is the real problem. The power required to move a bike at 60mph is 8 times that needed to go 30mph. That's at steady state speeds not counting acceleration from 0 mph on a dragstrip. So you'd need even more power to get to the desired 60mph due to the limited amount of time available to achieve that speed. Whether it can be done or not is up in the air. I tend to think it could be but not with a stock China girl motor kit. Besides the work on the engine that's going to be needed the lightest chain and thinnest sprockets and perfectly mounted rear sprocket is going to be important. A chain tensioner would be a real drag and should be eliminated. A streamlined fairing aft of the engine might help. One thing that might be worth considering would be turning the piston and cylinder around and replacing the intake filter with a ram horn or simply making an air ram horn that wraps around to the carburetor in the usual location. That won't give as much boost but it would still help. Small tires and lots of pressure would also be important. The important thing here is to get the most power possible out of the engine and the least drag in the chain drive system. Gluing some shrink wrap to the bike wheels rims to smoothly cover the spokes would also reduce some drag. That's what was done on WWI aircraft that had spoked wheels. It really is an interesting challenge.
 
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exavid

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You really don't have to worry about slowing a 60mph bicycle, it's kinda like throwing a cotton ball, once you take the power off it will slow rapidly just due to the air drag.
 
corgi1

corgi1

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At 60 mph on a bike cotton or not theyed be sucked up so tight that I wouldn't get that much air drag lol
 
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