Extreme Heat and Humidity = HUGE MPG gains

[Nerys]

OK I REALLY hate hot and humid but Ryo-Oki LOVES it. I mean REALLY REALLY loves it.

I had to try hard NOT to get 60mpg and better !!

now that its going away my MPG's are going down.

So how much is there in this? both my pop (96 town car) and my brother (84 carb buick) both remarked that the last few tanks they REALLY saw visible measurable increases in FE so it was not just my "skills" causing this :-) the towncar also has a fuel computer so he can get instant and average measurements.

he saw a 1.5 to 2.5 average mpg increase during this hot and humid spell (for a 22-24mpg car thats huge)

SO is there anything we can do to SIMULATE this?

how much of it was heat how much was humidity??? (mild form of water injection???) I hear water injection increases "power" and more power for us means we need "less foot" to go so better FE.

This might be part of the reason my washed gas gives me so much of an increase ?? some from lack of ethanol and some from left over "water" in solution in the gas ???

anyone have anything concrete on this ??

if I directed my intake over my manifold and sealed up the bottom (partial belly pan) to increase the "heat bank" inside the engine bay to feed the intake.

what would happen? what about heating coils INSIDE the intake? water pump pumping coolant through copper tubes wrapped around the exhaust and coiled inside the intake air tube. ie "that much more heat" to add to the mix.

suggestions? thoughts? ideas? info?

anyone else seeing these results over this past heat humidity wave?

[bwilson4web]

Originally Posted by Nerys

OK I REALLY hate hot and humid but Ryo-Oki LOVES it. I mean REALLY REALLY loves it.
. . .
SO is there anything we can do to SIMULATE this?
. . .

I've observed two effects with my Prius:

• lower air density - several years ago in a winter drive to South Carolian and back, the temperatures ranged from 15F -> 40F -> 18F and the highway fuel economy followed the change in air density as a function of temperature.
• warm-up effects - engine, transmission and tire warm-up takes about 5 minutes until things plateau. Warmer weather reduces the warm-up by starting a few degrees higher and with lower heat loss during the warm-up interval. Tire pressures are also likely to be higher from heating.

[SoobieOut]

I agree with bwilson here. High Humidity and Temperature will lower the apparent drag from the air.

In aviation terms they call this a high density altitude, requiring longer runways for take-off on hot humid days.

[t vago]

You also have to consider that, on humid and warm days, there is effectively less oxygen being drawn into the engine, compared to cooler and less humid days. This requires that the driver open up the throttle a bit more to get the same amount of output power, which will reduce pumping losses in the engine. This will also cause fuel efficiency to go up.

[oil pan 4]

Originally Posted by Nerys

SO is there anything we can do to SIMULATE this?

suggestions? thoughts? ideas? info?

Maybe a warm air intake with mild water injection.
Only problem with water injection is its not proven to boost FE on N/A gas engines at least with stock cold air type intakes.

For FE on a gas engine during compression you want your air/fuel mix to get as hot as possible with out preignition and with out having to pull timing before being lit off by the spark plug.

[Nerys]

well thats what I am curious about. was it just the heat? or the combo of heat and humidity? you see it was 100+ degree's for several days with humidity over 95%

ie TRULY nasty. we do not "get" 100' days with "low" humidity so I can't test.

I am curious to see what people in other climes get. ie do people in not quite so hot but almost always NASTY HUMID florida see the same higher mpg?

what about people in nevada and arizona? ie super hot but LOW humidity?

is it one or the other? or do you require BOTH to see these results? is it possible for us to simulate this even partially?

[oil pan 4]

The humidity could aid in preventing preignition.

[Nerys]

Hmmm what would cause pre ignition?

[CigaR007]

Originally Posted by Nerys

Hmmm what would cause pre ignition?

If the temperature of the air/fuel mixture entering the cylinder is already quite high, it will be further increased during the compression cycle, meaning there is a risk of pre-ignition; or the mixture igniting itself (compression = heat) without the need of the spark plug; which is bad.

Somebody correct me if I am wrong.

[Nerys]

ahh so the humidity (ie water in the air) would dampen this. I get it. so it might be critical to have BOTH present.