'Turbo Boost'

[mikey k]

Lowtimer said:

Of course, simply preventing a turbo engine from boosting doesn't turn it into the normally aspirated engine of the same range. It will almost certainly have lower static compression and therefore be inherently less efficient off boost than the engine built for normal aspiration.

the other issue the 2.5XT suffers from is drive train losses which pushes the consumption down. My wife is similar to the OP and gets about 26 mpg
OP you are going to need to change it to a none permanent 4x4 to get better mpg

[Mastodon2]

Lowtimer said:

Of course, simply preventing a turbo engine from boosting doesn't turn it into the normally aspirated engine of the same range. It will almost certainly have lower static compression and therefore be inherently less efficient off boost than the engine built for normal aspiration.

As above, if you "disabled" the turbo it would drive like a turbocharged engine with a broken turbo - it will definitely feel broken and probably won't see amazing fuel efficiency anyway.

If your wife is not a quick driver then it's unlikely that she is using anything close to full boost anyway.

[danllama]

Fit a secret dash cam and watch her hoon it when she's out alone!

[themanwithnoname]

My Forester STI does about the same fuel consumption with 330bhp

Disabling the turbo would be a bad plan, simply as its a low compression engine with big drivetrain losses.

[trickywoo]

aka_kerrly said:

Assuming that the OP has a Forester of the 2002-08 variety a XT turbo manages to average 26mpg with 226hp and the non turbo with 155hp manages 30mpg (info from Parkers)



Keep the turbo

God that's st. I get 26mpg from an e60 545i without trying. 4.4 litre 330bhp v8 for the uneducated.

[Jasandjules]

FFS I can get 28mpg out of a 5.0 V8 TVR....

[iloveboost]

Lowtimer said:

Of course, simply preventing a turbo engine from boosting doesn't turn it into the normally aspirated engine of the same range. It will almost certainly have lower static compression and therefore be inherently less efficient off boost than the engine built for normal aspiration.

True but modern direct injected turbo engines are all higher than 10:1 compression, I think. I guess the difference with them is something like 10% more fuel burned when cruising compared to an NA of the same capacity? Anyway it's not a lot compared to older, 8-9:1 turbo engines.

[FreeLitres]

I remember seeing an old American advert on YouTube for a car that had a special key that was used in the dash to select or de-select the turbo/super charger. In the advert, the son used the car without the boost then the dad got in and used his key to activate it.

I quite like that idea

[V8RX7]

Jasandjules said:

FFS I can get 28mpg out of a 5.0 V8 TVR....

You're proud that you drive like a Granny

I averaged 13mpg on optimax from my 300bhp 5.0 Griffith.

[trickywoo]

V8RX7 said:

You're proud that you drive like a Granny

I averaged 13mpg on optimax from my 300bhp 5.0 Griffith.

You'll probably want to get those binding calipers checked sooner rather than later.

[Jasandjules]

V8RX7 said:

You're proud that you drive like a Granny

I averaged 13mpg on optimax from my 300bhp 5.0 Griffith.

Nope, but on a run she will do 28mpg. With "enthusiastic" driving, it is somewhat less than that....... The OP is saying his wife is hardly putting the pedal down hard yet still getting similar MPG figures..

[ORD]

Wife's figures are average. 'On a run' is typical PH irrelevance. My 911 will get over 30mpg on the bloody motorway, but it averages more like 20mpg. I bet 2/3 of 'on a run' as the average is fairly typical (if not better than typical).

[Nedzilla]

Lowtimer said:

Of course, simply preventing a turbo engine from boosting doesn't turn it into the normally aspirated engine of the same range. It will almost certainly have lower static compression and therefore be inherently less efficient off boost than the engine built for normal aspiration.

Many years ago I had a stage 1 sapphire cosworth which was pretty potent and remember once disconnecting the wastegate actuator and leaving it open to see what it was like. It was an absolute dog,and I'd be surprised if it had 100bhp!

[themanwithnoname]

trickywoo said:

aka_kerrly said:

Assuming that the OP has a Forester of the 2002-08 variety a XT turbo manages to average 26mpg with 226hp and the non turbo with 155hp manages 30mpg (info from Parkers)



Keep the turbo

God that's st. I get 26mpg from an e60 545i without trying. 4.4 litre 330bhp v8 for the uneducated.

However the Forester will get to 60 from a standing start .3s quicker and is a full 1 - 1.2 seconds faster in a quarter mile dash. (The STI variant, make that 1.5 seconds to 60 and 1.7 seconds in the quarter)

Given a stretch of B road, or A road for that matter, the 545 wouldn't know which way the Forester went.

For the uneducated you understand....

[ORD]

You're kidding, right? It's a fking AWD soft-roader! It wouldn't outrun itself, let alone a 5 series.

[V8RX7]

trickywoo said:

God that's st. I get 26mpg from an e60 545i without trying. 4.4 litre 330bhp v8 for the uneducated.

Your BMW is only turning 2 wheels and one diff the forester will never be as economical as it's turning 4 wheels and 3 diffs

[xRIEx]

ORD said:

You're kidding, right? It's a fking AWD soft-roader! It wouldn't outrun itself, let alone a 5 series.

A forester is a soft-roader?

[themanwithnoname]

xRIEx said:

ORD said:

You're kidding, right? It's a fking AWD soft-roader! It wouldn't outrun itself, let alone a 5 series.

A forester is a soft-roader?

Nope its an AWD estate car - Impreza WRX chassis with longer travel suspension. Supple in the bumps but something something poop and blanket....

Unless you're talking SH (2008) onward, then yes, they're quite soft.

Edit to add: This is also part of the reason some of us have them... for ORD's response.

Edited by themanwithnoname on Sunday 29th November 21:17

[ORD]

No idea about back the day but recent ones are definitively SUVs

[themanwithnoname]

ORD said:

No idea about back the day but recent ones are definitively SUVs

Enjoy - VBH with an Impreza STI and a Forester STI around Anglesey

https://www.youtube.com/watch?v=2uyPkavo66Y