general Q about EVO VII

fto617 · Post by **fto617** » Wed Jan 25, 2006 1:37 am

so guys...can anybody tell me hwo bad are the fuel consumptions???
top gear on SBS said the evo maintanence cost more than a porsche is it true???

Nacho · Post by **Nacho** » Wed Jan 25, 2006 8:37 am

Depends how its driven actually. To my understanding by turbocharging a car it actually improves fuel efficiency.

Out of all the mechanical engineering books I've read, they all say that something like 60-70% of energy is wasted and only the rest is converted into Work. By using the exhaust energy.........blah blah blah

Don't get me started!

ahew · Post by **ahew** » Wed Jan 25, 2006 10:23 am

gonna play devil's advocate here

nacho - agreed. utilising the exhaust waste energy is a lot more efficient than letting the actual gasses go to waste.

but that would only be in a perfect textbook situation...... not realistic.

in real life terms, a turbo car uses less petrol off boost than a normal car of the same engine make due to the turbo causing a restriction on exhaust flow. in a perfect situation, the turbo's restriction to airflow isn't really taken into consideration.

however, on boost, a turbo car would be using 40-50% more fuel as it requires the engine to pump more fuel to meet the demands of the pressurised airflow. the bonus is that you get more power out of the same sized engine. there isn't really a happy medium. more fuel = more power. VTEC YO!!!!!/MIVEC/VVTLi/ blah blah blah all go by the same theory as well. still "driveable" and less fuel consumption below a certain RPM, but rev it's tits off and expect to pay at the pump.

FTO338 · Post by **FTO338** » Wed Jan 25, 2006 12:19 pm

fto617 wrote:so guys...can anybody tell me hwo bad are the fuel consumptions???
top gear on SBS said the evo maintanence cost more than a porsche is it true???

Thats the QF400 mate, & not your standard EVO VIII

nacho wrote: Out of all the mechanical engineering books I've read, they all say that something like 60-70% of energy is wasted and only the rest is converted into Work. By using the exhaust energy.........blah blah blah

Don't get me started!

Now we know where you get all your misleading false info from

Have you actually had a turbo car before??

Nacho · Post by **Nacho** » Wed Jan 25, 2006 2:49 pm

I wish......

But you know I will eventually.......

Actually this false information I'm getting coming from these books I'm reading, is that why so many mechs can't diagnose a problem and just absolute f*ckwits?!

GPXXX · Post by **GPXXX** » Fri Jan 27, 2006 12:48 pm

rofl, since you had not owned a turbo car before i'd be careful before sharing dodgy info from books or worse still, labelling mechanics as 'absolute fuckwits' because chances are - sooner or later - you WILL need them for your monster project lol....

at the end of the day, fuel consumption will all depend on the quality of the tune. Some turbo cars are tuned rich from the factory, but with a bit of tweaks to the fuel & ignition maps, you will actually notice a slight increase in performance with better fuel consumption (ie: WRX's).

moral of my post: whatever you read from books nowadays does not necessarily apply in real life... hell, you'd be hard pressed to find an identical engine that puts out the same numbers on the dyno these days (all other things being equal)!

WildRide · Post by **WildRide** » Fri Jan 27, 2006 1:07 pm

So if I understand the arguements correctly, while turbo'ing a car may improve its fuel "efficiency", it cetainly dosen't improve how much of the damm stuff it chugs down....

WR

GPXXX · Post by **GPXXX** » Fri Jan 27, 2006 1:23 pm

no, turboing your car makes the engine produce more horsepower efficiently, not necessarily fuel-efficient...

but yes, you WILL notice a difference in consumption between NA and turbo'd variant of the same engine!

SG · Post by SG » Sat Jan 28, 2006 4:13 pm

BuCkEt wrote:Not that it matters much anymore, aren't the STi's going to 2.5L??

wrx's are all going to 2.5l last i heard and are pulling out of the wrc because they said they've "entered the rally, delevoped enough technology and so got what they cam for, and now feel its time to leave wrc"... IMO i think its because they're out of ideas for technology increases for their car and want to make it 2.5l instead of 2.0 to keep up with the EVO production model... and because wrc rules means u cant have a rally car based off a production model that isnt 2.0l.

so guys...can anybody tell me hwo bad are the fuel consumptions???
top gear on SBS said the evo maintanence cost more than a porsche is it true???

they're expensive because the manual says u gotta service it/ & the turbo etc every 10-15,000 k's.

in2deep · Post by **in2deep** » Sat Jan 28, 2006 11:13 pm

for a longer life span on a turbo motor you are advised to change the oil every 5000km as the turbo bearings are proned to failure due to the oil sometimes carrying contaminates around and fouling the bearings

as for fuel i know from experience that when we give the 8 abit of stick and run up in the boost range the bloody thing drinks fuel like a sailor drinks beer but its fun to get that nice kick that comes on when the turbo`s spooled up and the car starts to fly

as for the service costs thats just part and parcel of owning a performance car and i just live with it

Nacho · Post by **Nacho** » Mon Jan 30, 2006 11:50 am

Sorry WildRide......I don't think we're actually arguing anything. I've just been reading "Motor Vehicle Engineering Volume 3 - Tom Denton)" and the direct quote from the Turbochargers section was:

- engine power output can be increased, by up to 30%, without increasing the engine speed or displacement

- utilising exhaust enegery improves performance and increases fuel efficiency

- reduced emissions

- lower exhaust system noise

- increased engine torque giving better vehicle acceleration and pulling power

A normal petrol engine only uses about 30% of the energy contained in the fuel; the remaining 70% of this energy is lost as follows:

- 37% heat energy to the outgoing exhaust gasses

- 17% heat energy to the engine's coolant system

- 9% heat energy to the surrounding air

- 7% heat energy to overcome friction, pumping and component movement

This is the sort of stuff that you would read as an apprentice or at uni these days, hence it appears that really isn't the case in real life.......

FTO338 · Post by **FTO338** » Mon Jan 30, 2006 2:09 pm

Nacho wrote: This is the sort of stuff that you would read as an apprentice or at uni these days, hence it appears that really isn't the case in real life.......

Thatâ€™s right, cause these entire figure will change depends on the weather/room temperature or the layout of the engine, even with just half a degree different, the outcome would be huge. I think thatâ€™s why during the Motor Mechanic Apprentice, it is base on 95% practice & 5% theory.

Nacho perhaps you need to talk to my uncle, who was one of the engineer for Holden, he just retired last yr. And he can tell you how much bullshit these engineering books are.

Nacho · Post by **Nacho** » Mon Jan 30, 2006 4:31 pm

Hey I'll go to anyone you want me to talk to. But it seems that you'd be the best person to speak to with all the stuff I need. But you're really busy man!

It's all good though coz at least those books give me more info than HPI or Fast Fours.......

Taking my engine and tranny out atm is a great learning experience........

fto617 · Post by **fto617** » Tue Jan 31, 2006 1:39 am

so anybody have any experience how much a normal service would cost for the evoVII or wrx?
my mate told me his wrx cost at least 400+ for a normal service...
thats such a big difference from the servicing cost of my fto.

FTO338 · Post by **FTO338** » Tue Jan 31, 2006 9:47 am

The lowest i've ever paid for my VW was $800, & with an average bill of $1000.

Consider Rexy Boxer engine layer are harder to service, $400 is cheap. EVO shouldn't be expensive when it comes to service, as its got a very simple layout.

But by saying that, people usually charge more for a higher price car, i know its stupid, but most service people will say "If you can afford a higher price car, you can afford the high price service"