Does 1litre of air weigh 1 tonne? Can't see that myself.

You're a factor of 4 out. 9000 rpm = 150 revs per second, and 2 cylinders will be on an induction stroke in the process of 1 revolution. So that makes 429.9 * 2 * 150 = 129 litres per second, or 7740 litres per minute. Which if you look above isn't far off what I said.

 

Ah yeh, school boy!

Thanks mate, maybe I am not as bad as I first thought!

 

AFR at 9k rpm dips off to about an AFR of 11 from memory. About 12.5 at 8000 rpm. Richens up for safety.

 

Woah!

Steady on.

Swept volume isthe capacity.
You compare the swept volume to volume of the head to get the static compression ratio.

The volume of air going into the engine (disregarding losses due to restrictions) is half the capacity of the engine per revolution.

This is because each cylinder has one induction stroke per two revolutions.

The volume of air going in does not change with the temperature nor does it change with the humidity.

The density of the air does change however and since it is more dense it contains more oxygen per volume.

A bit of moisture in the air will make the engine more powerful regardless of whether you have a turbo.
This is because damp air resists temperature changes better than dry air and will help keep the manifold temperature down.

It is a marginal difference but it is there and damp air will also (marginally) reduce the dynamic compression ratio allowing more timing before you get knock, giving more power.

You can work out the mass of 1 litre of air using molar weights and such but I'm off to bed and I can't be bothered.

 

No; the valves are closed for the duration of the rest of the cycle so there's no charge/discharge.

Ignore the exhausty bit since it's confusing.

In fact, I'd even ignored valve duration, so it's only sucking for part of the cycle, but that column is 'pulsed' by another valve closing on it in a four or a V8...

Hence why it's less than 500cc per pot.

As for what Ginge say; this is right; don't start confusing the mass of air with its volume - it's a head f u ck!

 

Yep. Easiest thing to do is just apply volumetric efficiency since it'll take all in.

Mix in a dash of Ideal Gas Law and you should be able to work it all out

 

I agree, its low 11's, and about 12.5 at 8k rpm as you say.

However richen it up isn't all to do with safety high revs. According to my mate the engine its losing its efficiency to bring in air at very high revs hence very rich which also add's to the effect.

As you say though its also for safety, cooling and lessening the strain of bouncing off the rev limiter.

^ A member on here had his kitcar mapped by my mate which i also helped with (several year ago), its Pete Findlays kitcar .

Haven't got a fecking cool about the question , plus I'm watching a Frankie Boyle DVD so cant concentrate .

 

I'll hold off phoning Comet to order my freezer until you lot come with an answer....

 

OK fag packet maths
9000rpm = 9000L swept volume per minute as already stated
Apply volumetric efficiency (for an engine such as this think about 92~93%) so it'll be taking in 8280L I think I worked out

Use PV/T=PV/T and make some assumptions about an initial condition and a current condition (I used 293.15K & 273.15K for temperature and pressure will be largely constant; ok it won't actually be but different is negligable so far as the calculation goes).

That gave me something like 7715L.

i.e. due to the density change 7715L at 273.15K would do the same job as 8280L at 293.15K

Depending on what answer you want you then multiply the answer by 40 to answer the original question of how much air would be needed for a 40 minute journey.

I've had a couple of gins and am watching a film so please somebody check my maths but the principle should be about correct

 

Well, since you are the only one to have mentioned the rather critical VE, Fluffy, i'd reckon you are very close. Numbers indeed look good

Unfortunately this cold dense air won't make your car any faster