effective fuel economy - modified cars

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

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 :thumbsup:

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.

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.

Quote:

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Originally Posted by 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.

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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

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

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 =)

Quote:

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Originally Posted by jared

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

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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

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Originally Posted by incoming

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

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good old breeze mate :p

Quote:

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Originally Posted by ProECU

How does this apply to a cylinder head & engine?

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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

Quote:

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Originally Posted by ProECU

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

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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 :o

Quote:

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Originally Posted by saxman

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

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correct, it also helps atomise the mixture.

good to see you're all learning :)

my untuned b16 does about 550 kms off 50L
with i/h/c/e.. and 17s and my crazy driving hehehe

Quote:

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Originally Posted by incoming

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 =)

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YEAH!!!... my first half does 300!! and im thinking!! mad!! i can do 600!!! but when it gets to 500, blardi light comes on...:D Then again, 55 bucks per week is ok for fuel...:)

after intake, header exhaust and hondata, my economy has improved dramatically. I used to get roughly 380-400/tank, now i get anywhere up to 475 on a tank.

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Originally Posted by FR33K

my untuned b16 does about 550 kms off 50L
with i/h/c/e.. and 17s and my crazy driving hehehe

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that's damn good. Is that b16a2?

hmmm. well it seems the answer is yes then? or maybe just for egSi... :P

and gettin into that golf ball dimple question... well its already been answered, but has anyone else here seen some doco about how (aus?) troops had to do design a bomb to blow open a dam and they made one like a golf ball, so that it would bounce on the water before sinking? interestin hey?!

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Originally Posted by ginganggooly

after intake, header exhaust and hondata, my economy has improved dramatically. I used to get roughly 380-400/tank, now i get anywhere up to 475 on a tank.

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i get around 500 out of my turboD. Beating on it. 16psi :) DynoDave knows how to tune hondata, thats for sure.

I/H/E and a few other slight mods...and bit of zippy driving....and I usually average from between 7.6L/100 - 8.3L/100 km. It also helps having a little extra RON in my tank each time ;)

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Originally Posted by civtir

that's damn good. Is that b16a2?

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narrrrr 1st gen JDM b16
mix between highway and traffic (i drive from st marys to crows nest everyday in moderate peak hour)

Quote:

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Originally Posted by ProECU

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

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nah mate im not in yr 10 you fool lol im doin me hsc and i have one exam to go just remember alot about the topic as it was covered in senior science i was studying in yr11 and 12

The ED Civic with D15B VTEC conversion is getting around 600+Km's per tank of fuel, with I&E mods, advanced timing, no sub box and 17's. 16 litres from Coffs Harbour to Coolangatta, filled up before we left & again when we got there. Return trip was similiar consuption except drove a little harder cause fuel was so cheap up there.

my ls/vtec does 270-300 to a tank
shocking but its driving hard and untuned

ehh, since when aftermarket ECU save more fuel???...this is smth very new...

anyway, Voltage stabiliser (e-power) is the solution....should try it u honda boyz...i got mine..haha...not bad...improve TB resp, better lighting, and i also pressume that if you got a much better sparkplug, you'll get abit more power and save more fuel...currently i'm getting 20km more just by installing..haha..not bad huh...since the price of fuel is going up...20km means 2-3 bucks for me...hahaha...

my friend goes 60km more in a full tank just by installing as well...so yea, get the Epower voltage stabiliser..hahaha.