what effect if any does warm air have on fuel economy

[Thunderchild]

I've been thinking. what effect would the temperature of the air taken in have on the engines consumption and performance. What about damp air ?

I've noticed that most intakes are deliberately made near the front of the car, what is they took air from say behind the engine in the engine bay. Any improvement likely ? But then how important is airflow in the air intake ? would too much pipework be a problem ?

[TWR]

The air intake from the front is to assist the radiator Thunder.

[Thunderchild]

I'm referring to the fact that the air intake into the carburetter / injector is often pipe to the front of the engine taking in the coldest air possible. I thought putting colder fuel mix into the engine would lower performance and impact fuel economy. As soon as it warmed up my car started running better - or it could be a result of my maintaining it since I bought it.

[TWR]

Any vehicle may it be a Bike / Scooter / Car / HGV, will perform well providing it's maintained well Thunder, when you start the tend of missing out on servicing on a given date, thats when types of car's etc start to cost money, most cars now do not have a carb as such, the intake of air is calculated by the ECU.

[alavahalf]

If you direct air into your injectors .. you have an engine they can't run.

[gingejbee]

Petrol engines are said to run better in cool, damp conditions.

[ChuckFickens]

Cold air is denser so contains more oxygen for a given volume of air. more oxygen means you can get more power out of each cycle of the engine which means its more efficient.

[Thunderchild]

are sure, why ?

I bought it about a month ago and started using good fuel, did the valve clearances and changed the thermostat

[Thunderchild]

@chuck fikens, ah yes that also make sense a bit like the turbo engine concept, more mix in less space

[TWR]

What are you getting at Thunder? is your car running rough? explain some may find the cause of your problem.

[Thunderchild]

no it was just a hypothetical question and i wondered if the improvement in my cars performance and drop in fuel consumption was due to air temperature or the fact that I am probably looking after it better than the last owner

[Hopkirk]

I get better fuel consumption in the summer than the winter.

The engine is more efficient when up to operating temperature, and it gets there quicker in warmer weather. Also any cold start mechanism switches off earlier.

I remember cars in older times having air intakes which took from near the exhaust manifold when the engine was cold, then switched to the front grill once up to temperature. I haven't seen this layout for a while though.

[ChuckFickens]

You must be doing a lot of short journeys if the time the car takes to get up to working temperature makes a noticeable difference to your overall fuel economy.

[Hopkirk]

Twenty minutes to work.

[MantaRay]

Hopkirk you are right, older cars directed warmer radiated air from the exhaust manifold. This assisted warm up and helped to prevent carburettor or throttle body icing during that stage. Oh I miss those days of playing with the choke control to keep an engine going during the first few minutes of running!

I did experiment with my previous car in colder weather, redirecting warmer under bonnet air to the intake snorkel and I feel it did benefit in slightly smoother running. However, the intake noise got on my nerves so I resorted to putting it back to standard.

It has to be said that manufacturers spend millions developing exhaust and intake systems and will be optimised perfectly for a standard road vehicle, so after market mods and alterations will always have a negative trade off.

[Thunderchild]

I have noticed that I do get nippier performance in cool weather with a hot engine