I have a 98 WRX and having filled up the Scoob with SUL from Esso with a bottle of Millers I used to get around 240 from a tank ( I have a 50 litre tank)

Haven't used my 4th tank of Optimax with Millers (my ECU should have adjusted by now), I get around 200 to a tank, doing exactly the same driving?

I should be running on 100 ron using Optimax using Octane booster,but only 98 ron using Esso and Octane booster and as Jap Import cars love higher ron, why is taking more fuel???


I've spoken to a couple of guys with UK Scoobs and some with Jap imports, and the UK scoobs have better MPG and the imports worse MPG. Are any of you experiencing the same???

Jay

Hi Jay

STi5 report

Hmm, no drop here - was running Shell SUL then Optimax - LOVE IT TO DEATH! - only run Millers OB when expecting a long, busy weekend ;) and haven't tried both together yet.

Anyway I've just had car serviced & it's running real nice now (well done the boys @ C&K Manchester)

Avg consumptions (me being an anorak :)):
Avg to date = 23.62 (36k miles)
Aug = 21.96
Sept = 23.85
Oct = 22.41 (pre-service)
Oct = 23.12 (just for the last tank following a lube major service with some good test runs over the moors to & from work) :D :D :D

FWIW
Paul :cool:
PS Pete @ C&K raves about Optimax as well !
PPS down to 74.9p/litre (that's £3.40/gal in old money)


[Edited by Paul Frank - 10/22/2001 11:56:05 AM]

I haven't noticed a drop in MPG since using Optimax.

I also keep details on my fuel consumptions (does this make me an sad anorak bod too?).

I've always done it as I think it is one of the cheapest ways to health check your engine. For example, if your driving style doesn't change, but MPG falls through the floor, this should sound an alarm bell to perhaps pay a visit to your local mechanic.

regards, Mark.

I'm on my 4th tank of optimax (MY01 WRX) and I think it is getting a better MPG... I'll run it up to scotland this week and see what happens.

rapiddescent

JayRaj,

Doesn't a 98 WRX have a 60 litre tank? Have you got an STI, TypeR, RA etc or a standard one? I've got a standard 98 WRX by the way and always thought it had a 60 litre tank...

all 96 and onwards imprezas have a 60 litre tank, some pre 96 seem to have one too!

hmmmmm.....

The most I have filled up is 48 litres??

I definetely have a 1998 model, version 5.

Anyway 240 miles out of that isn't bad!!

Jay

My record for one tank before yellow light = 295 miles (flat out motorway @ 11pm Sunday night)

& no I didn't take the bulb out :D :D :D

PaulFrank

Were you being towed???? ;0

(I'll get me coat).

J

Pah! I'll see your 295 miles, and raise you 325 miles! :D

Twas on a run to Kent and back, on normal UL. Normally get about 280 miles on the weekly commute. :)

'Eco-friendly' Whip ;)

BUT at what avg speed Whip?

The run to Kent was pretty much at 80 all the way, as someone on here said that was a good speed for economy and I was testing the theory. :)

The commute is 20 miles each way, speed varying between 40 and 80mph.

Whip ;)

that's the answer then . .
:D :D :D :D :D :D :D :D :D :D

Is running at a steady 80 in 5th going to be more economical than running at about 60 in 5th?

I thought 56mph was most ecnomical or is that just a figure that is used for testing purposes?

I'm seeing a slight improvement in MPG since running Optimax - nothing major maybe 1 or 2 miles per gallon, but I do keep a note of my mileage and it does appear to be improving. Can't say that the car performs any better (or worse for that matter) running Optimax, but anything that helps the fuel economy must be a good things :)

Chris

JayRaj,
I think you'll find that's because even when the Scooby sais it's empty there's still about 10 litres in there. Not tested this theory out for too long though...

Rikki,
I believe that less throttle means a lower fuel consumption therefore 60 in 5th is more econocial than 80 in 5th. Obviously you're covering ground at a faster rate at 80 but I think this is offset by the increased fuel consumption due to throttle being applied more. The optimum situation for economical fuel usage on a flat road is probably at sensibly low revs in 5th at a constant speed, maybe 2000 or so rpm - I could be wrong though. I guess every car has it own optimum speed depending on the characteristics of it's engine and gearing.

[Edited by scoobysnacks - 10/22/2001 5:32:39 PM]

56mph is just the govt agreed economy testing speed, not sure why though. Scoobs seem to be at their most economical speed at the point where the turbo is *just* starting to help things along. I find that's arond 75-85mph. Below that you've got a normally aspirated low-compression (inefficient) engine, and above that it tends to chuck loads of fuel in.

Not exactly the most technical explanation, but I'm sure you catch my drift. :)

Whip ;)

Jay

Totally agree! My Sti5 RA goes like stink on Optimax but even driving "normally" its 2-3 mpg DOWN on Esso/BP Super.

Oh Well. its worth it! :D :D :D

Rus

A couple of comments

I suspect that Optimax = bigger grins = worse fuel consumption! In theory for identical driving conditions it should be more economical - but we enjoy our cars more driving it.

Also, Jay, I don't think that Optimax + Millers will give you 100 RON. My own experience (objectively measured) is that Millers makes no difference to the characteristics of Optimax - if anything it makes the fuel feel less clean.

Certainly Millers is an excellent additive to other SULs, but not this one. This may well be why other threads are saying Optimax is not as good. As they are expecting it to work like SUL with two doses of booster.

The most likely explaination is that Optimax already contains booster like chemicals - and there is a limit as to how many you can beneficially add.

Trout

Whip - not sure if I agree/understand. I kind of understand what you are saying about the turbo aiding the efficiency of the engine but you are using more throttle to raise the revs to use the turbo, therefore using more fuel - I would have thought this increased consumption?

Also, for my guage to register positive boost pressure at around 75-80mph, I think I would need to be going uphill. Positive boost pressure on the flat would cause the car to accelerate, even at 75 -80 mph?

I usually stick to around 60-70 on work days because I can keep revs quite low and doesn't take a lot of throttle, so I assumed this would be more efficient. Would like to be proved wrong so I can cruise a bit quicker :)

You should be able to cruise at over 100mph before getting positive boost pressure.

Cars are most efficient at a full throttle opening, but this is hard at cruise :p;)

Trout

Rikki

Not entirely sure I understand it meself m8, that's just the way it was explained to me! Having tried cruising at 65mph for a tank and then at 80 for a tank there was a good increase in mpg at 80. Cruising at 65 got me exactly the same mpg as if I drove normally, so imagine how gutted I was after spending a week in the slow lane :D:D:D:D

What you're saying makes sense, and is how I imagined things to work but there must be some reason for it.

Try it and see

Whip ;)

I am disputing your suggestion at all but I would be *happily* surprised if this works but also a little dissapointed as I have been cruising at like 60-70 for ages to try and increase fuel economy. I will try it though.

I am sure that I read somewhere that increasing your speed by like only 10 mph on a motorway can drastically decrease fuel economy.

Anyone else have any knowledge or opinions about this? - and also about the 'turbo helping the engine' question I raised a couple of posts ago?

M8, give it a whirl, that's all I can say.

Might wanna post a msg in the Drivetrain forum, perhaps someone in there will be able to shed a bit of light on it?

You're right of course, 80mph = increased drag so there must be an explanation.

Whip ;)

Come on you techie bods - please answer

May post in the techie forum when I get a min. :)

PS my earlier post was supposed to say "...*NOT* disputing..." ;)

Rikki - this was the original thread m8.

http://www.scoobynet.co.uk/bbs/thread.asp?ThreadID=26773

[Edited cos the link didn't work]

Whip ;)

[Edited by whip - 10/23/2001 12:05:56 PM]

Cheers Whip - I had a read of the post - I remember it actually.

DavidRB made a comment similar to yours - saying that the extra air when the turno spins, makes it more efficient until the point where you need more fuel. :confused: To get to the point where the turbo is spinning I would need to go faster than I am currently cruising, therefore press the fast pedal down further, therefore using more fuel anyway?? I still think, just a guess, that on a flat piece of road in 5th, if I have the throttle down far enough to make the guage register positive pressure then I would accelerate? :confused:

Edited for readability :)

[Edited by Rikki 95WRX - 10/23/2001 12:38:27 PM]

I would claim that any increase of engine efficiency is going to be MASSIVELY outweighed by the increase in aerodynamic drag which increases with speed squared I believe.

True, to get to that speed you'd need to boot it a little, but once there the car settles at a certain throttle opening. To me, it feels like I'm using the same, if not less throttle at 80 than at 65.

As I understand it, on a turbo engine the same throttle opening doesn't necessarily equate to the same volume of air into the inlet - it depends on what the turbo's doing, which in turn depends largely on engine rpm. So at two different speeds could I conceivably be using the same throttle opening, with the increased air volume being due to the turbo? A question for someone like Mr Felstead I reckon, I'm still learning about turbos myself. I suppose it just depends on how the turbo behaves on a steady throttle.

Course I could be talking bollox, all I know is 75-85 works best for me in my scoob :)

Whip ;)

I've noticed a drop in MPG in the cossie when using optimax.
Not sure why though. :confused:
However, I will still use it cos she seems to like it! :D
astraboy.