E-TEC Direct injection explained.

[2smoker]

http://www.ski-doo.com/en-CA/Technologies/Index.htm#

go down a bit.. Click on 2 stroke and 4 stroke technologies.


Watch it carefully!!! Etec engines kick ass! They all crave about the low-end power and throttle response after watching the feedback videos from Ski-doo. Best fuel consumption, lightest sled of the industry.



http://www.evinrude.com/en-CA/Videos/Why-ETec/ETEC

[Chris2T]

yep, incredible. and that's where i snatched my avatar from. i think it's a miracle in itself that they've kept or enhanced nearly all the positives of the old 2 strokes and did away with the (perceived) negatives. i just wonder why this hasn;t made it to big bikes or even cars. Check this out
 2010 MX-Z 800R E-Tec

[TMKIWI]

 

Now if they will only put 1 in a new CanAm 

[Chris2T]

One thing i've noticed about the evinrude e-tec engines - their oversquare bore x stroke dimensions!! Check out the following:
Evinrude 250hp - 98mm X 73mm per 546cc piston
Evinrude 200hp - 91mm X 66mm per 432cc piston

Compared to the big 4 strokes:
CRF450R - 96mm X 62mm
KX450F and RMZ450 - 96xx X 62.1mm
Yamaha YZ450F - 97mm X 60.8

Or the big 2 strokes:
Kawasaki KX500 - 86mm X 86mm
Honda CR500 -  89mm X 79mm

So interesting because 2 strokes have very seldomly been designed specifically for high revs, unlike modern 4 strokes, who've found a new lease on life through higher revs. How beautiful would it be for the direct injected 2 strokes to beat 4 strokes at their own rev game!   

[TMKIWI]

One of the reasons for the short stroke is to keep the engines compact.
Being multi cylinder engines they have large piston areas.
The porting is optimized for torque over a large rev range.
The old V4 90 had a flat torque curve from 4000-6000rpm. The revs boats cruise at.
The newer ones are pretty much the same.
Thats where they have the advantage over the four strokes that only have a flat curve from 5000-6000rpm.
And the two stroke peak readings are higher as well.
BRP got cleaver when they released the engines. Most parts from 40hp- 200hp are the same.
Pistons,Con Rods,Injectors,Heads etc.
The 40hp twin is half the 115 V4.Same heads
The 90hp triple is half the 150V6.Same heads.

[SachsGS]

I'm stuck inside with the flu rambling about the Internet when I came across a very interesting bit of information. Turns out the very first fuel injected car in the world was a German 1952 Gutbrod and I almost fell out of my chair when I read  that it was a TWOSTROKE!. The second car to be fitted with fuel injection was the Mercedes Benz 300SL and it was direct injected!. Surely 60 years later these technologies can  be applied to two stroke motorcycles.

[bearorso]

It's fairly simple.

A 2ts "valves", when looked at / using a description that a 4t person can understand, is the piston. Reed, disc and exhaust power valves / trapping valves are but a small part ( but, important ) of a 2ts "valve train".

The "lift, duration,opening and closing" of the "valve" is controlled by the length of stroke / width of the bore on a  2t.  And these have very definite limitations.

DFI and many of the other ways fuel delivery that can / might be put into use on 2ts, has the ability to get much better fuel delivery and retention within the combustion chamber - Quicker and more efficient charging.

This brings the possibility for shorter bore  / stroke ratios, bringing in the time old use of more revs for more power. And an appreciable 'spread' of a 2ts torque/power curves.

All of the above is fairly simplistic in the writing, but correct. I, and a few others here, I think, could get into a lot of mathematical and engineering details, but come up with the same end point.

2ts, with the development they have so long been starved of, will become better things, in All ways.


Looked at in realistic terms - 4ts have more to be worried about when it comes to being the first of the extinct ICE engine formats than 2ts. At some stage, engineering and total environmental / energy costs cannot be ignored by ICE producers.

[TMKIWI]

Worth reading again 

http://twostrokemotocross.com/2009/06/two-strokes-strike-back/

[JETZcorp]

That's an excellent article.  If I recall correctly, I used some information from that one to formulate my big bad English class essay about two-strokes.  On that note, let me just say that an argumentative essay gets much more difficult to write when you have to spend half the paper explaining to the teacher exactly what a two-stroke is, in the first place.  That paper was even more difficult to write than the one I did on Bigfoot, but at least both came out well.