Landracing Forum
Misc Forums => How To Section => Topic started by: olepaw on February 22, 2010, 08:32:39 PM
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I just ordered a rule book, and have a old 87 firebird with cage not assembled, engine trans . But is this the place to get answers to thousands of questions? tires axle ratios?
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Yes on your questions. This is the LSR answer. Hundreds of years of experience offered here. Ask away and someone will get back to you. Enjoy the best web site for the sport. :cheers:
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thanks sounds great
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So, you wanna go 200?
Work out how many revs you can "afford"...... ie: calculate how much you want to spend on a motor, 5000rpm is a no-brainer, 6000 will need some non-stock gear , once you go beyond that there is a very steep curve of increasing expense.......
Generally production style cars struggle to pull a final drive with a numerically lower ratio than 2.4.
You will want to run 1:1 in the box, some people run an overdrive but it is generally accepted as good wisdom to go 1:1.
You can get tires up to 32 inch, generally you will see 26 or 28's on what you intend to run.
Your car will need somewhere north of 750 HP.If you do really well on the set-up you might get there with less , but you mightn't get there quickly enough......
OK , say you have 28inch tires...( I'll work in metric here its easier)
tire height = 700mm, ~ circumference = 700 x 3.14 = 2198mm(lets call it 2.2m)
The diff gears it down , lets say you have a 3.0:1 then the factor is 1/3 ~ .3333
so, we need revs x gearbox x diff x rolling distance x 60(minutes to convert to hours)/ 1000( convert metres to kilometres)
6000rpm x 1 x .3333 x 2.2 x 60
----------------------------- = 263.97km/h
1000
OK I can hear you all groaning about metric.....263.97KM/h is about 158.4mph
At this point when you want to go faster ( assuming your car doesn't want to go tail first at this speed or lower) you will need more gearing, or a motor that will rev harder, see above.
All this is ALSO based on the assumption that the drag that your car produces is LESS than the amount of power your tires can transmit to the salt. Picture this , you have parked your car with the front bumper resting against a tree , if you get in and try to drive it forwards the tires will spin. If instead it was a D9 you'd parked there you will push the tree over because the tracks are capable of transmitting more force to the ground than the roots of the tree.
When you are increasing in speed on the salt the force acting directly against you increases exponentially, soo you will not be able to overcome it, either your motor will rev no higher, or, your tires will spin.You can add ballast to increase your "thrust" ( you can't change traction, it is constant) and go a little quicker....ballast is generally regarded as preferable to downforce as it doesn't increase drag.............
wow, this, is getting complicated. :roll:
If you make an exact copy of a car of the same make and model as yours it is likely you will go slower until you work out how to drive it.......but who wants to copy someone else?.....look at what other cars like yours are running( thankfully in this game folk are generally pretty keen to talk about it)....then ask them what they would do if they had their time( and their money) again.
at that point you are getting close to "cutting edge"
Then, multiply everything you have heard time and money wise by five, or seven if you don't want to kid yourself.
If this sounds ridiculous then you can always build a lakester or a streamliner, they'll go much faster with a lot less power ....but they, um, are a whole other can of worms :evil: :evil: :evil: :evil:
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It's a lot eaiser to go 200 with a 454 than a 350
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Man-o-man, does the title of this thread bring it all back -- that very phrase is what got me started. Beware of what you ask for -- it'll cost you all the money you've got -- but will yield more fun and happiness than you could believe at this point.
Yeah, Nancy says I started mumbling "I want to go 200" a bunch of yers ago -- and now look at (both of) us.
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You have a great start with your car body and your rear axel the GM 7.5 with a series 2 carrier will do 3.08 down to 2.14 with a series 2 carrier---the ratios are cheap on Ebay---you will have to do c-clip eliminators.
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The first time we went to Speedweek We thought "Geez, It'd be interesting to go 200 MPH" Well, its been 3 years of building and about 20 grand to get our lakester ready for a go at it. One seasoned veteran of the salt told us "You cant run 200 on junk parts" man, was he ever right! Study the rulebook CAREFULLY and make a plan. Everything will cost twice as much and take 3 times longer than planned. You will love every minute of it! Nothing but the best of luck to you. Hope to meet you out on the salt.
We documented our lakester build on a weekly basis so others might know what to expect Here's a link
http://kaparich.homestead.com/Bellytank.html (http://kaparich.homestead.com/Bellytank.html)
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Yup, I said the same thing. It isn't cheap even on busa. The problem is after you make the elusive 200mph and get your Red Hat, whats next. In my, and most cases, its a new goal. 10mph once you are over 200 is a whole new challenge, read expensive and time consuming. And it is all so much fun. :cheers:
Fred
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Whoa didn't think i'd get so many responces. thanks all of you,man this great. realy great!
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Well, here's the formula I use to make my way to our own LSR goal.
1. Ascertain your current available credit limit = CL. Times that number by a factor of at least 2.5 then multiply that number by say .5 for every MPH over said goal,then add 33.3% to the total number. If you'd like you can divide this total number by 365 to get a total dollars per day break down.
CL x 2.5 +33.3%= X (dollars)
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365 =X per day (dollars) XPD
2. If you own a home begin to cultivate a strong relationship with a friendly Mortgage broker,you will find this helpful when you exceed the above XPD formula and discover you need to take out a second on your home. I suggest you start with casual lunches first,dinners will come later in your project.
3. Start to subtly inquire on the internet as to the current market value of any spare children you might have, don't forget to add 10% to the value (per child) if they have a college education. Remember not to sell all of your offspring as you will need one or two crew members. Also take take in to consideration that if you had a wife she will have left some months ago... Subtract 1 from the crew member total.
There you have it,these are my observations so far. I'm sure as our project develops I will have many more equations to add.
In closing I would like to say. Have fun, go fast, it's worth every penny.
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When I was working we had a business consultant come to a management seminar. He told each manager that you must bring in a minimum of $1500 p/day to make the company successsful. I find that directly comparable to LSR and specifically, 200 MPH.
DW
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Olepaw, while we're having fun teasing you -- it's pretty true stuff that you're hearing about LSR taking lots of cash and all of your time and spare energy. But what a great way to go!
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Same thing in every type of racing. Cars, Trucks, Airplanes, Horses, etc.........
Speed cost money!
How fast can you afford to Go?
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OlePaw, land speed racing is one of the most reasonable forms of racing, cost wise. At Speedweek, World of Speed, the DLRA meet, and others you can race alongside the best in the world. A person can ride their daily transportation, have fun, and set an occasional record. Its a chance to meet our heros and to race in their wheel tracks.
Going really fast does not have to be expensive. There was a used bike capable of 200 mph on sale for a good price a few weeks ago. Sometimes nice cars come up for sale, too.
LSR can be expensive if we let it, but the enjoyment is not related to the outlay. A walk though the pits of any race will show this. Folks with goofy rides and homebuilt creations have the most fun, lots of times.
Goals are good to have and they keep us focused. The journey toward those objectives is just as important. A philosophy of "I will do my best today, enjoy myself, and we'll see what happens."
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Since we are talking about 200mph and differential gears were mentioned ...
Is the better - safer - wiser center section a spool or limited slip of some design ?
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Since we are talking about 200mph and differential gears were mentioned ...
Is the better - safer - wiser center section a spool or limited slip of some design ?
Perennial, but the cheap versions of the quaife are getting some good ticks........truth is you'll never get everyone to agree on this one, actually anyone..........
http://www.landracing.com/forum/index.php/topic,3514.0.html
http://www.landracing.com/forum/index.php/topic,3696.0.html
The first time we went to Speedweek We thought "Geez, It'd be interesting to go 200 MPH" Well, its been 3 years of building and about 20 grand to get our lakester ready for a go at it. One seasoned veteran of the salt told us "You cant run 200 on junk parts" man, was he ever right! Study the rulebook CAREFULLY and make a plan. Everything will cost twice as much and take 3 times longer than planned. You will love every minute of it! Nothing but the best of luck to you. Hope to meet you out on the salt.
We documented our lakester build on a weekly basis so others might know what to expect Here's a link
http://kaparich.homestead.com/Bellytank.html (http://kaparich.homestead.com/Bellytank.html)
$20K?.................looks good for 20K....didn't amortise the cost of that workshop I'm figurin Chaz......
Good one, I love your car........