Pinewood Derby Tips?

[RXTC]

After being disqualified by a small town "BS" troop leader for using BSA certified wheels, but not the wheels supplied in the kit. (Which was later over turned by the main scouting office in Indy)


My son would like to make a come back this year.


So does any one have some tips to make his car as fast as possible?


He's already been told that the car probably won't look as cool, but he's ok with that if he wins.


So far;


- axles have been trued in a lathe and a groove cut where the wheel rides.
- axles have been polished
- wheels have been trued, and polished.


I have 2 body designs, one low wedge design, the other is pretty much a thin block about a inch  wide, flaring out only to support the axles.


Any one have ideas on weight placement?


I'm pretty sure they are outlawing aligning one axle up, so you are only riding on 3 wheels.

[spacevomit]

The most wind cheating design would approximate this shape, the Sears-Haack body (or "scout-kebab" ):

[Jarhead Steve]

-weight in the rear as low as possible is best
-graphite, graphite, graphite on the axles
-get it as damn close to 5oz (or whatever the weight limit is now) as you can. it's better to have a little extra weight (pour some lead into it and drill some out after you weigh it on the official scale)
-mount the axles at 5-10 degrees above horizontal so the wheels move outward


my dad and I had pretty good success with several of mine

Biggest thing is dont let people play with it after it's built. That's the main thing that ruins chances for winning. It's not a matchbox car.

[Pez]

Spread the wheel base as far as possible
Weight as far rear as possible
Bend one front axle up a little so the wheel is just off the track, 3 wheel friction is less than 4
Cut a groove in the front so that the cleavage of the groove would straddle the starting pin on the track. Then bridge the cleavage at the front of the car with a paperclip that bends upward, before it bends across, so it touches the starting pin at the highest point.  That way, as soon as the starting pin is rotated forward, the car starts moving and the cleavage is clearance so the car doesn't hit the pin as the car moves forward, if the car moves faster than the pin is dropped.
Hollow out the middle as much as possibe so the weight can be concentrated in the back.

I just made 2 cars that got 1st and 2nd in their class, and one got 2nd overall

[Speedfab]

Ceramic ball bearings. 

[jim3]

Put the ball bearings in the back for weight.  Other than that the above tips are golden.  My 4 sons have always done well with those tips.  A few champions.  Above all, let the kid do the work, it's not hard to oversee the work.

[RXTC]

Thank you for the tips so far, anything else?

[Jarhead Steve]

its your fuel map man, its got a nasty hole...thats why your unloading in third

just tune the nos timer, leghten the injector pulse another millasecond, you'll run 9's.

[gc3]

its your fuel map man, its got a nasty hole...thats why your unloading in third

just tune the nos timer, leghten the injector pulse another millasecond, you'll run 9's.

pinewood derbys can have fuel maps now? and i thought nascar was going hi-tech