62 replies to this topic

[tmh983]

I get 250km to a tank, or 350 if its on the highway... twin turbo converted outback...

[Matt]

I get 250km to a tank, or 350 if its on the highway... twin turbo converted outback...

Thats shocking?!
Lances 300+kw engine in his b4 uses that much? Yours must be rich as

[Adam]

Lance was getting about the same economy as me last cruise!

[FR34KO]

i get around 480km per tank, mixed highway and city. so ~10.2L/100kms... When i do the intake hoping i get a lil higher

[tmh983]

Thats shocking?!
Lances 300+kw engine in his b4 uses that much? Yours must be rich as

yeah there is something wrong with my car. I think the afm could be buggered.

[Dimeb4g]

i havent done too much more to it... i haven't even painted it yet!

did the exhaust just cat back 2.25 system and thats it... mileage hasnt improved greatly since i put the exhaust on... but still around that 500km mark before the light comes on

[Soop]

I can get 8ltr/100km from a 5.7ltr engine. You lads are doing something wrong.

[Soop]

Okay I'll try and be a little more helpful.
Do any of you blokes have a WBo2?

Fuel economy that bad can only be a result of bad tuning or malfunctioning components. Because especially with FI, there should be allot more efficiency then whats being shown in this thread.

With regards to the turbo cars, I strongly believe its due to the turbo being used outside of its efficiency range.When the turbo is being asked to pump more air then it can do so efficiently it begins to super heat the intake charge.
The rule of thumb with this is, as pressure increases volume decreases. (re boyle's law)

This rule is relevant to Naturally aspirated engines, but in a different way. Specific to turbo charged engines firstly this means that as you increase boost pressure you slowly reduced the amount of oxygen contained in the boost charge. Without oxygen molecules to attach to the ocatane molecules you can't have an efficient burn. (this happens with NA motors as well, but is largely controlled by the VE maps within the tune if other systems are sound). This effect is in motion all the way through the turbo's efficiency range, but as you move out of this range you the effect magnifies.
You need to remember that boost pressure is a measurement of restriction. Hot air expands as we know, so the manifold will fill quicker but have less oxygen molecules.

[skillionaire]

Hi,

Comparing fuel efficiency over the internet is about as useful as comparing insurance quotes. The variables are ridiculous.

Cheers,
Nik

[Soop]

Hi,

Comparing fuel efficiency over the internet is about as useful as comparing insurance quotes. The variables are ridiculous.

Cheers,
Nik

Yes, but if people are averaging the same, you can make a fairly accurate guess that they're all doing a similar thing.
Frankly, getting more then 10ltr/100km is absurd from a 2.5ltr motor. Turbo charged or not. You can CERTAINLY do allot better with a little fiddling and know how.

[skillionaire]

Hi,

Definitely agree with that, I pull consistent 7.2/100 on an auto H6.

So many variables though.

Cheers,
Nik

[Soop]

Hi,

Definitely agree with that, I pull consistent 7.2/100 on an auto H6.

So many variables though.

Cheers,
Nik

If you're doing that with a standard car, then I'd bet it can be even better.
The problem is manufactures have to calibrate to suit a WIDE range of scenario's. Unless you frequently travel from sea level desert to high altitude alpine area's you don't need that flexibility.
Also I know specifically with Holden they do some really absurd things to comply with emissions, most of which do nothing for economy. Some even hamper it.
The thing with emissions is, its only a measurement of Co2 being emitted from the exhaust. You can have low levels of Co2 with unburnt fuel. Just as you can with an efficient burn. But from an OEM calibration standpoint its always safer to be a little richer and run a little less ignition advance then it is to be leaner with more advance. Purely due to the range of scenario's a single product will encounter.

[FR34KO]

****. I want to employ your knowhow to marvellously improve the fuel economy of my vehicles. How much do you charge. Seriously.

[Soop]

Nothing I'm an amateur.

Is it possible to reflash your PCM?
If so, you can help yourself by finding a scan tool with which you can start data logging your car.That information is invaluable to finding area's for improvement.

Efficiency improvements are relative to how off the initial tune was, but as I said, OEM is usually far from optimal.

[FR34KO]

unsure what a PCM is.. I know basically what reflashing the CPU is...
I understand what data logging is but faced with the actual prospect of turning numbers into usable information in order to modify the components of the tune; im completely and uterly lost. .. My success or even minor progress would depend how the data is presented by the scan tool. whether its plain to see: oxygen:fuel ratio, temperature scaling and relation,etc etc; or not. ...

[Soop]

PCM = powertrain control module. Which is GM lingo I guess. Sorry for that.
PCM = ECU.

The display from the scan tool would depend entirely apon the scan tool I guess. One would hope that they would be displayed in a sensible manner.

Here is how my scan tool works, this is EFIlive which I use for GM PCM's



That is the scan tool display, or one of the displays. I find that particular method is more accurate then the digital dashboard they also offer.
I realise that this is can seem a little overwhelming but I can assure if after maybe a day of looking at the data it all becomes very much second nature.

[FR34KO]

ok in that case, im not sure if my ecu is able to be reflashed or not? lol yeah it does seem a 'little' overwhelming. idk what anything means. Any idea how much a scan tool and program similar to this one would cost? Because overall, i assume it wouldnt be worth my hassle as you seem like you work on GM's quite a bit? Instead i should just get it professionally tuned.. And btw this is in reference to whatever turbo car i get next.. most likely a XT forester..

[Soop]

I do think you can flash your ECU.
I also think you can get open source software to tune Subaru's and Mitsu's with OBDII. So you could well do it for free.

I highly recommend educating yourself and having a crack, its fun and can be extremely rewarding.
Also, there are allot of "guru's" in the tuning world. Most of whom know no more then I but profess to know it all (I don't and won't, I answer only as I can)
You would do yourself a great disservice to pay a "professional" and not know what alterations he is actually making. There are some rather dubious methods I've seen used by so called "professionals".

It doesn't really matter what I work on most of the time, all internal combustion engines work on the same principles, and I did tune my Subi, though via a Haltech.

[FR34KO]

Well that sounds cool! Open source for cars haha.. Have you had any experience with the OBDII or heard of its results? sounds pretty interesting.
Yes of course. Oh well if i used a 'pro' i wuldnt be like 'here, do what you guys do'. Nah; id be there buggin him and gettin him to tell me what he's changing cos afterall id be payin him..
lol, ive heard of Haltech; i thought it was a brand. So whats tuned via a haltech?
Thanks mate!

[Soop]

Haltech is a brand, my Gen2 has a standalone ECU. Replacing the original.

OBDII is an interface protocol used by OEM manufatures as a means of compliance with emmisions regulation. But its really flexible. Basically renders standalone ecu replacements redundant in the majority of instances.

For your car, you should look up rom raider and go from there.