More power in winter?

silverpolo · Post by **silverpolo** » Fri Oct 31, 2003 12:10 am

my tdi feels faster in the cold the in the summer heard that turbo cars loose power with warm air going into the turbo then cold air.

so im getting the full 75bhp at the mo

KarlM · Post by **KarlM** » Fri Oct 31, 2003 12:18 am

cold air is denser so creates a bigger explosion in the combustion chamber, but i'm not sure how this works with diesels

fredwolff · Post by **fredwolff** » Fri Oct 31, 2003 1:16 pm

The same works with diesel. Turbo models (petrol and diesel) use to have intercoolers to lower the air temperature (denser). If the external temperature is low, the intercooler will work better than in hot days.

One of the advantages of the NOx systems is to lower the intake air temperature by expanding the compressed gas (adiabatic expansion), admitting a denser air to the combustion chamber.

Nelson_Wilbury · Post by **Nelson_Wilbury** » Tue Nov 11, 2003 10:27 pm

You'd see a POSSIBLE power increase as all engines like colder air (hence the reason they perform better in the mornings). The increase would more noticably be in torque though.

In a diesel engine the air/fuel mixture is more extreme and compression is used to ignite it rather than sparkplugs on a petrol engine.

Basically, as the diesel engine is on its induction stroke, its draws in a full charge of filtered air. On the compression stroke both the inlet and exhaust valves close. The air is compressed but at a much higher rate than a petrol engine. As the piston comes back up the injectors blast (on a PD engine like your the injectors are powerful enough to cut an engine block in half!) in the fuel. The hot air mixed with the fuel creates the explosion.

The explosion created by a diesel engine is much more powerful than a petrol, hence the reason diesels have got so much torque

Looks like the Audi technical course paid off!

Sadgeek · Post by **Sadgeek** » Fri Nov 14, 2003 1:35 pm

Nelson_Wilbury wrote: The explosion created by a diesel engine is much more powerful than a petrol, hence the reason diesels have got so much torque

I thought that you get more torque because the diesel burns rather than exploding, giving you longer push on the piston on the downward stroke, but hey, I'm no mechanic.

Just goes to show what you can learn here.

Nelson_Wilbury · Post by **Nelson_Wilbury** » Fri Nov 14, 2003 7:40 pm

Sadgeek wrote:
Nelson_Wilbury wrote: The explosion created by a diesel engine is much more powerful than a petrol, hence the reason diesels have got so much torque
I thought that you get more torque because the diesel burns rather than exploding, giving you longer push on the piston on the downward stroke, but hey, I'm no mechanic.

Just goes to show what you can learn here.

You are right

It's just my term of explosion, I should have really said it 'burns' under compression.