Modern Turbocharging Power Torque And Fuel Economy, How?

[Powerslide]

What exactly are major manufacturers doing with turbocharging and fuel economy other than simply for engine mass reduction? How do they get those good MPG on really early boost and how do they use direct injection and a rather high compression set up to hit these target?

[Tommy Cookers]

downsizing
it reduces friction, reduces pumping losses, and reduces throttling (thermodynamic) losses
so improves economy (if CR is kept high)

the only disadvantage is that below a certain rpm the engine starts to behave like an N/A engine of reduced size
(if the turbo could make more boost than it does at this engine rpm that would cause detonation or need ignition retardation)
that rpm corresponds to about 60 kph in top gear

hoping that I didn't misunderstand the question

[Powerslide]

No misunderstand, good post. What sort air/fuel ratio are they running and what are the complete role of direct injection? is it to get optimum air/fuel ratio plus maybe some accurate placement of cooling properties in the combustion chamber?

[Tommy Cookers]

FWIW I believe they run 1.02 (slightly rich) much of the time, because the catalyst needs this to treat the NOx
and some leaner running, at the times when the NOx is lower than usual
during this leaner running the NOx cat will store NOx awaiting treatment commencing on resumption of 1.02 mixture
same as N/A engines

suggest you look at thread 'Talking to a turbo expert' around page 15-18
especailly pgfpro post on page 17 giving Ford Ecoboost paper

http://www.f1technical.net/forum/viewto ... &start=210

[wgknestrick]

Knock is mainly managed by controlling in-cylinder temperatures, and fuel has been the "goto" coolant to control this in the past. Direct injection generally yields a more knock resistant engine, hence less excess fuel required over Stoich to avoid knock.

We still haven't seen a lot of the latest gen turbo technology hit the mass populated auto sector yet though. Turbo tech on most affordable cars is 20years old, while diesels generally get the best of the best.

I would love to see water injection start to get a good look in a production car. Turbo+water injection could yield an incredibly fuel efficient vehicle since water has a higher specific heat than fuel.

[J.A.W.]

Funnily enough, the initial production turbo road car cars were from GM Detroit ~1/2 a century ago..

The Oldsmobile Jetfire 3.5 litre V8.. ..a novel ( for America) small displacement aluminium unit..
( which formed the basis for the `66-67 F1 Championship winning Repco-Brabham),
.. also featured ADI (~ water injection) - but ran into reliability/warranty issues - with owners failing to replenish the supply,
& the engine management system (of the day) like-wise failing to cope with a lack of charge cooling..

[Tommy Cookers]

wasn't there a turbo road Corvair before this ?
similarly with ADI and problems

EDIT - just checked, FWIW the first turbo Corvair is said to be the 1962 Monza Spyder model

that Oldsmobile engine (NA), and Buick's version a bit earlier ? changed the motorsport world ie CanAm, McLaren
50 years ago
deserves a thread

and Steve Wittman tried it for homebuilt aircraft, as being 10% of the cost of the usual light aircraft engine

casting-in the cylinder liners was something no-one could do, including GM ??

OT

[bcoxa]

wasn't there a turbo road Corvair before this ?
similarly with ADI and problems

Both about the same time (month apart), but both were limited runs. Which was the same for the bwm 2002.

First true mass production turbo was the saab 99.

[autogyro]

Would it be better to use LPG as a primary vehicle fuel today?

[J.A.W.]

A-G, such machines were made & sold in Australia, even using sophisticated liquid injection systems..
..however the price of LPG compared to petrol rose so rapidly - due to export pricing/taxes - that it became uneconomic..

According to 'American Supercar' by R. Huntington, P.129;

"The Jetfire was a short-lived project, dropped in `63." ..(introduced in `62.. ..& GM then sold the engine to Rover UK).

& "But Chevrolet continued developing the Corvair turbo..." ..( production ran from `62-66, - phased out for `67 Camaro)..

"Chevrolet engineers protected their engine by purposely building in excessive intake & exhaust restrictions:
The engine was choked to death above 4,000rpm.
You could blow the engine by putting on a bigger carburetor & exhaust-turbine housing!"

In its final form.. ( & 5 years in the showroom - must surely rate as series/mass production..)
..the Corvair Corsa( 'a poor man's Porsche').. "...was pumping out 180hp, or about1.1hp per cubic inch!"

"Incidentally, instrumentation on the Corsas was respectable with a cylinder-head-temperature gage
& a manifold-pressure boost gage."

& it wasn't like the SAAB turbo didn't have reliability/durability issues, esp' in hot climate running..

[flyboy2160]

..and running counter to the prevailing wisdom/urban myth:

http://www.consumerreports.org/cro/news ... /index.htm

[Moose]

..and running counter to the prevailing wisdom/urban myth:

http://www.consumerreports.org/cro/news ... /index.htm

Notably though, they do comment that the Audi/VW group engines are impressive, and weren't included in the study.

[J.A.W.]

An odd side-effect of turbo mills which can catch you out - is the characteristic of power-band/pick-up..
..whereby when not running on cruise control ..
..they can imperceptibly gain boost/speed against an apparently steady throttle application..
..which can result in an unexpected/unpleasant tax-sanction for exceeding the arbitrary speed limit..

[autogyro]

autogyro Would it be better to use LPG as a primary vehicle fuel today?

A-G, such machines were made & sold in Australia, even using sophisticated liquid injection systems..
..however the price of LPG compared to petrol rose so rapidly - due to export pricing/taxes - that it became uneconomic..

I had the same problem in the UK.
We had a complete factory set up to convert production engines to run on solely LPG rather than as a dual fuel.
Government taxation increases put a stop to our work, I wonder why!!!!

I consulted on the Vauxhall BTC designed for LPG.
It was faster than any of the petrol powered cars.
Of course the FIA banned it.

I keep saying it but I will again.
Motor Sport and road car design today are purely tools for those in power, they have NO innovation that means anything allowed.

[Tommy Cookers]

An odd side-effect of turbo mills which can catch you out - is the characteristic of power-band/pick-up..
..whereby when not running on cruise control ..
..they can imperceptibly gain boost/speed against an apparently steady throttle application..
..which can result in an unexpected/unpleasant tax-sanction for exceeding the arbitrary speed limit..

EDIT
my moan against the Ecoboost (from Ford's own data) was the clear implication of poor speed control around the UK 30 mph
(and my small NA automatic is a pain there, due to throttle map and/or ratio-selection 'intelligence')

once the engine has reached the falling part of its torque curve the car is 'speed-stable' ie control is easy
modern cars operation usually has the torque curve still-rising (also less drag), so have degraded speed stability and controllability
in our CAFE world there are no free lunches