Stock volumetric efficiency

[seth98es]

Does anybody know the stock volumetric efficiency for a 2.0L 4g63t? I did a search which brought up two results, one for the 420a and another thread which had some information but mixed results.

This link was posted about a calculator, but the calculator no longer works(at least for me).

http://www.turbofast.com.au/tfcalc.html

I found a forumla to calculate the VE which is:

    (3456 x CFM)
VE = -----------
     (CID x RPM)

I calculated CFM to 254.167 CFM, and CID to 122 CID. With those numbers thrown into the above equation I get a VE of 100.000131%. Could I assume that this is correct?

Im just bored and looking for a new turbo but want to get the efficiency range at certain boost levels of the turbos I am looking at.

Also I have been told that with the AEM EMS, if you use it to tune the car, it will generate a VE chart for you, anyone have any info?

If I am wrong at all, please correct me!

[Edit]
BTW this was calculated at 7200RPM since I forgot to mention that key factor.

 

[Defiant]

I don't think your formula accounts for forced induction.

 

[2gGSX]

There's a method to plot your setup's VE using DSMLink if you have access to it or know someone with it that has some free time.

 

[Enraged78]

Does anybody know the stock volumetric efficiency for a 2.0L 4g63t? I did a search which brought up two results, one for the 420a and another thread which had some information but mixed results.

This link was posted about a calculator, but the calculator no longer works(at least for me).

http://www.turbofast.com.au/tfcalc.html

I found a forumla to calculate the VE which is:

    (3456 x CFM)
VE = -----------
     (CID x RPM)

I calculated CFM to 254.167 CFM, and CID to 122 CID. With those numbers thrown into the above equation I get a VE of 100.000131%. Could I assume that this is correct?

Im just bored and looking for a new turbo but want to get the efficiency range at certain boost levels of the turbos I am looking at.

Also I have been told that with the AEM EMS, if you use it to tune the car, it will generate a VE chart for you, anyone have any info?

If I am wrong at all, please correct me!

[Edit]
BTW this was calculated at 7200RPM since I forgot to mention that key factor.

First off, it is entirely possible to get over 100% VE from any modern motor. However, it is not possible to get over 100% VE actually INSIDE the combustion chamber without forced induction. I can see Honda guys reading this and their heads hitting the ceiling, so please allow me to explain.

The reason that you can see volumetric efficency numbers over 100% on many newer naturally aspirated engines is because there are certain times where it is beneficial to have valve overlap. Valve overlap occurs when one or both of the intake valves is open at the same time as one or more of the exhaust valves. This causes some of the intake air to swirl and exit with the spent exhaust gasses. The question you should ask yourself is why would I want valve overlap?

Sometimes you wish to use the extra overlap to help the partially fresh intake charge cool the exhaust valves and help quell detonation. Sometimes you want it to help with exhaust emissions. Either way, what this information should leave you with is on very important fact:

Volumetric Effiency calculations are arbitrary, and knowing how much air passes through the intake ports does not allow you to understand what percentage of atmospheric pressure is present inside the combustion chamber.

To complicate things further, the volumetric efficency tables within the AEM EMS system are not going to be representative of the real combustion chamber VE number either. These numbers are also arbitrary, and only based on the working paramaters of the AEM EMS system. They will not correlate with any VE numbers from a flow bench analysis, or any numbers that you will calculate. They might be 'close', but they will not be correct. They are the AEM systems 'best guess' of how much fuel to add based on manifold pressure(or vacuum), air temperature, barometric pressure, a formula, and a table.

The only way to verify that the table is working propery is by a system of trial and error. This can be done most efficently on an engine dyno equipped with a wide band O2 sensor.

On DSMLink, you will find that they have already calculated a DSMLink VE table for you, in case you decide to also use a MAP sensor in conjunction with your MAF sensor. This table is also a 'best guess' based on specific engine components, and again limited to the constraints of the DSMLink parameters. It will work just fine for DSMLink running on a lightly modded 4G63, but will require some fine tuning to get it just right for you motor.

One more fact to keep in mind is that turbocharged engines run with significantly less valve overlap than naturally aspirated engines. How much overlap you run depends solely on your camshaft profiles.

Sorry for the book, but I had a very long conversation with a friend of mine about this very subject. This particular friend is the owner of a dyno shop with over 30 years of professional engine building experience. I was annoyed that with modern MAP based fuel injection systems, the engine really doesn't know the volume of air entering it. I was curious how a proper volumetric efficency table could be built for the AEM EMS system without a Mass Airflow meter. Long story short, it doesn't matter, because the AEM doesn't use an exact VE table based on cylinder head flow, and neither does your combustion chamber.

If you're looking for the right turbo for your application, the best idea would be to search the forums, and see what other folks are using. Ask youself what you really want to get out of your car, and spend as much time as you can reading.

Otherwise, you might get some crazy ass like me write your a mildly educated dissertation on why fuel injection volumetric efficency tables are wrong.

Hope this helps,
Matt.

 

[TSIfreek]

What does this matter just put a bigger turbo on therses your CFM!!
Out motors are not complecated at all its all in the turbo and boost you run. Its all about the boost. More air in more presure on the pistons.

 

[nanokpsi]

If you are just looking for a way to plet stuff on a compressor map and gauge a compressor's efficiency, then just go on the generally accepted airflows found in various threads. For example, a 1g 2.0 without cams or a smim will flow around 35-36lb/min at 20psi. Just going to the sorresponding plot on the compressor and there you go. Granted, this is kind of rough, but the better the intercooler, the less compressor efficiency even matters.

 

[TSIfreek]

If you are just looking for a way to plet stuff on a compressor map and gauge a compressor's efficiency, then just go on the generally accepted airflows found in various threads. For example, a 1g 2.0 with cams or a smim will flow around 35-36lb/min at 20psi. Just going to the sorresponding plot on the compressor and there you go. Granted, this is kind of rough, but the better the intercooler, the less compressor efficiency even matters.

Very good point!!

 

[seth98es]

Thanks for the replys everyone. And I know my "equation" is way too simple and doesnt account for a lot of things that can change. I know I can just do a search and find out that the Evo3 16g will be the best "bang" for your buck turbo out there. I just want to know the missing link in the equation to find out technically when it should spool, what air flow it will see at what RPM at a certain boost level.

It might be something that cant be calculated by any equation as there are certain variables you cant really put into an equation.

And I like reading people's "books" aka posts as I find this stuff interesting. If anybody has any links on any good writeups about the subject or just compressor maps in general post them up!

 

[Injected]

First off, it is entirely possible to get over 100% VE from any modern motor. However, it is not possible to get over 100% VE actually INSIDE the combustion chamber without forced induction. I can see Honda guys reading this and their heads hitting the ceiling, so please allow me to explain.

The reason that you can see volumetric efficency numbers over 100% on many newer naturally aspirated engines is because there are certain times where it is beneficial to have valve overlap. Valve overlap occurs when one or both of the intake valves is open at the same time as one or more of the exhaust valves. This causes some of the intake air to swirl and exit with the spent exhaust gasses. The question you should ask yourself is why would I want valve overlap?

Sometimes you wish to use the extra overlap to help the partially fresh intake charge cool the exhaust valves and help quell detonation. Sometimes you want it to help with exhaust emissions. Either way, what this information should leave you with is on very important fact:

Volumetric Effiency calculations are arbitrary, and knowing how much air passes through the intake ports does not allow you to understand what percentage of atmospheric pressure is present inside the combustion chamber.

To complicate things further, the volumetric efficency tables within the AEM EMS system are not going to be representative of the real combustion chamber VE number either. These numbers are also arbitrary, and only based on the working paramaters of the AEM EMS system. They will not correlate with any VE numbers from a flow bench analysis, or any numbers that you will calculate. They might be 'close', but they will not be correct. They are the AEM systems 'best guess' of how much fuel to add based on manifold pressure(or vacuum), air temperature, barometric pressure, a formula, and a table.

The only way to verify that the table is working propery is by a system of trial and error. This can be done most efficently on an engine dyno equipped with a wide band O2 sensor.

On DSMLink, you will find that they have already calculated a DSMLink VE table for you, in case you decide to also use a MAP sensor in conjunction with your MAF sensor. This table is also a 'best guess' based on specific engine components, and again limited to the constraints of the DSMLink parameters. It will work just fine for DSMLink running on a lightly modded 4G63, but will require some fine tuning to get it just right for you motor.

One more fact to keep in mind is that turbocharged engines run with significantly less valve overlap than naturally aspirated engines. How much overlap you run depends solely on your camshaft profiles.

Sorry for the book, but I had a very long conversation with a friend of mine about this very subject. This particular friend is the owner of a dyno shop with over 30 years of professional engine building experience. I was annoyed that with modern MAP based fuel injection systems, the engine really doesn't know the volume of air entering it. I was curious how a proper volumetric efficency table could be built for the AEM EMS system without a Mass Airflow meter. Long story short, it doesn't matter, because the AEM doesn't use an exact VE table based on cylinder head flow, and neither does your combustion chamber.

If you're looking for the right turbo for your application, the best idea would be to search the forums, and see what other folks are using. Ask youself what you really want to get out of your car, and spend as much time as you can reading.

Otherwise, you might get some crazy ass like me write your a mildly educated dissertation on why fuel injection volumetric efficency tables are wrong.

Hope this helps,
Matt.

This is a good post, but not entirely true nor all encompassing of the facts. You CAN get over 100%VE in a N/A engine. Newer engineers are using resonance and frequency to actually achieve positive pressure in the combustion chambers and greater thant 100% cylinder fill.

The thing to really understand is that VE is typically understood as a static condition. This means that boost shouldn't matter. You may achieve above atmosphere pressure in the cylinder, but if you only filled 95% of the cylinder with air pressurized at 2 bar, then you still only have 95% VE and the pressure will actually decrease a slight bit inside the cylinder to fill the void.

It's actually a complicated problem with the nomenclature of the entire 'car-guy' society.

 

[No_Skillz]

Sorry to bring back an old topic, but I was looking at compressor maps recently trying to find a turbo that fit a profile that I liked. I'm having trouble starting off because I don't know the airflow of our motors so I'm having trouble plotting along a compressor graph. To my knowledge, a rough/basic calculation of airflow depends on VE, boost, displacement, and RPMs. Basically, anyone know an approximate VE for the 5g63?

 

[Enraged78]

Sorry to bring back an old topic, but I was looking at compressor maps recently trying to find a turbo that fit a profile that I liked. I'm having trouble starting off because I don't know the airflow of our motors so I'm having trouble plotting along a compressor graph. To my knowledge, a rough/basic calculation of airflow depends on VE, boost, displacement, and RPMs. Basically, anyone know an approximate VE for the 5g63?

Use 95%. It's not going to be exactly what the 4G63 engine flows, but it's a conservative number that should get you in the ballpark. For more information, look here:

Estimating Required Air Mass Flow and Boost Pressures to reach a Horsepower target:
http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech103.html

An easier way would be to plot out the horsepower target you wish to reach and look at some of the turbochargers that other members use.

Good luck,
Matt

 

[No_Skillz]

Thanks Matt. I've actually been doing some guess and test. I've found that using 100% VE gets pretty close plots of performance to what others have claimed for their certain turbo applications.

The equatio I'm using for airflow is
(Displacement x Pressure Ratio x VE x RPM) / 5660 = CFM = Lb/min x 14.27

It's definitely oversimplified for the hardcore turbo technician, but by using this and a simple excel spreadsheet I've managed some decent graph points.

 

[Big Woo]

If your trying to figure out VE on a forced induction engine you may want to use the

PV=NRT equation for a volume at a specific pressure and tempature.


There are in fact NA engines out there that have over 100% VE, but currently they are only used in Formula one. At the end of the 2006 season Ferrari, BMW, Mercedes, Renault, and Honda all reported VE's in the neighborhood of 120 to 125%.

 

[DSMunknown]

^^ I thought modern-day funny cars and other extreme drag racing vehicles often see (or claim to see) 100+% VE as well.