My truck weighs 4800 lbs race weight...it made 401/487 SAE @ the wheels. Ran 109.84 mph. It shifts @ 5000 rpm...it is all torque at these rpm.

On the highway, the truck runs mucho better because I have the benefit of a nice cold intercooler...at the track, it is just cooking because I don't have much time to cool it off after I just smoked the tires off in the burout box and staging.

What people don't realize when comparing #'s is how fast are you going at XX time. What I mean..on my 12.705@109.84 run, I covered the 1/8 in 8.191 seconds @ 86.03 mph. Your car ran 84.39 mph in the 1/8...which I'll guess around 8.67 seconds. One would assume your under 2 mph than me at the 1/8..and you would be right...somewhat. But when I am at the 1/8, you are not. So when I hit the 1/8, your probably around 82 mph. Same thing with the 1/4 with your 13.452@107.24. When I go thru the 1/4 @ 12.705 seconds, your going around 103.8 mph.

So who pulls harder? Race a Lightning that runs like mine from a 50 mph roll, an easy 3 car lengths by 110 mph it will be ahead...and pulling.

 

Sorry, that's just not realistic. (Not a flame, BTW.) Aerodynamics start to come into play at around 30 mph. And the rule of thumb is that you need to quadruple your power in order to double your speed - or, in other words, it might take only 25 horsepower to drive 30 mph (for a given coefficient of drag), but for the same car, it would take 100 HP to drive 60 mph.

(Those numbers are given as examples only, don't flame me if they're way off!)

Thus, when you're talking about triple-digit speeds, you're already using a non-trivial percentage of the power that your engine is capable of producing. That's why having a car that's capable of 100 mph is nothing particularly special, but having a "150-mph car" isn't bad, & a "200-mph car" is all but freakin' unheard of! Ever wonder why cars like Ferraris, Porsche 911s, etc. all have top-end speeds that are fairly close together? Physics imposes the same restraints upon everyone...

 

Actually it's quite realisitic. Find vehicles that have a similar trap speed as a stock Lightning and you'll find that they also have similar hp/weight ratios. At 200 mph there's a HUGE difference due to aerodynamics, but at at the 100 mph area, the difference just isn't large enough to make a claim that you'll start pulling on an L due to aerodymaics. This is the math part. Now see CantonRacers post for the real world results. They match up nicely.

By the way, drag is a square function, and the power required is a cube functionl. IOW, if you double your speed, drag goes up by 2^2, but the power required to attain the speed is 2^3. As a tidbit of information, the same is true of pumps. Doubling water flow increases delta pressure (d/p) by 2^2 and the power required to run the pump so it flows twice as much water is 2^3.

 

I think the answer to this disagreement is quite simple. The guy with the Lightening is in Ohio, the other guy is in Florida. I know with my Cobra if I try to run when the motor is heatsoaked, like it would be from a highway roll, I'll lose 3-4 mph. I imagine it is the same for a L. The heat and humidity down here kills a blower car, especially a Heaton.

 

Hm, so all these years I've read all the BS about all motor cars suffering from the same things and elevation must be pure BS then too eh?
And the fact that 'they' say FI motors do not suffer as bad as N/A motors do?

 

I just always heard anyway, that FI cars dont suffer as much

 

Last I checked wind friction exceeds ground friction after 50MPH. So why exactly are you suggesting that aerodynamics don't matter at twice that speed?

Seems kind of silly.

- Z28WannaB

 

It has nothing to do with elevation and everything to do with the heat and humidity. The L's and 03-04 cobra run an eaton blower. An eaton produces alot of heat. To combat the heat they run an air to water heat exchanger. At anything above 150 degrees inlet temp the computers pull huge amounts of timing to keep the motor safe. While an NA car, LT1 or LS1 may lose 3-4 tenths due to temp and humidity, an eaton car (truck) loses 6-8 tenths and about 6-8 mph. This is all due to the fact that the blower produces so much heat. For the same reason, guys spraying small shots on these type of vehicles are getting tremendous gains. I know of one guy picking up over 150 RWHP on what should be a 75 dry shot.

 

With my Lightning...if I run back to back, I lose 1 mph from heat soak...that is all.

I also do a lot of highway racing and I race cars that run a similar mph to me and I run dead even.

How a anything runs is based on elevation, humidity and barometer psi...

 

I didn't say it doesn't matter, I said it doesn't matter *much* in the *110 mph* range. Rule of thumb is it takes 15-20 horses to cruise at 60 mph for most vehicles. There are those tiny cars that get 60 mpg that are need less horsepower, but for most cars and trucks, the thumbrule works.

Here's where the math kicks in... drag is square function, and power is a cube function.

Doubling speed increases drag by 2^2, or 4 times. Doubling speed increases required horsepower by 2^3, or 8 times. In rough terms, that means most cars will require anywhere from 120 horses to 160 horses to do 120 mph. The math is simply 8 times the horsepower required to do 60 mph, or 8*15 and 8*20. Even the lowliest of cars can typically do 120 mph.

NOW... when you're talking 180 mph, or 3 times the initial 60 mph... since the two functions are still square and cube functions, you take the 3 times the intial condition and plug it into the function, like so:

3^2 for drag is 9 times as much drag at 180 mph as at 60 mph
3^3 for power is 27 times as much power for 180 as at 60 mph

Need 20 horses to do 60 mph? You'll need 540 horses (20*27) to do 180 mph.

The mathematics add up, and matches the real world experience of most Lightning owners, who typically say that the "I'll catch up because of aerodynamics" simply isn't true. Not until you're north of 120 mph.

 

Is this pissing match still going on...who really gives a ****

 

Apparently you don't, so why did you even bother to reply? An even better question is, do you even have a car that can do better than a 16 second 1/4 mile yet?