Motorcycle Powered Kart: Father Daughter Project

[Tune-A-Fish]

Wheelbase seems a bit big. I'm not an engineer but maybe scale it from something like the Cayman:

 

[DohcBikes]

This thread may have just ruined my brain... worse. A big Grizzly 660 into a side by side or crawler... hmmm.

You mean, like this?

 

[Tune-A-Fish]

Yes, that would be fun

 

[Dale]

You mean, like this?

Try this one on for size. Check out the angle of the seats. :-D

 

[Dale]

Wheelbase seems a bit big. I'm not an engineer but maybe scale it from something like the Cayman:

Yes! An excellent example of a well handling car. Ive driven the Caman R, and it was a lot of fun. Beautifully balanced car.

So took your idea, and cross referenced it against the X-Bow, and the Cooper S, which is also a great handling little car.

Scaled the wheels, (granted they could have different sized wheels, but its a fair assessment to be making, trying to figure out proportions this way).

Interesting how the axle to axle wheel bases are all pretty much exactly the same. The Mini has a slightly narrower track than the Porsche, and the K-Bow is notably wider.

The layout in the garage is currently 1800x1400, based on the size of our wheels in relation to the X-Bow. Gonna run with it! :-D

 

[Tune-A-Fish]

My last DD: was a Cayman Base with a bump in power and brakes, had a few 911's, but the Cayman was far better for on/off ramp drifting. Was i right though or is the axle position XYZoom on the money?

 

[Dale]

Nice little car! What 911's have you had??

The wheel base mocked up in the earlier pics were in fact a scaled down version of the X-Bow (1800x1400). The pics DID make them look a little long wheelbase wise, but thats photos for ya! Always hard to gauge. Looks better in the flesh. BUT a good exercise to have gone through. It def solidified the wheelbase issue!



AIRBOX

Ill be straight with you guys. The only reason I'm looking at this is for aesthetic reasons. Nothing else. Shameful I know.

If this little block of plastic wasn't as in your face at the rear of the car, I wouldn't have touched it.

So here's where I'm at with this, and hopefully you tuner guys can give me some info here. I've looked up as much info and math on the interwebs as I can care for reading, but I've stumbled into something which I'm not sure about.

This is the first airbox I have ever made, so here goes:

One thing I think I have improved is the flow, as the air no longer will have to go through a dog leg, but will flow directly towards the inlet.

1. Measured up the internal air volume of the stock box

2. Created a cone shape that matched the volume

3. The filter in the stock box sits roughly in the middle, creating 2 compartments, one open and one between the filter and inlet. I measured up that internal volume.

4. Matched up this new volume with my cone shape

My question is this: Why does the airbox need these two compartments? [fig.1] Why not just put the filter on the end? [fig.2]

[fig.1]

[fig.2]

 

[2_DONE_THE_TON]

ooh yeah i´m in.

 

[Tune-A-Fish]

Nice little car! What 911's have you had??

76 Targa and 80 Carrera, gone a long time ago.

 

[Maritime]

I think it has the 2 compartments so air enters, stabilizes, then pulls through filter and the space after the filter allows a volume of filter air for the carb to draw from. May also keep the filter cleaner longer?

 

[Tune-A-Fish]

Because its also for a young person, keep the burp screen in the design... An airbox fire might not be fun

 

[DesmoDog]

My question is this: Why does the airbox need these two compartments? [fig.1] Why not just put the filter on the end? [fig.2]

A larger filter will have less restriction than a smaller one, everything else being the same... basically if one filter has twice as much area it's only filtering half as much air per square inch, so less flow and less velocity through any one part of it. I haven't done this stuff for so long I've forgotten anything I might have known about how the filter location effects the flow dynamics/acoustics of it all.

 

[irk miller]

if you can come up with a waffle or accordion filter design you can increase surface area significantly.

 

[Maritime]

if you can come up with a waffle or accordion filter design you can increase surface area significantly.

Can you find a K&N that can go in the cone and leave the right volume of air etc.?

 

[jpmobius]

Pleated media and as much filter surface area as possible. Goal is to have as low an air speed through the media as practical. Stock area is useful as a guide, but different media has different resistance so keep it in mind. Interior volume between the filter and throttle is less important than constant air pressure at the inlet. Probably not a major concern since your application will have a pretty slow speed at least for now. As the vehicle speed gets higher, keeping the wind from changing the inlet pressure becomes more challenging. Carburetion will be different at 0 to 30 mph than at 100 to 130mph if the inlet is out in the air stream which would obviously impact the inlet pressure. Stock air boxes also are heavily designed with sound attenuation in mind. Open carbs are tremendously loud compared to any stock air box - not noticed so often as people invariably add a much louder exhaust at the same time as changing the intake hardware. Consider the prospect of water getting into the inlet (rain, splashing, washing), and having a drain so it can drip out before it gets to the media if it does. And of course dirt thrown off the road by tires.

 

[Dale]

Gentlemen, thanks for all the thoughts, brainstorming, ideas and flat out knowledge in your responses.

Some things like water getting in didn't even cross my mind. Will address this too.

Hugely appreciated!


Some progress:

The first green highlight will be where we put some kind of screen. Im thinking plain old window screen mesh?
The second is where we'll be placing the filter media.

3D printing the bodies

Painting them up

(Yes they are water / air tight)

Guy at the auto shop where I bought the filter said that he used this same filter for his lawnmower, used a dremel to cut it.

 

[jpmobius]

Since you already have a cone shape, why not try to incorporate a conical filter as well? The pleats are of course a very good thing, but put into a straight cross section of your "air box" will offer a rather pitiful filter area despite the pleats. Also (and I am a big proponent of extra safety), the spark/flame arrestor screen is a bit of overkill unless you hot rod the motor. OEM's don't consider it necessary (they use cam profiles that make a flaming backfire unlikely), and certainly if you have a wire mesh screen as part of the actual filter it is redundant. Based on your design so far, I think I would consider a "scaled up" version that could contain a conical filter section that still shrouds it sufficiently to keep the inlet air at reasonable constant pressure. I would also offer that the value of "velocity stack" based inlet shapes has pretty limited value (it's still worth doing) from the perspective that when very close to the actual throttle (slide), it only gets a full head of steam when the throttle is completely or nearly wide open (and at big power revs). Since this most often is not the case (except when racing), it shouldn't drive the rest of your design process.

Absolutely awesome work so far (as usual!).

 

[DohcBikes]

Your engine is actually not really particular about the type of intake it runs. Feel free to experiment with reckless abandon.

 

[DohcBikes]

By the way could you please post the model number which is stamped on the lower part of tghe engine. It will be something like 163fml or 169fml. Once i know the model number i can tell you how to make more power.

 

[redwillissuperman]

http://www.greenfilterusa.com/find-filter-cone-cylinder.php