Why so smooth in the rain ?

[Paul in NZ]

Also when it's raining I notice more power and smoother, this is because the water is no longer vaporized in the air, but is falling as drops to the ground, so again the motor is getting less humid air when it's raining.


The other variable is air temp, cooler air is more dense and is therefore better for performance.

isnt that what we have been saying throughout this thread?

[kick7ca]

but I'm proposing it happens for a different reason.

[Ausmpower]

When I flew C-135 aircraft for USAF, we had water-injected J-57 engines. Water injection increased takeoff thrust by ~25%, til the water ran out.

Generally, wet weather is cooler weather, so the air would be denser on that account, helping engine performance (more air/fuel in the cylinders).

However, at a given air temperature, moist air is less dense, so the wings generate a bit less lift and the engines would have a bit less air to breathe.

Moisture in the air/fuel mix slows the combustion process, making a reciprocating (piston) engine run smoother.

In WWII, various piston-powered fighter planes had water injection systems, to augment thrust for combat. The added weight of the water, however, compromised manouevability of the plane.

Those WWII aircraft actually used water/ methanol injection since they lacked intercooling in any form and they were all super charged (Spitfire, hurricane, p51 Mustang, p38 lightning etc) the power increase was due to the air density increasing from the evaporation of the water/ alcohol mix(which also eliminated detonation).

[Traian]

Hmm, does anyone know why everyone isn't doing this, if it burns less fuel AND makes more power AND emits less pollutants according to the sites? I was also wondering about water being incompressible and all, but I guess the vapour produced by the combustion IS compressible and there is a very small amount of it. Is that the explanation?

[VentoGT]

Also when it's raining I notice more power and smoother, this is because the water is no longer vaporized in the air, but is falling as drops to the ground, so again the motor is getting less humid air when it's raining.

When it is raining, the ambient air is at 100% relative humidity, so the air is most humid when rain is falling. As for the other statements in the thread, I don't know enough about them to comment, but the colder air=more dense=more power is correct.

[BillionPa]

why isnt everyone doing it? because a properly calibrated water injection system with 3D mapping control costs about $1000

[nizmainiac]

the air is denser , alot better for engines , turbo or n/a