A while back, someone posted a video of Honda's I-VTEC I engine which has direct fuel injection.

Here is a site about direct fuel injection (specifically bosche's)
http://www.jonfry.com/2005/07/....html

I was wondering if anyone with boosted engines has looked into this. I did a search on direct fuel injection without finding any posts....if this is a repeat, forgive me.

With a system like this, the benefit of basically eliminating detonation alone seems to be worth it along with the other benefits. I suppose 'where to put it' would become a large issue with the current design of heads (being that directly above the piston is the best location), I would assume you could still get good benefits even if it wasn't idealy located 'directly above' the piston.

 

is this the same as having the injectors on the intake manifold? cause i saw that the jg victor x had predrilled holes for nos, but they have a kit to put injectors there to help with boosted cars. that would be one place to put the injectors.

 

No, because the problem is that it still has to inject during open intake valves. The benefits of direct injection is the fact that it can inject right around at TDC almost eliminating chance of detonation and is almost immediately ignited.

 

Intriguing...

 

i dont know anything about this, but im subscribing and hoping someone else does, but this intrigues me as well.
zero detonation practically on an fi car, who isn't interested. does this mean we could run leaner and make every ounce of power under boost?

 

I haven't seen any GDI (gasoline direct injection) heads in the USA personally but most big names are doing work with them overseas, especially Mitsubishi. I've got a bunch of info on it somewhere as I wrote a grad research paper on the subject We're (as racers) more interested in traditional homogeneous mode where the fuel mixture in the cylinder is uniform while improving everything from combusition mixture to volumetric efficiency. However many car manufacturers are interested in running the car in stratified combustion mode. In stratified form the engine can burn as lean as 40:1 AFR by using a small area of traditional mixture in the spark area to provide an ignition method as 40:1 will not ignite

 

And for those of you thinking of converting, don't get too excited. Those systems run very high fuel pressure, over 1000psi, and require over 100 volts to open an injector. They're really pretty complex systems.

 

What about the bosch system? Does anyone know if those are reasonably priced? Just in general, is there anyone that's even attempted this?

 

If by reasonably priced you mean do a system like this for less than $10k, then forget about it...

 

Wow, they're really that expensive?

The video I saw from Honda was dated 2003 and we still don't see i-vtec i engines in production (that I know of at least). How long till we start seeing these do you suppose? Once a mass produced car comes standard with new technology (say direct fuel injection), it should come down much more in price don't you agree?

BTW, here's the transcript version for those who didn't see the video from honda:
http://en.wikipedia.org/wiki/T...ction

 

many of the diesel vehicles on the market today utilize this technology. For example most of the VW tdi engine use the bosch setup with rail pressure in exceed 1000+psi

 

Yea, that's right. I forgot about that fact. I never realized that the pressure had to be THAT high. makes sense being that it has to inject during piston compression.

 

Ok, I was a little wrong about 'better emissions'. So it's the opposite, you have higher NOx levels...

This is a year ago's information but...
"Currently, only the BMW 760Li, Rolls Royce Phantom, and Isuzu Axiom offer direct injection in the US."

Might be interesting to look into these as well as what they've done for emissions for those who want to do this while still passing emissions...

 

Here's how Isuzu does it:

"Since DI engines also allow for higher compression ratios than a typical fuel injector, Isuzu pumps a standard air-fuel mixture into the cylinder, but at high pressure. This added pressure makes the gas burn so much more efficiently that the new Isuzu Axiom—equipped with the first DI engine sold in a mainstream American vehicle—generates 250 horsepower (20 more than last year's model) while squeezing out 2 more miles per gallon. And it's EPA-certified as a low-emissions vehicle."

So in theory, you can increase your compression higher, keep the standard air-fuel ratio, and keep emissions down....

Question is the price/time vs the actual gains out of doing this...

 

Sorry for being the only one contributing but I keep thinking of stuff and wanting to add here.
I am by no means any expert so forgive any misconseptions here as I'm going off of what I've learned/read which can be wrong when it's solely based on information on the web.

With the ability to raise compression, and keeping emissions down by maintining normal air-fuel ratios, now you can more flexibly and reliably boost with higher compressions without the worry of detonation. I know there are people here with b18c5's boosted without issues. So I assume in this case, it will allow even higher compression ratios with higher boost levels? At the least, it will allow ones to boost with higher compression levels even without the 'perfect tune'...

I would like to see someone take the DI from an Axiom (from a wrecking yard or something) and try to convert a MPFI engine whether it's honda or any other brand and boost it.

 

Almost all of the newer Audi and some of the VW cars are using direct injection and seriously high compression ratios 12.5:1 and above to acheive REALLY nice power output in the stock motors.

Yes, pre-ignition and detonation are much less likely and timing and compression can bumped up.

Alot of it (from what I have heard from my almost father-in-law, Audi parts manager) helps emissions and gas mileage...has to do with the fact that there is no longer a 'swirl' chamber needed to mix the gas and air before it enters the combustion chamber. Not exactly sure from a physics standpoint how this helps but I am sure some of the engineers in here should be able to chime in.