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Does anyone know the volumetric efficiency of a stock naturally aspirated TD42?I need this information to buy a donaldsons pre cleaner because I have to figure out the range of airflow rate.The only changes I've done are using a K&N air filter and a 3" safari snorkel.
 

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I could be wrong but can you times the 4.2ltr x the rpm to give you an approximate
4.2ltrr 4500rpm =18900ltr per minute

That's obviously at 100%ve which it won't be but a little more is better than a restriction
 

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From HP Wizard web site, best one to give a estimation

The theoretical volumetric flow rate (Qth) is more or less chosen arbitrarily, based on atmospheric air density. Because air is compressible, a volume does not limit the quantity of air that can be pushed in, especially when gas dynamics are considered.


So volumetric efficiency is not a true «performance» criteria for an engine because what counts is the air mass flow rate. With everything else equal, an engine with a large VE burns the same amount of fuel and gives the same power output than a larger engine with a smaller VE. But values do compare with similar engines.


Mathematically, only a complex gas dynamics analysis can give a good approximation of the volumetric efficiency, but here are some ballpark values:

521268



Sources:


An ordinary low-performance engine has a VE of about 75% at maximum speed; about 80% at maximum torque. A high-performance engine has a VE of about 80% at maximum speed; about 85% at maximum torque. An all-out racing engine has a VE of about 90% at maximum speed; about 95% at maximum torque. A highly tuned intake and exhaust system with efficient cylinder head porting and a camshaft ground to take full advantage of the engine's other equipment can provide such complete cylinder filling that a VE of a 100% − or slightly higher − is obtained at the speed for which the system is tuned.


For contemporary naturally-aspirated, two-valve-per-cylinder, pushrod engine technology, a VE over 95% is excellent, and 100% is achievable, but quite difficult. Only the best of the best can reach 110%, and that is by means of extremely specialized development of the complex system comprised of the intake passages, combustion chambers, exhaust passages and valve system components. The practical limit for normally-aspirated engines, typically DOHC layout with four or more valves per cylinder, is about 115%, which can only be achieved under the most highly-developed conditions, with precise intake and exhaust passage tuning. Generally, the RPM at peak VE coincides with the RPM at the torque peak. And generally, automotive engines rarely exceed 90% VE.


Typical numbers for peak Volumetric Efficiency (VE) range in the 95%-99% for modern 4-valve heads, to 88% - 95% for 2-valve designs. If you have a torque curve for your engine, you can use this to estimate VE at various engine speeds. On a well-tuned engine, the VE will peak at the torque peak, and this number can be used to scale the VE at other engine speeds. A 4-valve engine will typically have higher VE over more of its rev range than a two-valve engine.

Or if you want to do your brain in and have access to all the measurements of the engine you could use this web site "How to calculate the volumetric efficiency"

Good luck on the last one
 

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Discussion Starter #4
Thanks for the reply. That's a lot of info. Is there anyway someone could contact someone in Nissan and ask for the exact volumetric efficiency of a naturally aspirated TD42. I mean the guys who designed the engine should know it right?
 

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Thanks for the reply. That's a lot of info. Is there anyway someone could contact someone in Nissan and ask for the exact volumetric efficiency of a naturally aspirated TD42. I mean the guys who designed the engine should know it right?
Someone at Nissan doubtless knew. But considering how long it has been since the TD42 was designed they may well have retired. And the information filed....
 

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I guess the real answer is 75-80%, perhaps even a bit lower at maximum RPM, but for the purposes of the exercise it is probably a good plan to use a higher percentage as already stated by Davrai.
 
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