Diesel engine max revs per minute

[Jetronic]

Many current factory spec diesel engines have a 5000 RPM fuel cut off, but the redline as indicated on thetacho can be a bit lower, typically 4500 RPM.

When you remove the fuel cut-off (software) some can make decent power all theway up to 6000 rpm, with the peak around 5500 RPM, but not all will survive this.

I've seen one wher the crankshaft timing pulley had a broken key and this vehicle, due to the different engine timing, made 6000 rpm without removing the governor. It did however melt several MAP sensors before the problem was found and corrected. Unsure if the melting was due to an excess of exhaust gasses through the EGR or very high boost temperatures, or both.

 

[Clevy]

Isn't piston speed a determining factor as well.
Byron what I understand a diesel tends to have a long stroke which is good for torque so even though the rpm may be low the piston speed might be very high.
When going big bore on my harley I did a crazy amount of reading so I could make prudent choices as far as my build and I learned a ton about rpm,flame propagation and piston head speed and how it relates to power.

 

[asand1]

Big forged pistons and heavy rods with lots of stroke can't move all that fast. Spinning them fast is usually disastrous.

 

[Jetronic]

the stroke isn't longer than you'll find in petrol applications, but the piston weight is, of course.

 

[artificialist]

Originally Posted By: Jetronic
the stroke isn't longer than you'll find in petrol applications, but the piston weight is, of course.

The connecting rod and wrist pin are also heavier. Ever compare the insides of a VW TDI versus any other gasoline powered VW 4-cylinder?

 

[Jetronic]

the engine with the highest torque rating gets the strongest conrods and wristpins. No surprise there.

 

[A_Harman]

Watched the WEC 6-hour race from Silverstone on Sunday. They had on-screen telemetry from both the Toyota and Audi LMP1's. The Toyota gasoline engines were shifting at 9000 rpm, and the Audi diesel engines were shifting at 5000 rpm.

 

[Tornado Red]

Originally Posted By: artificialist
Combustion chamber design also has an effect, prechamber engines typically have a higher redline than direct injection engines.
VW IDI engines tended to have a 5000 RPM rev limit, whereas many TDI engines had closer to a 4500 RPM redline.


The redline is actually over 5000 rpm, but in stock form most TDIs run out power between 4000 and 4400 rpm. With a custom tune my 2003 will rev effortlessly to 5000, which is nice.

 

[Cujet]

Audi 120 degree V6 racing diesel. It has all the "tricks". It's a hot V, with intakes on the outside, 120 degree, 3 throw crankshaft, perfect primary balance, and more. It's no wonder Audi has done so well with this engine. It's extremely low center of gravity is a big plus too. I don't know the redline, but from the sound of it at Sebring a couple years ago, I'd say it's no higher than 6000 RPM in practice.

I'd love to see this type of configuration in an aircraft.

 

[Clevy]

Originally Posted By: Cujet
Audi 120 degree V6 racing diesel. It has all the "tricks". It's a hot V, with intakes on the outside, 120 degree, 3 throw crankshaft, perfect primary balance, and more. It's no wonder Audi has done so well with this engine. It's extremely low center of gravity is a big plus too. I don't know the redline, but from the sound of it at Sebring a couple years ago, I'd say it's no higher than 6000 RPM in practice.

I'd love to see this type of configuration in an aircraft.

Now THAT is an interesting piece of hardware.