dwightlooi

Is a 1.4L Turbo the right answer?

125 posts in this topic

GM's new Family Zero engines will span 1.0 to 1.4L with some members including the 1.4 also spawning a turbocharged variant. The family Zero powerplants were designed specifically for economy and will be deployed in vehicles for markets within and without the USA. The question is... are they the right answer to the challenge of developing the optimum compact car power plant?

In my opinion, no. I think GM is chasing the wrong ball -- that of minimizing displacement.

I am assuming that the goal is to make the most economical 140hp power plant to power whatever Civic/Corolla challenger GM has in the works. I do not believe that going to 1.4 liters and bolting on a turbo will improve economy over a 1.8 liter class engine of the same output. The reasons are:-

  1. Displacement is not the biggest determinant of fuel consumption.
  2. Using a turbocharger is detrimental to cruising economy because it precludes resonance intake tuning and a low exhaust port pressure.
  3. Using a turbocharger diverts the engine budget away from more useful technologies.
  4. Using a turocharger adds weight beyond that which can be saved by going from 1.8 to 1.4 liters.

Displacement

Displacement is really LOW on the scale of factors that contribute to fuel economy or the lack thereof. Just look at the Nissan 350Z and the Corvette for instance. The 6.2 liter LS3 puts out more power and twist and comes in at 16/26 MPG. The 3.5 liter VQ35 in the 350Z comes in at 20/27 MPG. The Corvette is a 3200 lbs car the 350Z is a 3350 lbs vehicle. As you can see, practically halving the displacement doesn't buy you much economy. Saving a couple of hundred pounds and having a tall cruising gear probably does more. It takes fuel to make power and it the relative economy advantage of trying to generate the same power from smaller displacement comes from the marginally lower parasitic loss of slightly smaller slugs and tappets, which isn't much. Better results can sometimes be had with a larger displacement but using technologies that enhances combustion efficiency such as HCCI or bearing drag reduction.

The disadvantages of a Turbo

The Turbocharger is great for squeezing a heck of a lot of power from a small swept volume. But it does carry a significant set of penalties. For one, a turbo works only when the engine is being asked to carry a significant load. In short, it works great under full throttle and when you are accelerating with determination. It practically does nothing when cruising on the highway for instance where the manifold pressure is mostly in vacuum. Also, many of the tricks we have learned over the years such as intake resonance tuning and managing exhaust pulses so back pressure is low and an exhaust pulse from one cylinder does not reflect back onto another when its exhaust valve opens are no longer applicable when you drop a turbocharger's exhaust collector and intake plenum into the mix. Also, when you go from say a 1.8 liter engine to a 1.4 liter engine then bolt on a turbo, you add the weight of the turbo, its plumbing and the intercooler which pretty much negates any weight and/or packaging savings you gained from going to a smaller displacement. Finally, a turbo is no free -- they are about $500~600 a pop plus additional incidentals like the pipings, the bypass system, the boost control solenoids and the rather expensive intercooler for about $1000 extra. This is $1000 that can no longer be spent on other technologies such as a mild hybrid system.

What I think is a better formula

Displacement: Stick to a 1.8~2.1 liter

Aspiration: Stick to NA

New features and technologies:-

  1. HCCI
  2. Flywheel integrated alternator/starter + 36V electricals
  3. Complete elimination of the belted accesory drive

HCCI

Using Direct Injection, Dual continuous VVT and 2-stage VVL to implement HCCI allows for a notable jump in combustion efficiency benefiting both city and cruise efficiency. A 1.8 liter HCCI power plant should have no problems matching or exceeding the output of a 140hp . It will also match or exceed the economy gains of a 1.4 turbo.

Flywheel integrated alternator/starter.

The Belt Alternator Starter and 36V electricals used in the GM "mild hybrids" may not win any tree hugger awards, but it is the only hybrid system that makes economical sense even with $5 a gallon gasoline. Everything else requires the owner to fork over thousands of dollars which will not be recouped for 7 to 13 years. But we should go one step further and integrate it into the flywheel. In essence the flywheel will carry a set of permanent magnets, and it will be surrounded by a series of coils setup to turn the flywheel into an alternator/motor. A similar device is already in use by Honda in the Civic Hybrids and is about 1" thick. The device makes 5~20hp and is sufficient to crank the engine or even provide minimal power assist. More importantly, it eliminates one of the most common failure modes of an internal combustion engine -- a failed starter kick mechanism. Most of the time when starter needs replacement it is because the spindle is no longer able to kick out and engage the flex plate or ring gear -- the slamming and springing back over the years have worn out the device. A flywheel integrated alternator/motor has no kick mechanism eliminating this common failure mode, it has no brush contacts, no impact drive, no springs.

Elimination of the belt drive.

Getting rid of the belt allows the engine to basically have no scheduled component replacement for 200~300K miles. Basically, it'll make the dream of a car which you can drive with no scheduled maintenance except for a once a year or two oil change (every 12,500~25,000 miles*). The accessory belt and stuff mounted on it accounts for the majority of non-catastrophic engine failures and work. The belted acceosry drive also forces the location of many accessories to the front of the engine and forces the engine to drive them constantly even when they are not needed. Think about it, the waterpump, the A/C compressor, the Power steering Pump, the alternator. With the alternator already relocated to where the flywheel used to be we can get rid of evertyhing else by making the car more "electric". The power steering system can be electric -- that is already the case on many cars. The A/C compressor can also be electric. The water pump can be driven via the timing chain (ala the GM 2.3 liter Quad-4 of yore). Aside from eliminating belt accessory parasitic drag and scheduled belt replacement, getting rid of the accessory belt drive also frees up the electrically driven A/C Compressor, power steering system and water pump to be located with a lot more freedom. The AC system can be in the trunk for instance in some applications or on the inside of the engine compartment divider wall. The water pump can be on the output side of the engine along with relocated timing chains (ala the Audi 4.2 liter V8s in the B5/B6 S4s for instance where the timing chain is moved to the rear of the engine to shorten the powerplant.

* Yes, 12.500~25,000 mile, 1~2 year oil change intervals can be reliable and healthy for the engine if a good synthetic oil (ala Mobil 1 Extended Performance) is used along with a failsafe bypass filtration and electronic oil quality monitoring.

From a marketing standpoint this combination is also more attractive... I mean what's more a more interesting sell?

A new 1.4 liter Direct Injection Turbo?

Or

A new 1.8 liter HCCI engine with diesel like economy and sporty performance, which requires no maintenance for 200,000 miles?

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Unless GM puts their cars on a serious diet nobody is going to be satisfied with the "performance" of a vehicle with these tiny little engines. Who the hell is going to feel comfortable getting onto a highway in a car that takes 15 seconds to get up to 60 MPH?

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Unless GM puts their cars on a serious diet nobody is going to be satisfied with the "performance" of a vehicle with these tiny little engines. Who the hell is going to feel comfortable getting onto a highway in a car that takes 15 seconds to get up to 60 MPH?

yes, but this will go into cars already using ~150hp engines and less, and if this engine has a flat torque curve like the 2.0L T, then it won't have much problem getting up to 60,70, or 80.

Dwight, I see what you mean with this article, but while turbos are kinda expensive, they know how to use them very well, compared to putting HCCI in an engine, when there is not an engine on the market yet that uses that. HCCI will come around maybe in the mean time, but for the first few years, i think turbos will do fine while they get lots of various use out of the "epsilons" they sell with the HCCI engines to fine tune the tech more and bring the cost down, hopefully.

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I'm thinking that a turbo engine should not be the base engine. In general, turbo setups are not as cheap to build as n/a, and aren't as reliable as n/a. Base engine options on economy cars should be simple, cheap, and reliable.

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I'm thinking that a turbo engine should not be the base engine. In general, turbo setups are not as cheap to build as n/a, and aren't as reliable as n/a. Base engine options on economy cars should be simple, cheap, and reliable.

Do you not consider the Duramax reliable? That is Turbo as far as I know. What about the 3.8T from the Grand Nationals? The SAAB 2.3 seems to be dead nuts reliable (being built for over 20 years in some form probably helps). What makes you think that turbos can't be reliable?

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Do you not consider the Duramax reliable? That is Turbo as far as I know. What about the 3.8T from the Grand Nationals? The SAAB 2.3 seems to be dead nuts reliable (being built for over 20 years in some form probably helps). What makes you think that turbos can't be reliable?

I'm not saying turbos aren't at all reliable, I'm saying the simplicity of a n/a engine inherently makes it more reliable, on top of cheaper to build and repair. Every component added to an engine is another potential fail point. Turbo engines are great options, I'm just saying I'm not sold on a turbo engine being the base engine.

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i would guess for most people the really good 2.2 is a better base engine. and that engine gets great mpg to start with. turbo is fun but often times doesnt equal the same real world mileage when hammered on.

blown turbos because of owner neglect could become a real warranty problem and it adds $$$$ to the cost of the car.

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I like the idea of BAS being standard in every vehicle, but OEMs probably have to absorb part of the added cost as people don't want to pay significant price premiums for those technologies.

HCCI seems a little too far out for the time being.

I think a DI 14.L turbo I4 can be powerful enough to move whatever vehicles use bigger displacement engines in the 120-150hp range. EDIT: I don't think reliability is an issue.

Edited by ZL-1
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I like the idea of BAS being standard in every vehicle, but OEMs probably have to absorb part of the added cost as people don't want to pay significant price premiums for those technologies.

In the short-term, BAS standard isn't doable, as GM has been having trouble even making very many of them available due to battery supplier issues. They should keep reducing cost and increasing reliability and performance (mpg performance mainly), and maybe someday standard BAS will make sense for them. I'm not sure I would want it forced on me, though. Remember, some people still prefer manual window cranks, as they want less things that can break. I'm sure the same applies to drivetrain technology, so making it standard too soon could be a big mistake.

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I like the idea of BAS being standard in every vehicle, but OEMs probably have to absorb part of the added cost as people don't want to pay significant price premiums for those technologies.

HCCI seems a little too far out for the time being.

I think a DI 14.L turbo I4 can be powerful enough to move whatever vehicles use bigger displacement engines in the 120-150hp range. EDIT: I don't think reliability is an issue.

No, I am saying:-

(1) Integrate the alternator into the flywheel and get rid of the accessory belt drive.

(2) A 1.8 liter with 140 hp can be just as efficient even without HCCI, just as light and just as compact as a 1.4 liter Turbo making 140hp*

*Because the 1.4T carries additional plumbing, the Intercooler, the Turbo itself and other "stuff" associated with turbocharging. The reason -- displacement really doesn't matter that much when it comes to economy. Also, the turbo exhaust and intake manifolds are inefficient at cruise or light loads.

Remember 140hp is nothing from a turbo, we should be able to get 180~190hp out of a 1.4 liter Turbo in the same state of tune as the 2.0 liter LNF. The problem is that this is a economy car and it precludes the use of premium gas which puts a cap on how liberal we can be with boost.

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Unless GM puts their cars on a serious diet nobody is going to be satisfied with the "performance" of a vehicle with these tiny little engines. Who the hell is going to feel comfortable getting onto a highway in a car that takes 15 seconds to get up to 60 MPH?

In real world conditions, most people take this long to reach 60mph in cars which have the capability to get to that speed in half the time. The only people likely to notice much difference are inexperienced teenage drivers who feel the need to constantly thrash their cars.

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My '87 Dodge Shadow ES was a POS in so many ways, but to Chrysler's credit the turbo never gave me any troubles, even well after 100,000 miles. (The same cannot be said of the 2 headgaskets, rack & pinion, 2 starters, ignition linkage and myriad of other things that went wrong with that car from new.) If Chrysler could do it 20 years ago, I am sure a reliable turbo can be had today. Coupled with VVT, direct injection, etc., I think an ecotec could be quite a rice burner at 1.4 litres.

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In real world conditions, most people take this long to reach 60mph in cars which have the capability to get to that speed in half the time. The only people likely to notice much difference are inexperienced teenage drivers who feel the need to constantly thrash their cars.

Yeah, you've never been to LA, Houston, Dallas, San Diego, or Phoenix. Nice try, though. :rolleyes:

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(1) Integrate the alternator into the flywheel and get rid of the accessory belt drive.

Great idea... there's a little problem with Honda holding the patent on it.

What about making a stripped down version of the two-mode transmission for use on lower end cars?

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Yeah, you've never been to LA, Houston, Dallas, San Diego, or Phoenix. Nice try, though. :rolleyes:

I've been to three of the cities you've listed - and experienced traffic congestion in all three. I think the "nice try" is firmly in your direction. Some of the teens on here treat the whole world as if they'd fallen from the top of a Christmas tree.

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In real world conditions, most people take this long to reach 60mph in cars which have the capability to get to that speed in half the time. The only people likely to notice much difference are inexperienced teenage drivers who feel the need to constantly thrash their cars.

Here's the problem - he's talking about a car that when pushed to its fullest takes 15 seconds to get to 60. Normal people in everyday driving don't/won't push their car as hard as it will go, but more like half to 2/3 of what it will do tops. That means a car that can do 0-60 in 15 seconds will be doing it in 25-30.

You've long made comments about how much (or rather, little) hp people need. You still don't seem to get that sales are based on what people want, and many people don't want a car that can't get out of its own way if pushed, let alone at a leisurely engine load.

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Here's the problem - he's talking about a car that when pushed to its fullest takes 15 seconds to get to 60. Normal people in everyday driving don't/won't push their car as hard as it will go, but more like half to 2/3 of what it will do tops. That means a car that can do 0-60 in 15 seconds will be doing it in 25-30.

You've long made comments about how much (or rather, little) hp people need. You still don't seem to get that sales are based on what people want, and many people don't want a car that can't get out of its own way if pushed, let alone at a leisurely engine load.

Thanks for your concerns, but I'm entitled to my comments. Americans are already starting to squirm with petrol as cheap as $4/gallon. Trust me, when you get to $6 and $7/gall plus - which will come, you can count on it - most people won't give a toss whether their cars get to 60mph in 8 seconds, 15 seconds or 30 seconds. How do I know that? Because I've already lived through such transitions.

I'm confident Americans will go through the same transition, perhaps an even more pronounced one ... because most Americans generally drive incredibly slowly to begin with, especially once off a motorway. That's the reason I find the bickering on here over a couple of seconds' 0-60 laughable!

Seriously though, what's obvious to me is that many on here clearly don't have a great deal of experience of small cars, or cars with modern small engines. For a B-segment hatchback, 85bhp is quite ample and provides ample acceleration for practically all real-world everyday needs (unless your surname is Fittipaldi, perhaps). 105bhp from a 1200cc engine as is the case with VW's new TSI in its Polo really is phenomenal, and in a car of that size will take just about anything you intend to throw at it. I understand the problem is what people want, but the real problem lies with not knowing the capabilities in the first place because of culture-based perceptions. As economics change, so will those wants, and indeed that's already happening in the States. You're not fooling me for a second, mate.

Edited by aatbloke
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If there is any construction on the highway, there are days my car never gets to 60mph, its reasonable to think I'm not the only person who experiences this, and it is reasonable to assume Americans will accept a slightly slower car if they get better mileage.

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Allow me to introduce myself. My name is Ocn Fittipaldi.
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Allow me to introduce myself. My name is Ocn Fittipaldi.

Then I hope you have the former F1 driver's money - in the next couple of years you'll need it.

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Well, I am not American and we are used to $1.35 a litre and climbing. Anything less than 100 hp is a joke, IMO. My '87 Shadow had around 130hp (if memory serves correct) with the turbo and with the 5 spd stick it was a little more than adequate (although steep hills in northern Ontario had to be run at), but the 3 spd auto I test drove at the time was sadly lacking.

Fast forward 20 years and normally aspirated engines can easily get 120 hp (like on my Optra 5), however, one has to take the vehicle with a manual if one wants to get a) decent mileage and b)any sort of power. Not in the city traffic I drive through every day, thanks.

Toronto has the Worst Traffic in the Known Universe, and that is nothing to brag about. Even though many days I am not able to go above 30 km/hr on the 'freeway,' when I get that hole in the lane beside me, a quick shot and surge of 50 meters makes my day, but even with 120 hp on my Optra it can be scary trying to spool up the motor to do the quick shot.

It is going to take a long time to convince many people on both sides of our border that anything less than 100 hp is adequate. My recent trip to Chicago was done mostly at 130km/hr and I wouldn't have wanted to do that in a Corsa, thanks. At least not the ones I rented in Brazil.

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Well, I am not American and we are used to $1.35 a litre and climbing. Anything less than 100 hp is a joke, IMO. My '87 Shadow had around 130hp (if memory serves correct) with the turbo and with the 5 spd stick it was a little more than adequate (although steep hills in northern Ontario had to be run at), but the 3 spd auto I test drove at the time was sadly lacking.

Fast forward 20 years and normally aspirated engines can easily get 120 hp (like on my Optra 5), however, one has to take the vehicle with a manual if one wants to get a) decent mileage and b)any sort of power. Not in the city traffic I drive through every day, thanks.

Toronto has the Worst Traffic in the Known Universe, and that is nothing to brag about. Even though many days I am not able to go above 30 km/hr on the 'freeway,' when I get that hole in the lane beside me, a quick shot and surge of 50 meters makes my day, but even with 120 hp on my Optra it can be scary trying to spool up the motor to do the quick shot.

It is going to take a long time to convince many people on both sides of our border that anything less than 100 hp is adequate. My recent trip to Chicago was done mostly at 130km/hr and I wouldn't have wanted to do that in a Corsa, thanks. At least not the ones I rented in Brazil.

Los Angeles, with its ancient and poorly planned freeways, isn't much better. The Pasadena 'Freeway' was built 80 years ago, when cars were slow and few, and 500 ft to accelerate to the speed of traffic (if any existed) was deemed sufficient. Compare that to today, when cars come out of a bend charging at you from a stupid 70 mph, and you've just run out of on-ramp. Every bit of reserve power is useful in these situations, in the same way strong brakes and good handling can help avoid accidents.

Just the other day, the freeway I was on merged with a faster-moving freeway, and I needed to get across 7 lanes of traffic to make the soon approaching off-ramp. Again, it helped that I had a good amount of power, because I used every one of those horses getting my six passengers up to speed.

I would gladly sacrifice 2-3 mpg (US) for the extra level of safety you get from greater power reserves. According to the NEDC, the 200PS Golf GTI gets just 5.6 fewer imperial mpg, combined, than an 80PS 1.4 Golf. And at high speeds, small engines labor as large engines dawdle. Last week's episode of Top Gear nicely illustrates how at high speed, small petrol engines can have higher fuel consumption than larger ones.

I drive up a 6% grade hill everyday, and I've found during that stretch, I average higher mpg in a 2.8 liter inline-six than in a 1.8 turbo. The 1.8T occasionally needs third gear to maintain 50 mph, which makes instantaneous consumption increase to a lovely 7 mpg. The big inline-six soldiers on in fourth.

Edited by empowah
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In my reality, with freeway construction and traffic congestion, I rarely get above 60 mph in the day to day drive...most of it is 45 or 55, with one brief stretch 65. With metered ramps to get on the freeway, acceleration is important, but my 4.0L Jeep (which is probably in the 9-10 sec range for 0-60) is fine..

20 years ago, I drove a 2.0L 52hp Escort diesel, and it was probably 15-20 sec to 60, with a manual trans. Wouldn't want to drive it now (too basic) but the 50+ mpg highway would be nice. Even my 5.0L 225hp Mustang got over 25 mpg highway back then..

Edited by moltar
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Even my 5.0L 225hp Continental got 25 mpg highway back then..

fixed for my case.

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