WTF is Mule trying to say (poll)
 

I have no idea whatsoever what Mules point is.

perhaps you should just ask......instead of commenting?

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Here's your answer, there is no way on God's green earth or any other planet, that the second atmosphere makes more hp than the first.

The farce of this is that why would anybody go to the time and expense of 1 bar of boost without also optimizing the engine for said boost.

I have a 91 Mustang, rated 220 flywheel, and more like 160 rwhp in stock trim. If I put a Kenne Bell blower on with 7 psi of boost and rwhp goes up to around 260 rwhp, maybe 275 depending on minor changes to the intake. Thats more than 50% at the rear wheels and I am using crank HP to spin the blower. The boost makes the crappy stock heads flow well enough that the HP peak is now a bit higher in rpm.

In real engines, that are not race optimized boost is NOT a linear effect on HP.

OK show me one example where the second atmosphere, or half, quarter or whatever makes more than the first (legitimate example) (on earth). Check with Corky Bell. Remember, the second atmosphere contains no more air than the first did.

Turbos rule the forced induction jungle and that is all that really matters.

and here we go again......

I look at it this way:

when the engine is sitting still, that's normal every day 14 psi in the cylinder.

when the engine runs (on the "intake" stroke) that's negative pressure in the cylinder--- in other words, vacuum or suction.

when you strap on a blower (or turbo) and said device is operating on a 1:1 ratio, it still is negative pressure (on the intake stroke). this assumes that the blower's internal volume is the same as the volume of the cylinders it is feeding---most volumes are not the same, so there ends up being some addition to the actual volume of the air being fed into the cylinders, even if the blower is underdriven.

when you strap on a blower, and said device is operating on an overdrive ratio (or a turbo starts to spin up to overdriving the intake flow), it then becomes positive pressure, as long as it's over 14 psi.

This is why street cars with blowers rarely are seen to have more than a 10% overdrive, while Top Fuel cars are running around 50% overdrive. Of course, I would be remiss if I didn't include that street cars are running maybe 93 octane gas, while Top Fuel cars are running a 90% nitro methane/10% methanol mix.


I am no engineer, nor do I have a degree in physics, but that's just how I see the way this talk of atmospheric pressures and blowers, turbos, and such pans out......

This talk of one bar here, two bars there, is a little beyond my feeble mind, but if you want to talk pressure, a in pounds per square inch, that's something I can relate to.

Then again, what the hell do I know about boosting an engine?????


(If I get 43 psi on my turbo gauge in my big rig, and the pyrometer doesn't go beyond 1100 degrees on the cold side of the turbo, [that's around 1350 degrees in the combustions chamber...] I'm making nearly 780HP and over 2100 ftlbs of torque pulling over 260,000 gross pounds and doing one hell of a job getting it done......)

Short of all this, I'm probably wrong in my examples, but I do know that 43 psi makes some badass pulling power...

Feel free to pick this one totally apart for the fun of it-


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In an internal combustion engine, as most marriages, suction does not exist. Give that some thought.

Here, I'll go ahead & let the cat out of the bag. All engines are "forced induction." Without a compressor they are "forced" at 14.7 lbs or 1 atmosphere. When the valve opens the air is "forced" in under 14.7 lbs. This is why the second atmosphere can't make more power than the first (with proper tuning for both conditions). There are no mystical packing velocities, efficiency improvements or any other magical phenomenons that can cause this.

Physics is physics.

It's not semantics. If there was not atmospheric pressure, when the valve opened nothing would happen, suck as it might, nothing would happen. You absolutely feel pressure differential when you put your hand over the carb. But without atmosheric pressure it ain't suckin' nothin'. Forced induction is what engines run on.

Check with your local physics professor.

This discussion needs beer and a chalk board.

True, air flow is all push, nothing pulls, what you feel over the carb is the weight of the air in the column miles above it pushing down with little opposition.

My argument is that flow through the engine is not a linear function of pressure, or even of mass (pressure at constant temperature), and that power generation isn't a linear function of mass either.

Isn't it possible for boost to shift the peak HP up in rpm?

Actually you were pushed in. ;)

Thinkin hard about Smokin Moe's on Main in HB, for some pig and swig.

I've got no idea if push, pull, blow, or suck has any real bearing beyond language on HP. I do know this is a picky ass argument that has so far avoided any of the picky ass details that do matter.

I hope I didn't waste my stupid question of the month on Speedtalk forum, but I asked there for some input since some of those guys run high pressure differential flow benches, but that turd hasn't finished its polishing yet.

Normal atmosphere is in essence 0 PSI because it is the same everywhere, and yes, you can pump air as well as fluids.

Can an engine make more than double the HP at one bar ? Possibly, if you are flowing more air and fuel than double the NA amount. I believe this would be a lot easier to achieve with an inefficient engine with a restrictive exhaust, as a supercharger doesn't care about the scavenging effect of a good exhaust. It just fills regardless. Also, it can overcome a poor intake setup as well, which is severely limiting to a NA engine.

If you really want to blow your mind, consider a jet airplane motor. The tubine has to be spinning, to harness the explosion of air and fuel into thrust. It also uses this energy to power the turbine that harnesses the explosion. However, you cannot light a jet without first spinning the turbine to create that harnessing pressure, because one atmosphere won't cut it at a net pressure differential of zero.

When a NA engine fires a cylinder, yes it draws air into an ajacent cylinder, and yes atmospheric pressure helps to fill that void. At very high revs, a restriction will cause vaccume. A lack of restriction and a long intake runner will cause flow at velocity, and velocity causes the mass of air molecules to keep moving down the runner and actually pack the runner with a net positive pressure so that air will be forced into the cylinder as the valve opens, with a greater than atmospheric force. Scavenging momentum and draw in the exhaust can help lower the pressure in the cylinder, further enhancing cylinder filling. This is why so many high performance engines have overlap between the opening of the intake valve, and the closing of the exhaust, and why headers are so important in utilizing the pulse timing of the different cylinders to draw the exhaust from each other. As overlap is only really effective at high RPMs where velocity is a factor, Variable cam timing is used to eliminate overlap at low RPMs on some modern engines.

These things are much less important to a blown engine.

Also, consider that an engine can have low or high compression. Low compression does not really add any energy to a combustion explosion. Higher compression adds energy to the explosion in the form of heat and molecular velocity, which is very much the same thing when you quickly compress a gas. Forced induction raises compression, which also raises horsepower, about 4% for every point you raise compression. That is independent of the method by which you raise compression.

Just more stuff to think about.

I thought I explained this stuff fairly well, but I'll try a different approach......


normally aspirated engines do not run on forced induction, but the vacuum action of the piston headed south on the intake stroke.

Forced induction would be superchargers or turbochargers, spinning their impellers to force the air into the cylinders.

to follow your example of atmospheric speak:

1st atmosphere is 14.7 psi----the same "pressure" that exists while the engine is sitting still (not running).

somewhere between 1st and 2nd there exists an idling engine, but the atmosphere is now negative atmospheres, because of the vacuum generated by the down stroke of the piston.

2nd atmosphere is where the engine is running with twice the pressure (29.4 psi). My Cummins diesel is now making about 525 hp.

you state that 2nd atmosphere does not/will not demonstrate any power improvements. wrong.

you are mistaken in this example, because if I shoved 29.4 psi into my truck (Cummins Signature 600) engine, you better believe it makes more power than at idle, a lot more power.....

similarly, at 3 atmospheres (roughly 44.1 psi) the same diesel engine will be making approximately 785 hp.


semantics aside, these are the performance figures of fact relating to pressure per square inch of turbocharged boost.


turbocharging/supercharging a gas engine is relatively the same as it relates to this discussion.

it's all about pressurizing the cylinder while on the intake stroke. packing more fuel and air into the cylinder than is normally sucked in by the intake stroke of the piston. in other words, artificially creating a higher compression ratio by forcing more air into the cylinders.

in a normally aspirated engine, air is not "forced" into the cylinder, it is sucked (vacuum) in by the downward stroke of the piston. there is no forcing of the air into the cylinder by some force on the back side of said volume of air going into the intake ports......

on the intake stroke, a NA engine always has negative atmosphere (vacuum). turbo/super charged engines have the same negative atmosphere at idle, but when the rpm is increased, the atmosphere (s) are increased due to the "pressurization" of the intake port/stroke (because the impellers are now spinning at a higher rpm allowing the charging device to overcome the negative pressures created by the intake stroke.)

it is rare that super/turbo charged engines do not have negative atmosphere (vacuum) at idle. I can not think of any that would not.....maybe top fuel motors, but that's another subject-----they are running near 50% overdrive on the blower these days.

High compression ratio engines do make more power (until you reach the point of detonation) because you are squeezing the fuel/air mixture into a smaller space before ignition. (as opposed to low compression ratio engines)

the principle is the same for turbo/super charging. you are forcing more fuel and air into the cylinder by these devices.

static (sitting still) compression ratio for my diesel is about 10:1. once you crank it up and the turbo starts feeding the cylinders, this ratio goes to near 22:1.

at atmosphere 1 (sitting still-not running), it makes zero power. at atmosphere 2 (idling, un-boosted) it makes about 100 hp. at atmosphere 3-4, it makes significantly more power....say as much as 800hp on the high end of things.


I suggest you go to your physics teacher and relay these figures to him and get his thoughts.......


If he still tells you we don't know what the hell we're talking about, tell him to take a trip over to his local diesel shop and see for himself.


this has become excessively long and there will be further arguments made by all, but this a common sense way to explain what's actually happening in a charged environment.....Enjoy----


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And your point is??????

See thread title, I haven't changed my vote.

Everyone in this thread clearly has at least a basic understanding on how a motor works and what makes power.

Mule keeps saying pressure, but I think he understands its actually the mass of air flowing through the engine, not just the input pressure unless other factors like temperature are kept constant.

I don't believe its exact, but I suspect its "close", to say 14.7 psi of boost will make no more than twice the NA HP, but I can think of half a dozen points that should be clarified, like is this RWHP, Flywheel, or whatever the name is for HP without any parasitic losses. RWHP is after driveline losses that are RPM related, not HP, so in an extreme case where the engine is only slightly more powerful than the driveline losses doubling "base" HP will more than double the RWHP.

Thermodynamics of combustion aren't simple and linear either, but I don't know em.

*** now engaging popcorn mode ***

I have played with turbo’s a little and found that sometimes there is no ease explanation for some results found when applying more or less boost after doing a modification.
I remember once when I was trying out different Intercoolers, I found that I had to tailor my boost at different RPM’s and pipe diameters to optimize for each one (IC).

Turbo projects are supposed to be fun, lets keep it that way :)

I think you should all stop by this weekend and help me finish the sewer pipe system for the 32VTT :)

Danglerb, I find it amusing how you are trying to get ebveryone to pile up on Mule. You were the one getting picked on over at Rennlist and were forced out. I'm sure you didn't like it too much. Why would you do the same to someone else?

I think that most people here fully understand the point that Mule is trying to make. I think he may have alterior motives or he may not. Its hard to tell. His basic point is how you can make more than twice the power by keeping EVERYTHING the same except the boost pressure which would double. This means that the fuel ratio would be the same, the dyno, the weather, exhaust, etc. He's bringing up a good point that most would rather ignore because they either have a vested business interest in doing so, or do not understand the subject well enough to answer intelligently. This is not a stab at the turbo builders, the SC guys have been embelishing their results for a few years now. I guess I am off on a tangent so I will stop. My point is this, quit picking on people Danglerb. And while I'm at it, rjhames needs to lay off of Dangler too. This pelican board doesn't have enough people posting to have the luxury of feuds.

My intention was to engage not exclude, and get Mule to really lay out what he is trying to say. If it boils down to all you boost guys fudge your numbers, well I'm still glad we aren't talking politics, and we are all in the same religion, Porsche 928's.

Maybe its a fine point, but I wasn't forced off rennlist. I asked JohnD for a refund of my membership fee and was immediately banned. Prior to that I was planning on a new "fresh start" acct using my real name, and RandyV told me that was a "good idea". I think its a bit petty of them, but maybe over time they will lighten up and remove the ban. Its certainly a PITA trying to read the threads without being able to see the images.

Back on topic, most people aren't doing "science" here. Methods and apparatus are rarely revealed, and testing is not precise. Thats just the nature of the beast. I have a 91 Mustang, and there is no public consensus on which headers are best or how much HP they add after 20 years of competition and magazine testing.

OTOH if we didn't have anything to discuss it would take a lot of the fun out of drinking.

Re: WTF is Mule trying to say (poll)
 

In a 100% efficient system 1 bar of boost is the equivelant to doubling displacement, so yes...it is the same as doubling HP.

In reality, no street legal system gets much beyond 90% total system efficiency.

The reason a forced induction setup MAY create more HP per % of boost at say 30psi as it might at 20psi is a matter of intended system efficiency at a given RPM range and boost level. However, even in a 100% efficient system, 1 bar of boost will produce EXACTLY twice as much HP as a 100% VE NA motor in motors of identical displacement.

There are many factors at play here.

Also, it is entirely possible to achieve positive boost on a naturally aspirated engine in an intended operating range.

One example would be a "Tunnel Ram" dual quad intake.

Re: Re: WTF is Mule trying to say (poll)
 

It took a while but someone finally got it.

Re: Re: WTF is Mule trying to say (poll)
 

Sorry, but that isn't confusing enough.

Whether volumetric efficiency stays the same is part of the basic question, and I think input pressure does effect VE.

If you double displacement at half the input pressure does the HP stay the same? I don't think so, it mucks around with the thermodynamics and you get less power.

*******************

Two practical issues make this question seem silly, the amount of boost is easy to change, and an engine optimized for boost is setup differently from a NA motor, other than low boost systems like 7 psi lots of other stuff gets added or changed.

Re: Re: Re: WTF is Mule trying to say (poll)
 

The real question that should be a poll, is what are you trying to say?

Re: Re: Re: Re: WTF is Mule trying to say (poll)
 

If Mule doesn't like some of the HP claims, he is not alone, most of us are saavy to the "up to 30% HP gains from a muffler" rules of the marketplace. Posting it as a question for all of us to try and explain the issue to him when he is as familiar with the answer as any of us is by definition a troll, and I am all done feeding this one.

If all other conditions are the same a motor operating at 100% efficiency at 1 bar of boost will produce exactly double the HP of a 100% VE naturally aspirated one.

Of course a 100% VE motor or a 100% effiicent turbo or supercharging system are both unobtanium.

Sorry if you got your feathers ruffled Dangler. Sniper hit the bull's eye. My point is this. When you see claims that exceed this ratio, you are looking at claims, not reality. Sniper was also 100% correct in saying that there will always be some loss of efficiency so the best anyone will ever do is going to be less than 100% improvement.

Thanks Corky.

Ready fro something better than that? I'm at the track one day talking to a guy who builds $50 - $60k turbo motors (mostly sb Fords). Not your typical race car guy, more like a college professor. His motors have lots of championships. I say Ronnie, how much power are these motors making, is 1850 real? He shrugs his shoulders & says "if you've got to pick a number that's probably a good one. But what difference does it make?" I says Huh? He says "what really matters is how quick it will rev not how much power it will make." Now I'm really confused.

Glad me and Corky could help. :)

Nobody here does or has disagreed with your basic premise, just wondered what you were driving at in saying it, and questioned the terms you put it in. Pressure without temperature and other details doesn't define HP.

"Now I am really confused" I'd say that was the professor's goal. OTOH in a rules based competition the edge may be in something you would not expect.

Help Corky help!

Read his book, PV=nRT, its not just a good idea, its the law.

http://en.wikipedia.org/wiki/Ideal_gas_law

n is the item of interest, how many molecules of O2 per unit of time decides the HP.

n = (PV)/(RT)

Women say it's all about the o, you say it's all about the n.


WTF is Dangler trying to say?

That I prefer even an inane discussion about cars to cleaning my garage.

Its still mass and not just pressure. Pressure gauges as far as I am concerned are mostly useful so the customer has something to watch move after spending a load of money.

Garage cleaning is winning now, can't wait for the next episode.

pressure gauges are an absolutely useful tool in monitoring a turbo/supercharged engine, not just an add-on toy for amusement.....

mule didn't get what I was saying either, but what the heck?

this discussion of atmospheres has gotten pretty much into the argument of semantics, until Sniper chimed in.

However, Sniper was off when he claimed tunnel ram intakes create forced induction. Having operated numerous tunnel ram equipped engines, both cast manifolds and fabbed sheetmetal t-rams, I have never found that the intake charge was under pressure. It was always under some amount of vacuum, even in the high-end ProStock engines I was privileged to run. I have never seen any tunnel ram create positive pressure (atmospheres as this discussion calls them) in any rpm range, regardless of load or not on the engine.

as for the issues of percentage of improvements, to be blown or not to be blown, the comment that 10% improvement is unattainable is false.

if you supercharge (or turbo for that matter) a given engine at an overdrive percentage, you can overcome the 100% increase in HP. My diesel engine example in my earlier comments demonstrate this example.

My diesel won't hardly run without the turbo, but makes 600 plus HP at only 2100 rpms. Take the turbo off, and you'll be lucky to get 100 HP at the same rpms.

this same example should be applicable to gas engines as well, although I have no actual number to back up this up. it is just a common sense approach to the question at hand.

Herr is on track with some very good numbers as well, but I have found holes in his R&D as well. His latest clutch issues will skew his dyno numbers, because there may have been slippage on the old clutch (before turbo), and now that he's got a non-slipping clutch (after turbo) the numbers may be skewed. His addition of bigger stickier tires will skew the numbers as well.....

Your discussion of facts and figures as they relate to dyno this and dyno that...... are dependent upon consistent conditions for comparison. ambient temps, barometric pressures, engine components, etc., all have bearing on hp and torque claims.

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James, what Sniper was referring to was the effect of port tuning on the intake side which absolutely causes a slight increase in pressure. If I need to explain the principles of port tuning I will but this is how they produce increased power. If you don't believe me call the guy who built that sheet metal intake. I guarantee he can explain it.

Your diesel will produce power in the same ratio we are discussing as any other engine. Why? Cause diesel needs air to burn just like gas.

I'm still waiting for somebody to give me a real example of exceeding 100%. so's Corky.

http://www.bellengineering.net/

It seems kind of sad after all the stuff he has done for him to still be waiting.

mule:

after running tunnel rams (both cast and sheetmetal fabbed up whatever's) on various ProStock/comp engines over the past thirty some odd years, I have yet to see one that creates "pressure" in the intake tubes as you describe.

following your example of 1st atmosphere this and 2nd atmosphere that, there is no positive pressure on naturally aspirated engines in the intake. just vacuum, and various amounts of it depending upon application and rpm. Vacuum is negative atmosphere, let's say, in your atmosphere speak, therefore is not positive pressure.

Put a pressure gauge on one of the intake runners on a tunnel ram and you'll see what I'm talking about-----only vacuum. Tunnel rammed engines usually have cam profiles which huge amounts of overlap, losing vacuum to the point that you can't use vacuum assisted power brakes (not that you would want PBs on a prostocker.)

Port tuning is a matter of making the air charge run into the Combustion chamber at a higher velocity for increased filling of the cylinder, to overcome inefficiencies of the port design(s). Again, it is not pressure as you assert.

Back in the early '70s, we experimented with individual runner sheetmetal intakes (no plenum chambers), coupled with 1150 cfm dominators individually tuned per port, trying to simulate fuel injection (which is illegal in all prostock racing), but had greater success with tunnel rams that had plenum chambers above the actual tubes. that research has lead to very shallow plenum chambers that you see on every prostock engine in competition today.

And yes, I still have the last tunnel ram/1150 Dominator package I ran, sitting on my garage shelf.....Two very rare Holley Dominators, originally given to Ronnie Sox by Chrysler Performance in late '69 (engraved part/serial numbers). the air horns are still intact-the meter blocks, accelerator pumps/squirters, throttle bodies are heavily modified-and they will out flow anything short of current use prostock technology.

Been there, done that, got the tee-shirt two and a half decades ago.

The exhaust side of things is no different as well, as there are now header collectors (comp eliminator) that actually promote cylinder scavenging, making the exhaust run out of the engine faster (creating vacuum on the exhaust side). Again, vacuum instead of pressure. In fact, race engines with these collectors won't hardly idle, as they are designed to operate efficiently at high rpms.


as for the diesel discussion, I pretty well covered it in my post as it relates to your atmosphere speak.....

Your original assertion about higher altitudes, barometric pressures and their relationships to power production was incorrect as well, and you didn't clarify your statements about it in your further argument.....

your original discussion about 100% volumetric efficiency and the multiplying affect of turbo/supercharging was well intended, but not very well articulated.....not surprising that the Danglerb character didn't quite get it, as he is still on a very long learning curve------Sniper was much closer in his writings-


all of this stuff is very argue-mentive, but does nothing to educate the masses when you have folks writing opinions and not facts.



Next we'll be arguing again about which dyno is better than which dyno.......again.


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Rh said:
Port tuning is a matter of making the air charge run into the Combustion chamber at a higher velocity for increased filling of the cylinder, to overcome inefficiencies of the port design(s). Again, it is not pressure as you assert.

Let me attempt to step up my articulation.

Is it suction? Let me save you some work. No it's not.

I guess I have to try to explain the principle of port tuning (which is totally unaffected by valve overlap). If you have a tube filled with a gas (air) and that gas is moving in the tube. If you close the tube at one end the gas near the closure stops immediately, however the gas at the other end of the tube continues to move, effectively compressing the gas in the tube. Compress = increase in pressure. If the tube we are referring to is an intake port on an engine, the goal is to have the valve re-open at the maximum increase in pressure (compression) thereby more fully filling the cylinder. This is why, suck as the engine might, ram type manifolds make more power than others. The effect of intake port tuning is to increase the pressure (compression) in the intake port near the valve. This is how under certain circumstances a N/A engine can exceed 100% volumetric efficiency.

You covered the diesel discussion? How by stating that in your opinion (with no supporting facts) that your diesel is different? Not exactly.

As for altitude, this effect is constant at whatever altitude.

Air density is determined by 2 factors BAROMETRIC PRESSURE and temperature and it ABSOLUTELY affects power production.

My original statement still has yet to be challenged by any FACT, or even a credible opinion showing that that a second, third or fourth atmosphere of pressure will support more combustion than the first.

If you know all these race car types give somebody a call. I guarantee that Jason Line, Warren Johnson, Larry Morgan or even a backyard engine builder with even a rudimentary understanding of port tuning can explain it.

Here's a link that may articulate it more effectively. I hope this will help you get your helmholtz resonator in order.


http://www.grapeaperacing.com/GrapeApeRacing/tech/inductionsystems.pdf

Here is a statement from ATI Procharger on how much power can be expected from boost. Maybe Dan Jones & Jim Summers need to contact some of our crowd to find out how to get it right.

How much horsepower will a supercharger add to my engine?

Although some manufacturers claim a specific horsepower increase, superchargers actually add horsepower as a percentage gain (percentage of an atmosphere). Assuming an engine with a compression ratio of around 9:1 running pump gas,if a supercharger gives your engine 14.7 psi of boost (another atmosphere) that will essentially double the output of your engine, everything else being equal. After adjusting for thermal and mechanical energy transfer, if an efficient centrifugal supercharger is generating 7.5 psi (approx. 1/2 an atmosphere), you will see around a 35-40% gain in horsepower and torque at your non-supercharged maximum horsepower rpm. If detonation forces you to use an ignition/timing retard system, you will of course see less of a gain because backing off several degrees of timing will greatly reduce an engine's power output. At higher boost levels, the heat generated by compressing air will produce diminishing returns as the boost is increased, although the use of intercooling or racing fuel can avoid this scenario of diminishing returns. Assuming the use of intercooling to run higher boost levels while maintaining reliability, a 100% increase can generally be achieved at around 17 psi on an engine with 9:1 compression running pump gas. The gains in horsepower and torque delivered by each ProCharger system can be found on the price list as well as on the "ProCharger Systems" page within this site

The original Grape Ape drag car was in the same body shop as my car getting restored before hitting the nostalgia tour this summer.