E-tec 130hp

[sho305]

Still don't you want around 14:1 air/fuel in an engine and more like 12:1 for maximum power?

14.7? I assume that would be the most efficient burn we can get so far, and then should lead to the least amount of emissions (mostly). I have never seen that max power could be made at that lean of a ratio though can it?

Wow, that must have been fun working on that stuff....if you didn't have an office full of idiots with you anyway. The only DI I have seen is the Audi V8, the BMWs, and I think the new hipo I4 in the Solstice (is the ecotech turbo) is the first American one. Ford made a show engine with the new 3.5 but you know Ford, they will never make it or at least wait until everyone else has already done so. (the TwinForce) There are a couple others I read that are on the way.

[theoldwizard]

Still don't you want around 14:1 air/fuel in an engine and more like 12:1 for maximum power?

You may be right. We were primarily interested in emissions. Power was always secondary

Wow, that must have been fun working on that stuff....if you didn't have an office full of idiots with you anyway.

The idiots (engineering management) didn't show up until much later. When I left in Feb, I had more more "on the job experience" in my current position than the next 5 levels of management combined had on their current positions (most had less than 1 year in their current position, some less than 3 months). They have no idea "what it takes" to actually "get the job done" !

The only DI I have seen is the Audi V8, the BMWs, and I think the new hipo I4 in the Solstice (is the ecotech turbo) is the first American one. Ford made a show engine with the new 3.5 but you know Ford, they will never make it or at least wait until everyone else has already done so. (the TwinForce).

Ford will be there, eventually. Kind of hard to do DI with twin turbos and a whole new diesel control system, plus running changes on the existing EFI systems, with 30% less engineers !

[sho305]

I've always been a Ford guy for some reason....but don't get me started on their current predicament! Talk about poor management, it has to be a textbook case. GM has been pretty good with powertrains excepting trucks maybe, though everyone seems to have a hard time with HD light trucks. The old Taurus really needed a GM transmission to be a good car, and 50 more HP.....but Ford figured they would let it die and killed it until now. Why keep your best selling car around? Maybe they have figured some things out and will stay alive. Their past "good enough" product is not going to make it in the future, just like all US makers. On the other hand GM is bringing Europe over in Saturn, I'm no marketing guy but about time. Ford also has some impressive products in Europe and Australia....but sorry to get off topic! IMO if the government wants to do something about energy here they need to hit it from all sides, including pushing new tech like DI on most engines because it works...a better mouse trap is always good. New fuels, fuel supplies, hybrids, etc should all be addressed too; but that is likely about 1,743 years worth of work for our government at the rate they do work so we will have to wait....

And yes the obvious conclusion is what happened to all the liberal-save-the-planet-by-using-less-fuel people gone? Like I said before just using diesels they have in Europe today would save 1/3 the fuel for the lifespan of every one sold.....yet nobody seems interested, maybe they are all full of something? Lets not use today's tech that works right now....lets try to use maybe tomorrow's hydrogen and electric that is not ready and we have to wait for...when we could have both? I sure don't get it.

[Markus]

As for "running lean" (stratified) that is not a requirement. Most (all ?) of the DIs only run stratified during a portion of their operation, typically just off idle to mid part throttle; trolling and cruising range. The only reason it is done at all is 1) improve fuel economy and 2) they can do it

Yamaha HPDI does not have a stratified mode, or at least it didn't for the first few releases.

That is why its fuel efficiency is the same as etec and Opti at WOT, but lower at low rpm.

It was the shift out of the stratified mode that killed the first generation FICHT engines, by the way. Since OMC's tests were only run at WOT, they did not find the bug.

[sho305]

http://en.wikipedia.org/wiki/Lean_burn--
"Lean burn is an internal combustion of lean air-fuel mixtures. It happens at very high air-fuel ratios (up to 65:1), so the mixture has considerably less amount of fuel in comparison to stoichiometric combustion ratio (14.7 for petrol).

A lean burn mode is a way to reduce throttling losses. An engine in a typical vehicle is sized for providing the power desired for acceleration, but must operate well below that point in normal steady-speed operation. Ordinarily, the power is cut by partially closing a throttle. However, the extra work done in pumping air through the throttle reduces efficiency. If the fuel/air ratio is reduced, then lower power can be achieved with the throttle closer to fully open, and the efficiency during normal driving (below the maximum torque capability of the engine) can be higher."

The engines designed for lean burning can employ higher compression ratios and thus provide better performance, efficient fuel use and low exhaust emissions than those found in conventional petrol engines. Ultra lean mixtures with very high air-fuel ratios can only be achieved by Direct Injection engines."

[Honda]--
"This stratified-charge approach to lean-burn combustion means that the air-fuel ratio isn't equal throughout the cylinder. Instead, precise control over fuel injection and intake flow dynamics allows a greater concentration of fuel closer to the spark plug tip (richer), which is required for successful ignition and flame spread for complete combustion. The remainder of the cylinders' intake charge is progressively leaner with an overall average air:fuel ratio falling into the lean-burn category of up to 22:1."
"This lean-burn ability by the necessity of the limits of physics, and the chemistry of combustion as it applies to a current gasoline engine must be limited to light load and lower RPM conditions. A "top" speed cut-off point is required since leaner gasoline fuel mixtures burn slower and for power to be produced combustion must be "complete" by the time the exhaust valve opens."

http://en.wikipedia.org/wiki/Air_fuel_ratio--
"A stoichiometric mixture unfortunately burns very hot and can damage engine components if the engine is placed under high load at this fuel air mixture. Due to the high temperatures at this mixture, detonation of the fuel air mix shortly after maximum cylinder pressure is possible under high load (referred to as knocking or pinging). Detonation can cause serious engine damage as the uncontrolled burning of the fuel air mix can create very high pressures in the cylinder. As a consequence stoichiometric mixtures are only used under light load conditions. For acceleration and high load conditions, a richer mixture (lower air-fuel ratio) is used to produce cooler combustion products and thereby prevent detonation and overheating of the cylinder head."

"In Naturally Aspirated engines powered by octane, maximum power is frequently reached at AFRs ranging from 12.5 - 13.3:1 or λ of 0.85 - 0.90"


----

In addition to that often the "swirl" in the chamber can not be maintained at higher rpm and intake velocities is what I have read, and obviously you can make more power with a normal mixture for maximum output just because you get the most fuel in there to burn....though not as efficient, but you don't have throttling loss at wot either. I believe the DI can place the fuel at the spark plug and reduce/eliminate knock so much better, thus the ability for it to support stratified burn. Knock is a huge problem with lean burn otherwise.

It would be interesting to see if a Miller cycle could run stratified. Its a cool engine though only 4 stroke. http://en.wikipedia.org/wiki/Miller_cycle
Also note the Audi V8 with DI redlined at 8200rpm factory...sweet.

[theoldwizard]

... "swirl" in the chamber can not be maintained at higher rpm ...

Swirl (or tumble) is used to create a homogeneous air fuel mixture that can be easily ignited and burn completely and consistently.

Stratified is the exact opposite of homogeneous. (See your Honda reference.)

The problem is lighting a stratified charge is you need a "blow torch" not a "Bic Lighter". You don't necessarily need DI. The Honda CVCC had a "pre-chamber" with an extra intake valve. The pre-chamber received a rich mixture that was ignited by the plug creating a "flame thrower effect" into the main chamber which held the stratified charge. The original CVCC used a carb.

The Ford PROCO (prototype) stratified charge engine (late 1970s) used a small, deep cup in the center of the piston to receive the direct injected fuel, which occurred near TDC. A spark plug with an extremely long "nose", reached into that cup and ignited the very rich mixture. As the piston proceeded downward on the power stroke, the volume of the of the combustion chamber increase drastically, so combustion became stratified. (Hint - find a picture of an E-tec piston )

Knock is a huge problem with lean burn otherwise.

Knock (a.k.a. pre-ignition or ping) occurs when excessive heat (possible caused by compression) cause spontaneous ignition of the fuel charge prior to the spark event or in a different part of the chamber. Lean mixtures run hot, hence knock. (Higher octane fuel will not ignite until higher temperatures which is why they prevent knock.)

Also note the Audi V8 with DI redlined at 8200rpm factory...sweet.

WOT is outside of the EPA test area, so you can get away with a lot

[waynekerr135]

Very, very interesting reading again Mr Sho.
Going to read this a few more times to digest your point.

At the moment, it looks like getting more out of the 115 means less efficiency, that's fine with me, it's for racing! If it's going to go Bang in the long run, I can live with that.
We ran XR2's in the past, if it didn't go bang at sometime ,,,,, you were not winning races!

Buy the way, a mate of mine who frequents the Evinrude site tells me that the 130 release is imminent! What do you guys know ????

[sho305]

Maybe "swirl" is the wrong word, but in other words they can't control the action in the chamber at high rpm/HP in order to keep the rich mixture near the plug so it will ignite. I'm sure they will keep improving and that is good for us.

Years back (early 90s?) I ended up with a broken Honda when I went through a lot of cars to make pocket money. Head gasket was blown, as I recall it was a civic with a 1.6L and carb with 235K on it. Well, the head was strange looking so I investigated and it was a leanburn engine. The new gasket was an amazing $15 given the cost of Honda parts then and improved in the place it blew out. Every bolt I took out I could comb my hair in and they all snapped perfectly to come loose (original & untouched)....needless to say the car was a total mess with plenty of dirt all over and 5lbs of candy stuck in the carpet, some rust outside. It ran great after the repair, I towed it home for $50 and sold it for something like $500 back then. Took me a couple of nights scrubbing to get it clean, in fact I think I opened the doors and pressure washed the carpet before I started. I remember the end of the bumper was loose, so I ran some drywall screws into it to hold it on good.