Competition Volumetric Efficiency

[BGarofalo]

Has anyone calculated true V. E. for a stock cummins engine? Common rail prefferably but other generations would be helpful too.



Im doing some estimates based on a few known numbers and Im getting differant values with differant calculations. Im getting between . 50 and . 70 in my calculations.



Thats a pretty big range If anyone has any true calculated numbers they dont mind sharing it would be helpful for me.

Thanks

 

[COMP461]

its related to boost and intake restriction. I have put a airhat flow meter on one of my race engines and it flower 2100 + cfm of air at 4800 rpm and up

 

[CanadianCarGuy]

Was that 2100 cfm on a cummins? How much boost?

 

[COMP461]

This was on a SuperFlow 904 engine dyno , This was the NitroFlash Engine with about 42 lbs of boost



On a Cummins or any race engine the most important area to pay attention to is air flow,

You can achieve this by high boost numbers, which carries with it heat, and the need to reduce compression ratio’s to keep the parts from melting. This also requires a abnormal about of time to spool up. This type of engine lacks acceleration and this is critical in Drag racing, the higher the boost level, the longer it take to get there. This coupled with a low compression ratio; give up low end mechanical advantage. This also hurt acceleration.



The best way is to increase airflow; the engine in question had almost double the airflow of a stock Cummins. The compression is up there for a 1200 hp engine around 15 to 1 .



I would farther go to a speculation and an engine I am currently building a high compression CR engine around 19 to one. This type motor is a high efficiently project and the max hp is 600. In reality, an average guy can barely use 600 hp in that trim all the time

 

[COMP461]

These are pictures of a top port job on a 12 valve done by ZZ fab. This head flows like a sewer pipe and with the custom individual tuned runner manifold has a direct effect on volumetric efficiency. Any one that tells you that a diesel is not affected by resonance tuning is uneducated. Or just plain BS'ing . The headers are another essential component to the equation. It is the fact that the pulses are directed at the turbo volute that makes the biggest gain possible. This is only part of the puzzle. Now with resonance tuned headers you have the ability to drive the turbo with pulse and not just drive pressure. With this in play , you can select a much larger AR ratio and relieve drive pressure , and drive the same compressor. This equates to more power.



The days of boost levels over 50 psi to make big drag racing power are just about over. The reduction in drive pressure and lower boost also translate in to less heat. Now you can maintain compression ratio’s and regain all the lost efficiency’s in the motor. This means faster spool up, easy starting, and the ability to accelerate

 

[CanadianCarGuy]

Have you done any 24valve heads yet? I love the turbo header, are they for sale! I like where your going with this...