Direct injection technology?

[blue72s]

I've always liked MFI but never liked its fuel consumption. Motronic or EFI isn't direct injection and never produced power like MFI, so what about the latest technology - Gasoline Direct Injection, such as Siemens Piezo?


http://www.siemensvdo.com.au/press/releases/products/2006/piezo_injection.htm

Could this be better than MFI?

[gestalt1]

i wonder if they make an injector that screws directly into a sparkplug hole. you could twin-plug the heads and use one plug hole for the injector.

[cstreit]

And no more deposits on your intake valves as an added benefit!

[jluetjen]

Originally posted by blue72s
I've always liked MFI but never liked its fuel consumption. Motronic or EFI isn't direct injection and never produced power like MFI, so what about the latest technology - Gasoline Direct Injection, such as Siemens Piezo?


http://www.siemensvdo.com.au/press/releases/products/2006/piezo_injection.htm

Could this be better than MFI?

What's not to like about MFI fuel consumption? I get 20 MPG out of my 2.0E day after day. It's definitely better then carbs.

As far as Piezo style direct injectors, that's what the Audi R8's and R10's use for their direct injection systems. It's hardly just a bolt-on improvement. My understanding is that the combustion chambers need to be designed to take advantage of the direct injection, as well as a sophisticated engine management system and a high-pressure injection system. Basically, in order to get the mileage improvement, you need to design the motor pretty much from the get-go as a DI engine. It does allow some neat benefits, such as I seem to remember Dorsey Schrader once saying that when the R8 engines were restarted after a pit-stop, that the direct injection system practically allowed them to start without the starter, just by injecting fuel into the compressed cylinder, and lighting it off.

As far as the 911 is concerned, it's not clear to me how you'd be able to get much benefit out of Piezo injectors.

[J P Stein]

The direct injection I have seen drawings of (gas engines) has shown the fuel injected into the cylinder.....through the cylinder wall at some point in the compression stroke.
Granted, this was some time back .... the advantages were primairly due to the evaporation process cooling the cylinder and providing a homogeneous mixture at the ignition point.
These were MFI systems.

[jluetjen]

JPIII, are you talking about the old Mercedes Benz system that was used in their race cars?

[J P Stein]

Originally posted by jluetjen
JPIII, are you talking about the old Mercedes Benz system that was used in their race cars?

Yes, their F1 car from the 50s.....W196 IIRC.
I dunno if their DB601 from WWII was direct injected, but it was MFI

[beepbeep]

Originally posted by blue72s
I've always liked MFI but never liked its fuel consumption. Motronic or EFI isn't direct injection and never produced power like MFI, so what about the latest technology - Gasoline Direct Injection, such as Siemens Piezo?


http://www.siemensvdo.com.au/press/releases/products/2006/piezo_injection.htm

Could this be better than MFI?

Hmm...why do you say that EFI "never produced the power like MFI"??

If that was the case, wouldn't we still use MFI in F1 cars and the like?

In reality, MFI is not the ultimate injection system many afficionados would like it to be. Arguably, EFI is same thing as MFI. Only difference is that it doesn't wear out and that fuel pressure is somewhat lower. There is a cult of "higher pressure gives better atomization" -followers that believe that there are drastic differencies in power. In reality, difference is negliable and EFI's fine tuning possibilities and absence of wear compensate more than enough.

[blue72s]

Thanks all.

Originally posted by jluetjen
What's not to like about MFI fuel consumption? I get 20 MPG out of my 2.0E day after day. It's definitely better then carbs.

I had a '72 2.4S and it drank like fish.

My understanding is that the combustion chambers need to be designed to take advantage of the direct injection, as well as a sophisticated engine management system and a high-pressure injection system. Basically, in order to get the mileage improvement, you need to design the motor pretty much from the get-go as a DI engine.

I will send an email to Siemens soon and ask for advice.

It does allow some neat benefits, such as I seem to remember Dorsey Schrader once saying that when the R8 engines were restarted after a pit-stop, that the direct injection system practically allowed them to start without the starter, just by injecting fuel into the compressed cylinder, and lighting it off.

Wooo that's even better throttle response than MFI..

[tadd]

This would be like the holy grail for liquid propane injection. The fly in the ointment is the 'largish' vapor pressure of propane at 'hotter' temperatures. Splits regular injectors wide open (350 psi to be safe). Some people are playing with the diesel EFI injectors, but this would be so much better.

tadd

[911 tweaks]

bump...any update??