Just Purchased 2001 XC70

[howardc64]

You can feel it, but can you hear it? I thought my turbo was just shy when I bought my '01 - but after reading some threads and changing my turbo vacuum lines I can really hear and feel it now. Easy and cheap fix.

Curious what turbo lines did you change to make the turbo come alive? I did the IPD HD TCV update along with the 2 out of the 3 hoses (I skipped the 3rd due to access difficulty) and got a pretty good power gain at the cost of 1mpg. Are these the lines are you referring to?

[JayPinNC]

Curious what turbo lines did you change to make the turbo come alive? I did the IPD HD TCV update along with the 2 out of the 3 hoses (I skipped the 3rd due to access difficulty) and got a pretty good power gain at the cost of 1mpg. Are these the lines are you referring to?

Yes, the same two lines. For some reason my turbo came alive - the first few times after changing the lines, I found myself looking around because the sound was like a siren approaching. And I lost that 1mpg as well. All this was before I did the DIY HD TCV which added a little more responsiveness.

As for that 3rd line, I could get my fingers on the clamp but couldn't get a tool up there to get the clamp off.

[Seamus]

Just curious, wouldn't more power from the turbo improve fuel economy since it doesn't use gas?

[Astro14]

Fundamentally, power is created by combustion. Burn more fuel with O2, get more heat, get more power...

so, if your car is making more power - and you use it, you're going to burn more gas...

A turbo in and of itself is run on exhaust gasses, so no, it doesn't directly burn fuel, but it does impede exhaust flow - and taking energy from the exhaust flow isn't exactly "free" - there is a slight loss in exhaust efficiency to spin that thing....

Comparing engines of equivalent HP, the turbo engine will generally get better MPG than a Normally Aspirated one. The NA engine will be larger in displacement and have more friction and pumping losses associated with its larger mass, more friction surface and more closed throttle plate - air has to move past that - and creating the vacuum takes energy...pumping loss...(this is part of why diesels are more efficient...no throttle plate = less pumping loss...they also have more BTU/Liter of fuel, but that's another discussion...)

But at high boost, a turbo engine is deliberately run a bit rich to preclude detonation under high cylinder pressure - so at full throttle, or near it, you won't get a great deal of MPG improvment over NA, even though the turbo runs on waste heat - that increased richness overcomes the benefit...

At part throttle cruising, you'll see a slight benefit in the turbo engine over NA...I think that's part of why Volvo has gone the Turbo route in so many cars - have you seen gas prices in Europe?


personally - I think Howard was enjoying the newfound power in his turbo car...;-)

[Seamus]

Thanks, I never understood that but now I get it

[JayPinNC]

Just curious, wouldn't more power from the turbo improve fuel economy since it doesn't use gas?

The way I understand it - you lose mileage when your car is in 'boost' - more air from the spooled up turbo means more gas to add to the mixture = lower economy.

You can try to drive at lower RPMs and stay out of boost as much as possible - that'll help your mileage.

[howardc64]

I have the same understanding as Astro14. If you look at modern high mpg engine designs, it has evolved towards the direction of "small displacement". But with small displacement. how to do you achieve power when you need it?

- One solution is to build big displacement engines with cylinder deactivation at low loads. Obviously, deactivated cylinders don't burn fuel. Thus, "small displacement" is achieved. Honda 6 cylinder engines been doing this for awhile. That is how they get that amazing mileage on a minivan. I think they are up to like 27mpg on high way speeds now.

- turbo or super charger to boost power when needed. Our 5 cylinder Volve engines is this example. Ford and VW are pushing new I4 engines in this direction as well. As Astro14 says, when you are boosting... you are consuming more fuel.

Either way, they want to run small displacement at low loads to get mpg.

By the way, I would guess this is obvious improvement area for Volvo's new I6 engine. They increased displacements and didn't do cylinder deactivation I guess 500 extra pounds on the new XC70 don't help either.

[coreelements]

You can feel it, but can you hear it? I thought my turbo was just shy when I bought my '01 - but after reading some threads and changing my turbo vacuum lines I can really hear and feel it now. Easy and cheap fix.

I do hear it winding down or charging but it is not as defined as my Audi! Good suggestion because any leaks can negativly affect the over all performance of the turbo. I have plans to replace all the PCV breather lines and the lines off the Turbo.

[coreelements]

Do you remember those after market spiral air duct that you add in you intake hose?
The turbo charger is essentially doing the same thing with the air by spiraling it suppose to make it more efficient though the TC is utilizing the exhaust waste...

[Astro14]

Dude - I have no idea what you're talking about!

Spiral thing? Huh? turbos don't "swirl" the air...they pressurize it...

Turbos run on exhaust gas pressure, but while it's "waste" gas - it's not free, it hampers the flow and there is a small efficiency penalty.

"Swirling"
"Vortex"

Whatever, they're all marketing code words for non-engineers...to the uninitiated, they mean "buy my product, give me your money...you're too ignorant to know that this is bogus..."