Drag Racing Tech - Hitting 140mph inside 1KM

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NataSS Inc

04-16-2003, 11:08 AM

Hey guys, need a little input from you. I am running in an Open Road Race in June. the Bonnoville 100. It is a 50 miles out and 50 miles back, High speed, time, distance, rally in Wendover Nevada. Part of the event is a 1K standing drag. You run solo for safety reasons. What I need to know is:
Would it be possible for a SS w/ 420RWHP and 400RWTQ be able to hit 140mph inside of that 1Kilometer? I would really like to know if this would be possible. I have run the car in the 1/4 yet but the HP is there to trap 12X. this run is not timed, it is a top speed shootout.

I need to know before I start talking some smack to the other drivers.

Plum Crazy Rob

04-16-2003, 11:55 AM

1 km??? that's so Euro-gay <img border="0" alt="[rainbow]" title="" src="graemlins/gr_rainbow.gif" /> <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

That's like 3000 feet..140 should be a piece of cake even on "road race" tires

Fenris Ulf

04-16-2003, 01:01 PM

Let's see:

Assuming a drag coefficient of .34
Frontal area of 22 ft^2
Air density @ 7000 ft: ~1.9X10^-3 slugs/ft^3

would give a drag force =
1/2*(density)(A*Cd)*V^2 or
Df = .007106 * V^2 lbs with velocity in ft/s

For example, the drag force at 140 mph would be
140 mph = 205.3 ft/s, Df = 300 lbs
Or at 200 mph, Df = 611 lbs

This is assuming a constant drag coefficient which is probably wrong, I bet it varies somewhat with velocity. These figures would net a theoretical top speed of 215 mph with optimal gearing etc and neglecting frictional losses, so take it with a grain of salt.

So now your resultant force is = force applied by the drive wheels - friction forces - drag forces

Ftotal = Frwtq - Ffriction - Fdrag so then
Acceleration = (Frwtq - Ffriction - Fdrag)/m where m is the mass of the car. The instantaneous force applied by the engine to the tires is
Frwtq = (rwtq) * (Gear ratio final) * (Gear ratio in tranny) / (tire diameter/2)

So now you can open up a spreadsheet, enter your rwtq values in 500 rpm increments or whatever and graph instaneous acceleration in terms of velocity. Since acceleration is the first derivative with respect to time, you can integrate and solve for velocity in terms of time and distance. Or...

You can bring a bottle and not worry about any of the above <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

NataSS Inc

04-16-2003, 01:13 PM

<blockquote>quote:<hr />Originally posted by Fenris Ulf:
 You can bring a bottle and not worry about any of the above <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> <hr /></blockquote>Just found out from the promoter of the event that "no bottles allowed" <img border="0" title="" alt="[Frown]" src="gr_sad.gif" />

Fenris Ulf

04-16-2003, 01:45 PM

<blockquote>quote:<hr />Originally posted by NataSS Inc:
 <blockquote>quote:<hr />Originally posted by Fenris Ulf:
 You can bring a bottle and not worry about any of the above <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> <hr /></blockquote>Just found out from the promoter of the event that "no bottles allowed" <img border="0" title="" alt="[Frown]" src="gr_sad.gif" /> <hr /></blockquote>It's only cheating if they catch you <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Plum Crazy Rob

04-16-2003, 04:08 PM

How much altitude? 5000 feet?

Don't assume that just because some car is supercharged (frequently "thrown" on otherwise stock motors) its faster than your well built "heads/cam" car could be. It might be - and it might not be!

Dynojet apparently has already created a routine << example >> (http://www.ws6.com/race9.htm) using the calcs Fenris described and your actual dyno. Don't forget to have them factor back the HP for the altitude.

Fenris Ulf

04-16-2003, 05:05 PM

<blockquote>quote:<hr />Originally posted by Plum Crazy Rob:
 How much altitude? 5000 feet?

Don't assume that just because some car is supercharged (frequently "thrown" on otherwise stock motors) its faster than your well built "heads/cam" car could be. It might be - and it might not be!

Dynojet apparently has already created a routine << example >> (http://www.ws6.com/race9.htm) using the calcs Fenris described and your actual dyno. Don't forget to have them factor back the HP for the altitude. <hr /></blockquote>Altitude is around 7000 ft. Unfortunately that dynojet program can't account for gear changes or drag data specific to a certain vehicle. I have several random dynos laying around my house, I will do some excel calcs when I get a chance.

Plum Crazy Rob

04-16-2003, 05:42 PM

7000 ft in the summer! yikes! You won't make it...
you're talking about 10000-12000 ft density altitude and a dyno de-correction factor of about 0.8...where your 420 RWHP engine makes about 335 RWHP....probably works out to around 130 MPH assuming a perfect launch and some other things that aren't likely to happen. The calculated data will be interesting. I'm too lazy to do the Excel <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

[ April 16, 2003, 05:46 PM: Message edited by: Plum Crazy Rob ]

Fenris Ulf

04-16-2003, 06:00 PM

I am with Rob, I doubt you will hit 140 but who knows.

PNYKILR

04-16-2003, 07:50 PM

I'm at 5,600 feet elevation here. Stock LS1 cars make around 250rwhp, Stock Z06, around 290rwhp, so that should give you some idea of the hit in hp your going to take. At 7000 feet, me thinks a 70 to 80 hp power hit.

NataSS Inc

04-17-2003, 12:05 AM

<blockquote>quote:<hr />Originally posted by Plum Crazy Rob:
 1 km??? that's so Euro-gay <img border="0" alt="[rainbow]" title="" src="graemlins/gr_rainbow.gif" /> <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

That's like 3000 feet..140 should be a piece of cake even on "road race" tires <hr /></blockquote>its 3281 ft. Dont ask me why they chose 1 KM. Last year they had a supercharged C5 BARELY hit 140mph. I think the altitude may have something to do with it.

NataSS Inc

04-17-2003, 11:40 AM

the elevation of the city is 4500ft. I am guessing the 1K run is fairly close to town.

LEO

04-17-2003, 03:26 PM

I think you'll be able to do it. If you ran the 120 mph trap speeds thru the 1/4(1,320 ft) you still have 1,961 ft to accelerate an additional 20 mph to complete the standing kilometer(3,281 ft). Good luck and have fun! <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

Louis

04-17-2003, 05:28 PM

Little OT, but Fenris, that is some time consuming math and typing. Thanks for taking the time <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

Boyce,
It will be close for sure. Its misleading. 3k feet, but its at 7k altitude.

NataSS Inc

04-17-2003, 05:32 PM

the city of Wendover is at 4500ft of elevation. That should help with the equations. I wonder if running my G2 SCCA spoiler will put the drag CD all out of whack. 130mph seems to be where the "wall" of air is, after that its harder to accellerate.

NataSS Inc

04-18-2003, 12:18 AM

Fenris, you come up with any brain child #'s yet?

Fenris Ulf

04-18-2003, 12:38 AM

I did some of the calcs last night. I am going to need your car's weight, rear gear ratio etc.

NataSS Inc

04-18-2003, 12:43 AM

I have never weighed the car but I am guessing it is in the 3600lb range. Once the cage gets in it, it will be a bit heavier than the normal weigh in of an Fbody.

Fenris Ulf

04-19-2003, 02:49 AM

Even if you hit only 116 mph in the quarter with the elevation you should still break 140 by the time the 1 km mark comes.

1900+ feet is plenty of distance for that extra 2X mph you need. I don't know what was up with that supercharged C5...

DriveATransAm

04-19-2003, 09:02 AM

superchargers like dense air <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Fenris Ulf

04-19-2003, 02:35 PM

<blockquote>quote:<hr />Originally posted by quickWS6:
 <blockquote>quote:<hr />Originally posted by DriveATransAm:
 superchargers like dense air <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> <hr /></blockquote>I always thought that supercharged/turbocharged motors didn't take as big a hit at high altitudes as a N/A car does.... <hr /></blockquote>They usually don't since you can up the boost to compensate.

Holes02

04-19-2003, 04:19 PM

I'm curious as to why they'd allow supercharged and turbocharged applications but not nitrous injected? It's a power adder just like the other 2....

Good Luck!

quickWS6

04-20-2003, 12:06 AM

<blockquote>quote:<hr />Originally posted by DriveATransAm:
 superchargers like dense air <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> <hr /></blockquote>I always thought that supercharged/turbocharged motors didn't take as big a hit at high altitudes as a N/A car does....

NataSS Inc

04-20-2003, 11:48 PM

<blockquote>quote:<hr />Originally posted by Holes02:
 I'm curious as to why they'd allow supercharged and turbocharged applications but not nitrous injected? It's a power adder just like the other 2....

Good Luck! <hr /></blockquote>I think there are a few reasons for it but I have never asked why. Here are my guesses.

1)A person could jet so much nitrous into a motor as to make his speed astronomical inside of the 1K event. And with the speeds that could be achieved the risk factor goes through the roof. I think they are trying to eliminate some of the risk.

2)Not allowing nitrous would keep the playing feild alot more level. In these events most N/A cars can run just as fast as the boosted cars in any given speed class.

Example: Rolland Roths RUF Porshce barely gets over 200mph. But Todd Carpenters Z28 cruises at 215mph.

I honestly think it is a safety issue with the nitrous. You can use it in the Silver State Classic events but the rules make it very cost prohibitive. All lines must have steel fittings, NO annodized stuff. And having a compressed bottle of that stuff in the car in a rollover accident at 165+mph "could" cause a serious problem.

<blockquote>quote:<hr />Even if you hit only 116 mph in the quarter with the elevation you should still break 140 by the time the 1 km mark comes.

1900+ feet is plenty of distance for that extra 2X mph you need. I don't know what was up with that supercharged C5... <hr /></blockquote>Fenris, I hope your right brother! Because I am about to make a few wagers for some serious dollars.

[ April 20, 2003, 11:50 PM: Message edited by: NataSS Inc ]

Fenris Ulf

04-22-2003, 12:52 AM

You should be able to do it, but mark off a 1 km strip and try it out before you put down some change.