Rumors about T/Cing and Economy

[Wicked_Sludge]

twin turbo is out of the question IMO. you'll tear up the stock bottom end before you run out of boost on just one turbo.

as for finding a turbo, thats really up to you. buying used is a hard game to play because it takes a keen eye (keener than mine) to know if your getting a good deal or not. but buying new will cost you...

 

[shadetree]

Common sense will tell you that if you add more air to the engine, it will need more fuel else it will run lean and not last long. More air/fuel = less economy. The supercharged engine will usually be get less mileage because you cannot always keep it out of boost, and if you could, why have the supercharger in the first place. I suppose you could have a mechanical bypass and only engage it for those times when needed, but don't know, never tried it.

The turbo is only producing boost when needed anyway. At cruise it is in an "idle" mode. shady

 

[Wicked_Sludge]

GM (i think it was a GM car anyway) did something like that a while back. they had a supercharged engine that used a pulse width modulated super charger clutch (much like an a/c compressor clutch) to moderate boost. this would be ideal since you would not only be able to turn the s/c off during cruising RPM's, but you could regulate the amount of boost without the addition of external bypasses and valve.

might not be the easiest thing for the average joe to set-up and program, however...

 

[Kdawg532]

that would be fun to try tho

 

[SixFoFalcon]

Just because you add a turbo doesn't mean you are necessarily putting more air (thus more fuel) into the engine, especially at light throttle. It's all about how you set things up and what components you use. Given equal quantities of air/fuel, a properly built & tuned F/I engine is more efficient than N/A. The backpressure of the exhaust turbine would seem to be an issue, but as long as you aren't using too large of a turbo (too much load) it is more than offset by the more efficient filling of the cylinders on the intake side. If it's all set up properly, overall efficiency goes up, not down.

One thing to consider is that when you talk turbos a lot of times people start envisioning massive power-adders on large V8s. In those applications you aren't even thinking about saving fuel--you are ONLY turbo-ing to make a lot more power for a given displacement. Nowadays most of the turbos on the market are used to bring a small-displacement engine (usually a 4-banger, say one or two liters) up to par, power-wise. Those smaller turbos are the ones we should be talking about if fuel economy is the goal. It doesn't pay to spin a big-ass turbine around if maximum power isn't your goal.

The single vs. multi turbo argument is all relative--It's all about using the right size tool for the job. Two tiny turbos can provide less boost overall than one large turbo, for example, so in fact it is concievable that a twin turbo setup could be acceptable for the topic at hand.

 

[SixFoFalcon]

GM (i think it was a GM car anyway) did something like that a while back. they had a supercharged engine that used a pulse width modulated super charger clutch (much like an a/c compressor clutch) to moderate boost. this would be ideal since you would not only be able to turn the s/c off during cruising RPM's, but you could regulate the amount of boost without the addition of external bypasses and valve.

might not be the easiest thing for the average joe to set-up and program, however...

The smaller Mercedes-Benz "Kompressor" cars often use a clutched supercharger. Cruising on the highway only the pulley turns, but when you step on it the clutch engages and you've got boost.

 

[AllanD]

I don't know. There must be more to it because the EPA shows a worse loss at highway speed than in town accelerating. I think in town you accelerate faster and use more fuel, and on the highway it becomes a restriction. The throttle plate probably has something to do with it, because a diesel sees a healthy gain no matter what. I'll bet with a gas motor since the amount of air going through matters, the throttle plate is pushing back against the incoming air and the pumping losses aren't reduced very much--if at all.

Diesels and turbos are like Paul McCartney and Stevie Wonder sharing a piano.

Will,

all I need to prove that whoever made up the old mileage test proceedure
spend too much time huffing model glue as a child is ask you to compare
ANY Volvo with an auto against the identical model with a 5sp.

I KNOW that with a turbo enbine driven the way the EPA tests
them will get worse mileage than driving it the way the ENGINE wants to be driven.

Basically on the highway you run the SNOT out of it while accelerating
then back all the way out to cruise power.

Yes you burn more fuel while accelerating, but you spend LESS time
accelerating and more time cruising.

there was a similar case with the Concorde SST.
The aircraft COULD accelerate to it's Mach2 cruising speed
without using afterburner but it spent so much time pushing
through "Max Q" that it was more efficient to use afterburners
all the way to cruising speed then retard the throttles
andput the engines into their "supercruise" mode.

Saab actually did a test where they determined that best
mileage witha 900 Turbo was accomplished by an absolute
"Mario Andretti" launch away from a stop shifting at the rev
limiter, but only using 1st, 3rd and 5th.
that way the engine is working against maximum resistance.

WORK is being accomplished with the fuel burned and that
is the other side of efficiency

Driving a turbo car gently will get mediocre economy.

I managed to get 30mpg out of my Saab 900T while cruising
at 85-90mpg and while a friend of mine who is generally better
at squeezing mileage out of his car could get 33mpg and
occasionally 35mpg out of his non-turbo Saab 900
he couldn't get that kind of mileage at speed.

The worst mileage I ever got from my Saab?
13.2mpg. I wasn't trying to get good mileage
on that trip and I was averaging ~120mph for
that tank of fuel.


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[inferno94]

Will,

all I need to prove that whoever made up the old mileage test proceedure
spend too much time huffing model glue as a child is ask you to compare
ANY Volvo with an auto against the identical model with a 5sp.

I KNOW that with a turbo enbine driven the way the EPA tests
them will get worse mileage than driving it the way the ENGINE wants to be driven.

Basically on the highway you run the SNOT out of it while accelerating
then back all the way out to cruise power.

Yes you burn more fuel while accelerating, but you spend LESS time
accelerating and more time cruising.

there was a similar case with the Concorde SST.
The aircraft COULD accelerate to it's Mach2 cruising speed
without using afterburner but it spent so much time pushing
through "Max Q" that it was more efficient to use afterburners
all the way to cruising speed then retard the throttles
andput the engines into their "supercruise" mode.

Saab actually did a test where they determined that best
mileage witha 900 Turbo was accomplished by an absolute
"Mario Andretti" launch away from a stop shifting at the rev
limiter, but only using 1st, 3rd and 5th.
that way the engine is working against maximum resistance.

WORK is being accomplished with the fuel burned and that
is the other side of efficiency

Driving a turbo car gently will get mediocre economy.

I managed to get 30mpg out of my Saab 900T while cruising
at 85-90mpg and while a friend of mine who is generally better
at squeezing mileage out of his car could get 33mpg and
occasionally 35mpg out of his non-turbo Saab 900
he couldn't get that kind of mileage at speed.

The worst mileage I ever got from my Saab?
13.2mpg. I wasn't trying to get good mileage
on that trip and I was averaging ~120mph for
that tank of fuel.


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BINGO!

 

[AllanD]

"Bingo!" what?

Each mechanical device weather a car, a cat or a woman likes to be "tickled"
in a particular way.

Rub it the wrong way and you'll get results you don't want.

The greatest myth is the one about "jackrabbit starts"...
when by comparison "creeping" away from a stop like a
Turtle on Thorazine is worse.

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[vulcan99]

The 3.0 L was not designed for turbos

 

[shadetree]

The Saab is kinda in a category of its own. It is designed from the start to do what it does. It is not an afterthought like most of the equipment we deal with here.

I have driven Merkurs and a Ranger with a T-bird engine for the last 12 years. I have worn out two of the Merks. When you are in boost, these engines use lots of fuel. Boost pressures can go as high as 16 lbs for the Merks, and 18 lbs for the T-bird at wot. I have driven them in all sorts of manner, and found that the best mileage was with normal driving, and staying out of boost as much as possible.

Some of this can be attributed to the higher compression of the Saabs, smaller engine, intercooler, better engine management control, etc., which improves efficiency.

I know Allan didn't suggest this, but comparing a Saab to most of the stuff we drive is apples/oranges. shady

 

[AllanD]

Actually my Saab had a far LOWER C/R than any Ford 2.3turbo engine.

The mechanical C/R was 7.2:1.

the later "APC" equipped single cam engines were at 8.6:1

The 16Valve engines were somewhere over 9:1.

the secret to the saabs whas that they had a "True" 5sp trans (5th was 1:1)
but their "overdrive" was accomplished without increased frictional drag
by doing it in the chain drive between the clutch shaft and the transmission
input. (this also allows you to "quick change" the overall gear ratios by
swapping out input sprockets)

And I'll concede that the Saab engine was MUCH better built than the ford 2.3T.

Their Steel crank alone was nearly bulletproof as was the block.
And the Mahle pistons used in the turbo engines are quite frankly
the best pistons that can be bought at any price.

I've run a Saab single cam turbo engine with a certified EGT showing 1600-1650F for more than 90minutes and that engine went another 100,000 miles after that little demonstration.

Typically ford turbo engine owners freak the Fok out when they et to see their exhaust manifold glow dull red.

I had to put stainless steel heat shields on the inner fender to keep
from burning the undercoating out of the wheel well AFTER I had burned the paint off the engine side of the inner fender.

While the Saab engine really wasn't designed for turbocharging from
the beginning, it was a MUCH better engine to start with than
the 2.3Lima ford engine is and the engineers putting a turbocharger
onto it were not particularly disturbed by the cost of "doing it right"

Let me point out that one of the 4400 1978 Saab 99 Turbo's
(I have two in the yard and I've parted out several others)
actually sold for essentially the same price as a Corvette in in78,

The various small "flaws" in the turbo installation in the Saab 99 led to
the redesign of the front of the car (basically everything forward of
the front door hinges)that created the Saab 900

Ford probable sold more turbocoupes in 1987 than saab sold 900's that year.
And they probably sold more BLACK turbocoupes than Saab sold 900turbos.

a more appropriate analogy is comparing a piece of pickled herring to an apple.

But after all that the 2.3T has several things going for it.

The first that it is practically a bolt-in to a Ranger.

Putting a turbo onto a 3.0Vulcan is an entirely different kettle of fish.

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[Kdawg532]

i know there will be a massive amount of fabrication involved, i just want to try it would be nice to have an engine like the vulcan that can handle all sorts of abuse and it have at least 250 horses

 

[MAKG]

I suspect the "better fuel economy" thing with turbos is just a misunderstanding.

It's usually true that a turbocharged engine will get better fuel economy than a naturally aspirated engine with the same peak power, just because it's lighter, generally has fewer cylinders, and so on.

But comparing it to one of the same displacement is just wrong. The turbo will NEVER use less fuel to accomplish the same thing. There is a perfect RPM where the turbo cancels air pumping losses, but it's not at cruise in any sensible vehicle. The turbo is basically along for the ride at cruise. Expect the perfect RPM to be several thousand.

And a factor of two slower RPM will cause the turbo to work against you, resulting in more pumping loss.

 

[shadetree]

My Merks would get 28mpg if driven sanely. Overall daily mixed driving was 24 to 26mpg, again sanely driven. The Ranger doesn't do as well due to gearing, driving style, etc., but it still gets a respectable 20 to 23mpg. shady