Advantages of Tungsten

[DuckOfAllTrades]

What are the advantages of using tungsten to weight your car? I understand it takes less of it to weight a car with lead or something comparable, but outside of that, are there advantages? Is it worth it to skip the lead and drop the money on tungsten, or is it more of a convenience than a necessity?

 

[Pinewood Outlaw]

Well with tungsten 1/4" cubes or bars you can make your car body really thin say 5/16" and carve out weight pockets in the rear. You can also make a really light ladder body car and use tungsten cubes. With lighter bodies you can place more weight further back with tungsten cubes compared to lead. The more weight you cam throw back the greater for potential energy since we are talking aboit gravity powered cars starting on a slope

 

[DuckOfAllTrades]

I get that part of it, but what I mean is, will it somehow make your car faster? or is the only advantage being able to use less weights and be more flexible and go thinner the only advantages. I know that sounds like a dumb question! In theory weight is weight. But it allows you to concentrate weight better.

 

[Pinewood Outlaw]

Can you get 4oz of lead in the cavity underneath a 5/16 car?? If so go for it

 

[Mojo Racing]

The advantage is the density of the weight and the ability to place more weight exactly where you want it vs having to spread it out over a larger area in the car.

 

[M Tull]

Several expert racers on this forum over the years have asserted the closer the weights are together the faster the car ... which is what Mojo was referring to regarding density vs spread out over a larger area. Not to steal your thread DuckofallTrades or Mojo's thunder but I was wondering if anyone can explain why? My best guess is both rotational inertia when the car rotates from the hill to the flat and also because you have weight higher on the hill and also on the hill longer. A simple explanation of rotational inertia:

 

[IAE Racing]

it doesnt take less. If you need 4 ozs you need 4 ozs. Tungesten is 1.6 time denser then lead. as mentioned above, allows for easier placement. It is still possible to get 2 oz lead behind the rear axel, but yould have a thicker car. IE, <.30 inch with tungesten and somewhere around .5 inch thick with lead. I dont remember exactly. Once upon a time DDH had a video showing the speed advantage of thinner car.

 

[Jimmy & his 2 Kids]

Can’t believe I’m actually going to take a stab at this one...
so I learned this watching a science vid as it affects Pinewood Derby. It makes total sense. This may not be the whole story why... but it certainly is a lot I think...
so here goes nothin’...
Weight traveling down the slopes hill portion is kinetic energy which = speed. Weight traveling along the flat portion of the track is now drag = brakes.... gravity causes speed on the hill but slows cars down on the flat section.
That being said take 2 cars built exactly the same ( is there such a thing?) and to help picture this... car 1 has weight in the front... car 2 has it in the back... all things being the same, including the speed down the hill to the transition the car whose weight levels off first starts to slow down before the car that has t at the back. When they hit the transition at the same time. Weight in front starts to slow down while the weight in the rear is still pushing causing speed.
So in the grand scheme of things in league racing where .0002 can make all the difference in the world, that weight in the back passes the car with weight in the front and has a faster time that wins.
The car with weight in the rear has a car length more of kinetic energy time than the car with weight up front.

Now axle placement of course affects things. Can’t have all the weight behind rear axle or you loose stability up front and car can even lift as it rocks backwards.
But me... I’m putting weight in the back.
Hope that helps put it into perspective???
I may even have just confused myself!

Jimmy

 

[Pinewood Outlaw]

The car with weight in the rear has a car length more of kinetic energy time than the car with weight up front.

Now axle placement of course affects things.

Jimmy

So also a 4 3/8 wheelbase car will have 5/8" extra travel time down the slope before the front wheels engages the transition versus a 5" wheelbase car.......or am mistaken?

 

[Jimmy & his 2 Kids]

So also a 4 3/8 wheelbase car will have 5/8" extra travel time down the slope before the front wheels engages the transition versus a 5" wheelbase car.......or am mistaken?

Oooooh no... no more answers for me... I think that last one caused an aneurysm...
well... really what I would think about is when the weight makes the transition vs the front wheels. I would think (starting to hurt) that rear axle placement if anything affects range of COM. But then there’s another rabbit hole altogether...

 

[Pinewood Outlaw]

Think about a 5" wheelbase car as the front wheels hit the transition point....now imagine the car stopped at that point. Imagine where the front edge of the car is on the track. Now a 4 3/8" wheelbase car comes down....as his front wheels hit the same transition point wouldn't the car have actually traveled a little further on the slope before it's front wheels where in the same spot as the 5" wheelbase car and thus the nose of the shorter wheelbase car be ahead of the longer wheelbase car....ie closer to the finish line.............should be a slight advantage

 

[DuckOfAllTrades]

Thanks guys! I am able to get the weight near the rear with lead, but it does hang down below the body. I don’t know if thst hurts the speed or not. I always cover it with tape and never have had a problem with it bottoming out. It’s just not as pretty or concentrated!

I asked because honestly, I can’t afford it. But I was curious if it is something I will have to afford to have a fast car. Keep in mind, speaking for scout builds and not pro cars. Hopefully it works ok.

To get the lead in the back, what I do is take a 1/16” piece of plywood and draw out the exact dimensions of the weight pockets. I then cut it out and lay it on top of the weight pockets. Make sense? They are lined up and essentialy deepens the pockets by 1/16”. Then I melt and pour the appropriate amount of lead in the weight pockets. Let it dry then remove the plywood. Not pretty, but it works. Just want to make sure I’m not killing the speed on our scout builds! It does hang down a bit, but never the full 1/16”.

 

[IAE Racing]

Thanks guys! I am able to get the weight near the rear with lead, but it does hang down below the body. I don’t know if thst hurts the speed or not. I always cover it with tape and never have had a problem with it bottoming out. It’s just not as pretty or concentrated!

I asked because honestly, I can’t afford it. But I was curious if it is something I will have to afford to have a fast car. Keep in mind, speaking for scout builds and not pro cars. Hopefully it works ok.

To get the lead in the back, what I do is take a 1/16” piece of plywood and draw out the exact dimensions of the weight pockets. I then cut it out and lay it on top of the weight pockets. Make sense? They are lined up and essentialy deepens the pockets by 1/16”. Then I melt and pour the appropriate amount of lead in the weight pockets. Let it dry then remove the plywood. Not pretty, but it works. Just want to make sure I’m not killing the speed on our scout builds! It does hang down a bit, but never the full 1/16”.

A well built lead car can beat an average tungsten any day. How I used lead was similar to you with an added tweak. I didnt pour the hot lead in the car. I made a mold similar to the weight pocket on a different piece of wood. I had several forms. After the lead had cooled, id hammer the ingot into shape, so I could place it into the car. If you have weight hanging down, be aware of the aerodynamics of it also, but as you know, keep it off the track.

 

[DuckOfAllTrades]

A well built lead car can beat an average tungsten any day. How I used lead was similar to you with an added tweak. I didnt pour the hot lead in the car. I made a mold similar to the weight pocket on a different piece of wood. I had several forms. After the lead had cooled, id hammer the ingot into shape, so I could place it into the car. If you have weight hanging down, be aware of the aerodynamics of it also, but as you know, keep it off the track.

Absolutely will be aware! And thanks for sharing. I should add, I pour the lead slightly over weight, then when it cools I pull it out. I sand it completely flat for aerodynamics and to meet weight then reinsert and epxoxy in place. I cover it in tape to hopefully further help the aerodynamics. I know this is less than ideal, but hopefully it’s not killing my speed! I spend less than two dollars on fishing weights instead of 20 for tungsten.

 

[Thinkin'Bout Racin]

Unless you are in a District with Bracket Racer, MoJo, BRegal, 5kids, or one of the other pros here, a well built lead car can be fast enough to win. If you are in one of "those Districts" then you can use tungsten and still get beat.

So, no you are not killing your speed ...yes you are giving up some, but focus on other aspects of the build first. There is more likely speed to be gained there and when you eventually switch to tungsten, everything else you have learned will benefit even more.

 

[Jimmy & his 2 Kids]

I just want to say this... not to debate because what everyone has said is certainly valid... but with tungsten’s denseness and versatility and where .0001 can make or break a points lead... there will be no lead cars that climb to the top rung of the ladder in league racing.
I personally love the small increments, and being able to put them in with the proper 2 sided tape and easily pop them back out whenever I want to make a change or need the weights for another application.
Just my 2 cents based on what I am seeing and racing against.
Jimmy

 

[DuckOfAllTrades]

Thanks again everyone! Based off this information, sounds like I need to invest in some tungsten! If anything, I could buy enough to do two cars and easily swap it out for another car in a pinch. A few more questions.

1. How much do you need! The way it is packaged, I think in 3 ounces, it forces you to buy at least two packages, am I right?
2. It comes in cubes, right? At least the ones I've seen, and the cubes are all the same. Or do you buy smaller ones too? So if they are in heavy cubes, it looks like you'd either be really under weight, or over weight. With large increments, how do you meet the weight.
3. How are they attached so that you can easily pull them out and donate them to another car.
4. Based off of what I've read, I should put 2 ounces behind the wheels and the rest in front of the back axle, but not worry about the COG. Is that correct? I've been setting my COG at .75"

Thanks again in advance.

 

[Vitamin K]

Unless you're running in a really competitive district, my opinion is that you don't need tungsten at the Scout level.

Have made some cars that were plenty fast using lead bars or even 3/8" lead rod.

 

[Thinkin'Bout Racin]

I just want to say this... not to debate because what everyone has said is certainly valid... but with tungsten’s denseness and versatility and where .0001 can make or break a points lead... there will be no lead cars that climb to the top rung of the ladder in league racing.
I personally love the small increments, and being able to put them in with the proper 2 sided tape and easily pop them back out whenever I want to make a change or need the weights for another application.
Just my 2 cents based on what I am seeing and racing against.
Jimmy

Jimmy,

I agree completely that most any given person can build a faster tungsten car than they can made with lead. I know I can. And you are not going to place or win at league racing with a lead car. The competition at that level is just too great.

The point I am trying to make is that at most Scout level races, that a well built lead car can be competitive. For a budget minded family (possibly 4-5 cars and $80-$100 for tungsten), that lead offers an alternative that can allow them to race competitively. If they choose to race using lead, I encourage them to work on alignment, axle prep, and wheel prep. By increasing their skill levels on those things, they will become faster. Then when they do splurge and buy tungsten, they will be even faster yet.

Not trying to be argumentative, rather I'm trying to offer a different perspective.

I would also add that a person need to be careful around lead especially with young kids. Lead fumes and lead dust from sanding /cutting is a potential hazard. I use gloves when handling/cutting the lead until it is inside the car. Then all of the work space is vacuumed up and wiped down with glass and brake cleaner before the kids work in that area. All of my lead builds have the lead completely sealed inside the body of the car.

I have also poured about 9,000-10,000 jigs over the last 20 years, so I am comfortable working around lead.

 

[Jimmy & his 2 Kids]

Oh guys don’t get me wrong... I am only speaking in the context of league racing as I know Duck is gearing up to send one in.
Yes it’s not nec at the scout level.

And I only have enough cubes and putty for 3 cars and keep cannibalizing for other cars.