total volume of air in 6g72T

[mb3000]

85% Is a little low if you have intake & exhaust restrictions removed.

[RealMcCoy]

85% Is a little low if you have intake & exhaust restrictions removed.

Probably pretty optimistic after you factor turbine backpressure and thermal losses.... There's no way you're moving double the air by running 14.7 psi.

[mb3000]

Probably pretty optimistic after you factor turbine backpressure and thermal losses.... There's no way you're moving double the air by running 14.7 psi.

Touche.

[AdamVR4]

VE rarely exceeds 100% for normally-aspirated engine. VE exceeds 100% for forced-induction engines.

The JavaScript calculator below calculates the VAF (volume of outside air flow) in cubic feet per minute (CFM) and liters per minute (LPM) based on engine displacement (CI or L), speed (RPM), and volumetric efficiency (VE). For this exercise, I define the volumetric efficiency as the product of the natural flow capacity (NC) of the engine, at a particular RPM and load, and the overall density ratio (DR), due to boost pressure. When the actual volume of air (compressed or at partial vacuum) entering the cylinders equals the engine displacement then the NC is 100%.

For a stock, turbocharged, Mitsubishi 6G72 2.972-L engine, NC ranges from 75% to 95% at WOT. Overall density ratios are usually less than 2.5 (that is boost pressure is less than 24 psi). The overall density ratio is less than the ratio of absolute boost pressure to atmospheric pressure (the pressure ratio) because of frictional and heating losses. For normally-aspirated engines use a DR equal to 1. Engine redline is around 7300 RPM. However, peak NC usually occurs between 5000 and 6000 RPM in the 6G72 engine.

-stealth316

Assume:
NC = 75%
PR = 1.82
VE = NC x PR = 0.75 * 1.82 = 1.36 = 136%

Use 136% instead of the 85% I used for VE in my first post.

[J. Fast]

Still don't like seeing VE swung around greater than 100%. Thats perpetual motion machine range right there. If VE is greater than 100 you've lost the definition of efficiency.

[AdamVR4]

Still don't like seeing VE swung around greater than 100%. Thats perpetual motion machine range right there. If VE is greater than 100 you've lost the definition of efficiency.

Yeah, I'll stick with what I put in post #10. If you're using PR and NC to compute VE, PR actually goes into the air flow equation twice... And that doesn't make sense.