BoatBanter.com - View Single Post - DFI

wrote:

I've snipped hope that's Ok

Aha .. this definition of recirculation comes closer to the truth

All the time remembering that the piston in these engines is almost
totally uncooled, they claim the air flow through the crankcase(s)

cools

the piston(s) but this is just more knee jerk answer to a very good
question. "If" that answer is correct then the next question is where

does the heat go then?? up ontop of the piston?? so the piston gets
even hotter as this now preheated air is compressed to make it even
hotter?? then the piston really gets even more heat as the charge is
ignited??? no their answer is just more of the same.

Why didnt they spray a little oil at the piston? Might cause oil use
being too high?

If they tried to oil spray cool the pistons like nearly all diesels &
some other petrol 4 strokes then they would need to make a proper engine
with a proper oil pump & then attempt to separate the oil from the
transfer air. They would also need to effectively dry sump the
crankcase, all doable of course, but it's cost.

E-Tec is the most brazen attempt to stiff the public I've seen in years
they are quoting 4 stroke prices for what is not much more than a lawn
mower engine, except most lawn mower engines are better engineered:-)

E-Tec try ti inject the oil through a hole in the piston skirt & out
the other side so they can try to ensure both sides of the piston are
lubricated, they of course make all sorts of loony tunes claims about
the reasons benefits etc but I'd suggest they're desperate for the
engine to hang together long enough during detonation till the usr backs
off or the chamber cools itself.

I remember the first optimax motors suffered from excessive oil use ..
some people say 1:20 - 1:25 was seen in some motors ... was this oil
cooling?

No that was just more experimentation with consumers' money, they
claimed they doubled the break in oiling. The real issue is it would
take lots & lots of oil to effectively cool the pistons (ala the way
diesels or aircraft engines do it) then of course the oil itself needs
cooling to get rid of the heat. As I said if they had to actually fix
the problems then they spend as much as the rest & ... well there's no
ripoff in that is there?

The answer E-Tec should now give is; Yep we know all about that &

have

decided that if we're to remain EPA compliant with a cheap to build

high

profit 2 stroke, we will just accept there's a real risk of excessive

piston heat buildup when they operate in lean burn mode. However we

have

managed to find a brand new never before known to engine technology
aluminium alloy that we are hoping will be strong enough to survive

the

extreme heat caused when the detonation does occur.

People are praising these things (so far) lets see how it goes ... They
have nice features that hopefully will show up in the 4 strokes, like
no break in no gear ol change due to super duper materials and
tolerances.

Claims nothing more, none have been around long enough to say anything
good about them what is "known" is they're still Ficht, they still run
lean, they still multi fire the plugs, they still inject tiny amounts of
oil to lubricate, in other words yeah right:-)

But OK that's fair lets see how they go but my comments are logged.
What's not fair is to sell to the public before they've been properly
proven, these have not; just as they marketed Ficht & to a lesser extent
Optimax so the paying public could do their testing for them.

The praise comes from magazines & sellers this is just part of the
marketing BS, the same they ran when it was called Ficht. Hopefully
people will not be taken in this time.

Needless to say normal aluminium melts well over 1000F & petrol

will

auto ignite at any temp over 4-500F, so detonation is clearly what

they

know all about & instead of trying to solve the real cause they're

just

"trying" to make the pistons strong enough to survive detonation (&

To be fair: IF the problem is gone then we dont care how ... IF the
motor holds up to the abuse then let it be detonating away as it
pleases

Maybe you can even get it to diesel and power by turning the ignition
off hahaha

The Fichts detonated so much they actually forced the injectors out of
the heads!!! they also damaged the fuel plumbing such that the coast
guard made Bomb recall them!! Detonation is serious business, the only
reason they can even try this is because they use needle bearings which
can "maybe" stand up a bit longer.

The problem I have is they're amateurs, there are lots of huge Cos who
have all looked at these technologies & dismissed them out of hand,
probably for good reason???
t".

My boat is 19' and weighs 1400 lbs with 200 (2 stroke) HP in it you
have to experience the acceleration

The time they can get loaded up while still in lean mode is

What does "loaded up" refer to? = Heat build up in lean mode?

Sorry I meant the engine actually sees load, usually a boat engine
doesn't see much "load" unlike say a car going up a hill, other than at
or very near WOT.

The premises I described are the exception heavy boat, lots of
propeller pitch, ploughing along nose high, in the upper part of the
lean burn mode rev range.

Do I understand that the "lean mode" is just there for the EPA and the
motor could run with no detonation and be fine but not meet EPA?

Pretty much yes, once the engines are back to normal mixtures & single
plug firing there should be no issue, indeed the DFI use about the same
fuel as the old motors at power, all their marketing fuel saving claims
are predicated on low speed when lean.

when they're on a fixed pitch propeller boat with a high top speed ie

lots of propeller pitch. When this type of setup is then used for

long

periods in a say no wake zones the boat is usually ploughing along

nose

high & at lowish revs while still lean, this is when the heat can

really

buildup in the piston (the rest of the chamber stays cool via the
endless supply of seawater). Once the boat clears the no wake zone

the

usr invariably opens it right up to blast away & it's then with the
sudden change from lean mode into make full power & full rich mixture

that the deadly combination occurs, lots of fuel plenty of fire, an
overly hot auto ignition source inside the chamber (really hot

piston) &

very poor fuel atomisation because the injection pressure is just

plain

too low.

Sadly you have the same problem with a jet In harbors and such you
pretty much idel at speeds of 2-5 mph ... This would be bad as well.

Yes the boat behaves the same ploughing along nose high, but the jet
unit doesn't act like an over pitched prop, it's just a pump at low revs
it just makes & uses less power per unit of water out the back.

Whereas the propped boat can make the engine work harder than it's revs
would normally indicate, because the prop with a high pitch takes lots
of torque even to turn it when the boat is creating excess drag.

Completely discounting cavitation (both can & would) say you tied both
to a dock, the jet will still just rev out to max, the propped boat will
run out of power & not get to max, because the prop pitch needs to have
the boat traveling .

However during normal driving you hardly run the jet under 3000 rpm, in
fact it will not plane below 3600 rpm ....

Is it dafe to say that under these conditions (motor is above 3500) you
will never have hot pistons and problems from detonation?

Yes I'd agree with that, at 3500 the engine is on full mixture etc.

Also when you idle for along period of time and have your motor hot and
lean you will have NO detonation problems when you accelerate slowly to
let the motor cool?

Again long idles shouldn't be an issue not enough fuel to make any real
heat. It seems to be the long runs in the upper lean burn range AND
excess prop load from a heavy potentially fast boat ploughing along. We
initially thought the detonation was happening while in lean mode but
now say they're so lean there's only enough fuel there to heat the
piston up. (The fact the pistons get overly hot can't be denied, special
high temp oils & the killer is that now E-Tec have even gone to high
melting point aluminium!!!)

Is there a defined lean mode at a certain rpm range and then all of a
sudden it runs rich? Or is that a gradual process from lean to almost
normal to normal?

It varies but around 1800-2000 some change mode randomly cyl to cyl but
this is more so the usr doesn't perceive a sudden change.

The problem is that when the piston is overly hot (over 250C & auto
ignition is a certainty) it takes time to cool, as the engine changes to
a normal rich mixture usually that will cool the piston & the risk goes
away.

The trouble is in the changeover time if the extra mixture does
detonate it instantly caused a huge increase in heat, when then can
become self sustaining. Once that happens the only saving is if the usr
backs right off quickly, but the usr will not know it's happening
certainly won't hear it.

The E-Tec claim (they have lots of claims not real info & certainly no
runs on the board) to be able to "detect" abnormal combustion code for
they know these engines were being wrecked by lean mixture induced
detonation!!! code for a knock sensor big deal!!!

The real issue is a knock sensor will not hear any detonation in lean
mode (not enough to fuel to even create the knock) the detonation will
happen in the changover period & what will the ECU do about it???
Richen further??? OK that will just feed the detonation further, slow
the engine?? that might work but usrs will not be happy, shut the
offending cyl's fueling down momentarily so the temp can drop?? maybe
but again usr might notice & certainly the EPA might take an interest,
etc etc

In these premises I suggest the E-Tecs will go into detonation

exactly

the same, it's just that they're hoping the new super duper strong
pistons can hang together long enough, till either the usr pulls back

&

settles to cruise or the chamber self cools because there is now lots

of

fuel around because of the normal mixture, it's still a lottery. A
lottery none of the big engine makers will even buy a ticket in....
why????? Well gee they knew what was going to happen with Ficht & I

say

they know about this latest consumer funded experiment also.

Maybe they have a concept of keeping the motor cool with oil, also not
lielly as the ETEC almost runs dry.

At the temps generated by lean mix & then maybe detonation the excess
oil will just bake & then stick the rings, again even the old 2 strokes
most of them died the same way.

All the melted & damaged pistons were from detonation, it wasn't the
cause but finally something caused a part of the chamber to be over 250C
& then self sustaining detonation set in.

Good news for you is that a jet doesn't load the engine the same

way,

the only time the jet can load the engine up is at max power,

anything

below & the load is very much removed from the engine, you'll see

this

in your throttle position 1/2 throttle is lots of revs but not much
power (speed) so cared for you should be confident.

Why would it load at max power? at WOT it should run extra rich. Wont
that keep it nice and cool?

No I've not been clear the only time the jet unit can consume all the
available torque is at WOT.

I take it, you dont like Harry?

Na nor he me so it's all pretty fair in that regard:-)

Sorry if it offends you & in deference to you I'll keep today's

Krause

lie to one of his shorter ones, but hey someone has to stand up to

him:-)

Well ... it may offend Harry (not so much me) but please be nice.

Matt

Hmmmm I'll try :-)

K

& the Krause lie for the day is..........

Of course the big question with Krause's lies is just how does he
come up with these absurd BS stories?? After all it's clear he has no
education nor even basic intelligence, well here's an example;

Here's a funny. My bride had to fly out to San Diego Wednesday and
hitched a ride on her company's corporate jet. They landed in Salina,
Kansas, which is due north of Wichita and Skippy's suburb of Derby.

Notwithstanding it's just more of his racist based abuse of others
he sees as lesser people because of their address, the interesting part
is the endless lies he throws in about the non existent "young bride" lie.

Well look where he got the idea of the "corporate jet" lie; guess
what??? Good ol' Ullico spends genuine unionists money on a corporate
jet!!! & as with all their type they squabble over who gets the most of
other peoples' money!!!

ULLICO
Union Pension-Owned Company Set to Lose $20-$30 Million
Its stock windfall from the bankrupt Global Crossing now gone,
Georgine, former head of the AFL-CIO's Bldg. & Construction Trades
Dept., blamed chief financial officer John Grelle for the losses.
Days later, Grelle resigned in protest, blasting Georgine for not
selling the company jet, which costs $3 million a year.

Remember this is hard working in the main, ordinary honest
unionists' money they're ****ing away then fighting over the leftovers???