1972 Procharged 581 Camaro

[onevoice]

A corvette zr1 has 638 hp and will go a little over 200mph

Hot Rod magazine has run a 1980 camaro at land speed events, it has similar aerodynamics to yours with the exception of the wing. It went 246mph with a normally aspirated 572/720 GM big block crate motor, and 260 with a 150 shot of nitrous. It is admittedly a guess, but given the above knowns, even in your high drag configuration, you should reach 200 using only 800hp.

I picked 800hp because that seemed a conservative number for your car to reach 200. Your motor has been on the dyno, so you probably have the actual BSFC numbers for it. Those numbers will tell you how much fuel it uses at a particular HP number in 1 hour, ie BSFC units are lbs of fuel per hp-hr. Those numbers for just about any engine, NA, turbo or supercharged, are typically in the range of .3 to .5 .

It is therefore a relatively simple calculation to see how much fuel the engine will require over a known time period at a known HP output.

Fuel in gallons required = ((hp*BSFC)/(6lbs per gallon))*hours

I used .3 in the calculations by mistake, that would be on the lean side( I said I hadn't had enough coffee). Re-calculated using .5 the number would be approximately 25 gallons, which actually correlates much closer to the NASCAR numbers. There is certainly nothing wrong with carrying 45 gallons of gas in an unlimited class, it eliminates one more thing to worry about on race day. I was just trying to point out that if you needed extra room, you could squeeze some out of the tanks real estate.

The car looks great BTW. I am glad to see it being built with such a capable cage and attention to safety detail.

[speedjohnston]

I am aware of the ZR1's top speed and its HP. My example wasn't specific to it, just as a general comparison.
The camaro in Hot rod magazine that your speaking of has had extensive wind tunnel testing and has a drag coefficient around .21 if memory serves. His camaro was built specificly for land speed racing. It is no way close to my camaro or probably anybody elses of that vintage, and is even well under the drag of a new corvette. I have spoken with the owner on a couple occasions. A stock camaro of my vintage can be up to almost double the drag of keiths Camaro although it may not look it. Although mine is not stock, it is not close to Keiths either. My car is also not as aerodynamic as a NASCAR so neither is a viable comparison.
BSFC's are only taken usually on the dyno under wide open conditions and are often over .5 to the .6 range on High power big block blower and turbo cars.
That being said, I would rather be proven wrong and have fuel left than be right and run out 2/3 of the way. The 45 gallon stays. lol

[onevoice]

The H.R. camaro is more areodynamic than yours, but it has the same frontal area so the comparison is probably closer than you think. It so happens that this turns out to be an interesting comparison in another way. Because HP requirements change as the cube of velocity, and drag changes as the square, your numbers may actually prove something. The HR camaro does 246mph, with a .21Cd (your number). After going through the equations, it takes almost the exact same power to push your car to a slower 200mph with a Cd of double, ie .42, also your number.

Interesting huh? The actual numbers came out as
[email protected] = [email protected], given the same HP numbers

So, it stands to reason that your car will reach 200 with approximately the same HP as a 572GM crate engine. I think I remember tests putting it about 800 at the crank.

BSFC numbers are fuel flow, you can get pretty close using them.

[speedjohnston]

Originally Posted by onevoice

The H.R. camaro is more areodynamic than yours, but it has the same frontal area so the comparison is probably closer than you think. It so happens that this turns out to be an interesting comparison in another way. Because HP requirements change as the cube of velocity, and drag changes as the square, your numbers may actually prove something. The HR camaro does 246mph, with a .21Cd (your number). After going through the equations, it takes almost the exact same power to push your car to a slower 200mph with a Cd of double, ie .42, also your number.

Interesting huh? The actual numbers came out as
[email protected] = [email protected], given the same HP numbers

So, it stands to reason that your car will reach 200 with approximately the same HP as a 572GM crate engine. I think I remember tests putting it about 800 at the crank.

BSFC numbers are fuel flow, you can get pretty close using them.

I wasn't debating the approx HP to get to 200mph, just stating its a random # in your first post. Keiths camaro had 5 miles to get to that speed (going by memory again but I'm sure this was a salt flat #), I plan on hitting over 200 in less than a mile (and yes I know keith has done this as well). The comparison is still flawed because of rate of acceleration is using over 800hp. At every corner the acceleration can be more than 800 hp. I have allready done all these calculations in 100 different ways ages ago. All the formulas you are using have been pinned up in my garage for years I just wasn't going to redo my calculations based on this discussion, not knowing from the beginning I would have to prove myself. You must have a lot of time on your hands. lol
Probably a better discussion elsewhere, this is still a build thread.
P.S. I know what BSFC numbers are and I'm still keeping the 45 gallon cell

[onevoice]

Sorry for the thread hijack, big square tanks hanging below rear pan are just a pet peeve of mine.

Back to the build.

[speedjohnston]

My latest big part to arrive and keep me bottoms down. Scott Good at GoodAero has been one of the best people to deal with answering all my crazy questions and getting back to me right away even when I told him I wasn't purchasing for a while. I think I've been in touch with him since last year.
This is my first real carbon fibre part. Its almost ubelievable that the whole thing only weighs a little over 5lbs and can handle all that pressure. Keeping the wing level (front and back highest points) it will generate about 6-700lbs down on the back end, and less than 50lbs of drag. More obviously if it gets angled down at the front.

[MotleyDrew]

Originally Posted by speedjohnston

I'm still keeping the 45 gallon cell

Yes ! 1200hp is not even pushing this motor setup. If the owner so chooses he can turn up the wick which will require a lot more fuel.

[sik68]

Love what you're doing with the aero, especially the hood extraction. (and now the engine plumbing makes sense too ) Looking forward to more!

[speedjohnston]

Another rendering to share. Please move over if you see this in your rear view mirror.

[tones2SS]

Looks awesome Steve!