|September 10, 2000|
How does your car stack up?
In our previous article we guided you through the process of calculating the volumetric efficiency of our LS1. But how does your car stand up against everyone else's? Through the help of some fellow LS1 enthusiasts we have put together a small database of a wide variety of LS1's. This list includes the Icon Twin Turbo Stage I, Agostino Racing Engines Stage II heads/cam package, along with several other cars including the LS1 Hot Cam.
Taking a closer look at the findings
We decided to take a closer look at the volumetric efficiency of our engine at different rpm ranges. We took a log file using Auto Tap and placed the data in a spreadsheet. From this data we were able to calculate the volumetric efficiency at each data point. We immediately noticed that the volumetric efficiency varied enough through the rpm's to raise an eyebrow.
The following run was made in second gear. We have the following performance modifications: free ram air, K&N air filter (dirty), whisper induction lid, hyper tech power programmer three, and exhaust cut out.
Note: Both flow rate columns might contain slightly different numbers compared to working it out by hand as shown "Volumetric Efficiency: Calculating your cars volumetric efficiency". The spreadsheet carries the calculations out past 9 significant figures. This is nothing to be alarmed about.
|Engine Speed (rpm)||MAF Air Flow Rate (lb/min)||Intake Air Temp (°F)||Density||Actual Flow Rate (ft3/min)||Theoretical Air Flow Rate (ft3/min)||V.E. (%)|
You have read that it is generally accepted that most fuel injected cars have a eighty-percent (80%) volumetric efficiency rating. Look at the table above you can quickly see that our car is only falls in that range between 3900 and 4600 rpms at wide open throttle. I do not know how websites and magazines come up with that figure of eighty-percent but it seems odd that my car operates that that efficiency less than 13% of the used rpm range at wide open throttle.
A set of ported heads, higher lift cam, turbos, and superchargers all increase the volumetric efficiency of an engine. Common sense dictates that the more air that that is pushed into the cylinders, the more force that is supplied after ignition because there is a greater supply of oxygen to ignite.
- Eric Barger
Editor: Kelly Barger
1. Deskins, Tom. Interview.
2. Vizard, David. How to Build Horsepower. Volume 2. Page 60.
3. Green, Don, and Robert H. Perry. Perry's Chemical Engineers' Handbook. 6th edition. New York: McGraw-Hill, 1984.
Web Author: Eric Barger firstname.lastname@example.org
Copyright © 1999 - 2002 Eric Barger. All rights reserved.
Revised: June 07, 2007.