Just imagine a 7M direct injection, brand new cast head specially designed for the job.
I wonder if anyone has ever tried this or even thought about it
I wonder if anyone has ever tried this or even thought about it
Direct Injection for the 7M
- Thread starter gotsomegetsome
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You do realize you're talking about hundreds of thousands of dollars in R&D, right? I'm sure people have thought about it in a yeah, that would be cool sense, but not in a this is a good idea sense. Noone has tried it and noone is going to. If you have the brains and the bills to do it, you would probably just swap in and turbo an LSx motor or something.
They did. It's called the 2JZ-FSE. Three liters of direct injected fury. To bad it's only available in Japan.
:biggrinbo:biggrinboMAJOR NEWBIE HELP: I need big time help on this one. How is the 7m not direct injection? Don't the injectors go directly in the cylinder head head? what's the missing piece of the puzzle? Go ahead make fun of me!!!
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Koenigturbo;1579343 said:
Traditional port fuel injection has injectors in the head that spray fuel behind the intake valve. This compresses the air and fuel together, which is needed to create heat and light the mixture with just a spark.
Direct injection injects directly into the cylinder on the compression stroke. This abosorbs the heat from compression, lowering the chance for detonation and knock, and vaporizes all the fuel for better performance and effeciency. There is almost nothing left over.
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7m is port injection direct is like how diesels shoot there fuel in
injector tip's in the chamber
injector tip's in the chamber
Gasoline direct injection isn't that great for big power anyway, too many stumbling blocks while upgrading it, unless the system is designed around big power from the beginning. With the current technology available for street cars, port injection is still king. GDI only gains about 5% fuel mileage and power over a port injection engine, not worth the huge hassle unless you're an OE trying to build cars with great power that can still meet required fuel mileage and emissions goals.
Also, it's very efficient, but it still leaves black smoke out the exhaust on a turbo car, even if it's tuned correctly. You still run an A/F ratio around 11.7:1 in a turbo car, even with GDI.
Also, it's very efficient, but it still leaves black smoke out the exhaust on a turbo car, even if it's tuned correctly. You still run an A/F ratio around 11.7:1 in a turbo car, even with GDI.
I see direct injection having incredible potential for performance cars. Due directly to fact that with a properly designed squelch area you can create a stoichiometric cloud immediately around the spark plug while the area outside the cloud can be extremely lean. This makes for an environment that's very resistant to detonation and knock. As a result you can run higher compression ratios while maintaining elevated boost levels. Higher compression will give you better off boost throttle response as well as quicker spool up. But you keep the benefit of high turbocharger pressure levels due to the designs inherent resistance to knock.
The stoichiometric cloud is controlled by the injection timing event. The ECU calculates this event with info from many different inputs, including RPM, throttle position, load percentage and desired AFR's. When the compression stroke reaches the injection timing event the computer opens the injector. Extremely high pressure fuel is forced into the cylinder(Remember the pressures inside the cylinder are already very high due to the compression stroke. The fuel needs to be under even higher pressure to be injected into this environment). As the fuel enters the cylinder it comes out in a cloud, much like when you squirt a spray bottle. you see the mist expand out from the spray bottle, as it moves the droplets get farther and farther apart, allowing more and more air between them. It's the same for the fuel injector. As the cloud starts out it is extremely rich inside the cloud. Not much air has mixed with it. The area outside the cloud is very very lean. This is why you will hear some companies boast that there direct injection motors can run as lean as 60:1. As the cloud continues to expand inside the combustion chamber it takes on more and more air partials. getting closer and closer to the desired AFR's. Then at a time determined by RPM and piston location the spark plug fires and ignites the volatile mixture. It should also be noted that as the fuel is injected it cools. The reduction of pressure results in a reduction of temperature. This aids in cooling and further preventing knock.
This creation and control of the cloud is what gives the DI engines their potential.
However the current wall that people are hitting in terms of power produced on these motors is the fuel pumps not being able to provide the necessary pressures while maintain flow rates. Once better pumps are produced we will start seeing some pretty insane DI motors. With these motors it's not going to be the peak power that is going to be recored breaking it will be the amount of power produced inside the curve. There will be a much broader power delivery as opposed to current port injection motors that have a very peaky power curve.
The stoichiometric cloud is controlled by the injection timing event. The ECU calculates this event with info from many different inputs, including RPM, throttle position, load percentage and desired AFR's. When the compression stroke reaches the injection timing event the computer opens the injector. Extremely high pressure fuel is forced into the cylinder(Remember the pressures inside the cylinder are already very high due to the compression stroke. The fuel needs to be under even higher pressure to be injected into this environment). As the fuel enters the cylinder it comes out in a cloud, much like when you squirt a spray bottle. you see the mist expand out from the spray bottle, as it moves the droplets get farther and farther apart, allowing more and more air between them. It's the same for the fuel injector. As the cloud starts out it is extremely rich inside the cloud. Not much air has mixed with it. The area outside the cloud is very very lean. This is why you will hear some companies boast that there direct injection motors can run as lean as 60:1. As the cloud continues to expand inside the combustion chamber it takes on more and more air partials. getting closer and closer to the desired AFR's. Then at a time determined by RPM and piston location the spark plug fires and ignites the volatile mixture. It should also be noted that as the fuel is injected it cools. The reduction of pressure results in a reduction of temperature. This aids in cooling and further preventing knock.
This creation and control of the cloud is what gives the DI engines their potential.
However the current wall that people are hitting in terms of power produced on these motors is the fuel pumps not being able to provide the necessary pressures while maintain flow rates. Once better pumps are produced we will start seeing some pretty insane DI motors. With these motors it's not going to be the peak power that is going to be recored breaking it will be the amount of power produced inside the curve. There will be a much broader power delivery as opposed to current port injection motors that have a very peaky power curve.
lewis15498;1579280 said:
Why do people leave posts like this anyways?
Yeah I know it takes a good amount of knowledge and design to do something like this. But, obviously your missing the point.
I would love to get my hands on that 2jz-fse. Just the engine code sounds sexy.
For Dirgle: I'm not sure i get what you mean by "the cloud continues to expand" if the fuel is injected during the compression stroke, then ignited, transforming air + fuel into exhaust. Also, pertaining to a "wall" that people hit with DI, fuel supply I'm not sure has been a problem. There are plenty of stock engines running well over 400+ HP using DI, so how is the fuel system (or pump specifically) any less of a performer than any 40-80psi pump?
The engine in the BMW 135i/335i is an example of a broad powerband made with the help of DI.
2JZ-GTSE is a sexier engine code lol.
2JZ-GTSE is a sexier engine code lol.
Fuel doesn't instantly fill the combustion chamber it takes a certain amount of time to expand and fill the space. Times are within thousandths of a second, but it still takes time. When the fuel is initially injected into the combustion chamber it is nothing but fuel it has to expand to include the oxygen so that it can burn. As it expands it takes on more and more oxygen. This area of fuel and air is commonly called the cloud.gotsomegetsome;1579629 said:
Current limitations for DI engines are about 150hp per liter. This limit is caused primarily by the fuel pump. The latests figures I have heard for fuel pump pressures on DI engines are in the neighborhood of 2,900psi. Creating that much pressure when your not using any fuel is not that hard. However keeping the pressure that high while trying to provide an ever increasing amount of flow is very difficult, and the problem DI people are faced with.
There is always the Diesel DI way, and run HEUI. Not that anybody should try and fabricate that system.
I know what a cloud is, and I know it takes time to fill the chamber. However, the cloud does not actually "expand".
But that is not what I'm arguing about. You statements regarding the fuel pump. You'll need to cite your source, because I could not find anything mentioning fuel pump limitations of DI engines on SAE or any other noteworthy sources. I would assume one would simply create a parallel pump setup to compensate for the loss of flow you are mentioning. Thats what we can do now, so why would it be any different at higher pressures?
But that is not what I'm arguing about. You statements regarding the fuel pump. You'll need to cite your source, because I could not find anything mentioning fuel pump limitations of DI engines on SAE or any other noteworthy sources. I would assume one would simply create a parallel pump setup to compensate for the loss of flow you are mentioning. Thats what we can do now, so why would it be any different at higher pressures?
gotsomegetsome;1579708 said:
Umm yes it does.
And while it's not a super note worthy source the most recent occurance being an issue is here:
http://jalopnik.com/5488327/2010-mobsteel-ford-taurus-sho-first-drive?skyline=true&s=i
Just tell me who ever is dumb enough to waste what BMW spends billions on researching and developing for a 20+ year old 7M just throw me 1% of that fortune and ill be set for life its not like the head gasket will take those nice 40:1 ratios like that 2JZ did.
Closing this as there is no point in discussing such matters unless someone is ponying up the million some odd dollars...
until then, thread closed.
until then, thread closed.
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