Stagea Fuel Economy

[pixel8r]

no...cause in townsville (the land of 70kmph roundabouts, you are forever accelerating from 50km/hr to 70.. you are in overdrive, and so when you accelerate gently the torque converter takes up all the power, (you're in a high gear, with no torque lock because you have been back off the throttle). so you keep gently squeezing on the gas until you acelerate, but instead of the gears droping down into 3rd, it starts to lock up the torque converter, now if i was at 40 accelerating to 60 this wouldn't be an issue, but that extra 10km/h means that it doesn't drop down. You will be at higher revs so the turbo is ready and waiting to spool up, and it does,

so instead of accelerating at 3000rpm

with no boost in 3rd gear

Using natural torque of the engine at 0psi and a more acceleration friendly gear ratio

with the power going directly to the wheels cause the lock out torque converter is 'locking out' the slushiness

you inf act are accelerating at 2500rpm

with 10psi boost,

the stock ECU dumping fuel into your cylinders

and all the power going no-where except to the O/D

If i am ever in a straight line for a bit or cruising around, i slip it into O/D for a bit, but on approaching twisties i slip it back into 3rd

I am also experiment with keeping the A/T mode slector on POWER mode so that it shifts down instead of building boost, but i am finding it still seems to hold on to 3rd a little too long when doing the straight and narrow thing....although this may just come down to fine tuning my driving style when in 'POWER' mode for the auto trans.

It's like Ska said when he was doing his fuel efficiency testing, he selected lower gears going up hills instead of a higher gear with more boost.

Boost is what kills your fuel economy, not rpm.

higher revs with no boost

is better than medium revs with lots of boost and no power transfer to the wheels

I've yet to test this theory out in my stag, but it should be easy for me to do (I drive to work every day so most of my driving is in fairly similar conditions). This previous week I only managed 12.3L/100km even though I was driving a lot more sedately than normal - and intentionally cruising slowly up to speed for speed limit changes like 60-80km/h etc.

So far this tells me you are correct because normally I see about 12 or less L/100 in much the same conditions - and thats without going so easy on it.

There's a few questions I still have though - you mention that boost is what affects fuel economy, not rpm - but rpm is related to boost. Another thing is that normally when I'm in 4th gear, the revs are below 2500rpm which usually means the car wont be on boost anyway. The opposite would be true if I was to select a lower gear - I'd then be on boost more and hence use more fuel - at least as I understand it.

I'm not disagreeing with you, just trying to work out the theory for myself.

The simplest way I understand it is that to save on fuel you aim to get it into 4th gear and constant throttle for as long as possible when cruising, but use the gears when accelerating, and avoid allowing the torque converter to suck up your power (usually this is when slowly accelerating, correct?).

Does this sound close?

[munchstagea]

What you need to know is:

1. RPM

2. Injector duty cycle (including the size of the injectors)

Combine these and your result is consumption per minute. Measure these variables against different driving styles/situation and gear/throttle/boost applications and you should be able to determine the most efficient driving method. I would be interested to know the results.

That's my theory, I think it works?

One of these may help greatly.

Luke

[webng]

...- but rpm is related to boost. Another thing is that normally when I'm in 4th gear, the revs are below 2500rpm which usually means the car wont be on boost anyway. The opposite would be true if I was to select a lower gear - I'd then be on boost more and hence use more fuel - at least as I understand it.

That's what i thought too. Boost = More fuel used right? If you don't do the solenoid boost mod, you'll only have 4psi up to 4500rpm. If you do then it's 7psi all the way. Therefore, if you spend more time cruising below 4500rpm without boost or low boost, you should (in theory) save fuel. Practice might be different, will definitely have to try when i get the car.

[captinsane]

webnd:

I have a bleed valve set @ 10psi so no dual stage boost

definately more boost = more fuel

pixel8r

rpm is related to boost, but it is also related to load, TP etc etc... it is possible to be accelrating at 4000-5000rpm in a stock stagea and still be registering no boost, or possibly as little as 2psi... it depends on your TP, load etc etc as well... hence the reason your ecu gets tuned on a grid. It's not 'linear', it is parametric - relating to airflow, which is a rebroad minded person of TP and boost and load (and other stuff i am ignorant about).

munchstagea- i agree, RPM and Injecter Duty Cycle... when on boost, you have double the airflow, and as such, you have about double the fuel to retain a good air/fuel ratio (or even more fuel as the stupid stock ECU seems determined to have your stagea run at 9:1 AF ratio when on boost)

now, take into account that when cruising, say down the highway, your boost guage wuold usually read about negative 10psi or whatever it is... (mental block), right?

So it stands to my reason that when acceerating at 0psi at 5000rpm your injecter duty cycle will be simlar to what your duty cycle would be at 10psi at 2500rpm (maybe change 10psi to 1 bar... i dunno)

and if i remember correctly it's about 4000rpm in 3rd=100km/hr or thereabouts - so what is better for your fuel economy?

if you want fuel economy... make sure your tuner works your off boost a/f map as well as the on boost ones. At least up here in TSV, people think it's sufficient to just tune the boost map grids and leave the off boost ones, which is what you would be using when driving around town anyway... lean it out, use lower gears and enjoy some fuel economy

...i think - it seems to work for me.

Edited June 18, 2007 by captinsane

[pixel8r]

I really need to install my boost guage and then I'll be able to work it out for myself...

anyway, I'm trying using the tiptronic this week just to use the gears a bit more and see if that helps. I'm not driving the car any harder, just basically using different shift points.

The car feels much more responsive this way too - as I can keep it in its most efficient rpm range easier (anyone know what rpm range the RB25's most efficient in?).

After reading a bit about O/D, it seems that driving around in 4th at 1500rpm could actually be using more fuel - depending if the engine is under more load at this rpm than say 2000rpm in 3rd.

Also, I only have an SAFC to tune with which I think only works at anything over 50% throttle so I dont think I can tune on/off boost or anything - i think it just checks the throttle position and if more than 50% then it uses its load points to work out what to do. Its not very complex (but I'm happy with the results).

Will post up what I find out with regards to different driving styles and the effect on fuel economy...

But so far what I've found is that trying to always have a soft foot and just coast up to the speed limit all the time is NOT the most fuel efficient way to drive. I actually got slightly worse fuel economy than when I'm not making any effort to conserve fuel. Good enough excuse for me

[rev210]

I just done 420kms on a tank , 100% city driving. Stock as a rock.

[iamhe77]

Just been from Melbourne to Warnambool via the Great Ocean Road and back via the Highway on 1 tank. Odo said 702km's.

I typically get around the 600km's from a tank....

.... And before you ask, no I do not drive it like it is a Volvo....

[JVP]

jesus f**king christ....

have you hybrid-ised it?

thats awesome.

[Terminal]

I've been getting around 350km to a tank, but I've just installed a hi-flow and my 5spd gearbox is going in tomorrow, so I'll check it again after that.

[webng]

Well I'll be driving my S2 (stock) back from Melb to Adelaide so I'll make sure I keep a close eye.

[webng]

Well I'll be driving my S2 (stock) back from Melb to Adelaide so I'll make sure I keep a close eye.

Managed to get 10.5l/100kms on the way back from Melb. Average speed was around 120-130kph. Stock everything running on BP Ultimate.

Thinking of getting free flowing exhaust now, don't want anything loud, just to improve exhaust. Any recommendations? Should I go cat-back or turbo back? Not wanting to spend more then around $300-$400 if possible. Where's a good place to go in ADL?

[Boof]

Question guys..Im looking at getting a stagea in the new year, wanting a manual one...All these fuel economy figures, are the cars all automatics or manuals? Does the semi automatic make much difference over an automatic???

Reason i ask is right now i've got a mitsi 380 (work car) and its got the semiautomatic box in it, but the shifts are very slow (presumably so there's no great thump when it engages gears)..Whilst it does have the best of both worlds i find it very irratiating how slow it is to change gears!!!!

[webng]

Question guys..Im looking at getting a stagea in the new year, wanting a manual one...All these fuel economy figures, are the cars all automatics or manuals? Does the semi automatic make much difference over an automatic???

Reason i ask is right now i've got a mitsi 380 (work car) and its got the semiautomatic box in it, but the shifts are very slow (presumably so there's no great thump when it engages gears)..Whilst it does have the best of both worlds i find it very irratiating how slow it is to change gears!!!!

I have the tiptronic (steering mounted) but hardly use it. It's pretty slow, slower then using the gear shifter i feel. More of a gimmick i reckon.

[rb26stagea]

I get about 420km around town, and about 510km on hwy. I have RB26 manual. I have discovered this week that I get better economy in high boost (18psi) mode than low boost (14psi). I believe this is because the Power FC was tuned at high boost, and then the boost controller used to wind the boost down, so the car runs ultra rich at low boost, requiring more throttle opening to maintain speed..... does this seem feasable???

[tRUkbOY]

I get about 420km around town, and about 510km on hwy. I have RB26 manual. I have discovered this week that I get better economy in high boost (18psi) mode than low boost (14psi). I believe this is because the Power FC was tuned at high boost, and then the boost controller used to wind the boost down, so the car runs ultra rich at low boost, requiring more throttle opening to maintain speed..... does this seem feasable???

Thats something I am still yet to do, test the economy of the RB26. It appears so far to be more economical than the RB25DET (manual or auto) was as I get about 30 or 40 more kms from the usual $60 fuel. Mine is stock apart from the 3" exhaust & Trust Airinx Filters (yes stock boost even)

[pixel8r]

Question guys..Im looking at getting a stagea in the new year, wanting a manual one...All these fuel economy figures, are the cars all automatics or manuals? Does the semi automatic make much difference over an automatic???

Reason i ask is right now i've got a mitsi 380 (work car) and its got the semiautomatic box in it, but the shifts are very slow (presumably so there's no great thump when it engages gears)..Whilst it does have the best of both worlds i find it very irratiating how slow it is to change gears!!!!

I have some good news for you. The solution to the slow gear changes is to install a MV Automatics shift kit. MV Automatics are located in Blackwood SA, so you dont have too far to go

Its only a few hundred more than a regular transmission service and will improve your shift quality. It does make the 1st-2nd shift a bit more noticeable but the smoothness depends on how you drive. Drive it hard and it will clunk into gear (not uncomfortable however), or drive it smooth and you'll barely notice its changing gears.

In stock form its not too bad unless you try to use the tiptronic like a manual. If you use the tiptronic a lot, and/or just want quicker shifts, then a shift kit is a must I'd highly recommend it

[webng]

Its only a few hundred more than a regular transmission service

When are transmission services usually due?

[petrolfix]

i am not shure what all you's are doing to get less than 400km to a tank. fair enoughs mines a manual and it's a s2 with p/fc but i went on a 560km drive and giving it a resonable hard time in some windy mountain roads then through sydney then back home up the express way. and i got 480km to my first tank. then used a qurter to get the rest of the way home.

[Boof]

I have some good news for you. The solution to the slow gear changes is to install a MV Automatics shift kit. MV Automatics are located in Blackwood SA, so you dont have too far to go

Its only a few hundred more than a regular transmission service and will improve your shift quality. It does make the 1st-2nd shift a bit more noticeable but the smoothness depends on how you drive. Drive it hard and it will clunk into gear (not uncomfortable however), or drive it smooth and you'll barely notice its changing gears.

In stock form its not too bad unless you try to use the tiptronic like a manual. If you use the tiptronic a lot, and/or just want quicker shifts, then a shift kit is a must I'd highly recommend it

Ok thanks!! My first preference is to get a manual, but if i can't find one (or can't find one in decent condition) then i'll just get the auto, seems to get some fair economy outta them as well which is a huge plus!! The auto 380 around town i can only get around 550kms outta a 65 litre tank!! Most of my driving is port wakefeild road/heaslip road etc etc (all 90km/h stuff)!

[pixel8r]

Ok thanks!! My first preference is to get a manual, but if i can't find one (or can't find one in decent condition) then i'll just get the auto, seems to get some fair economy outta them as well which is a huge plus!! The auto 380 around town i can only get around 550kms outta a 65 litre tank!! Most of my driving is port wakefeild road/heaslip road etc etc (all 90km/h stuff)!

Ok, well I'm not sure if you'll get any better economy from the stagea. They're more powerful and heavier than the 380, which doesn't help with fuel economy. They're also designed for japanese fuel and will require 96 octane fuel or preferably 98 octane (japanese fuel is something like 106 RON so the closer you get to that the better).

Most people on here seem to average around 10L/100km at highway speeds and somewhere between 12 and 14L/100km in city driving / peak hour traffic. The stagea has a 68L tank, but if you drive till the needle hits empty you'll have used only around ~58L. Putting it all together I'd say you'd probably find the fuel economy pretty similar to the 380, depending on how you drive.

If AWD isn't a requirement, you can go for a RWD only stagea, which should do slightly better on fuel due to less drivetrain losses and less weight.

And/or if you get a manual, you'll get better fuel economy AND it will hold its value better than the increasingly popular auto stagea.

At the end of the day, it is a performance oriented wagon, so fuel economy is a secondary priority with this car. You need to weigh it up as a whole package. All things considered, its still hard to beat for price and overall value and features.