Author Topic: Simple Question, but Complex Answer?  (Read 3265 times)

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ProDrivers

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Simple Question, but Complex Answer?
« on: June 20, 2005, 11:01:43 PM »
It is time for me to race. I now have the luxury of the two things I did not have before. Both time and money. I have never been to land speed racing, not because I have not wanted to, mostly because I know that moment I step on the salt, I shall not step off.

I shall build a car. I have an idea, but I am open to suggestions. Although it is not possible for me to start this year, I shall start the project next. That will give me an entire year to sort out what I am going to do.

My first plan is to visit the salt flats next year, hopefully for more than one race. It will be to watch the races, but mostly for the research I know I need to do. Pictures, questions, etc.

My plan is to build a 1991(92, 93?) Firebird and join the 130 mph club first, then in the second year join the 150 mph club. Then I shall do what is neccesary and get the car over 200 mph.

So the question I shall start with is simple.

If I take a rear end ratio of 2.91, a transmission ratio of .82 and run the motor at 6000 rmp through 28 inch tires, my calculations say that combination will run 209 mph.

I know it is more complex, much more complex, than that.

So, the question is this, with that combination, and with a CD, lets say of .320, how much horspower will it take to get to that 6000 rpm.

All things being equal that is.

Is this a "how big is an Apple" type of question, or can this actually get down to a science?

There will be more questions, hopefully much more informed on my part as they go along.

Thank you,

Rocky

Offline Dynoroom

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Simple Question, but Complex Answer?
« Reply #1 on: June 21, 2005, 01:16:45 AM »
Welcome Rocky,

This site will give you alot of insight into land speed racing. No one will have all the answers, however many of them have quite a bit of insight. Remember this should be fun first, as the prize money is a bit short.
To answer your question it takes "about" 600 hp to go 2 bills in most late model cars from the mid '60's on. This can be done with most american V-8 engines without using "state of the art" components. As in most things you'll get from this site your millage may vary.

Good Luck and have FUN!
Michael LeFevers
Kugel and LeFevers Pontiac Firebird

Without Data You're Just Another Guy With An Opinion!

Racing is just a series of "Problem Solving" events that allow you to spend money & make noise...

John Beckett

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Simple Question, but Complex Answer?
« Reply #2 on: June 21, 2005, 07:04:39 AM »
Rocky

Your right 'salt fever' is very easy to catch and hard to eliminate once infected.

"91 - "92 Firebird will make an excellent choice for LSR.

Mike is right "about 600 HP to go 200 MPH". Not to hard to do on say a modern 350 V8, but on average you won't be making that number at 6000 RPM. More like 7500 to 8000, so get rid of the OD you won't need it.

JB

ProDrivers

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Simple Question, but Complex Answer?
« Reply #3 on: June 21, 2005, 01:51:04 PM »
Thanks for the info.

What is interesting is that I was thinking that around 500 hp would put me around 200 mph. So my guestimate was not too far off. I am sure a lot of it has to do with how well you get the horspower to the rear tires. Things like how much horspower the transmission will cost you by the time it gets to the drive shaft, how much power you lose when you make that 90 degree angel at the diff, etc.

Also, according to my calculations, then if the motor is running 7500 rpm, and if you use a 1:1 transmission ratio with a 2.91 rear and 28 inch tires, that would be 215 mph wheel speed.

Then how clean the car is. Of coure, the lower the CD, the less hp you need in the first place, but just the act of cleaning up the car should make quite a bit of difference.

This is where the time spent at the track just looking and talking to people who have done it will be very important.

I chose the type of car as I have seen 300 mph out of that body style already and I am not going to try and re-invent the wheel.

Instead of "building" a car (streamliner as an example) I am going to "modify" an existing example of what will work.

One thing I am going to do is that any modification will be done to meet the rules of /PRO. Even when I am just going after the 130 mph club.

I know that I can build the car when it comes to body, frame, cage, suspension, etc. but I also know that I do not have the expertise when it comes to the Drive Train. The engine, trany, etc. I will leave to those that have both the expertise and the tools to do it right when I head to the 200 mph part of the project.

If I buy well, the motor that comes with the car, should get me to 130 mph with only bolt on modifications.

I do want to go after a class record with the car. That will take me time. I want to sort out the car first, then the power.

When it comes time to go after a record, lets say D/Pro, then I will have to get a proper motor. And that will take proper dollars.

I think it was Mickey Thompson who said "The only substitue for cubic inches, is cubic dollars".

And I am also sure that the only sustitue for going 200 mph, is going 300 mph.

I know that when you double your speed, you quadruple the force on the front of the car. You know, at 50 mph it would be X, and at 100 mph it would be XXXX.

I am sure it works the same with cost.

landracing

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Simple Question, but Complex Answer?
« Reply #4 on: June 21, 2005, 04:16:01 PM »
welcome to the board and the site....

You are doing a very good approach to LSR racing by starting off the 130 club, most just want to come out and get it done, but you are easing yourself into the project. Good job.

Second, Dave Dahlgren has provided us a Bonneville program that will help aide you in proper gear selection, transmission with using all variables of the car. Even if you want to put nitrous on it. Very well designed and can help spending unwanted dollars on gears in long run. Will accept cd of vehicle in equation as well as the weight of the vehicle. A firebird will have most of this data ready available on the internet.

Here is a link to the program

http://www.landracing.com/miva/merchant.mv?Screen=PROD&Store_Code=L&Product_Code=GSLP&Category_Code=OSM

ProDrivers

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Simple Question, but Complex Answer?
« Reply #5 on: June 21, 2005, 10:17:45 PM »
Thanks for the input guys.

Now I have 4,000 posts to read. I am sure that it will give me 4,000 questions to ask.