Fuel Economy For 250Rwkw+

[Sklyn]

replacing fuel filter made my economy better by just over 1L/100km.

well worth it imo..

[XKLABA]

Sorry it was a typo I was meant to write 72L not 70 cause a r32 gtr has a 72L tank.

I think I stuff it all up and its around 600km or something for 72L tank

I meant your equation, 70x12 or even 72x12 is going to give the wrong amount, tank size is irrelevant as you can't use a full tank full, you have to work it out off what you use

Im sorry but if you have that power fuel econony should be the last of your worries.

If you want economy buy a diesel/hybrid.

funny thing about my 32 is I didn't build it for a power figure but for engine efficiency as the car has always been a daily driver and by uping the efficiency it also brought up the power level and made the car alot faster then it really should be

if built right you can have a very fast car that does have good economy

I have a diesel vehicle and it's not fun by any stretch of the imagination

[89CAL]

Yeah as above

My car isnt built for economy, but there is alot you can do to have the best (possible) of both worlds. This way you can baby it around town/on the highway and still get half decent economy and then have some fun when you want to.

The RB25 will never be the most fuel efficent engine but there is a bit you can do to make it half decent.

It's not like we mod it and go 'yeah its got power now so f**k fuel economy, I'll run AFR's of 12:1 everywhere' it doesnt work like this, the big benefit of turbocharged cars is it is possible to drive off boost and not be demanding piles of fuel

[seventhirteen]

Yeah as above

My car isnt built for economy, but there is alot you can do to have the best (possible) of both worlds. This way you can baby it around town/on the highway and still get half decent economy and then have some fun when you want to.

The RB25 will never be the most fuel efficent engine but there is a bit you can do to make it half decent.

It's not like we mod it and go 'yeah its got power now so f**k fuel economy, I'll run AFR's of 12:1 everywhere' it doesnt work like this, the big benefit of turbocharged cars is it is possible to drive off boost and not be demanding piles of fuel

You know when you boost, you accordingly use more petrol.And if you think leaning out the air to fuel ratio with more air will help it will only lead to problems such as pinging and overheating valves etc.

Edited January 4, 2014 by seventhirteen

[89CAL]

You know when you boost, you accordingly use more petrol.And if you think leaning out the air to fuel ratio with more air will help it will only lead to problems such as pinging and overheating valves etc.

Did you read what I wrote? I never once said anything about leaning the AFR's under load and clearly said in the second paragraph 'off boost'

Its not as simple as only tuning cruise AFR's, off boost means anything that is not positive pressure. This is where your fuel economy is. Tuning this sort of stuff is most of what I do with my car. I dont pretend to be a fantastic tuner at all but I know enough to do these sort of things

[niZmO_Man]

673/100= 6.73 62/6.73=9.21L/100km

That's my goal, to get my car to 10L/100km. I know it's doable and now you have provided proof. I need to find my damn missing AFM then get it tuned!

[XKLABA]

My biggest gain in fuel economy was in the cam gear settings

[V28VX37]

Here's some longer term numbers at 275 rwkw:

• Freeway: 10-12 l/100km
• City: 13-14 l/100km (stop start kills economy)
• Sandown: 33 l/100km (on boost most of the time)

So yeah 40-odd laps of Sandown drank 46 litres, which I thought was a good effort.

[zoomzoom]

This would be a good discussion for tuners. While some things associated with chasing power can negatively affect efficiency, like cams and larger injectors, I consider power figures and economy to be at different ends of the spectrum. Full power runs are about using as much fuel as you need to keep the engine safe, efficiency isn't a concern. But the smaller combustion charges at partial throttle pose less risk and so more energy can be extracted safely.

From personal experience, even the BEST dyno tuners can't spend long on the full map unless you are going to pay them many 1000's of $ for their time. Partial throttle is where all your economy will come from, and tuning it takes a long time to get right. Manufacturers spend millions on getting a tune right. There's a fine line between efficient AFRs and the engine getting a lean misfire when variables suddenly change, eg throttle position changes.

[V28VX37]

Yes I agree it's all in the tune. My car has had three power levels:

• 150rwkw - stock (auto)
• 199rwkw - bolt-on, boost and tune (auto)
• 275rwkw - bigger turbo etc. and tune (manual)

My current mixed driving economy is roughly the same as it was when stock, and marginally worse compared to when I ran 199rwkw with the auto. Gotta be happy with that. Also all quoted figures are from my logbook, not gut feel 'kms to a tank' stuff

The other thing I've find with both my previous 293rwkw heads/cammed V8 and this car is that stop-start is what kills the economy in a modded car. So respect to people who can deal with dailying their hotted up cars on Melbourne's/Sydney's congested commutes!

[DJBarnstar]

273RWKW GTST here and about 16 per 100. My old cammed VE 6L which made 331 RWKW was around 23 per 100.

Wish I still had the VE

[Mick_o]

My 336kw E85 chooned GTST used to get around 420-450km out of a tank on the highway and having a lil squirt here and there. Buzzing around town was around the 350-380km zone.

It was actually better on E85 with that power than it was with 203kw on Petrol lol!

As Mick stated its all about making the engine efficient

[GTR_JOEY]

Try 420rwkw on E85 around town.. Maybe 300km out of the GTR's 72L tank

Down the highway it was actually pretty good.. About 600km on pump