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Old 04-24-2014, 01:26 PM   #76
Vlad
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Take a look at Wikipedia

No throttling lossess=no pumping losses, without a throttle plate...

Seems like there are three types of direct injection:
There is one with throttle, Toyota uses it and seems like Subaru uses it as well.
One with auxiliary throttle, needed at low load
One with no throttle, that uses a concept called stratified charge. This provides fuel savings at low loads. Audi seems to use this, but possibly not for the US market.
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Last edited by Vlad; 04-24-2014 at 01:53 PM.
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Old 04-24-2014, 02:32 PM   #77
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Quote:
Originally Posted by Vlad View Post
Have you seen a diesel in-action?
They are direct-injection.
There is no throttle.
Engine speed is controlled from the injection pump.
You are correct, however on diesel, the parts to control the injection pump is referred to as throttle or throttle linkage, whereas no actual throttle body... at least on Mercedes TD.

Other manufacturers may reference the mechanism as throttle, likewise.
Can we agree its mechanism semantics?
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Old 04-24-2014, 02:48 PM   #78
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Diesel engines have a throttle now, basically for EGR/emissions control. However the load is still basically controlled by fuel mass injected (in addition to EGR rates).

When they talk about "dethrottling" on a gas engine, whether it's through valve events or through lean stratified combustion, it's really running a higher manifold absolute pressure. The goal is lower pumping mean effective pressure--you'll see it in a cylinder pressure trace. This is something that can't easily be done without careful coordination of an electronic throttle, spark control, and other actuators. You still need a throttle valve for failsafe operation and certain conditions where the engine won't tolerate dethrottled operation.

The software uses a gasflow model (Ideal gas law and/or saint venant flow equation, basically variation of navier-stokes) to control the AVCS/cam phasers and throttle valve for a target MAP. So if normally you'd run around 40 kPa MAP fully throttled, you can raise your MAP to anywhere between 40-90 kPa at a given speed and load point.

The simplest way to do that is with internal EGR from dialing in overlap by phasing the cams. You might get 60 or 70 MAP, maybe higher, with cam phasing alone. Your upward limit on MAP is about 90 kPa on a gas engine, because some vacuum is still required to drive evaporative purge, PCV, and other functionality. 90 kPa is typical on a lot of systems with continuously variable valve lift. However, in reality the dethrottling is limited by combustion stability. Combustion stability depends on a bunch of parameters like DI rail pressure, injection timing, spray pattern, intake port tumble characteristics, and piston bowl design.

Lean stratified combustion might run at lower MAP than 90kPa but the charge air is highly diluted like a diesel and thermal efficiency is higher.
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Old 04-24-2014, 04:14 PM   #79
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I had a thought that some kind of plate made its way into diesels.

My 1982 Mercedes 300SD had the compressor outlet bolted to the intake manifold with no in-between anything.
Inside the manifold there was the engine shutoff flapper, but that's different.

You can call the accelerator linkage to a diesel throttle linkage, but it in fact links to the fuel injection pump, where in a mechanical pump, the flow is controlled. Maybe that can be called fuel throttling.
The factory manual for that old boat was in German, so it has a name consisting from numerous letters...
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Old 04-24-2014, 04:57 PM   #80
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Talking about common rail diesels for passenger vehicles: Besides controlling the cooled EGR loops (high and low pressure on some engines) on a diesel engine you have to do a bunch of stuff to regenerate the particulate filter and NOx catalyst if applicable. That's where the throttle valve fits in.
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Old 04-24-2014, 06:00 PM   #81
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Quote:
Originally Posted by rexster View Post
I had a hard start this morning. I guess it's a known issue, but it surprised me nonetheless. The first time turning the key it didn't start. The second time turning the key I had to turn it over for three or four seconds, felt like forever, then it fired up fine. It hadn't been sitting for long, drove it to work and back the day before. Anyone else having this issue?
Was it anything like this?

http://www.subaruforester.org/vbulle...t-poll-259170/

-Dennis
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Old 04-24-2014, 10:12 PM   #82
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Quote:
Originally Posted by arghx7 View Post
The goal is lower pumping mean effective pressure--you'll see it in a cylinder pressure trace.
You'd see the difference with unthrottled operation on a vacuum gauge, just like you don't see measurable vacuum on a diesel.
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Old 04-24-2014, 10:13 PM   #83
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so do we have throttle bodies or not? I suppose i could pull the cover off and look
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Old 04-24-2014, 10:21 PM   #84
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Please do.

The info I found refers to the BRZ and you can see that it has a TB.
Then that injection system is linked to a Toyota direct injection that does have a TB.
Now that partial FA20DIT teardown from the Japanese site that someone linked, showed something similar with composite TGV housings.

The point I was trying to make is that with a DIT, these could be a lot more than just TGV.

I wonder if these become the .. part time throttle plates? Then maybe you won't find a central unit.

Also, the DI field seems to be moving fast, new things come out often.
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Old 04-24-2014, 10:24 PM   #85
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These engines do have a throttle like normal
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Old 04-24-2014, 10:25 PM   #86
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saved me the trouble
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Old 04-25-2014, 07:43 AM   #87
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Quote:
Originally Posted by Vlad View Post
Please do.

The info I found refers to the BRZ and you can see that it has a TB.
Then that injection system is linked to a Toyota direct injection that does have a TB.
Now that partial FA20DIT teardown from the Japanese site that someone linked, showed something similar with composite TGV housings.

The point I was trying to make is that with a DIT, these could be a lot more than just TGV.

I wonder if these become the .. part time throttle plates? Then maybe you won't find a central unit.

Also, the DI field seems to be moving fast, new things come out often.
The TGV's control the tumble characteristic of the intake port. VW uses them on most of their DI engines as well. TGV's don't control load, even though they do restrict flow.

I know it sounds weird, but you can't have an "unthrottled" gasoline engine without a throttle. You're still using the throttle even when the valve events are limiting load. You also use it during starting and as another form of torque control during various events. I
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Old 04-25-2014, 08:13 AM   #88
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I'm going to venture a guess that everybody here knows what TGV's do, it's not necessary to repeat that... again.

I was talking about ... new... TGV ... additional... assignments.


An engine with no throttle plate is possible.

Here's a quotation from BMW:
"This highly advanced technology replaces the conventional throttle butterfly with a electrical mechanism that controls the amount of lift of the individual intake valves on each cylinder. Your engine is able to breathe freely, delivering better performance while using less fuel.
The performance of the engine is more efficient and immediate, thanks to the elimination of the pumping losses and air-flow disturbance caused by a conventional throttle butterfly. Instead, air can flow through the intake manifold freely, and Valvetronic precisely regulates the quantity of air entering the cylinders"

So yes, it is possible, not only possible, but one is currently in production. And the whole point of this engine is to achieve control with a method other than using a throttle. It's not semantics, it's real pumping losses savings.

Here's a quotation from Wikipedia:
"The cited gains are achieved by the precise control over the amount of fuel and injection timings that are varied according to engine load. In addition, there are no throttling losses in some GDI engines, when compared to a conventional fuel-injected or carbureted engine, which greatly improves efficiency, and reduces 'pumping losses' in engines without a throttle plate. Engine speed is controlled by the engine control unit/engine management system (EMS), which regulates fuel injection function and ignition timing, instead of having a throttle plate that restricts the incoming air supply"

As always, they base info on articles and one can research the notes that lead to the articles.

So at this point, let's go back to the FA20DIT.

Last edited by Vlad; 04-25-2014 at 09:40 AM.
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Old 04-25-2014, 12:55 PM   #89
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Can anyone list all of the different things that are connected to the crank pully? A/C compressor, alternator, etc.

Last edited by Sinsear; 04-25-2014 at 01:07 PM.
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Old 04-25-2014, 01:58 PM   #90
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A/c, alternator, power steering. Just like any other car, unless they switched to electronic power steering.
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Old 04-25-2014, 02:00 PM   #91
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A/c, alternator, power steering. Just like any other car, unless they switched to electronic power steering.
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Old 04-25-2014, 02:03 PM   #92
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you can sort of see what the belt is doing 8 mins into my monotone walk around vid

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Old 04-25-2014, 02:28 PM   #93
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Quote:
Originally Posted by HinshawWRX View Post
A/c, alternator, power steering. Just like any other car, unless they switched to electronic power steering.
It's EPS, so no more HPS pump. Additionally, I'm pretty sure the water pump is also now electric.
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Old 04-25-2014, 05:46 PM   #94
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Quote:
Originally Posted by Celery GT-5 View Post
I was at the gym when I replied, too lazy to google. Plus I haven't followed crap of the new ones.

Quote:
Originally Posted by Sinsear View Post
It's EPS, so no more HPS pump. Additionally, I'm pretty sure the water pump is also now electric.
EPS is a great thing.
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Old 04-25-2014, 05:52 PM   #95
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Quote:
Originally Posted by Sinsear View Post
It's EPS, so no more HPS pump. Additionally, I'm pretty sure the water pump is also now electric.
Water pump is not electric, it is driven off the v belt now
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Old 04-26-2014, 07:35 PM   #96
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Anybody seen or try any TMIC setups yet?
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Old 04-26-2014, 11:17 PM   #97
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Anybody seen or try any TMIC setups yet?
I believe there are 2 companies already, one might be AVO ... theres a few pictures somewhere on the forum. Also since there isn't many tuning options you wont see people with intakes or TMIC's until the Cobb AP is out
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Old 04-29-2014, 11:12 AM   #98
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I can't wait for the first FA20DIT GC8 swap.
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Old 04-29-2014, 12:54 PM   #99
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Anybody seen or try any TMIC setups yet?

One here: http://legacygt.com/forums/showpost....&postcount=710
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Old 07-08-2014, 10:42 PM   #100
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I've been searching the past few days for info on fa20dit interchangeability with the old ej platform. I'm guessing the fa and ej platforms can't be used for a hybrid setup like we did with the ej205 heads and ej25 short block. Can anyone point me to post where people have looked using fa20dit heads on an ej25 short block? Or... Any threads about bolting the STi 6speed to an fa20 short block? The previous wisdom was any ej trans would bolt to any ej short block.... So I'm wondering if the fa bell housing bolt pattern is now different.

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