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Old 12-28-2011, 08:12 PM   #11 (permalink)
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Quote:
Originally Posted by redpoint5 View Post
How can a compression stroke be shorter than a power stroke? Are the con-rods variable length or the crankshaft morphs?

Also, why haven't gasoline engines been DI from the beginning, with no spark plug?

Last question, what is the difference between OTTO and Atkinson?

It seems to me the most efficient car would have a puny motor (3 cylinder 1L perhaps) and a turbo charger. Make this diesel with electric assist and regen and you would have one heck of an efficient vehicle.
Q1: When the engine is in Atkinson cycle mode, the intake valve is open part way through the compression stroke, so some of the air comes back out to the ait manifold thing, then the intake valve closes and compression happens but the compression stroke in this case is shorter than the power stroke.

Q2: DI does not mean no spark plug, DI just means fuel is injected straight into the cylinder. No spark plug in a gas engine requires lots and lots of sensors and a fair amount of computation power. DI, I don't know why it hasn't been implemented from the beginning. Some cars many many years ago had DI but I don't why they didn't continue to have DI.

Q3:See Q1. With OTTO cycle, the intake valve is closed all the way thru the compression stroke, so compression stroke is around the same length as power stroke.

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Old 12-28-2011, 08:44 PM   #12 (permalink)
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Here is the original Atkinson cycle conceived to get around Otto's patents.

Animated Engines - Atkinson

Modern engines achieve a similar effect with cam timing and offset crankshaft journals.

Direct Injection was used on the DB 601 engine in the ME 109 of WW2 fame.
The original Flathead Ford engine of 1932 had an offset crankshaft.
CVTs mostly go back to the Van Dorne belt patent of the mid 1950s.

Nothing new here and Honda has been in decline since old man Honda died in 1991. Back then they really tried some cutting edge engineering, now they are more like GM in decline, riding their laurels since about 2000 when the first Insight came out.

My 94 VX was a great car. the 2002 Insight was neat but had a lot of warranty issues $7k in work in 1 year. Honda kept timing belts too long as well as interference engines.

Probably get slammed for this post, but that is just the way I feel about new Hondas. My 84 CRX was fantastic. The 77 Accord the old man drove up and down US 1 in the Florida Keys averaged right at 40 MPG.

The best of them all was the VX, a truly marvelous piece of engineering. After that peak they have not really done anything that I would come close to calling really innovative, and bragging about ancient technology just convinces me the whole thing is a propaganda campaign.

The new Prius 3 I think, lightweight with the old 1.5 engine and low 50s combined MPG at just under 20k is going to send the 2nd gen Insight to the scrap heap.

regards
Mech
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Old 01-03-2012, 09:04 AM   #13 (permalink)
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...wonder if those new Honda engines will also be Flex-Fuel capable, ie: equipped with re-sized fuel injectors and wide-range exhaust O2-sensor(s)?
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Old 01-04-2012, 10:54 PM   #14 (permalink)
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While Honda is in a bit of a rut, I think they're not too badly off in terms of technology... the R-series engines are pretty good, and the integrated exhaust manifold and EGR were pretty nifty when first introduced. The L-series engines in the first-generation Fit with dual spark made for some pretty impressive economy numbers, though the CVT was a real stinker when it came to maintenance and longevity. The problem is, everyone is catching up and leapfrogging them, while they've basically had the same engines for the past seven to eight years.

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Originally Posted by danwat1234 View Post
I don't know why it hasn't been implemented from the beginning. Some cars many many years ago had DI but I don't why they didn't continue to have DI.
I think the difference is in the injection pressures and the benefits derived from the higher pressures you can get out of new injectors.

I recall that Mitsubishi had some of the first modern, electronically controlled direct injection engines in the 90's (contrary to Audi's claims), but they didn't continue with them. Shame. Some of those engines were very good, and included some innovative touches like continuously variable radiator fans (a pain to wire up when you were swapping one of these babies in).
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Old 01-08-2012, 05:35 AM   #15 (permalink)
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Wouldn't the cvt hinder fuel economy? My room mate got a Nissan cube with cvt as a rental once after he hit a deer, and at 45 mph the engine was at 4500 rpm. Wouldn't running wide open at cruising speeds like that be worse than shifting? Maybe i'm wrong, someone please enlighten me
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Old 01-08-2012, 08:49 AM   #16 (permalink)
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Quote:
Originally Posted by BackroadBomber View Post
Wouldn't the cvt hinder fuel economy? My room mate got a Nissan cube with cvt as a rental once after he hit a deer, and at 45 mph the engine was at 4500 rpm. Wouldn't running wide open at cruising speeds like that be worse than shifting? Maybe i'm wrong, someone please enlighten me
He did something wrong. That sounds like about 3k too high an RPM at 45.
Should be 15-1700.

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Old 01-08-2012, 12:48 PM   #17 (permalink)
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Quote:
Originally Posted by Old Mechanic View Post
Here is the original Atkinson cycle conceived to get around Otto's patents.

Animated Engines - Atkinson

Modern engines achieve a similar effect with cam timing and offset crankshaft journals.

Direct Injection was used on the DB 601 engine in the ME 109 of WW2 fame.
The original Flathead Ford engine of 1932 had an offset crankshaft.
CVTs mostly go back to the Van Dorne belt patent of the mid 1950s.

Nothing new here and Honda has been in decline since old man Honda died in 1991. Back then they really tried some cutting edge engineering, now they are more like GM in decline, riding their laurels since about 2000 when the first Insight came out.

My 94 VX was a great car. the 2002 Insight was neat but had a lot of warranty issues $7k in work in 1 year. Honda kept timing belts too long as well as interference engines.

Probably get slammed for this post, but that is just the way I feel about new Hondas. My 84 CRX was fantastic. The 77 Accord the old man drove up and down US 1 in the Florida Keys averaged right at 40 MPG.

The best of them all was the VX, a truly marvelous piece of engineering. After that peak they have not really done anything that I would come close to calling really innovative, and bragging about ancient technology just convinces me the whole thing is a propaganda campaign.

The new Prius 3 I think, lightweight with the old 1.5 engine and low 50s combined MPG at just under 20k is going to send the 2nd gen Insight to the scrap heap.

regards
Mech
I love/d Hondas and I won't slam you for this criticism. I have become really disappointed with the Hondas. The CR-Z looks great but the last Honda that really wowed me was the 2001 Insight. I'm looking more at the Hyundais and Fords these days--partly on your adivce on these pages I think. If something happens to this old Honda of mine... those are the brands I'm looking at. I just want to be lucky not to get my Civic totaled until the 3-banger Fiesta turbo is a couple years old and on the used lots.
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Old 01-08-2012, 02:29 PM   #18 (permalink)
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Quote:
Originally Posted by Old Mechanic View Post

The best of them all was the VX, a truly marvelous piece of engineering. After that peak they have not really done anything that I would come close to calling really innovative, and bragging about ancient technology just convinces me the whole thing is a propaganda campaign.


Mech
I would agree with all you wrote.

Early to mid 90's hondas are truly amazing. Solid, quality cars.
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Old 01-08-2012, 03:12 PM   #19 (permalink)
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I just did some research. The D series engine was introduced in 1984.

It was last used in 2006. Pretty amazing.
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Old 01-09-2012, 03:14 AM   #20 (permalink)
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Quote:
Originally Posted by BackroadBomber View Post
Wouldn't the cvt hinder fuel economy? My room mate got a Nissan cube with cvt as a rental once after he hit a deer, and at 45 mph the engine was at 4500 rpm. Wouldn't running wide open at cruising speeds like that be worse than shifting? Maybe i'm wrong, someone please enlighten me
Like Old Mechanic says, that sounds wrong. Small cars with CVTs are usually doing 2.5 - 3k at 60 mph.

CVTs are just like any other transmission... the final ratio is what decides your cruising rpms in top gear. Bigger engined cars with CVTs usually have lower cruising rpms than smaller ones, to take advantage of the extra torque.

Honda's CVTs have excellent economy, just as good as their manuals or better in the real world, but the clutch packs are problematic over the long term.

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