Ceramic turbos.

[KiwiBacon]

Originally Posted by jdc0589

I was unaware of any negatative impact to economy due to VV in petrol engines, will you please explain?

On a side note, is porsche making their own vv turbos or are they still getting all their stuff from Borg Warner?

Quite simply you get the best efficiency from a petrol engine with close to wide-open throttle.
Being able to run a turbo engine at cruise in a region where it's near full throttle without boosting gives you the best economy.

With a variable vane turbo, you're going to be boosting before full throttle. Which means you're throttling boosted air. A very bad thing for efficiency and economy.

Car makers don't make their own turbos. Even house brands like toyota are made by turbo companies under special agreements.

[2.2 Straight six]

i believe Mitsubishi manufactures turbos. although, i think they ones they make are used for diesels, and their petrol engines use turbos from other companies.

[KiwiBacon]

Originally Posted by 2.2 Straight six

i believe Mitsubishi manufactures turbos. although, i think they ones they make are used for diesels, and their petrol engines use turbos from other companies.

Mitsubishi Heavy Industries and Mitsubishi Motor Company are not the same outfit.
Same with Mitsubishi TV's and pencils.

[jdc0589]

Originally Posted by KiwiBacon

Quite simply you get the best efficiency from a petrol engine with close to wide-open throttle.
Being able to run a turbo engine at cruise in a region where it's near full throttle without boosting gives you the best economy.

With a variable vane turbo, you're going to be boosting before full throttle. Which means you're throttling boosted air. A very bad thing for efficiency and economy.

Car makers don't make their own turbos. Even house brands like toyota are made by turbo companies under special agreements.

This is true, but it depends on engine load. You will never have positive boost while simply maintaining speed on a highway unless you are traversing a hill. Sure, under partial throttle acceleration you are 100% correct, as the engine is under enough load to produce boost. This is why the MKIV supra gets aweful economy in the city vs decent economy on the highway. the sequenial system can produce ositive boost by 2,000rpm given the required load, which isnt that much.

I didn not know about all the mitsu corporations being seperate. Ill rephrase the question, was porsche or borg warner the one to really develop the vv technology for their turbos?

[KiwiBacon]

Originally Posted by jdc0589

This is true, but it depends on engine load. You will never have positive boost while simply maintaining speed on a highway unless you are traversing a hill.

With a variable vane turbo you can easily boost at cruise. But as you're implying, such a setup is pointless on a petrol engine.

Originally Posted by jdc0589

I didn not know about all the mitsu corporations being seperate. Ill rephrase the question, was porsche or borg warner the one to really develop the vv technology for their turbos?

Why do you need to ask such a question? It's like asking if Donald trump drives his own limo.
Car companies develop cars, turbo companies develop turbos.

[jdc0589]

Originally Posted by KiwiBacon

With a variable vane turbo you can easily boost at cruise. But as you're implying, such a setup is pointless on a petrol engine.




Why do you need to ask such a question? It's like asking if Donald trump drives his own limo.
Car companies develop cars, turbo companies develop turbos.

Didnt know the adjustability was extreme enough to allow boost during low load cuise, so I glad I asked.

Was simply curious about the porsche turbo's. The used to all be KKK units but Borg Warner bought up most of the small european companies; nothing more than simple curiosity

[UncleBob]

many newer cars have pretty smart BOV/bypass valves that stay open at lower throttle openings. This will not remove the restriction of the VV in the exhaust housing, of course.

Really, if your car is producing 15hp to cruise at speed, the difference between 2psi and 0psi isn't going to have much impact on economy. One of my turbo bikes, for example, makes 10psi while cruising on the freeway (measured before the TB) and it gets very close to the same mpg it did before I turbo'd it.....thats a much more extreme pressure difference compared to a car at speed, because this bike in particular is using a large percentage of its availible power to cruise on the freeway, comparatively