How to find (VE) Volumetric Efficiency - Dodge Caliber SRT-4 Forums

macsperformance · 08-05-2006, 08:50 PM

This little equation can help you determine the Volumetric Efficiency (air passing through the motor) of your engine at a given load cell/break point in a base fuel table.

(VE) = Theoretical Airflow / Actual Airflow
Theoretical Airflow = (RPM / 2) X (Displacement / 1,728)

RPM = revolutions per minute
2 = the number of revolutions a four stroke engine has to turn to complete one full cycle
Displacement = as expressed in cubic inches
1,728 = a cubic foot of air or 12 X 12 X 12 or 12 cubed
CFM = cubic feet per minute

Here is an example:

Theoretical Airflow = (6000 / 2) X (140 / 1728)
3000 X .0810185185 = 243.05 CFM of airflow

243 cfm of airflow at 100% VE

If you had 120% VE you would have 291.66 CFM of airflow

Here is an example:

243 CFM X 1.2 = 291.66 CFM

If you had only an 80% VE you would have 194.4 CFM of airflow

Here is an example:

243 CFM X .8 = 194.4 CFM

Thank You
Chris Macellaro

bjeffries · 08-05-2006, 08:52 PM

OK, this maybe the wrong place but it sounded relavent

Why is the cold air intake so small on our cars? What can we do about that. It looks like the intake is 100% covered over when we close our hoods? If it can't breath.......well you know that isn't good. Heck I would rather know it is getting hot engine air then no air at all.

macsperformance · 08-05-2006, 09:07 PM

Quote:

Originally Posted by bjeffries

OK, this maybe the wrong place but it sounded relavent

Why is the cold air intake so small on our cars? What can we do about that. It looks like the intake is 100% covered over when we close our hoods? If it can't breath.......well you know that isn't good. Heck I would rather know it is getting hot engine air then no air at all.

Sorry B...

I can not give you a good answer to that question.

I guess the engineers saw fit for the design as it is. It does not make a lot of sense to me either though as you describe it.

Chris Macellaro

bjeffries · 08-05-2006, 09:31 PM

NO it doesn't. Obviously I don't know tons about these kinds of things but I do know the the more Oxygen the engine has the better it is going to run. I will have to post pictures of this thing so you can see it....its insane!

txdragnfly · 08-05-2006, 10:34 PM

Ok B. I totally understand what you are saying, my question is to macsperformance... what exactly do I do with this info you are giving us?
It is stricltly performance related stuff or a must for any car owner?
Sorry.... I'm a little slow on the uptake here.

macsperformance · 08-06-2006, 11:50 AM

Quote:

Originally Posted by bjeffries

NO it doesn't. Obviously I don't know tons about these kinds of things but I do know the the more Oxygen the engine has the better it is going to run. I will have to post pictures of this thing so you can see it....its insane!

You are correct... Yes please post some pictures up for all of us to see in this thread.

thank you
Chris Macellaro

macsperformance · 08-06-2006, 12:06 PM

Quote:

Originally Posted by txdragnfly

what exactly do I do with this info you are giving us?

Hello!

Every engine management (your car's computer) uses a formula like this or similar to this to figure how much air is being ingested in the engine at any given operating condition. This formula is used to help find the correct numbers to input into a vehicle's computer so the proper amount (ratio) of fuel can be added to make the engine run properly. My business revolves around the performance industry, but every engine is an air pump as it moves air in and out.

Quote:

Originally Posted by txdragnfly

It is strictly performance related stuff or a must for any car owner?

Although your Dodge computer uses something similar to this equation, the information is to help people understand a little more in detail of what actually goes on behind the scenes in your cars computer thousands of times each second while driving your car down the road.

Thank you for your question friend!
Chris Macellaro

Neb · 08-09-2006, 02:59 PM

This is why tuning any vehicle's engine to run efficiently is important when adding aftermarket parts like exhaust or intakes, and especially tubrochargers and superchargers.

okiecaliberguy · 08-10-2006, 12:53 PM

is it true that you can retune the ecu, post-mods, by warming the car up, then turning it off and disconnecting the battery for a while? does that really reset the ecu?

macsperformance · 08-10-2006, 03:03 PM

Quote:

Originally Posted by okiecaliberguy

is it true that you can retune the ecu, post-mods, by warming the car up, then turning it off and disconnecting the battery for a while? does that really reset the ecu?

Hello!

No sir... Resetting the ECU in this way (disconnecting the battery) resets all the fuel trims and the computer has to go through a learning process. The ECU will revert back to the same operating parameters as before. This is not actually what tuning is. Tuning involves interface with the ECU and actually changing the values (reprogramming) in these look-up tables or maps as they are referred to.

I hope this helps friend!
Chris Macellaro

08-05-2006, 08:50 PM	#1 (permalink)
macsperformance Supporting Vendor Join Date: Aug 2006 Location: Arlington, Texas Posts: 52	How to find (VE) Volumetric Efficiency This little equation can help you determine the Volumetric Efficiency (air passing through the motor) of your engine at a given load cell/break point in a base fuel table. (VE) = Theoretical Airflow / Actual Airflow Theoretical Airflow = (RPM / 2) X (Displacement / 1,728) RPM = revolutions per minute 2 = the number of revolutions a four stroke engine has to turn to complete one full cycle Displacement = as expressed in cubic inches 1,728 = a cubic foot of air or 12 X 12 X 12 or 12 cubed CFM = cubic feet per minute Here is an example: Theoretical Airflow = (6000 / 2) X (140 / 1728) 3000 X .0810185185 = 243.05 CFM of airflow 243 cfm of airflow at 100% VE If you had 120% VE you would have 291.66 CFM of airflow Here is an example: 243 CFM X 1.2 = 291.66 CFM If you had only an 80% VE you would have 194.4 CFM of airflow Here is an example: 243 CFM X .8 = 194.4 CFM Thank You Chris Macellaro __________________ Macellaro's Performance Tuning Freelance Traveling Automotive ECU Tuning Services www.macellarosperformancetuning.com chris@macellarosperformancetuning.com 817-542-4151 Instructor for EFI University www.efi101.com/contact.html World Wide Freelance Tuning Service Overview

08-05-2006, 08:52 PM	#2 (permalink)
bjeffries Senior Member Join Date: Jul 2006 Location: Indianapolis Posts: 182	OK, this maybe the wrong place but it sounded relavent Why is the cold air intake so small on our cars? What can we do about that. It looks like the intake is 100% covered over when we close our hoods? If it can't breath.......well you know that isn't good. Heck I would rather know it is getting hot engine air then no air at all. __________________ Marine Blue Caliber, SXT Indianapolis, IN

08-05-2006, 09:31 PM	#4 (permalink)
bjeffries Senior Member Join Date: Jul 2006 Location: Indianapolis Posts: 182	NO it doesn't. Obviously I don't know tons about these kinds of things but I do know the the more Oxygen the engine has the better it is going to run. I will have to post pictures of this thing so you can see it....its insane! __________________ Marine Blue Caliber, SXT Indianapolis, IN

08-05-2006, 10:34 PM	#5 (permalink)
txdragnfly Senior Member Join Date: May 2006 Location: Houston, Tx Posts: 341	Ok B. I totally understand what you are saying, my question is to macsperformance... what exactly do I do with this info you are giving us? It is stricltly performance related stuff or a must for any car owner? Sorry.... I'm a little slow on the uptake here. __________________ Txdragnfly's "Steel-ingUrhrt" Blue Steel Caliber, SE, Houston, TX

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08-09-2006, 02:59 PM	#8 (permalink)
Neb Senior Member Join Date: Jul 2006 Location: San Francisco, California Posts: 161	This is why tuning any vehicle's engine to run efficiently is important when adding aftermarket parts like exhaust or intakes, and especially tubrochargers and superchargers.

08-10-2006, 12:53 PM	#9 (permalink)
okiecaliberguy Super Moderator Join Date: Aug 2006 Posts: 384	is it true that you can retune the ecu, post-mods, by warming the car up, then turning it off and disconnecting the battery for a while? does that really reset the ecu?