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atomiclightbulb
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I've long been skeptical that direct injection improves fuel economy very much, but the automotive press has been falling all over the technology for years. Looking at the fuel economy figures for the Honda Accord, I think my skepticism is justified.
From the published figures at fueleconomy.gov, I looked at the differences between 7G, 8G, and 9G Accord with I4 and manual transmission:
2007 (5MT): 23 City, 31 Highway, 26 Combined
2012 (5MT): 23 City, 34 Highway, 27 Combined
2013 (6MT): 24 City, 34 Highway, 28 Combined
If direct injection was so great, I would have expected better numbers from the 2013 Accord. The 9G Accord has the advantages of lower weight, better aerodynamics due to body shape & underbody panels, and an extra transmission gear. Still, even with the Direct Injection K24W, it manages only 1 MPG better in the City cycle, and no better on the highway cycle.
This leads me to believe that Honda adopted direct injection for the K24 because they needed to fatten up the torque curve and the K block could not be bored or stroked for higher displacement.
Nissan achieves class-leading results in the EPA test through the use of a port-injected 2.5L engine. Performance against the Accord was pretty similar: http://www.motortrend.com/roadtests/sedans/1212_2012_2013_midsize_sedan_comparison/altima_camry_passat_specs.html. Both the Accord and Altima returned 0-60 times of 7.7 seconds. The Accord had slightly better passing performance, and the Altima did slightly better in the quarter mile. The Altima returned 0.5 MPG better fuel economy than the Accord in this test.
So Direct Injection did not improve fuel economy numbers significantly for the Accord's K24. The Altima returned similar performance numbers and slightly better fuel economy with a slightly larger displacement port-injection engine.
Can someone explain what is so great about Direct Injection?
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notyper
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I'm sure you already know my stance on DI in NA engines (generally not worth it), but if you'll note, Honda did get equivalent performance from a smaller engine in a heavier package. And while the EPA numbers are slightly lower, real world is a wash. The primary difference here is that the Accord is rated as a PZEV vehicle while the Altima is a SULEV. Minor differences in emissions profile (and splitting hairs IMO), but the Accord is cleaner in the ratings, and I know that is important to Honda.
From my sources inside engineering and R&D, they had to work very, very hard to get that rating (far harder than they thought they would) and there were probably some compromises in output to get there. Don't forget that close coupled catalyst and lack of exhaust VTEC really kill this engine, yet it still manages to run with the 7% bigger QR25.
I'd still rather have a properly done dual VTEC, dual VVT K24, DI or not and give up a bit of economy or emissions for 20-30 hp more.
SC
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Bullwinkle
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notyper wrote:
I'd still rather have a properly done dual VTEC, dual VVT K24, DI or not and give up a bit of economy or emissions for 20-30 hp more.
SC
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I think you will get your wish, just not in an Accord. Remember that is the volume overall good performance version of this technology.
A performance version would be different.
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TonyEX
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notyper wrote:
I'm sure you already know my stance on DI in NA engines (generally not worth it), but if you'll note, Honda did get equivalent performance from a smaller engine in a heavier package. And while the EPA numbers are slightly lower, real world is a wash. The primary difference here is that the Accord is rated as a PZEV vehicle while the Altima is a SULEV. Minor differences in emissions profile (and splitting hairs IMO), but the Accord is cleaner in the ratings, and I know that is important to Honda.
From my sources inside engineering and R&D, they had to work very, very hard to get that rating (far harder than they thought they would) and there were probably some compromises in output to get there. Don't forget that close coupled catalyst and lack of exhaust VTEC really kill this engine, yet it still manages to run with the 7% bigger QR25.
I'd still rather have a properly done dual VTEC, dual VVT K24, DI or not and give up a bit of economy or emissions for 20-30 hp more.
SC
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So, let's think for a second.
Imagine AHM decided to make an ED TSX and because of volume they did not need PZEV.
So, with a proper DOHC iVTEC ED head, direct injection and 91 octane gas, how much power could a K24W2 make?
215 bhp and 190 ft/lbs?
IMHO, with a 6ATSS this would be an exceptional engine for a TSX. Almost as much power and torque as the old J30 but much lighter and more fuel efficient.
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superchg2
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TonyE wrote:
So, with a proper DOHC iVTEC ED head, direct injection and 91 octane gas, how much power could a K24W2 make?
215 bhp and 190 ft/lbs?
IMHO, with a 6ATSS this would be an exceptional engine for a TSX. Almost as much power and torque as the old J30 but much lighter and more fuel efficient.
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While they're at it, Honda would also need to come up with a 6 speed automatic for an I-4, something they have not done before.
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Bullwinkle
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superchg2 wrote:
TonyE wrote:
So, with a proper DOHC iVTEC ED head, direct injection and 91 octane gas, how much power could a K24W2 make?
215 bhp and 190 ft/lbs?
IMHO, with a 6ATSS this would be an exceptional engine for a TSX. Almost as much power and torque as the old J30 but much lighter and more fuel efficient.
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While they're at it, Honda would also need to come up with a 6 speed automatic for an I-4, something they have not done before.
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REPEAT AFTER ME: C-V-T! C-V-T!
I would be surprised as hell if you ever see a non-CVT automatic on a Honda four-cylinder EVER AGAIN.
If you don't think so, go drive a new Accord 4 with a CVT. Spend half an hour with it and see how long it is before you forget it's a CVT.
I was skeptical. Not anymore.
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atomiclightbulb
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notyper wrote:
The primary difference here is that the Accord is rated as a PZEV vehicle while the Altima is a SULEV. Minor differences in emissions profile (and splitting hairs IMO), but the Accord is cleaner in the ratings, and I know that is important to Honda.
From my sources inside engineering and R&D, they had to work very, very hard to get that rating (far harder than they thought they would) and there were probably some compromises in output to get there. |
Ah, thanks for the insight on the emissions rating. It hadn't even occurred to me to check how the Altima scored. Good for Honda for achieving that PZEV rating.
Bullwinkle wrote:
REPEAT AFTER ME: C-V-T! C-V-T!
I would be surprised as hell if you ever see a non-CVT automatic on a Honda four-cylinder EVER AGAIN.
If you don't think so, go drive a new Accord 4 with a CVT. Spend half an hour with it and see how long it is before you forget it's a CVT.
I was skeptical. Not anymore. |
I agree with this. Almost without exception, the automotive press has been pleasantly surprised at just how natural the Honda G-Shift CVT feels during driving. I think Motor Trend snarkily recommended to Nissan in their latest comparison review that Nissan look at Honda to see how a CVT is properly implemented :-p
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TonyEX
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Bullwinkle wrote:
superchg2 wrote:
TonyE wrote:
So, with a proper DOHC iVTEC ED head, direct injection and 91 octane gas, how much power could a K24W2 make?
215 bhp and 190 ft/lbs?
IMHO, with a 6ATSS this would be an exceptional engine for a TSX. Almost as much power and torque as the old J30 but much lighter and more fuel efficient.
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While they're at it, Honda would also need to come up with a 6 speed automatic for an I-4, something they have not done before.
|
REPEAT AFTER ME: C-V-T! C-V-T!
I would be surprised as hell if you ever see a non-CVT automatic on a Honda four-cylinder EVER AGAIN.
If you don't think so, go drive a new Accord 4 with a CVT. Spend half an hour with it and see how long it is before you forget it's a CVT.
I was skeptical. Not anymore.
|
So long as it has the Sport Shift mode with paddle shifters I'd be good to go. With all the additional torque and a bit more power it would be like going from an 00 to an 02 Odyssey (more power, one more gear).... It would allow comfortable cruising at 90mph, whereas today that's at 82 or so and it would really be great for passing power in the 40 to 50 mph range.
The additional torque and extra "gear" would also work towards a very relaxed cruising speed... like 2300 rpm at 80mph with excellent mileage all day long...
204 TSX Sport Wagon with such a powertrain... in blue... my ride!
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CarPhreakD
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notyper wrote:
I'm sure you already know my stance on DI in NA engines (generally not worth it), but if you'll note, Honda did get equivalent performance from a smaller engine in a heavier package. And while the EPA numbers are slightly lower, real world is a wash. The primary difference here is that the Accord is rated as a PZEV vehicle while the Altima is a SULEV. Minor differences in emissions profile (and splitting hairs IMO), but the Accord is cleaner in the ratings, and I know that is important to Honda.
From my sources inside engineering and R&D, they had to work very, very hard to get that rating (far harder than they thought they would) and there were probably some compromises in output to get there. Don't forget that close coupled catalyst and lack of exhaust VTEC really kill this engine, yet it still manages to run with the 7% bigger QR25.
I'd still rather have a properly done dual VTEC, dual VVT K24, DI or not and give up a bit of economy or emissions for 20-30 hp more.
SC
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I have a pretty good suspicion that it took a LOT of work on the EGR system in order to get there (and a resulting high amount of it). The DI had to be tuned for less NoX output as well. Such a shame, since in racing that's one of the first things you chuck out the window =)
Really though, this is a mass market economy engine. Not as frail as the even cheaper R, or the cheapEST L engines (I think Honda needs to get rid of one engine family); but a performance engine would dictate a significantly more advanced valvetrain design.
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CivicB18
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I'd personally like to see the K23T return with a 6AT, DI and some other EarthDreams technologies. Honda sometimes baffles me as they will make something that's not so great yet instead of improving that said product they kill it. I really think the K23T had a lot of potential!
~Patrick
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notyper
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Certainly the K24W provides a better basic platform for a turbo engine than the old K24 did. Drop the compression a point, debore by 1mm and replace the big, close coupled cat with a small, GT25 turbo. Easy 300 lbs-ft and 270 hp and great spoolup.
Of course, the lack of exhaust VVT makes overall tuning a bit more of a compromise......
SC
Last edited by notyper on 10-14-2012 17:41
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nash24
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Bullwinkle wrote:
superchg2 wrote:
TonyE wrote:
So, with a proper DOHC iVTEC ED head, direct injection and 91 octane gas, how much power could a K24W2 make?
215 bhp and 190 ft/lbs?
IMHO, with a 6ATSS this would be an exceptional engine for a TSX. Almost as much power and torque as the old J30 but much lighter and more fuel efficient.
|
While they're at it, Honda would also need to come up with a 6 speed automatic for an I-4, something they have not done before.
|
REPEAT AFTER ME: C-V-T! C-V-T!
I would be surprised as hell if you ever see a non-CVT automatic on a Honda four-cylinder EVER AGAIN.
If you don't think so, go drive a new Accord 4 with a CVT. Spend half an hour with it and see how long it is before you forget it's a CVT.
I was skeptical. Not anymore.
|
Be suprised then Bullwinkle!!
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