LG John

Ok, I'm sure this has been thought of before and dismissed for a very obvious reason but as a non-enginy type guy I got to wondering if there is a way to modify or programme your scooby not to run any boost. In other words the turbo wouldn't spool up and it would be dog slow but you'd get good fuel economy. If this 'mode' could be switched on and off from the cabin it would be useful for the motorway or around town when you don't want to go fast. Thoughts/reasons??

Bugger, forgot the 't' in the title!!

[Edited by Saxo Boy - 5/24/2002 5:13:17 PM]

Attu

Dont think that even the non turbo Impreza's are good on fuel.

Andy

LG John

Still a lot better than a spooled up turbo though!!

Attu

Yup that it is
I had a laguna before i bought a Scooby turbo and told the Girl friend that the petrol economy would be about the same
I was putting £20 per week in the Laguna ive put £60 in the Sub so far this week

Andy

LG John

Ha, she must really love you now! Can't believe she bought that one!

Sparks

I think you'd find the car pretty horrible to live with.. mainly due to the compression ratio being low for effectively a NA car.. it'd be pretty gutless.

Steve001

iTrader: (7)

£60 wow

im fast approaching £400 for this month alone

The owner of my local Shell Station now gives me a warm welcome (i wonder why?)

S.

Floyd

iTrader: (9)

Not so silly an idea really.

Ideally I'd love a three way switchable map on the ECU:
Track day mode- full on power
Economy mode- low boost, slow throttle reaction
Cruise mode- very smooth boost curve for lazy speed

F

John Stevenson

.............you need to get out more !!!!!

spence7

Saxo Boy you could just go easy on the old right foot antics !

Actually on the M-way whilst cruising at constant speed i.e. not accelerating, the turbo is running zero boost anyway. And if you get yourself a boost gauge, you can check out when you're using boost and when you aint.

I was quite surprised you can make ok progress on a m=way journey by not using the turbo. Obviously incredibly difficult to actually do, but it is possible !

Floyd

iTrader: (9)

Question: Is 0 boost not using boost at all?

On a normally aspirated car the more throttle you use the more vacuum you would get in the i/l manifold. As you go faster in a turbo car then the boost guage reads higher levels from say full vacuum available at -12psi.

Typically I can cruise (70mph) at -5psi but is this actually boosting slightly?

F

Stephen Cole

Actaully on a normally aspirated car the more throttle you use the LESS vacuum you would get in the i/l manifold.

I still remeber the old add on vacuum 'economy gauges' of the 70's/80's -- the more vacuum and less throttle opening, the higher the indicated economy

I can also cruse at motorway speeds at approx -5 psi

As someone else said, the turbo engine has a relatively low compression ratio, as so isn't particularly efficient or powerfull 'off boost'

Whether the turbo is helping or hindering (ie restricting) the input at -ve pressure (off boost) scenerios is another matter for debate

PS I year or so ago there were a few threads about running in econony mode, restricting yourself to 7psi
(as 7 psi is normally when the waste gate opens and stops the boost increasing more)
Normally the ECU 'bleeds off' some of the effective boost that the waste gate sees, to allow boost above 7psi to occur.
If you temporarily stop this bleed off, you limit yourself to 7psi
Still enough to give good performance, without 'wasting fuel and money' on excessive acceleration !

Blue

Running the car on 0 boost is no good - I've done it (through no choice of my own I add)
Its great if you want a 20 yr old 600cc 2CV to out perform you right through the rev range though.
If you want fuel ecenomy, don't buy an Impreza!

Jolly Green Monster 2

Fit a boost gauge and then drive it with the boost as low as possible.. then you can floor it when you like and it will use less fuel etc..

I try and keep mine around 0bar and the fuel economy goes up..

Obviously you have to be diciplined.. I manly do this when towing my trailers.

JGM

SCOSaltire

SB
get a Prodrive chip and let it get into economy mode...
works a treat