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I am very interested in studying the flow characteristics of the R's engine.<p>I see most engine are between 75%-85% and this number obviously changes the higher you go into the RPM range.<p>Anyone know the number for the R?<br>Or if anyone happens to know the <B>ACTUAL</B> CFM at a given RPM, that would help too.
 

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Re: Volumetric Efficiency of the R engine? (phuz)

I created this excel sheet using the ideal values, and then using a 75% volumetric efficiency across the entire RPM band.<p> <IMG SRC="http://i66.photobucket.com/albums/h251/mpk155/Rflow1.jpg" BORDER="0">
 

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Re: Volumetric Efficiency of the R engine? (phuz)

Turbo engines have greater than 100% VE. Turbo engines with variable valve timing such as the R can vary these numbers even more.<p>Are you really looking for CFM? Why not get yourself a scan tool and watch the mass airflow? That's what your ECU is doing, among other things.<p>Tom.
 

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Re: Volumetric Efficiency of the R engine? (tmtalpey)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>tmtalpey</b> »</i></TD></TR><TR><TD CLASS="quote">Turbo engines have greater than 100% VE. Turbo engines with variable valve timing such as the R can vary these numbers even more.<p>Are you really looking for CFM? Why not get yourself a scan tool and watch the mass airflow? That's what your ECU is doing, among other things.<p>Tom.</TD></TR></TABLE><p>nothing is more than 100% efficient.<p>simply put, the R is 2.5L, or 0.5L per cylinder. At 14.7psi (2 x atmosphere), there is double the amount of air attempting to get in the cylinder, but the intake stroke doesn't get ALL of that air in there, which would be 100% efficient.<br>See what I am after now?<p>If I had a tool to read the MAF, I would, but I don't. Maybe someone could help me out.
 

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Re: Volumetric Efficiency of the R engine? (phuz)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>phuz</b> »</i></TD></TR><TR><TD CLASS="quote">Or if anyone happens to know the <B>ACTUAL</B> CFM at a given RPM, that would help too.</TD></TR></TABLE><br>I don't know, but maybe you can figure it out. There is dyno data here that includes air/fuel ratios across the speed range. If there is a way to get the fuel rate from injector pulsewidth data or something, you could calculate the air flow rate. <p>With that, plus knowledge of intake manifold conditions (boost and temp), you could calculate vol eff. Lots of missing data, though.<p>Or, pehaps air flow data is directly available from a scan tool. I know it is when I hook one up to my Audi.
 

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Re: Volumetric Efficiency of the R engine? (phuz)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>phuz</b> »</i></TD></TR><TR><TD CLASS="quote">nothing is more than 100% efficient.</TD></TR></TABLE><p>Actually, an engine with good, long, tuned intake and exhaust manifolds (like a naturally-aspirated engine with a tuned intake and headers) can acheive greater than 100% VE at certain speeds due to the "ram" effect of the incoming air charge. Basically, the slug of intake charge keeps moving at high velocity into the cylinder even after the piston has reversed direction. The trick is to close the intake valve just as the air starts to reverse itself out of the cylinder, thereby trapping greater than one cylinder's worth of air in the cylinder.<p>Hard to explain.
 

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Re: Volumetric Efficiency of the R engine? (Dyno)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Dyno</b> »</i></TD></TR><TR><TD CLASS="quote">Actually, an engine with good, long, tuned intake and exhaust manifolds (like a naturally-aspirated engine with a tuned intake and headers) can acheive greater than 100% VE at certain speeds due to the "ram" effect of the incoming air charge. Basically, the slug of intake charge keeps moving at high velocity into the cylinder even after the piston has reversed direction. The trick is to close the intake valve just as the air starts to reverse itself out of the cylinder, thereby trapping greater than one cylinder's worth of air in the cylinder.<p>Hard to explain.</TD></TR></TABLE><p>maybe really close to it, but not 100% <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"><p><br>come on guys...i know someone has a scantool on here <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/wink.gif" BORDER="0">
 

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Re: Volumetric Efficiency of the R engine? (tmtalpey)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>tmtalpey</b> »</i></TD></TR><TR><TD CLASS="quote">Turbo engines have greater than 100% VE.</TD></TR></TABLE><br>The textbooks (if you really care about what they say) define VE based on intake manifold conditions, not with respect to ambient conditions. I think Phuz did the math correctly.<p>This means that if you double boost, the air flow rate would change, of course, but VE stay about the same because it's relative to intake manifold conditions.
 

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Re: Volumetric Efficiency of the R engine? (Dyno)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Dyno</b> »</i></TD></TR><TR><TD CLASS="quote">I think Phuz did the math correctly.<p>This means that if you double boost, the air flow rate would change, of course, but VE stay about the same because it's relative to intake manifold conditions.</TD></TR></TABLE><p>yes! that is absolutely correct.<br>i don't care what anyone says, we are in 2006, and at this point on our time-line, there exists NO such thing as greater than 100% efficiency, FOR ANYTHING! (but thats another topic for the OTF)<p>my end result, which i am trying to achieve by finding out the true VE% for our engines, is what our CFM is at max boost all the way through the RPM range.
 

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Re: (R_Rated)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>R_Rated</b> »</i></TD></TR><TR><TD CLASS="quote">what does all this mean? All I knowed is when I step on the pedal to the right my car go vroom!</TD></TR></TABLE><p>this means that your car is 2.5L, ideally, so that on two revolutions (four strokes, or one complete cycle), your car SHOULD displace 2.5L, but it actually displaces 2.XXL.<p>2.XXL/2.5L is your volumetric efficiency...how MUCH air is actually getting moved vs. how much is supposed to.
 

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Re: (phuz)

VE is defined to be relative to standard temperature and pressure, not to the manifold conditions. It is used to characterize the performance of the overall engine, not of the interface from manifold to cylinder. That's what the turbo is all about! Ramming more charge down the poor thing's throat. <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/smile.gif" BORDER="0"> <p>That said, perhaps this link will help you in your quest. A scan tool will show you the engine rpm and mass air flow. Your dashboard will tell you the ambient temperature. Those three values will yield VE.<p><A HREF="http://www.installuniversity.com/install_university/installu_articles/volumetric_efficiency/ve_computation_9.012000.htm" TARGET="_blank">http://www.installuniversity.com/install_university/installu_articles/volumetric_efficiency/ve_computation_9.012000.htm</A><p>I guess if you wanted to know the VE of the engine naturally aspirated, you could pull the wastegate actuator and repeat the experiment...<p>Tom.
 

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Re: Volumetric Efficiency of the R engine? (phuz)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>phuz</b> »</i></TD></TR><TR><TD CLASS="quote">maybe really close to it, but not 100% <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"></TD></TR></TABLE><br><I>Au contraire.</I> I refer you to Fig. 5.32, page 247, <I>Advanced Engine Technology</I>, by Heinz Heisler.<p>Imagine a stream of people charging into a traincar. When the traincar gets sort of full, the people at the back of the line are still running at top speed, and end up crushing (compressing) the people already in the car. Close the door just as the last person bounces off the mass and tries to get out and <I>voilà</I>, you have a train car that is filled at more than 100% of it's rated capacity.<p>This is how get 800 hp from an old school carbureted V8.<p>Look ma! No turbos!
 

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Re: (tmtalpey)

EXAMPLE FROM LINK:<p>For actual:<br><IMG SRC="http://www.installuniversity.com/install_university/installu_graphics/articles/ve/computation/eq_actual_flowrate_b.bmp" BORDER="0"><br>For ideal:<br><IMG SRC="http://www.installuniversity.com/install_university/installu_graphics/articles/ve/computation/theoretical_airflow_complete.bmp" BORDER="0"><br>Calculating VE:<br><IMG SRC="http://www.installuniversity.com/install_university/installu_graphics/articles/ve/computation/ve_preview.bmp" BORDER="0"><p>In other words, your actual will NEVER exceed your ideal...therefore never greater than 100%. <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/wink.gif" BORDER="0">
 

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Re: (dugums)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>dugums</b> »</i></TD></TR><TR><TD CLASS="quote">Phuz is correct that nothing is more than 100% VE... It is by definition impossible to be greater than 100% VE.... <p>That being said, the point of forced induction is to get as close as possible to 100% VE.... Most supercharged or turbocharged engines are close...</TD></TR></TABLE><p>and if i can get my hands on a scan tool, or get someone to give me a reading of their boost pressure, RPM, and the MAF reading at that pressure, then i will have a true number for our VE. <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0">
 

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Re: (phuz)

I deleted the post that referred to the definition of VE...<p>There appear to be 2 or 3 recognized definitions of VE....<p>I will post them in a couple minutes... <p>After I make sure I understand them!!! <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/smile.gif" BORDER="0">
 

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Discussion Starter · #18 ·
Re: (dugums)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>dugums</b> »</i></TD></TR><TR><TD CLASS="quote">I deleted the post that referred to the definition of VE...<p>There appear to be 2 or 3 recognized definitions of VE....<p>I will post them in a couple minutes... <p>After I make sure I understand them!!! <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/smile.gif" BORDER="0"> </TD></TR></TABLE><p>whatever they may be...the one im referring to is simply (Actual/Ideal)*100=VE%
 

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Re: (phuz)

No, 100% is not "ideal". 100% VE merely means that you've trapped X liters of air in an X-sized cylinder. You can do better than that!<p>From page 48 of <I>Internal Combustion Engines </I>by Edward Obert...<p>"In supercharged engines the volumetric efficiency can be less or greater than unity. In some instances, the denominator of the equation may be based upon intake manifold conditions as a means of separating supercharger performance from engine performance."
 

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Re: (Dyno)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Dyno</b> »</i></TD></TR><TR><TD CLASS="quote">No, 100% is not "ideal". 100% VE merely means that you've trapped X liters of air in an X-sized cylinder. You can do better than that!<p>From page 48 of <I>Internal Combustion Engines </I>by Edward Obert...<p>"In supercharged engines the volumetric efficiency can be less or greater than unity. In some instances, the denominator of the equation may be based upon intake manifold conditions as a means of separating supercharger performance from engine performance."</TD></TR></TABLE><p>1 step forward, 2 steps back.<p><br>(how much air goes in)<b>/</b>(how much air is SUPPOSED to go in)*100=VE<p>that part CANNOT be argued <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"><p>that being established...i would like some numbers regarding MAF readings.
 
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