Landracing Forum
Tech Information => Technical Discussion => Topic started by: Dynoroom on July 23, 2008, 02:01:00 AM
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How do you mount your ballest in your race car? Do you bolt it down or put it in a box? What other ways do you add weight to your car?
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Mike, How much does the roadster wiegh now? Eric
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How do you mount your ballest in your race car? Do you bolt it down or put it in a box? What other ways do you add weight to your car?
It is bolted down and also in a box for Bonneville...depends on where and how much you need. :-)
J
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I might want to add about 1000 lbs. :evil:
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Are the lower frame rails rectangle or round tube? I would aim for no more than 65%rear bias. If you have ingots drill and bolt, if you are going to mold your own use standard rod coupling nuts , on one end weld a piece of 1"x 3" x1/4" flat strap, like a T and cast into your mold. Try and mount under axle center lines and between the front and rear axles.
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We bolted the rear shot boxes to the frame rails, the front piece is a poured ingot inside an aluminum tube (didn't have a steel one the right size) also bolted to the frame.
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How do you mount your ballest in your race car? Do you bolt it down or put it in a box? What other ways do you add weight to your car?
Dynoroom
On our Alston chassis camarro they put weight boxs behind the rear tires low just above the lower body line and the batteries mount on top of the box. We melted old lead wheel weights into small blocks and bolted the lid on.I forget the size but a little wider than the battery and about the same length, forget how deep but about 6''. The big intercooler tank (abut 38 gal) and the water tank below it.
Come by and see us and take a look at bville.
JL222
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Hi Mike, we pour lead shot into the frame rails. When we build the frame on the 511 we put bulkheads in the frame rails so we could make adjustments. The rest of the weight gets bolted down where we need it with 1/2 inch bolts. Also using 1/4 plate for the floor and firewall helps to have a good secure surface to bolt lead to. In the 811 we have 800 lbs. bolted down here and there.
In the new blown fuel roadster everything is heavy, really heavy :-o
Hope to see you on the salt 8-)
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Informational only:
Home Depot has lawn tractor suitcase weights. These are 43lb 12x12x3" cast iron weights with a convenient handle. About $50 ea, IIRC. We use them for sled pulling ballast. Sand is the cheapest weight but not legal for many forms of racing. Last pulling event I loaded up 1,700lb of 50lb sandbags for under $60? Just don't let the cats get to it...
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If I wanted to add weight to the front of my car. Could I put lead shot in the front spreader bar (as long as I seal it so none could come out) ?
Also my weigh balance with me in the car is 52% Rear and 52% Left... (with out me it is 50/50 front/rear and 50/50 Left/Right) within .1 % each direction... I am thinking the rear needs to be just slightly more % thna the front but don't know what the magic number is??
Charles
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If I wanted to add weight to the front of my car. Could I put lead shot in the front spreader bar (as long as I seal it so none could come out) ?
Also my weigh balance with me in the car is 52% Rear and 52% Left... (with out me it is 50/50 front/rear and 50/50 Left/Right) within .1 % each direction... I am thinking the rear needs to be just slightly more % thna the front but don't know what the magic number is??
Charles
Personally I think you are probably fine. Are you concerned about this for running Maxton or B'ville? How fast do you think you are going to go on the salt if that is the answer? Did you ever read the stuff on CG/CP? You could then decide if you think it applies to you.
c ya,
Sum
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Sum, I read the CG/CP info and it is a good read... I think I understand it, but I may have a bit of confusion, either way I am now confused at much Higher level... LOL
Most folks who have LSR experiance tell me the body style I am running would be most difficult to reach the record in class (201.xx) I do feel in E/CGALT that my motor sure has the stuff to do it (assume it stays together at Maxton the next two meets) I think I will take the "E" motor out of the 33 Vicky and build a more AREO classic body style for the salt,,,,
For Maxton, I currently hold the record and feel once I tech for the higher speeds this fall I can comfortably move the record up again (as long as she holds the bumps well and with no major cross winds)..
Last weekend,,, I did a 147MPH pass down the bypass near my house,,(6000rpm's in High Gear) She should pull all the way to the 8200 chip with no problem (made power to 8400 on the dyno)
Based upon my current tire, tranny and rear gear set up your speed chart shows that 8200 in high would be 205MPH...
By the way your speed chart is within 50 rpm's of dead on all the way from 30mph up to 147mph,,, thanks so much for the chart,,, it has helped me with my gearing and tire size etc...
Hope to have my new wheels and tires on for Maxton in Sept.
Charles
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Last weekend,,, I did a 147MPH pass down the bypass by my house,,, at 6000rpm's in High Gear... She shoould pull all the way to the 8200 chip no problem (made power to 8400 on the dyno)
Based upon my current tire, tranny and rear gear set up your spped chart shows 8200 in high at 205MPH...
By the way your speed chart is within 50 rpm's from 30mph all the way to 147mph,,, thanks so much for the chart,,, it has helped me with my gearing and tire size etc.........................Charles
The chart isn't off your tach, tire growth, slippage, etc. is :wink:.
There is one small assumption you are making about pulling all the way to 8200 in high gear even though you made the most HP there that will prove to be a problem. Let me try and explain:
On our record run we averaged 239.7 mph in the 5th mile and our exit speed was 241.2 at 7100 rpm, so we weren't going to run any faster even if the course would have been longer. On one of the previous pages we showed that we needed about 700 HP at the crank to run 240 mph and that is what the motor puts out at 7100 rpm (240 mph). Our motor makes maximum HP at about 7400 rpm, about 740 HP. So why couldn't we run up to 7400 rpm and maximum HP. Seems logical that we should be able to. I gave away the answer in the last paragraph. Our speed at 7400 rpm with the gearing in the car would be 250 mph. The answer lies in the fact that if it took us 700 HP to run 241 it would take 781 HP to run 250 and we didn't have that much so there was no way we were going to get to 250. We might have crept up to 245 or so if we would have had another mile or so and the motor would have stayed together.
So the moral of the story is try and be realistic about your top speed and try and get your gearing set so that you are at or near max HP at that speed/rpm. Use the spread sheets I've listed.
That was from ......................
http://purplesagetradingpost.com/sumner/bvillecar/bville%20-%20LSR%20Thoughts-5.html
.......... page 5 of your "required" reading 8-).
I'd like for you to run 205 with that car, but I'll wager some of my meager income that it won't happen :cry:, but that just may make you want to prove me wrong.
c ya,
Sum
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SUM,, also I am working on the scrub radius and caster (to ease the high speed wandering we discussed prior)
SR was off --- the intersection was to near the inside of the contact patch,, so if I read your stuff right and am using a narrower, taller tire and a narrower wheel with more BS. That should put the line at the center of the contact patch (or very close within 1/4 inch, it is currenty 2 inches inboard of the center)
Caster is 4 degrees and once new tires/wheels are on, I will have the alignment done..
Thanks again for all your help and that cool website,,,,
Keep up the good work on your build,,,, it is awesome,,, Hope you and Hooley have a great time at SW...
Charles
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Sum,,, I do agree with you that the 33 Vicky ("that car") would probably not go 205,,, my guess would be 175...
When I said bump the record, I was referring to the current record (mine) at Maxton,,, it is a soft record,
I was not referring to bumping the 201.xx record at B'ville, (did not mean to confuse the two ) I have no hope of the Vicky going that fast... The areo is just not there,,, neither is the handling (yet)
That is why I think a 80/81 Trans Am, FireBird or Camaro would be a better choice since I will only run in Classic Category... My search is for a Trans Am, I think it has better front area than a Camaro.
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That is why I think a 80/81 Trans Am, FireBird or Camaro would be a better choice since I will only run in Classic Category... My search is for a Trans Am, I think it has better front area than a Camaro.
I believe the Monza would be a better choice and is more aero than any of those mentioned.
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I had a Monza back in the day. The wing shape of the body made it lift but it was fast.
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Maguromic,
I agree the Monza would be a bit better... 2 reasons it is not my first choice.
1. It is harder to find one in decent shape around here.
2. I am not sure I can fit in it.. I am 6ft, 370lbs,,,
(not extremely flexible due to a M/C crash that broke 13 bones and a few pounds of stainless steel and titanium parts holding me together)
If I could find a Monza that has been drag raced and see if I can get in and out,m that would help make the final decision,, I know I can get in and out of the Trans Am style bodies,,, (longer doors)
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Cajun Kid,
You have to drive what makes you feel comfortable. Your idea of trying a Monza is a good idea. Do any show up to Maxton or any of the other races in your neck of the woods. Don't let you hight and weight hold you back. I have seen several 6 foot close to or over 300 lbs guys in roadsters.
I completely understand what you mean by having metal holding you together. I am in the same boat. I have so much metal I travel with a medical card, otherwise when all the alarms go off at the airport they take me to a private room for a search. :-o
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At the airport... been there done that,, after 9/11 it made air travel for even worse, they don't except the medical card,,, I still get the wand, frisk and sometimes the private room,,, hmmm now one time at Miami Airport,, the busy line I got in was a blessing,,, the security agent was a 6ft. Tall Bodacious Blonde,, and the frisk was so good, I just about turned around to go back through the line again.. :evil:
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Cajun, good job staying on topic.... :-D Looks like you have built in ballast and a steering dampener.... :-D :-D :-D :roll:
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Think I got it figured out?
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Am I on track?
Weight = good for starting line traction, may be needed for quite a while for same, but may interfere with stability (i.e., CG vs. CP) as speed gets well up. YRMV = given.
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Does ballast have to be fixed in place, or merely "secure against loss"?
(some will see where I'm going here) :-D
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Am I on track?
Weight = good for starting line traction, may be needed for quite a while for same, but may interfere with stability (i.e., CG vs. CP) as speed gets well up. YRMV = given.
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Does ballast have to be fixed in place, or merely "secure against loss"?
(some will see where I'm going here) :-D
With the Stude we added about 1000 lbs. last year and went faster. We are adding another 500# this year and Hooley, John, Patrick and Jerry just did that. My theory is it isn't going to hurt us accelerating as right now we can only use 25-30% throttle in 1st and 2nd without spinning the tires and our first gear is a very high 1.90 with a 2.47 rear. I'm hoping the extra weight will help us in 1st and 2nd with traction we need there and again at the top of 3rd and in 4th where we have had problems breaking the tires loose when we get to the "aero wall".
We need to accelerate faster to hopefully get our 2 1/4 speed up 8-10 mph if we are going to break 250, which is our goal.
Our added weight is going in to hopefully move the CG forward another couple inches and will only result in about 250 lbs. more on the rear as we have been keeping the car at a 50/50 balance, which in our case according to some crude calculations has kept the CG ahead of the CP by 6-8 inches.
I'm not sure if anyone has gone with movable weights that could move during a run. I for sure would want to get a ruling in writing before I proceeded with that. In our case I don't see how it could be done with all the other packaging requirements. Also as I mentioned above you need the required weight on the back tires on both ends of the run, so I would think moving it forward for stability on the top end of the run would then get away from the weight you need at that point of the run for traction to overcome the aero drag, but I don't know for sure what you have in mind.
Keep us informed,
Sum
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Mike, I used 4" square1/4 wall tubing which I welded a section of 1/4' 4x3 angle one before I filled with lead and one after and drilled a 1/2' hole for mounting to frame---I suggest you not make them over 100#---I made one for a specific place and it weighs 160# and it is a real bitch to deal with
this system makes it easy to relocatre the weight..