Direct Injection a reality?

[drcustom]

I came across an interesting article about direct injection, and how we could run ~3 bar without knocking on grade 87 gasoline.

I'm realizing that there are quite a few motors that utilize direct injection (TDI VW's for example). I know anything can be done with enough time/money, but reasonably, can you, or has anyone, used any type of direct injection for 4g63's?

[Mirage]

Most modern Diesels are this way. Either direct or Indirect Injection.

As far as gasoline engines, I do remember reading an article somewhere that makes it seem like it's just around the corner. That was about 3 years ago.

It would be interesting to see what they come up with.

Marcus

[Cloud]

There are cars running direct injection currently. Actually I believe there are several lemans cars doing this as well. Direct injection with gasoline doesnt mean you can run 40 psi on 87 but it does mean you can get a better knock threshold by waiting till you get closer to the spark before introducing the fuel to the heat of the combustion chamber. Expect better fuel economy and power from the same setups.

[drcustom]

Direct injection with gasoline doesnt mean you can run 40 psi on 87

Figures I can't find the article now...I have it saved at work, I'll post the link tomorrow.

It was an MIT project where they were actually injecting ethanol directly into the cylinder after the gasoline had been normally ingested by the engine...the ethanol was an add-on setup that was only activated on demand. Assuming I read the article correctly, they were seeing 3-4 bar of manifold pressure and no knock on 87 octane!

This was with a relatively small amount of ethanol, that was used not for it's octane, but for it's cooling properties. They also said that it has to be direct injection after the piston started compressing, not port injection to get this much benefit from it.

[Cloud]

Oh... well that's a little bit different. Alcohol fuels are pretty nuts with how much heat they can take away. But yeah that wouldn't surprise me... however you can probably run 40 psi on ethanol without direct injection. Stuff like champ car run a decent amount of boost on higher compressions without an intercooler on methanol and have absolutely no problems with it.

[drcustom]

http://www.psfc.mit.edu/library1/catalog/reports/2000/06ja/06ja002/06ja002_full.pdf

[Cloud]

Awesome read, however they seem to have very controlled experiments which leads me to believe the actual effects in the real world will be slightly less amazing. It's still a great idea, people have been doing meth injection for a while with very good results and I think direct injection would have even better results.

[JSMCPN]

On a slight tangent:
Saab variable compression engine with supercharger. Variable from 8:1 to 14:1 compression ratio.
1.6 liter 5-cyl making 225 horse/225 tq
http://www.saab.co.uk/main/GLOBAL/en/vepsilon/index.html

[matthewdesigns]

My wife's '06 Audi A4 2.0T is direct injection. Audi calls it Fuel Stratified Injection. Search "audi fsi injection" and you'll find articles about it.

Audi was able to raise the compression ratio from 9.3:1 in the old 1.8T, to 10.5:1 in the new 2.0T with the direct injection, thanks to the cooling effect it has on the charge.

[Sparetire]

It would be a major PITA to do, but I wonder if some machining of the spark plug well and some custom plugs would allow a direct inject setup on a conventional 4V head. I dont see how else to do it on our cars.

If the plug could perhaps be offset just a bit (I would think away from the intake valves) then perhaps a injector could also be fitted in there. You would really need a weird sort of module that had the plug and injector housed within it. But the cool thing might be that you could use the ignition system directly to fire the injector. So a few (~10?) crank degrees before the plug fires, the ethanol injector fires.

[drcustom]

It would be a major PITA to do, but I wonder if some machining of the spark plug well and some custom plugs would allow a direct inject setup on a conventional 4V head. I dont see how else to do it on our cars.

If the plug could perhaps be offset just a bit (I would think away from the intake valves) then perhaps a injector could also be fitted in there. You would really need a weird sort of module that had the plug and injector housed within it. But the cool thing might be that you could use the ignition system directly to fire the injector. So a few (~10?) crank degrees before the plug fires, the ethanol injector fires.

It's pretty ridiculous I almost don't want to admit it, but yeah that's kind of what I was thinking. I don't know that there's any such thing as a spark/injector combo, but maybe if you came in at an angle and injected right next to the plug you'd have some luck. What I'd like to do is see some of those injectors firsthand. If they were a little skinny thing I think that would open the door for some possibilities (although they'd definitely be a stretch even then). I don't know that you'd want to spray when the spark fires (it would need a chance to cool beforehand I think), but using that same system would be the idea.

[cyberslug]

I'm really excited for some of the direct injection cars coming down the pipeline. There is quite a few out there, Mazda/Ford disi 2.3, GM ecotec turbo, the previously mentioned vw/audi 2.0T, even mitsu has a one called GDI. Once these cars fall out of warranty it should be a fun time for turbo tinkerers. Having no chance of pre-det is pretty nuts too. I know the diesels use the injector to control timing... I presume you could do the same thing here too. Is anyone aware of this going on in the aftermarket yet? Seems very complex but I would think the payoff would be enormous. I don't even know how one would go about a conversion. Aside from the physical head considerations, the fuel pressure is crazy ~1500PSI, and syncing the injection timing with the existing ECU would be a chore too. Maybe AEM will start supporting this in future ECU's after the DI motors get more aftermarket play. Anyways, seems like this is the future... I'd better start saving for that saturn astra redline :)

[biglady112]

I have been amazed at what cars already have this in place and most people just don't know it.

[Carl Morris]

The new BMW 335 turbo motor has it, and the design is cool. Not something I'd want to try to retrofit to anything due to the fuel pump setup required. I think the pressure at the injector is around 200bar?