Talk:Volumetric efficiency

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This article is not entirely correct.... there are many mass produced engines that run greater than 100% VE without forced induction.

The mass produced Honda H22 (Prelude, Accord, Ect) runs at 104% VE and does not have any form of Forced induction. There are also several production street bikes that run at greater than 130% VE.


 * I've never heard of sleeve valve engines failing due to "popping"...Generally, I believe their biggest issue is sealing oil.
 * Helmholtz resonators have been used after the 70's. Many cars today use them to remove drops in torque at a certain rpm (e.g. Honda gen. 2 L-series).
 * LostCause (talk) 03:07, 17 March 2008 (UTC)

moreover the volumetric efficiency should be defined on the mass basis not on the volume as the volume occupied by the air fuel charge will always be equal to that of the cylinder —Preceding unsigned comment added by 59.160.18.209 (talk) 04:55, 18 August 2008 (UTC)

These motorbikes can only attain this efficencty by driving at speed where air is forced into the air intakes, this is not possible at static conditions. —Preceding unsigned comment added by Siripswich (talk • contribs) 22:20, 5 May 2009 (UTC)


 * ENDYN has achieved a VE of 137% with a naturally aspirated Honda K-series engine . IJB TA (talk) 18:03, 9 June 2009 (UTC)

This article might be a bit complex. What about a Simple English version? — Preceding unsigned comment added by Mbb1056 (talk • contribs) 20:43, 3 March 2014 (UTC)

Fundamentally incorrect
This article is very poorly written and incorrect. Referring to the oxford definition of volumetric efficiency:


 * 1) the ratio of the volume of fluid actually displaced by a piston or plunger to its swept volume.

Regarding the opening paragraph:

defined as the ratio of the mass density of the air-fuel mixture drawn into the cylinder at atmospheric pressure (during the intake stroke) to the mass density of the same volume of air in the intake manifold.

Should read something more like:

defined as the ratio of the mass of the air-fuel mixture drawn into the cylinder (during the intake stroke) to the mass of the same volume of air in the intake manifold (which is at intake air density).


 * 1) "Mass density" is mass per unit volume. We are only measuring mass here. Volumetric efficiency is measuring the ratio between the mass of air actually drawn into the cylinder, versus the mass of air (at intake manifold density ) that would theoretically fill that volume.
 * 2) It is not at atmospheric pressure or atmospheric density, but at intake manifold density (NOT intake manifold pressure). EG. if intake manifold density was currently at X grams/L, and our cylinder with a swept volume of exactly 1 litre displaced exactly X grams of air, then the current volumetric efficiency would be 100%.
 * 3) It is intake density, not intake pressure - as the weight of air per unit volume (mass density) is effected by both pressure AND temperature (not just pressure).

The paragraph under Internal Combustion Engines is closer, but still not completely correct:

More specifically, volumetric efficiency is a ratio (or percentage) of the mass of air and fuel that is trapped by the cylinder during induction divided by the mass that would occupy the displaced volume if the air density in the cylinder were equal to the ambient air density.


 * 1) It should be intake air density not ambient air density

The second reference/note to the carbiketech.com article is not a very good one and poorly written (EG its use of the term "suction stroke").

The whole article in general needs a lot of work. I have decided not to do any edits as I have never edited a Wikipedia article myself. But felt compelled to bring it to someone's attention after stumbling across it (after watching a misleading YouTube video that appears to have been influenced by the mistakes in this article). Pman92 (talk) 09:44, 25 August 2023 (UTC)