[Murco]

Originally posted by blindwhite




Second, doesn't anyone know that there is a column of air over a 100 miles up through the atmosphere for every square inch of ground that your car rolls on? That whole column or air produces 14.7 psi! Now your say to yourself, "where have I heard psi before?". Turbo's and Superchargers(or Blowers to you ci loving hotrodders) is what you come up with. Yes, you think of that because they are related. Your normally aspirated larger cc engine may suck in A LOT more AIR in regards to VOLUME and in relation to an engine half your size; but, going back to that column of air producing 14.7 psi, the large displacement engine's cylinders do not completely fill up its volume with air at BDC to have a pressure equal to the atmospheric pressure of 14.7 because of friction and air restrictions along the intake track. That 14.7 is what an engine performance tech would also call the Stoichiometric ratio. For every 14.7 parts of air you add/mix one part of Hydrocarbon. Meaning to say, that unless you are getting EXACTLY 14.7 parts of air in a cylinder, you do not add 1 part of fuel. 14.7 psi measured in the cylinder is 100% Volumetric Efficiency. Anything less that is definitely NOT 100%.

Now, I'd estimate that the single camshaft V engine has a volumetric efficiency of only 8-10psi(i dunno, correct me if I'm wrong), but it is definitely not 14.7. And what if you took a car with that engine to near Colorado Springs and drive it up that hill climb? You take that 500(bhp?) Viper up that hill the best you can and you'll never beat the Mitsubishi Lancer Evo which happens to be the fastest so far to get up there.
Reason for your poor performance? Inefficiency and the fact that at the end of the race you were producing 90 less horsepower.

On the other hand, if you take the Skyline GT-R tuned to 500hp or more up that hill, then you'll make it up there faster then your previous trial with the Big Block, and probably with enough gas to beat the Big Block down the hill. Reason for this Skyline victory is because on it's way up the hill it maintained as close as possible it's Volumetric Efficiency. As a matter of fact, it doing 500+ hp says that it is doing more work than at 100% 14.7 psi. It may be taking in a volumetric efficiency of 25psi. 14.7 plus 14.7 is nearly 30psi. That's like having TWO engines IN ONE. No wonder the Small volume High performance DOHC engine is beating the Single V Big Block. Its working more to fill it's cylinders with air two times more than itself, and three times more than the Big Block. At the top of that hill, the Skyline will still be producing 500 hp because it's lungs are still drawing in 25 or so psi, as compared to the Big Block Single camshaft drawing in less.


Third, if you want to measure ci to hp ratios then here is your Final Thought. You say the Dodge Viper has an engine of 8 Litres. 8 times 61 is 488. That means the engine is 488 cubic inches. The horsepower is 500(bhp?). That leaves us with a ratio of 1.02 hp per cubic inch.
Now, the Skyline GT-R R34 has an engine of 2.6 Litres. 2.6 times 61 is 158. That gives us an engine that is 158 cubic inches. The horsepower at stock is 280. That my steel junkie is a a ratio of 1.77hp per cubic inch. Does 1.77 look larger than 1.02 to you on the real number line?
How about if we take the Skyline GT-R around the Vipers ballpark? 316 cubic inches with 500+ Horsepower. The 8 litre beating Skyline has a power to volume ratio of ATLEAST 1.58 hp per cubic inch. My numbers may be off, but it still shows that 1.58 is greater than 1.02.
(Thanks to thrasher for additional info on other cars producing more than 1.02 hp per cubic inch. DOHC helps intake fullfill better volumetric efficiency).

Sorry this is off topic but its necessary.

If you don't understand a word I said, then just think about one thing:

Formula One
3.0 litre V-10 producing 800 Horsepower at 18,000 RPM.

Or, just ask what is hard to comprehend and I'm sure someone here will answer.

:sun:

Pikes Peak is more of a traction race than horsepower, you forgot that 80% of it is DIRT!! And yet, in every other racing venue in the world were horribly inefficient US cars compete head-to-head with others, WE ALWAYS WIN!!!