[Stan Weiss]

I have a number for the Firebird Trans Am with W62 Aero package @ 0.29 CD.

Stan

[Tom Vaught]

Originally Posted by Half-Inch Stud

was a joke dude. A joke. Let it go.

I suppose the 68 Bird has a Reynolds number near 2 million....

Maybe at one time if we were talking Burt Reynolds, Mark. (His Money)
Think he is not doing so well today. he owed over 1 million so the bank took his florida ranch and made the property into a school.

Tom V.

[starlightblack]

Originally Posted by KO

I wouldn't know anything about 170MPH....yet

KO you have a PM

[john marcella]

Originally Posted by John Langer

@170 mph it is worth around .06 and 1.5-2mph comparing a first gen f-body to a late model.

I would agree , but thats just the aero part of CD. And that just helps make my point to the clowns that think they can do a better job of figuring hp from MPH vs a dyno.

What about the drag/ efficiency of everything else? Trans , converter, rear end, superwamidyne bearings, brake drag, rotating weight on the wheels, alignment And so on.......

[John Langer]

Originally Posted by john marcella

What about the drag/ efficiency of everything else? Trans , converter, rear end, superwamidyne bearings, brake drag, rotating weight on the wheels, alignment And so on.......

Thats what seperates the winners from the whiners...

[cgeise]

the car thru the air can be closely compared to Ballistic coefficient the rest of the stuff on the car is contributing to the coefficient of drag--- I remember taking my drive train
out of the old Willy's and put in the Fire Bird -- it was about 4 to 5 mph

[Daniel Barton]

As one of the clowns in question, I would say one of the largest mistakes that I have seen novices make is to ignore an engines ability or inability to accelerate in order to find a horsepower number on the dyno. Most dyno's don't measure acceleration, but what do I know??? I'm just a clown who figures real world horsepower by a vehicles mph, or is the clown the person who ignores this intangible?

[Tom Vaught]

Originally Posted by cgeise

the car thru the air can be closely compared to Ballistic coefficient the rest of the stuff on the car is contributing to the coefficient of drag--- I remember taking my drive train
out of the old Willy's and put in the Fire Bird -- it was about 4 to 5 mph

Total HP to move a vehicle thru the air comes from 3 basic areas:

1) The parasitic loss from the vehicle moving thru the air (The Frontal Area and the Boundary layer thickness around the vehicle (as well as external objects attached to the body). To find a close approximation of the frontal area you use a special machine that takes a snapshot of the vehicle (from the front) and then calculates millions of 1 mm squares amd basically adds them up for a total area. The tire shadow exposed (looking from the front) as well as any exposed chassis parts are also included in the area count.

2) Then you have the parasitic loss from the Driveline. That can be measures using very special torque meters attached to the individual wheels. This number would include bearings, gear mesh friction, losses from drag with parts moving thru lubricants, etc.

3) Lastly you have Tire Rolling Resistance, which is a function of the tire material, the contact patch with the ground surface, and the deflection of the tire as it rolls.

Add them all up and you get a 3 term equation that describes THAT SPECIFIC VEHICLE.

So most of the BS out there with the calculators is really a crude swag based on many runs that are an average of an assumed HP vs the weight of the vehicle and the assumed HP to move the vehicle thru the air.

I have done Aero testing at Lockheed's Full Sized Wind Tunnel in Georgia, I have done Parasitic Loss testing at Fords Allen Park Test Labs, I have done Rolling Resistance testing on Ford's 67" drum rig at Building #5 in the Research & Engineering Center.

So I know a little bit more than the average guy. But I did not come up with the tests.
Aero Engineers, Tire Engineers, and Driveline Engineers came up with the tests. They are the experts. Just saying.

Tom Vaught

[John Langer]

There is a lot of good information in post 67 and 68...

[cgeise]

then again from looking at Langers avatar--- we are forgetting to take into account " rear bumper drag "

[mike leech]

All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident.
—
Arthur Schopenhauer, German philosopher (1788 – 1860)

[blueghoast]

HHmmmmm
I forgot what the hell this post was about.

GT.

[Chris Uratchko]

I've never seen an engine make less HP and accelerate on the track better.

I hear about it. I read about it. But I've never made more power on a given engine, and had the car go slower.... Ever. Can't say there wasn't changes required in the set up, converter, gearing etc... But its always faster in the end, with more HP. Speaking to averages, not a peak number.

I've seen instances say, with a carb too big, makes more power on the dyno but on track its off, but its easily identified as a fuel metering issue, not simply due to size alone like a smaller size just seems natural to accelerate better.... No.

[Daniel Barton]

I've had deals that have not performed as expected, Everyone has, instead of looking for something else to blame and believing solely in the flowbench or dyno, I let it eat at me until I figured out why I failed, and learned some of my best lessons by doing so...

[Daniel Barton]

Originally Posted by Chris Uratchko

I've never seen an engine make less HP and accelerate on the track better.

I hear about it. I read about it. But I've never made more power on a given engine, and had the car go slower.... Ever. Can't say there wasn't changes required in the set up, converter, gearing etc... But its always faster in the end, with more HP. Speaking to averages, not a peak number.

I've seen instances say, with a carb too big, makes more power on the dyno but on track its off, but its easily identified as a fuel metering issue, not simply due to size alone like a smaller size just seems natural to accelerate better.... No.

I have seen it...

[Chris Uratchko]

Another instance, where I've read it.

[Daniel Barton]

and Chris yours is surely not the only time I've heard someone say they haven't seen it... Just because someone has not yet seen something sure doesn't mean it doesn't exist!

[Chris Uratchko]

Agreed

[john marcella]

Originally Posted by Daniel Barton

As one of the clowns in question, I would say one of the largest mistakes that I have seen novices make is to ignore an engines ability or inability to accelerate in order to find a horsepower number on the dyno. Most dyno's don't measure acceleration, but what do I know??? I'm just a clown who figures real world horsepower by a vehicles mph, or is the clown the person who ignores this intangible?

If you pay attention to the average power across the engines "useful" power curve I do not think you will find yourself in that situation, chasing peak power numbers alone , sure.

So you figure "real world hp" from a vehicles mph. Can you share how you factor all the different variables and different forms of drag applicable from vehicle to vehicle?


Also how do you do you differentiate horsepower that will not accelerate the vehicle vs horsepower that will? Again I think it should show up in the average. but what do i know im just a novice right.

[Daniel Barton]

This should be obvious but we are not running 18 wheelers at 300 mph... simply put I would say experience is key.