VW's Gas Turbo/Supercharger 1.4L to replace diesels?

The new VW 1.4L engine with both a supercharger and a turbo charger has economy numbers rivaling our great TDI's. The Boston Globe reported a couple weeks ago this engine was capable of 40 city/ 48 highway. This hopefully is a misprint. Car and driver is reporting 29/46mpg. I really enjoy my 04 Passat TDI and hope the M.Y. 08 TDI's EPA economy numbers can reach mid 50's highway for the Jetta/Rabbit. With actual owners numbers higher than EPA.

Since VW is sharing the bluetech technology developed by Mercedes I don't see why VW can't hit mid 50's EPA highway. I have witnessed my wifes 07 E320 bluetech reach 35-38mpg highway, and 32mpg combined city/rural week after week. And the car only has 4500 miles on it! Her mileage is nearly as good as my Passat TDI, and she has +60hp more! If VW incorporates new technology into the 08 TDI model line they should be able to get 10-20% mpg improvements. We will have to see if they can catapault the TDI over upcoming gas powered high tech offerings.
VW's new gas turbo/supercharger is claimed to be $3000 cheaper to make than the euro TDI. See the Car and driver link for info.
http://www.caranddriver.com/carnews/11213/mini-test-review-2006-volkswagen-golf-gt.html

Bluetech is emissions related, not performance related, no?
That big E320 blutech gets the numbers it does for a few reasons: a great overdrive ratio in its 7 speed automatic. Secondly, the level of torque created by that motor at low engine speeds means she is barely turning on the highway.
FWIW, Benz's own E300D from 99 got 36 on the highway. Heck, a mid 80's full-size GM product with the 3800 V6 got low to mid thirties, simply becasue that motor made lots of torque down low.
I've always wondered why a turbo/super charger system couldn't be done. The S/C, while using power to creat power, could create acceptable numbers down low. As the S/C winds out, the turbo could come up on boost and keep pushing up the power. I'd hate to see the plumbing job for that to work!

The TSI twin-charged gasoline engine is not going to replace diesels any time soon. A gasoline engine is never going to be as thermally efficient as a good diesel no matter what you try. It's limited by detonation. The TSI is a premium-gasoline-only engine ...

If that engine performs like it is supposed to, that will trump diesel sales in the US.

Let's hold that thought until someone gets some REAL WORLD comparisons. Remember ... premium fuel only.

Real world observation that I have seen has been that downsized but forced-induction engines don't get better mileage than larger-displacement naturally-aspirated engines. The 1.8T didn't get fantastic mileage. The 2.0 TFSI (turbo only) doesn't get fantastic mileage. I betcha in the real world the 1.4 TSI (twin-charged with FSI direct injection) won't do better on fuel than the 2.0 FSI (normally aspirated, not avail in North America) ... and the 2.0 FSI is way less money to produce.

I think the 1.4 TSI is basically a "beat the taxman" engine for European countries that tax heavily based on engine displacement ...

If that's what it takes to move the world to use less oil...

Smaller moe efficient engines... gas or diesel..

Go Faster you bring up some good points.

My main concern is other gas manufacturers are making some good gains on our Jetta's/Passats/Golf TDI's. For example, In a gas engine FSI or as other call it direct injection can raise efficiency 5-10pts. Throw in a 6 speed tranny or even a CVT and there is another 5-10% added to mpg.
For example the 07 MY Nissan Altima 2.4L with CVT jumped +5mpg to a total of 35mpg highway EPA. That could put the Altima within 3mpg of the 04/05 Passats.

VW needs to keep up with the competition with a 6 speed in either manual/DSG or auto configuration. A CVT tranny could boost a diesels mpg more than a gas application I read in a magazine.
I think the new Electronic activated fuel injectors that Merc, and hopefully VW should save on engine losses. Just imagine the cam no longer has to activate the fuel injectors. That should cut down on losses.

Here's some fuel consumption stuff from http://www.vw.co.uk/new_cars/golf/engines that really lets one do some comparison due to the extraordinary number of choices over there (but not all of them).

1.4 TSI 170ps 6sp 3dr: Urban 9.9 L/100 km, extraurban 5.8 L/100 km

Flip over to the GTI version:
2.0 TFSI 200ps 3 dr: Urban 11.0 L/100 km, extraurban 6.2 L/100 km. BUT ... this is still a turbo engine. It would be nice to compare the 2.0 FSI non-turbo engine, but it's not available. I found it on the Eos model, though. Consumption ratings are practically the same as for the TFSI. The 1.4 TSI does about 5 ~ 10% better (but requires premium fuel, the 2.0 FSI should not but I'm not sure on that).

1.6 FSI 115ps 3dr: Urban 8.7 L/100 km, extraurban 5.6 L/100 km. Less fuel consumption than the 1.4 TSI.

FSI direct injection is better than conventional. The regular 1.4 litre 80 hp engine is 9.4 urban 5.5 extra-urban. More fuel consumption less power than 1.6 FSI. Neither power nor economy with that one. Still it uses a bit less than the TSI engine of the same displacement. You add supercharging, you use (a little) more fuel, the FSI isn't enough to make it up. For the 2.0 TFSI versus 2.0 FSI (No supercharger) there's basically no difference in the consumption ratings. That supercharger is eating some crank power ...

For diesels, this has the same power as the TSI but uses less power than either gas engine, and it's in the 5 door body style (doesn't seem available in the 3 door). This is the bad boy 170 hp piezo injector P-D engine, top of the range.

GT 2.0 TDI 170ps 6sp 5dr DPF, urban 7.8 L/100 km, extraurban 4.8 L/100 km. Gas engine can't match the consumption of a diesel even if the power ratings are the same. For that matter, the stingiest gasoline engine available in this car (1.6 FSI) can't match the consumption ratings of the strongest diesel.

Closest comparison to the PD100 that we have here in North America:

S 1.9 TDI 105 PS 3 door, urban 6.5 L/100 km, extraurban 4.3 L/100 km.

Roughly same power as the 1.6 FSI gasoline engine, but way lower fuel consumption.

The run of the mill 2.0 TDI 3 door uses 6.8 urban, 4.7 extraurban. (The 16 valve engine uses more fuel than the old fashioned 8 valve engine.) The 2.0 SDI 3 door non-turbo 75 hp version has EXACTLY the same consumption ratings.

Bottom line, that 1.4 TSI is still a gasoline engine and it still has gasoline-engine fuel consumption ratings. It's better than average because of the FSI direct injection.

Very good post that, some great info in it

The catch will be emissions, it seems to be easier to hit emissions targets with a petrol than with a derv, and the soot filters etc are already causing problems on some of the more modern diesels in the UK, particularly on short journeys.

Another thing to bear in mind I reckon is that smaller, more tuned engines, tend to warm up more swiftly, which for shorter journeys might prove a benefit. I wouldn't like to think about repair cost though

NHTDI said:

The new VW 1.4L engine with both a supercharger and a turbo charger has economy numbers rivaling our great TDI's. The Boston Globe reported a couple weeks ago this engine was capable of 40 city/ 48 highway. This hopefully is a misprint. ..

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Why would you hope it was a misprint? If someone comes out with a gasoline engine car that works well and gets 180 mpg at no additional cost, why would anyone not like it?

There is some unreasonable expectation of fuel consumption and incorrect logic at determining the EPA ratings from small-sample and anecdotal personal data.

The physics simply dictate that you're not going to achieve a huge 10+ MPG improvement in fuel economy in the same model and generation of car just from the change from, say PD to CR fuel injection. This has been discussed in numerous threads recently touching on different aspects of the irrational expection of fuel economy.

Those physical factors that are decisive for fuel economy, for example weight and aerodynamic drag (Cd*A, not just Cd) has not and will not change substantially in `08 models. In fact, they will likely worsen. You want to compare fuel consumption figures between a VW and a benchmark Mercedes-Benz E320 Diesel: compare the weights and Cd*A and you'll be surprised that they are not that far apart, and the science will give a stunningly accurate prediction of the fuel economy comparison of both cars. If we compare EPA figures as the gold-standard (none of this, "Well, I get 10 MPG over the EPA figures" nonsense for a moment), in order for a car to have 25% lower fuel consumption, it would have to weigh about 25% less and have an aerodynamic footprint (Cd*A) also 25% less, with city fuel economy weighted more by curb weight and highway more on aerodynamics.

Well golly gee, a 2006 Golf TDI Automatic weighs 3091 lbs vs a 2006 M-B E320 CDI Automatic @ 3835 (-24%) and although I don't have the precise Cd*A data for both cars (someone feel free to fill in), I can say they're within 15-20% of each other. Now look at the EPA figures for both cars:

VW (33 City /44 Highway)
MB (27 City /37 Highway)

City: -22% Advantage VW: Compare 24% less weight
Highway: -19% Advantage VW: Compare 15-20% lower Cd*A as I estimated.

Hmmmmmm.....

Conclusion: dream on if a same weight, same aerodynamic 2008 model with get 10 MPG more. In fact, I expect it to remain close or even worse because of the extra fuel consumption caused by the NOx catalyst and DPF regeneration penalties.

GoFaster said:

Real world observation that I have seen has been that downsized but forced-induction engines don't get better mileage than larger-displacement naturally-aspirated engines. ...

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That is because of how companies setup their forced-induction engines. At turbocharged engine is always going to be more efficient then its natually-aspirated counterpart because it uses energy that normally would just be thrown away out the tailpipe, the problem is that automakers usually use that extra efficiency to make the car faster. If someone wanted to make the ultimate efficient gas engine i would definitly be a turbo, and maybe this twin charger idea I haven't really looked that the thermodynamics of it yet.

GoFaster said:

Remember ... premium fuel only.

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Are you certain of this fact? I think it is only a reccomendation for optimum performance and not a requirement for operation.

Yes. (speaking for him).

These newfangled forced-induction engines all have knock sensors that will let them *run* on regular octane fuel, but the knock sensor is going to back so much boost pressure and ignition timing out that the engine will make less power and use more fuel. The TFSI is designed to run on premium and so is the TSI.

Premium vs regular gasoline is not an issue for me, since diesel is more than premium and has been for some time around here. However, unless there is a substantial benefit from running premium gasoline, I would not want to pay the extra cost over regular. That's the main reason I would never consider a Mini.

Bring on those fuel efficient fun to drive gassers!

lbhskier37 said:

That is because of how companies setup their forced-induction engines. At turbocharged engine is always going to be more efficient then its natually-aspirated counterpart because it uses energy that normally would just be thrown away out the tailpipe, the problem is that automakers usually use that extra efficiency to make the car faster. If someone wanted to make the ultimate efficient gas engine i would definitly be a turbo, and maybe this twin charger idea I haven't really looked that the thermodynamics of it yet.

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This is more-or-less correct; if you want an example of a supercharged engine organized for better economy then look at the Mazda Millenia from a few years ago with its Miller cycle engine. Basically, it uses funky intake valve timing so that the effective expansion ratio is less than the effective compression ratio. The nominal compression ratio is very high. The supercharger is to offset the reduced volumetric efficiency caused by the oddball inlet valve timing. When you are cruising down the road at light to moderate load, the supercharger is bypassed and the engine runs in this higher-efficiency mode.

Prius uses the same thing with their Atkinson cycle ... same thing but without the supercharger; that one simply lives with the reduced power output and makes up for it (sort of) with the hybrid system.

The new Civic uses the Atkinson cycle on the "low load" portion of the intake cam and uses the VTEC system to change to a normal intake cam profile at higher load so that it doesn't cost it horsepower.

BMW Valvetronic can do the same thing on a continuously variable basis.

I do not know how well this would match up to a turbocharger. The Atkinson/Miller setups all cost volumetric efficiency; you might end up with something that has no bottom end torque below the speed where the turbo spools up.

TDIMeister
Some good points but you fail to recognize engine revs. What if VW put in a 6spd manual or auto tranny that dropped revs by say 400rpm at 70mph vs the previous year car of same weight and cd. The car will now get better mpg by some factor. Nissan just did a +5mpg improvement by switching to a CVT tranny over the 06 MY car.
My "wish" is that VW will start to incorporate upgrades so that our TDI's maintain a solid led in mpg over our gas competition. Upgrades like a 6 or 7 spd highway geared tranny. Lower Cd, lower weight.
Otherwise we could lose our big edge (mpg) over the competition in the years to come.

NHTDI, reducing consumption is not that simple as using arbitrarily tall gearing. It takes a certain amount of power to run down the road, and if that's done in less engine revs then it requires proportionately more torque. There may be a slight change due to reduced frictional losses, but typically if the gearing is in the ballpark to start off with, that will be small. For example, my 0.681 5th gear gave no noticeable improvement in fuel consumption. Using really tall gearing pays a price in driveability and responsiveness, too. Over-gearing results in unfavorable driver impressions, I do not want it any taller than what I have.

Nissan's consumption improvement with the CVT on the Maxima is largely due to eliminating torque converter losses when comparing automatic transmissions, NOT necessarily the CVT function.

Don't neglect VW's DSG transmission, it also eliminates torque converter losses and it is very effective on the Mk5 automatics. Gear-to-gear transmissions (example: manual or DSG) ALWAYS have higher internal mechanical efficiency than CVT designs. VW is already "leading" by the use of the DSG transmission, on automatics. It is every bit as effective as a CVT.

If people keep wanting headroom and hip room, frontal area is not significantly reducible. The shape is already quite optimized; Cd's in general haven't improved much in the last 10 - 15 years. If government keeps wanting more and more stringent safety standards and people keep wanting more and more quiet and smooth ride and luxury features, vehicle weight is not going to go down, either. YES we know we can get better economy by trimming out the sound insulation and corrosion protection and so forth, but will people buy the resulting tin box, and will the tin box survive as long in the rust belt and will it survive as well in a crash? It's fine to dream, but it has to be able to be sold at a profit ...

I'd think the main advantage of the CVT would be to keep the engine at at the optimum RPM for efficiency, no matter what the vehicle's speed would be. For example, when we look at smaller marine powerplants and efficency, the diesel electric system is great because it keeps the engine at a constant 900 or 1800 RPM. When more power is needed, the engine is just fed more fuel rather than changing rpms and decreasing efficiency.

-Wes

That would be ideal, but most drivers would hate that engine RPM response to engine speed. That sensation is called "rubberbanding" and one of the primary reasons early CVTs were not well received.

Premium is 10 cents a gallon cheaper than diesel here.

lbhskier37 said:

That is because of how companies setup their forced-induction engines. At turbocharged engine is always going to be more efficient then its natually-aspirated counterpart because it uses energy that normally would just be thrown away out the tailpipe, the problem is that automakers usually use that extra efficiency to make the car faster. If someone wanted to make the ultimate efficient gas engine i would definitly be a turbo, and maybe this twin charger idea I haven't really looked that the thermodynamics of it yet.

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Turbo energy isn't free and it does exact a heavy toll at cruise conditions. While accelerating it may have a better efficiency (if they didn't have to run so rich), at cruise a decently sized turbo will be making boost that the engine isn't using. This is easily seen on my g/fs WRX which is making 1-2 psi of boost while the regular boost gauge shows vacuum. This creates alot of backpressure that hurts the little low compression engine.

Until Electric actuated VNT turbos are common on gasoline engines, you will not see a turbo gas engine meet the efficiency of a high compression N/A. Diesel doesn't see this effect since they are always running at atmospheric pressure or above, and have crazy high compression. Not the high backpressure while cylinders are recieving air under vacuum of a N/A engine.

GoFaster said:

Remember ... premium fuel only.

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All the documentation I have been able to interpret shows this engine needing 95 RON minimum. This is ≈90 or 91 AKI (ROZ+RON/2) or about midgrade gas here in the United States. This isn't a huge price premium over the lowest octane (87) gas being sold and is certainly less than the average yearly cost for diesel. Also, here in the Northeast, anti gel treatment is also an added cost during the winter months.

Midgrade here is 89 octane; TSI wants premium (91 - 94 depending on who it is; Sunoco has 4 grades the highest being 94 and the second-highest is enough).

Regarding turbo versus non-turbo engines, take a look at the VW UK site and look up the consumption ratings for the VW Eos 2.0 FSI and the 2.0 TFSI (this is the only car I could find that had both available). The consumption ratings are almost the same. I wouldn't describe the penalty of a turbo at cruise as "heavy".

KP Texan, indeed the claimed advantage of CVT is as you describe. As Dave noted, it makes for a strange driving feel, so most implementations aren't taking complete advantage of this. But even if they did, the slight theoretical gain due to getting the RPM *exactly right* as opposed to +/- 15% - 20% as with a good 5 or 6 speed automatic, doesn't offset the extra frictional loads that ALL CVT transmissions have compared to a gear-to-gear 'box. DSG is as good as CVT for efficiency (give or take a percent or two one way or the other) and doesn't have the odd feel to it.

Even "normal" automatics have benefited from the trend to more and more speeds. With more speeds they can get the RPM right by selecting the correct gear with the torque converter locked, instead of unlocking the converter. Transmission with many forward speeds allows a way more aggressive lock-up schedule to be used. Not all of them do it, though.

Here in MD, using the R+M/2 method, midgrade is 89 also. And I know from experience (and hearing of a similiar experince w/ my wife's co-worker's 1.8T), that using 89 in my 2004 1.8T was not a success. I try to use the local Sunoco's 91 (couple of cents cheaper than other premiums sold) or 93. Mid-grade will not cut it.

That Sunoco station also sells GT100, which under R+M/2 is 100 octane and the highest rated (street legal unleaded) fuel they sell. It goes against logic and VW's recommendations (so I do not plan to do it), but a part of me wants to fill up the wagon with that stuff to see what, if any, performance benefit would occur.

VW to unveil a Passat Bluetec with CDI injection. Even more efficient.
Numbers aren't out yet, but they mention the Polo had large improvements in mpg with the bluetec.
http://www.greencarcongress.com/2007/02/vw_to_introduce.html#more