effective fuel economy - modified cars

[MoDCoN]

hey guys, this sorta came up in my thread bout lightweight flywheels before, and i wanted to know what you think. basically what sort of effect does modifying a car have on fuel economy?

i know if you're running a huge turbo with larger fuel injectors on the track, then sure, you probably gonna eat a lot of fuel.

but what about smaller things, i.e., intake, header, exhaust? dont such mods improve volumetric efficiency,a dn as such improve economy at the same level... ie, given you dont drive harder, will you use less fuel?

and then say you tune it, i know that can be definitely used to improve consumpiton... im asking, can you modify a car lightly, and tune it really well, and end up having a car that pulls harder when needed, but drives better, more responsively and uses less fuel while driving normally... yeah im a cheap uni student but i also care about how much petrol im burning cos it affects the environment.

thanks! MoDCoN

[egSi]

man i got i/h/e + cam gears and soon to have tranny work, my car untuned is very economical.

i also have no interior, small enkeis and no aircon.

my car is very economical but goes ok when i want

[iamhappy46]

To make a car fuel economical, is dependant on how many factors.
For example, I/H/E mods with a proper tune up and running hi octane fuel will improve power when you need it(rev it hard) but if baby it around town and get excellent fuel economy.

For turbo applications, if you baby the motor around 'off-boost' you should yield similiar fuel economy as a n/a car as it requires similiar amounts of fuel until the turbo spools up and requires more fuel to keep air:fuel ratios correct to make big power.

Same as VTEC, when the cam kicks in, the ECU adds fuel and ignition timing to make power.

[ProECU]

Driving techniques aside... fuel efficiency is a bi-product of mechanical octane.

Things like effective piston & chamber design and the clearances between these two is a major contributor towards fuel efficiency.
So too is quality of fuel atomisation & combustion quality...

Side note, have you guys ever wondered why a golf ball is dimpled?....

+10 Rep to anyone who can give me a precise answer.

[jared]

Driving techniques aside... fuel efficiency is a bi-product of mechanical octane.

Things like effective piston & chamber design and the clearances between these two is a major contributor towards fuel efficiency.
So too is quality of fuel atomisation & combustion quality...

Side note, have you guys ever wondered why a golf ball is dimpled?....

+10 Rep to anyone who can give me a precise answer.

The dimples aid the rapid formation of a turbulent boundary layer around the golf ball in flight, giving more lift. Without 'em, the ball would travel in more of a parabolic trajectory, hitting the ground sooner (and not coming straight down)Despite the drag, a dimpled golf ball can even go further in air than it would in vacuum given the same initial velocity and low angle. However, a golf ball shot at 45° and 70 m/s in vacuum would go 500 metres to the first bounce, which exceeds all records.

there ya go mate i did an assignement on this in yr 9

[nedgeworth]

Create more pressure behind the ball, thus forcing the ball to travel further.

[incoming]

hahah i was gona google it...

but back on track... my car b18c IHE + ECU + tuned only gets like 450max on a tank of fuel
this is on/off hard driving, city and highway km's too...

its a wonder how trav's car gets soo much K's ahaha

side note: dont u hate it when on first half of the fuel indicator fuel consumption looks good but when it drops below half it goes so fast u feel rorted? i do =)

[ProECU]

The dimples aid the rapid formation of a turbulent boundary layer around the golf ball in flight, giving more lift. Without 'em, the ball would travel in more of a parabolic trajectory, hitting the ground sooner (and not coming straight down)Despite the drag, a dimpled golf ball can even go further in air than it would in vacuum given the same initial velocity and low angle. However, a golf ball shot at 45° and 70 m/s in vacuum would go 500 metres to the first bounce, which exceeds all records.

there ya go mate i did an assignement on this in yr 9

So you're in year 10now? lol

How does this apply to a cylinder head & engine?

Yeah, you're on the right track, anyone know how I can add +10rep, lol

[egSi]

its a wonder how trav's car gets soo much K's ahaha

good old breeze mate

[saxman]

How does this apply to a cylinder head & engine?

using a slightly rough surface on the intake tract creates a boundary layer between the metal and the airflow, increasing the velocity of the intake charge


basically
higher velocity air = more air able to oxidize fuel = more power

[bennjamin]

Side note, have you guys ever wondered why a golf ball is dimpled?....

IMO....
same reason a ported yet very slight rough surfaced is better than a full "polished" head ?
the dimples or surface guide create minute turbulence - effectively creating a air pocket for the airflow....Im just thinkign off the top of my noggin

*EDIT* actually what he said above is the same thing

[ProECU]

using a slightly rough surface on the intake tract creates a boundary layer between the metal and the airflow, increasing the velocity of the intake charge

correct, it also helps atomise the mixture.

good to see you're all learning