The "What's in the AF1 shop" Thread

[JAndrewG]

You know, I didn't think that last part through. In order to be clean the fuel must be injected after the exhaust port is closed (as the piston passes it), but of course done by the time it fires. Very little time. I'm sure there must be a math head here that could say how long that would be at say 10k RPM, but suffice it to say not much time.

The Evinrude 2t outboards are to be propped to run 5-6k RPM WOT, so about half of what one might expect from a 250 or 500cc bike.

Look what that does for you though. 195 fewer parts than a competative 4t...

http://www.evinrude.com/en-US/Engines/ETEC_V6

And look at the weight difference...

http://www.evinrude.com/en-US/Engine...V6/ETEC_300_V6

Since often there are a pair of these things hanging off the back, that's 500lbs. savings!

Alas, I'm afraid politics may never allow a return of the 2 stroke, but on the other hand if one is produced that meets current emissions and offers better performance through less weight and much greater simplicity... we can only hope.

[Micah / AF1 Racing]

Propane or LNG will allow the DFI high rpm 2t engine to live again...this is my guess since time required to atomize is very little with compressed gases stored in liquid form until the injection event. The Evinrude system in racing boats is working well up into the 7k rpm range BTW.

If anyone has any good friends at Evinrude please let me know via PM. Flip side, if anyone sees a stellar deal on a damaged e-tec v4 or I2 on eBay please let me know.

[JAndrewG]

Propane is a great fuel in some respects. I knew a few guys in the mid 80's that played with it. One of them ran dual propane carbs on a blown small block Chev (that was in a '38 Chev coupe). Made big HP, it has a greater resistance to detonation but requires a richer A/F ratio so MPG goes down, much like ethenol does.

I saw the inside of a small block from a tow truck that had run propane for 500k miles years ago. Couldn't believe how clean the combustion chambers were.

The problem with it is that we don't have the infrastructure to easily fill up a propane powered anything. That's why gasoline is so hard to replace. It's so easy in most states we've been doing it ourselves for decades.

[Viggen]

Don't know if you guys have seen this but there was a really good article in British Bike mag a while back about two-stroke revival....

They mentioned Evinrude and a company called Orbital that were building kits that made 2T scooters cleaner than 4 strokes! One engineer made the point you could detune a large capacity 2 stroke and it would more than match a similar sized 4 stroke on power but kill it on torque

Anyway the last part was about Lotus Engineerings latest prototype engine based on 2T cycle.

http://www.lotuscars.com/engineering...esearch-engine

This Omnivore engine should work on several different types of fuel, variable compression, exhaust trapping, direct injection courtesy of Orbital....many nice things

[Dale Zalaoras]

I would like to introduce you all to the Aprilia SR50 DiTech, direct injected 2 stroke, which meets Euro & USA emmission standards.

"The SR50 ‘DiTech’ model, which costs £300 more than the carburetor version, uses an injection engine. DiTech is merely the name Aprilia gives to their fuel injection system and engine, which is actually engineered and designed by Orbital. It is highly fuel efficient, achieving up to 100 miles per gallon."

re:
http://www.apriliaforum.com/forums/forumdisplay.php?f=37

[Micah / AF1 Racing]

I did not go into detail about the SR50 Ditech for a reason. It was the first application of DFI Orbital injection in a production 2t engine and to this day lags in sophistication and reliability of the DFI system. I have considered converting one to propane to see if higher rpms are possible with the existing system however.

[Axecent]

I owned a shitload of Orbital stock and kept in close contact with their technical staff and various industry analysts. Don't ask me how much I was down in that stock at one point. They finally got hooked up with Siemens in some real devices (Synerject) and I doubled down and managed to climb almost all the way out of that previously mentioned hole, but Orbital never really proved itself in 2T world beyond very small engine applications. And they penned deals with some of the largest scooter mfr on the planet....in India and China. I lost interest and have no idea where it has gone in the last few years....their patents had about run their course, anyway. I even researched the Bimota DI to determine how they had avoided Orbital's patents. Before I could make a determination, the VDue had already sunk Bimota's ship and I was unable to determine if their was any intrinsic value in their design or not (VDue was primarily a Manufacturing QC fuckup, IMO). AND, I lost interest because so many people were running around beating their chests about how Bimota was worth WAY more money than I knew I could raise to buy it......$3M was about all I could justify it was worth at the time to my kinda equity investors.

And Micah is right......Honda did drive a stake through the heart of 2T's. That, and the EPA. Turbo rotary engines are another area I think has potential with DI.

[Rebelyell]

Damn honda,what a bunch of sell outs to the greenies and sierra club.I will never buy a new Honda bike or car or truck of any kind honda puts out.

[jrflanne]

Well, I would hope that small, efficient vehicles would be practical and considered. I would like to challenge my Vespa to an electric motorcycle. I get to challenge the pit stops.

[DanRS500]

I have been talking to a guy in the States that has successfully DFI'd a banshee, and ha has been running DFI on his TZR250 powered super karts, he has to run a secondary injector to handle the high RPM. I am keen to try and retro fit this to my RS250 but I fear my skills are not up to the job. As discussion continues and if I make any head way I will keep you informed...

[Micah / AF1 Racing]

Dual Injectors per cylinder are the way I think the future pretty much has to look right now. We need good fueling to say 12.5k rpm, which is 6,250 on an equivalent 4t cylinder, which makes obviously the injectors come into range if there are two of them. I have wondered for a long time now why diesel race car guys are not using this strategy for higher rpm operation.

[Axecent]

Damn honda,what a bunch of sell outs to the greenies and sierra club.I will never buy a new Honda bike or car or truck of any kind honda puts out.

It dates back to WAY before the green movement....Soichiro pretty much always hated 2 strokes....a necessary evil, in his book.

[Axecent]

We need to fund up a research and development effort here.

[scottydog]

I sometimes wondered if you could not just use a secondary injector in a throttle body for high rpm use as at that point the engine is scavenging properly while on the pipe. This ups the performance with cooling the intake charge and ensuring good fuel atomisation. If it could be timed to overlap and take over from the direct injection in the cylinder head might be possible to make direct injection work for high performance applications. I'm sure it gets complicated to map it all, but pretty sure the idea might have some merit.

[Micah / AF1 Racing]

I know for sure Yamaha has experimented with a Port/DFI divided injection strategy, and gotten good results in prototype engines in watercraft.