Some MPG results.

[Atik]

Whether or not you have the boost set to 1psi or not, if you stay off the boost altogether as apeman69 above said, then you stay off the boost. Simple.

I recently took a long motorway drive and had the EBC set to 13.5psi boost, but for the whole 200-odd mile journey I only went into positive boost pressure about 4-5 times. I managed to return over 30mpg on that trip (and sorry to bring it up, but mine is manual so that would help).

This week, I took a similar trip and for the 200-odd miles I stayed at stock boost pressure and drove in negative boost pressure all the way. I also got over 30mpg on that trip. But on the return leg, I was at 13.5psi again and was driving like I stole it! I dont think I'll get 30mpg from that one.

My point being, drive the car economically and you will get 'better' mpg. Every car is different so there is no point comparing yours to someone elses.

And I agree on the whole compromise thing which is why my car is the way it is. Comfort and luxury with the power and looks.

[phosty]

I'm with you DomB - I just can't see why we can't get better mpg out of these cars whilst still retaining their fun factor when you want it.

I have tried setting the boost lower to see if that affected mpg - disconnecting the solenoid wire from the ECU means that the turbos are limited only by the wastegate spring so you still make ~ 6 psig boost. I think you'd need to adjust the wastegates to go lower. Anyway I didn't notice an effect on mpg.

I would love to know how people acheive anything more than 25mpg - I have over 2 years of mpg data for both and auto and a manual. Around town in an urban setting I get 19 mpg average in both. On motorways I can get about 25 mpg from both. Interestingly that's at speeds of 80-85 mph. Measuring AFRs at high motorway speeds both cars nudge into the mid 15's. At 70 mph it's lower.

Maybe the air is thinner up here?

[Atik]

I think a lot of that will most certainly be down to the car itself.

My car is 'blueprinted' really well. Ben at Eurospec says that mine is just running so good, so much so that my car is only limited in its power by the actual pistons. The engine and the rest can make more power.

Similarly, I would think any small variation in the blueprint of each individual car will ultimately affect the overall mpg of the car. Not everyone has the same mods on their cars. No two cars are tuned exactly the same.

When mine was auto, I still managed plenty of 28mpg runs. Since then I have added lots of extra weight by way of the leather seats but changed the gearbox to an overall lighter manual box. I drive in the same way and get 30+ on a steady motorway run.

Dont think anything more of it to be honest. These cars should be getting you ~25mpg on a steady motorway drive. Some will get better, others will get worse. Its par for the course.

[apeman69]

I wonder what economy the vr4 would do with boost set to only 1psi on the motorway.

My 'incredible' MPG on the run I mentioned was (I assume) due to the fact that I never once pushed the car to see any boost pressure. I had been getting spurious knock when on boost and the purpose of my journey was to get his sorted. The boost solenoid was disconnected (for a very good reason). The tuning of the MAP2 in my car must help with fuel economy, as would be expected.
I intended to do another one-click fill-up analysis of my normal home to work journeys in the near future just to see what sort of difference the MAP2 is making to fuel economy on my car during normal usage. However, I'm having the turbos replaced next week so I'll probably wait until I've had a good play with the new setup

[Dom B]

Well last weeks fuel check was 204 miles to 38.10 litres of 99octane super, which by my calculations is 24.3mpg. For 99% of that tank i drove like a saint staying off boost, keeping in high gears which seems to help. Yesterday i did 200 miles on a motorway return journey 70-80 all the way constant cruise and although i haven't filled up yet looking at the gauge (i know its not accurate but using my experience too) it looks like it also did 24mpg again. I will confirm this later in the week when i fill up, but if it is more than 25mpg i'll eat my hat lol.
Thing is the car seems to use more fuel if you go slower than 50 and more fuel if you go faster than 80 so it's hard to be more consistent or drive any slower to help.

Next cruise out somewhere we will have to do a brim up challenge between 2 petrol stations with several cars.

As far as blueprinting goes, it might make an mpg or 2 difference but not 5 or more. Something quite serious is causing this difference in mpg. I know my car is running well, i have no complaints about it's performance. I'd love to do a dyno run to see what it kicks out to be sure.

[AlanDITD]

wow this has to be the longest most boring thread in history.

[Nutter_John]

wow this has to be the longest most boring thread in history.

well said Alan

[AlanDITD]

well said Alan

I didnt mean that towards confused either Its good to see MPG figures every forum has these threads, but never have i seen such a technicall who ha about how to improve it.

Its a big heavy high powered 4x4 barge its meant to make trees fall down as you drive passed them.

[gareth001]

Its a big heavy high powered 4x4 barge its meant to make trees fall down as you drive passed them.

If VR-4's make trees fall down as you drive past them - think what Hummer's do!

[Dom B]

Constructive comments only please, otherwise go and write on the xfactor thread or something.

[AlanDITD]

Constructive comments only please, otherwise go and write on the xfactor thread or something.

IMO this thread is about as constructive as the xfactor.

[Dom B]

Well then stop posting on it and ruining it for those who do want to talk about it. There is nothing more irritating than people not wanting other people to do anything they don't want to do themselves. Honestly who would go to the effort of just moaning actually going to the effort of typing to moan that they aren't interested in something. Now i am wasting my time replying to such worthless junk too.

No wonder this country is in such dire straits, no body has a job they are all on forums posting chopping off work early or whatever so they can spend effort moaning on here.

I wish moderators would remove these inane moans as soon as they appear, it really detracts from the thread. I suggest they get moved to the off topic area.

[Nutter_John]

we have the right to post crap when ever we want , just as you do

[AlanDITD]

Well then stop posting on it and ruining it for those who do want to talk about it. There is nothing more irritating than people not wanting other people to do anything they don't want to do themselves. Honestly who would go to the effort of just moaning actually going to the effort of typing to moan that they aren't interested in something. Now i am wasting my time replying to such worthless junk too.

No wonder this country is in such dire straits, no body has a job they are all on forums posting chopping off work early or whatever so they can spend effort moaning on here.

I wish moderators would remove these inane moans as soon as they appear, it really detracts from the thread. I suggest they get moved to the off topic area.

Yes the country is in dire straights because i insulted your pointless and boring take of the fuel economy of a 280hp twin turboed car.

I think you have no concept of the idea of banter and maybe the inetitude of your social skills has more of an effect on society than my complaining.

And for the record, im 23 and pretty sucessful by my standards! And im currently working being paid enough money whilst sat on here.

Are you "chopping" off work to write this aswell?

[Atik]

In all fairness, my car is better cos it has a manual gearbox. So there!

[Turbo_Steve]

Alan, it IS a boring topic....but by definition, unfortunately, fuel economy generally is. The worst aspect of this is that fuel economy can be more difficult to achieve in tuning terms than out and out power.

This Bickering is pointless....

So whilst this is a long and boring thread, we could potentially distill some information out of it at the end.

However, I can offer a few guarantees around fuel economy:

1) Transmission losses make a big difference. Gearbox, Diff and Xfer fluids are all key. Autos (as we all know) are less frugal than manuals, but I am surprised by how much purported difference there is.

2) Different engines run better than others. Atik is on the money here, that an engine that is bang on tolerance will perform better...in every way.

3) The small turbos mean that most of us manage to get into positive boost pressure very easily. Too easily: mine makes boost cruising at 85mph. Whether this is because of my rotten standard exhaust, or because the turbos are just sooo small, I have no idea.

4) Software. This one is huge. With a proper ECU controlling the boost, ign, fuelling, the VR4 WILL be a lot more economical. A properly setup ECU will allow flexible boost control based on TPS, engine load, engine speed, and possibly even a "fuzzy response", just like the gearbox, which changes modes according to how you've been driving.

Modern cars use Throttle-by-wire to smooth drivers throttle responses (which is why they always feel a bit 'dead' and this will massively improve economy. Those little tweaks on the pedal all the time use a LOT of fuel in a VR4, especially if you're close to coming on boost.

And, whilst Alan has a point that these cars are never going to have brilliant fuel economy, My 300+bhp Subaru Legacy turbo didn't suffer economy this bad. Neither did the 500+bhp 300ZX. I'd like to find out what difference a manual box REALLY makes, but I like the auto too much. I can't believe the auto alone is responsible for all the fuel usage.

[Dom B]

Yes the country is in dire straights because i insulted your pointless and boring take of the fuel economy of a 280hp twin turboed car.

I think you have no concept of the idea of banter and maybe the inetitude of your social skills has more of an effect on society than my complaining.

And for the record, im 23 and pretty sucessful by my standards! And im currently working being paid enough money whilst sat on here.

Are you "chopping" off work to write this aswell?

Sometimes banter goes too far.
Read the homepage of this site. It is supposed to be a supportive and family orientated site. But when every single thread gets a worthless banging by comments that aid nothing at all to it other than to illustrate that people are now being paid to sit doing nothing.

I am not much older than you and i am not chopping off work as i am the boss in charge of when and where i work running my own business and i will be here till gone 10pm tonight.

PS there is such great comical irony when you spell 'ineptitude' wrongly when having a go.

[Dom B]

In all fairness, my car is better cos it has a manual gearbox. So there!

Mine is a manual too with all new oils less than 1500 miles ago in it's big summer service.

Got 26.06 mpg today after a 200mile motorway journey yesterday, that is almost the record on my car. I'd love to hook evoscan up to a 30mpg+ car and mine and look at the differences. Would be very interesting to see where the savings are made.

[Dom B]

Alan, it IS a boring topic....but by definition, unfortunately, fuel economy generally is. The worst aspect of this is that fuel economy can be more difficult to achieve in tuning terms than out and out power.




So whilst this is a long and boring thread, we could potentially distill some information out of it at the end.

However, I can offer a few guarantees around fuel economy:

1) Transmission losses make a big difference. Gearbox, Diff and Xfer fluids are all key. Autos (as we all know) are less frugal than manuals, but I am surprised by how much purported difference there is.

2) Different engines run better than others. Atik is on the money here, that an engine that is bang on tolerance will perform better...in every way.

3) The small turbos mean that most of us manage to get into positive boost pressure very easily. Too easily: mine makes boost cruising at 85mph. Whether this is because of my rotten standard exhaust, or because the turbos are just sooo small, I have no idea.

4) Software. This one is huge. With a proper ECU controlling the boost, ign, fuelling, the VR4 WILL be a lot more economical. A properly setup ECU will allow flexible boost control based on TPS, engine load, engine speed, and possibly even a "fuzzy response", just like the gearbox, which changes modes according to how you've been driving.

Modern cars use Throttle-by-wire to smooth drivers throttle responses (which is why they always feel a bit 'dead' and this will massively improve economy. Those little tweaks on the pedal all the time use a LOT of fuel in a VR4, especially if you're close to coming on boost.

And, whilst Alan has a point that these cars are never going to have brilliant fuel economy, My 300+bhp Subaru Legacy turbo didn't suffer economy this bad. Neither did the 500+bhp 300ZX. I'd like to find out what difference a manual box REALLY makes, but I like the auto too much. I can't believe the auto alone is responsible for all the fuel usage.

thanks Steve, nice to see someone with constructive conversation here, much appreciated. I know the car is going well with plenty of power, i better get to a dyno to get some figures on paper for reference and when i changed the plugs recently i did a compression test with all cylinders nicely balanced averaging around 11bar.

[miller]

hmmmm its what diesels were invented for!