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Interesting.

I don't doubt your math, but it really seems like the addition of 1 bar of boost doubles the hp. Or at least that's what my results have pointed to.

I have rear wheel dyno pulls on the same vehicle on the same dyno - both with and without boost, with no other changes other than the addition of a Vortech SC and my home-built air/water intercooler. I got right at 300rwhp without the blower and 582rwhp with the blower - at a max peak of 16 psi boost. (it was more like a spike to 16 psi, mainly 14-15 psi the whole pulls) According to your math I should only be at 480rwhp?

What other factors could fit the results? Was the transmission just eating that much power that now with the increase the "robbed" power remains a fixed number and not a percentage? I know the blower was eating a bunch of power (125hp?) - since swapping to a turbo from the blower resulted in an 8 mph gain and a second quicker on actually less boost. I haven't had the turbo setup on the dyno.

All of this doesn't quite add up unless it's a matter of the parasitic losses being fixed numbers and not percentages. Am I screwing up the math by being able to get the intake charge temps below ambient? Why would my results be different than the math says it's supposed to be?

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Good points, but let me refine my question, does air under say at 60 psi flow different, and require a different design, then air on a NA motor? Not really asking about the volume, more does it behave differently, have different dynamics, and are they linaer differences, etc?

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2. the gas expands and loses density just by virtue of being compressed

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"real world vs. theory"?

Not quite. That's not a theory (global warming is a theory, Darwin is a theory), it's that quite different thing: a fact.
There is no more "real world" than fact. Facts are still there even if no one believes them, they cannot be discussed (if I give up or change my mind, the gas laws are still the same way they've been for about 6 billion years).

Far too frequently, what people describe as theory (meaning "someone made that up, and it has nothing to do with actual parts"), what they're really telling me is "I can't distinguish between an opinion I disagree with (a theory), and a fact that I don't understand".

Attacking physics on the basis that someone who claimed to be well educated was wrong ("You sound like a guy I went to school with, always reading books - and couldn't make change for a dollar") is the same as "someone I know went to a doctor, and died anyway, therefore medicine doesn't exist".

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1. In these applications we are nowhere near supersonic port speeds, right?

Even if we do I don't see an Issue, only place I ever heard of Supersonic Stall is in Aircraft NOT Designed to go that fast and do. BAD JU JU!!!!

2. and when referencing boost as a measure of only port/valve restrictions, we are talking about a design that is less then 100% volumteric efficent?

N/A engines are always less than 100% efficient. Efficiency is the difference of what is put in and what is given back out in return. In this case Air/Fuel in and HP/TRQ out.

3. And why can't a boosted motor be over 100% volumetric with different optimized ram tuning tricks, etc.

Most Boosted engines are 100%+ efficient


4. or is it considered 200% efficent when using 14.7lbs of boost?

I'm not sure I would go that far!!!??? In some cases i could see it though!!!

4. And efi has a better chance of charge cooling then a carb, depending on design/layout?

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"real world vs. theory"?

Not quite. That's not a theory (global warming is a theory, Darwin is a theory), it's that quite different thing: a fact.
There is no more "real world" than fact. Facts are still there even if no one believes them, they cannot be discussed (if I give up or change my mind, the gas laws are still the same way they've been for about 6 billion years).

Far too frequently, what people describe as theory (meaning "someone made that up, and it has nothing to do with actual parts"), what they're really telling me is "I can't distinguish between an opinion I disagree with (a theory), and a fact that I don't understand".

Attacking physics on the basis that someone who claimed to be well educated was wrong ("You sound like a guy I went to school with, always reading books - and couldn't make change for a dollar") is the same as "someone I know went to a doctor, and died anyway, therefore medicine doesn't exist".

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No slight was intended but there are too many variables in this media for any hard and fast rules or formulas to be certain. I don't know what kind of experience you have with boosted high end applications but my life is saturated with it-the real world variety-going fast and winning championships. We don't use many formulas to get our car down the track. We test and take notes because that's what it takes to go fast.

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At 15 lbs of boost or 1 bar (however you wish to make it) you will effectively double horsepower

This has been repeated to death, and it's still not true. Yes, alllll the magazines have printed it, it's even on some blower websites.

It's that annoying "thermodynamic ratio of heats" thingy.

In brief:
1. no compressor is 100% efficient (although a good cooler can reduce charge temp below intake temp)
2. the gas expands and loses density just by virtue of being compressed
3. the difference in delivery volume between 2 pressures is the square root of their ratio.
14.7 ambient + 14.7 boost (assuming perfect, no temp, no para loss) is about +41%.
(14.7 + 14.7)/14.7 = 2
2^.5 = 1.414, or 141.4% of original charge mass.

More info?
Read my article:
http://victorylibrary.com/supercharger/super-c.htm

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At 15 lbs of boost or 1 bar (however you wish to make it) you will effectively double horsepower

This assumes
1 No heat generated (Compressed air is heated thus less dense, it will happen thus intercoolers)
2 No Parasitic loss, (Roots superchargers the worst, Turbos the best)
3 100% Efficient Supercharger (they are all different with their own efficiency curves) and Turbos usually have some sort of lag as well

Factor the above and you reduce the doubling of horsepower by each of the percentages. (Please check my understanding here)

PV = NRT Pressure x Volume = Number of gas molecules X a constant X temperature

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I'm still trying to figure out why pretty much everything I've turbo'd has followed the "wrong" rule of thumb that doesn't match the math. Which would be that pretty much everything has doubled in HP with 15 psi of boost.

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Interesting.

I don't doubt your math, but it really seems like the addition of 1 bar of boost doubles the hp. Or at least that's what my results have pointed to.

I have rear wheel dyno pulls on the same vehicle on the same dyno - both with and without boost, with no other changes other than the addition of a Vortech SC and my home-built air/water intercooler. I got right at 300rwhp without the blower and 582rwhp with the blower - at a max peak of 16 psi boost. (it was more like a spike to 16 psi, mainly 14-15 psi the whole pulls) According to your math I should only be at 480rwhp?

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As far as your comment on theories!! You live your ever day life revolved around a theory. "ELECTRICITY" It is nothing but a theory. There are Hundreds of Laws and Formulas that explains how it works, but to this very day there is no Physical FACT that that they are 100% correct. Physicist and Chemist stil to this day do not no for sure whether electricity flow + to- or - to +. In the Navy's elctronics schools both theories are taught to cover all bases.

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As for that article: Not too impressed. He states that Atmospere not Vacuum fills and engine and then immidiatelt starts talking about vacuum from the egine. (so which is is?) It is both. Vacuum and Pressure are both created by a difference in pressures. If an engine was only filled by atmosphereic pressure you probably wouldn't get muh if any air in the cylinder with the valves openeing and closing 1000's of time per minute. Now add the vacuum (difference in Pressure) that the cylinder creates as it makes a void on the down stroke and you will get some air forced into the cylinder as the valves open.

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Exhaust Back Pressure: I am adressing this cause this is the second mention I have seen. Yes you will have more exhaust back pressure with a Turbo, BUT this will not effect the engines output as a Turbo Cam correctly designed does not let exhaust gasses get pushed back into the cylinder. In fact most turbo cams will make you wonder what the plans are because the specs are usually way smaller than a N/A or even a S/C for the same power levels.

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ATMOSPERE: I'll address this one as well since that article wanted to get all Physics BUT left alot of details out. ATMOSPHERE= 14.7PSI or 1-BAR 0r 29.92 IN/HG @ sea-level on a Standard Day. Standard Day= 70*F and 70%.

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I see what the article was getting at and I will agree that you get more bang for the Boost at 7,8,10,12 psi than 15psi. You can usually make about 50-60% extra HP @7-8 psi and about 70-80% @ 10-12. And you'll be lucky if you get into the 90% range solidly with 15% on most street engines. That is why they call it a Rule of Thumb, NOT a BOOST LAW of physics!!

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Even if you believe the 14.7psi doubles the HP hype, you're saying that not only did you double your HP from doubling the atm. But you also magically found a way to do it without any power loss from the blower?

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Was the air/water intercooler filled with ice? If so, I guarantee that it would have made more then 300hp base to start with.

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If it was EFI, was it run with the same injectors?

Because it's fairly obvious an injector sized for 600hp is WAY too big for a motor at 300hp. And if you did swap injectors, of course different injectors can make different HP with better/worse fuel spray patterns.

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Obviously the whole intake tract was changed to swap from N/A to supercharger. What efficencies were gained there?

I'm sure you didn't just "Bolt it on" and gain 300hp. How much time was spent tuning the 600hp runs? If it really did pick up that much HP with boost and no tuning, doesn't that show how far off the original tune up was?

Fuel curve change/spark timing change/etc...?

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I'm just saying, it's not as simple as the data you've provided. Saying that we tested it "back to back" is misleading.

I know you didn't mean anything bad by it, but there are a lot of things that could have (and probably did) change between those two tests.

Plus what about the cam? How many times have you guys watched a "Nitrous" cam car, make a run N/A? They are usually an absolute PIG. Same thing goes for blower/turbo.

Mismatched components on N/A (small cam/big head) would make the N/A HP way below where it should be. But the boosted stuff might take advantage of it.

All I'm saying is that there is a lot of unknowns when you do this type of testing.

In the end, the laws of physics still exist.

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As far as your comment on theories!! You live your ever day life revolved around a theory. "ELECTRICITY" It is nothing but a theory. There are Hundreds of Laws and Formulas that explains how it works, but to this very day there is no Physical FACT that that they are 100% correct. Physicist and Chemist stil to this day do not no for sure whether electricity flow + to- or - to +. In the Navy's elctronics schools both theories are taught to cover all bases.

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What planet do you live on? Stop typing on your computer immediately. Electricity is just a theory and could blow up your keyboard at any second.

Somehow I doubt the Navy teaches two completely opposite aproaches to electronics (one well known, documented, and used vs. another abstract idea that hasn't been seriously concidered in 100+ years)

And what point did he say electricty was a theory? Weren't we talking about Gas Law's?

Join the NAVY and find out!! I did and remember sitting in a 2 day class in Avionics School learning about Electron Flow and Hole Flow theories. Even Ford teaches the same thing . My cousin who is a Ford Tech said they were taught the same thing.

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As for that article: Not too impressed. He states that Atmospere not Vacuum fills and engine and then immidiatelt starts talking about vacuum from the egine. (so which is is?) It is both. Vacuum and Pressure are both created by a difference in pressures. If an engine was only filled by atmosphereic pressure you probably wouldn't get muh if any air in the cylinder with the valves openeing and closing 1000's of time per minute. Now add the vacuum (difference in Pressure) that the cylinder creates as it makes a void on the down stroke and you will get some air forced into the cylinder as the valves open.

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Atmosphere IS what fills the engine 1000's of time per minute. No different then the way we breath. Your diaphram muscle lets up on your empty lungs, and the atmosphere fills them back up. Vacuum is just a measurement. It's not a physical thing. Vacuum is simply the pressure differential between the atmoshpere and the chamber.

The reason he uses "vacuum" in the text instead of "Atmosphere" is because it's the only relavent measurable thing when you're talking about N/A motors. Gauge pressure is always relative to atmosphere. Measuring pressure relative to outer space, or the depths of the ocean wouldn't make sense. You need to measure it relative to the atmospheric pressure you are dealing with at the time.

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Exhaust Back Pressure: I am adressing this cause this is the second mention I have seen. Yes you will have more exhaust back pressure with a Turbo, BUT this will not effect the engines output as a Turbo Cam correctly designed does not let exhaust gasses get pushed back into the cylinder. In fact most turbo cams will make you wonder what the plans are because the specs are usually way smaller than a N/A or even a S/C for the same power levels.

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It will ALWAYS rob power, no matter what the cam design. You could leave the exhaust valve open forever, it still doesn't escape the fact that the turbo exducer is being spun by the gas pressure. In a turbo cam you don't ever really need to worry about the exhaust backing up. You need to worry about getting it all out first!

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Explain how a WAISTED GAS being used for something productive is ROBBING POWER??

ATMOSPERE: I'll address this one as well since that article wanted to get all Physics BUT left alot of details out. ATMOSPHERE= 14.7PSI or 1-BAR 0r 29.92 IN/HG @ sea-level on a Standard Day. Standard Day= 70*F and 70%.

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The second sentence in the article states,

"Atmospheric pressure, not vacuum, is what fills an engine with combustible mixture to be burned. This is about 14.7 lbs. per square inch (29.92 inches of mercury) at sea level."

What are you trying to say...He's right? What exactly did he leave out? And guess what. 14.7psi is 14.7psi at any temp. 70 degree's or 1000 degrees.

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everyone uses 14.7psi like it is a constant, they try to throw the "at Sea-level" in there to make it sound even more consistent. In reality the 14.7psi Atmospheric pressure is very inconsistent. Ask anyone that flies planes. I calibrate Altimeters on a regular basis and have to call the tower within 30 mins of starting my tests just to get the current DA setting to make sure my readings are correct. Aircraft altimeters have a knob built in just for this and pilots have to use it constantly.

I see what the article was getting at and I will agree that you get more bang for the Boost at 7,8,10,12 psi than 15psi. You can usually make about 50-60% extra HP @7-8 psi and about 70-80% @ 10-12. And you'll be lucky if you get into the 90% range solidly with 15% on most street engines. That is why they call it a Rule of Thumb, NOT a BOOST LAW of physics!!

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You see what he's getting at, but you obviously don't understand it.

When you physically reduce the space air occupies, you see a higher pressure reading on the gauge. Part of this from compressing the molecules (this is the good part that makes power) and part is from heat (this is the part that doesn't make power).

You can NEVER have all boost increase from compression alone, it always has heat involved.

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