Engine technology thread.

[bambbrose]

It's got two bolt holes for the mounting of something, and the flat surface implies a seal in my opinion.

[old greg]

Originally Posted by Ryephile

Anyone else have an idea? Perhaps a vacuum pump?

I just noticed that the 1.6T engine has a similar appendage, though the casting is different. Seems to be an oil pump.

[bambbrose]

turbo oil feed??!!

I like the implications.

If that part is swappable, that means Subaru/Toyota developed this engine with external oil feeds in mind, and we would have a reliable oil feed source.

What is the yellow going to?

Blue is oil in?
Red is oil to turbo.



EDIT: Just realized what I think it is. I think its the feed for an oil cooler!

[Dimman]

Um... I've ASSuMEd from the beginning that this motor was not using a lift mechanism (cam profile switching, Subaru's AVLS).

Is this correct?

Looking at the torque curve/power separation on the VVTL-i-equipped Celica, and the fact that its 'big' cam is like 292 degrees and lifts over 11mm (massive lift) on the intake, I may very well be preparing for some humble pie. It also stuffs in 34mm intake valves into an 82mm bore (a bit over the 40% of bore diameter I have been using in my calculations).

The curve on the 2ZZGE shows that with sensible cams the torque does peak in the range where I think it should, also around 4000ish rpm. But after the 6000 rpm lift engagement, we end up with a super tight, secondary (and bigger) torque curve. Curve is nowhere near flat though...

Goddammit...

[bambbrose]

Do you think the VTC and the variable lift mechanisms can both be enclosed in the front?

Do modern Subaru boxers use chains or belts for the cams?

If it is a variable lift mechanism, why only the intake?

[chulooz]

What do you mean enclosed in the front? no

This model will have a chain, they have used both in the past.

Im still puzzled about the piece, its bugging the hell out of me.

[Soravia]

I have a question.

I see that FA20 engine has coated piston skirts for reduced friction which is supposed to be part of enabling higher RPM operations. I like higher RPM engines.

Will making vertical grooves on the piston skirt (without cutting too much into it to reduce strength) help enable higher RPM?

How much of a harmonic is affecting higher engine RPM. (The pulley fore of the crank)

Will changing crank and rod (increase rod length, reduce the crack turn radius) enable higher RPM?

Not considering combustion process, what are other mechanical factors of the engine pieces that limit higher RPM? I see that F20C can rev to 9,000 RPM red line and it's just an inline 4. Boxers are supposed to be better at higher RPM operations.

I'm talking about having the FA20 run at 8,500 RPM making power all the way there without taking it to a race engine builder.


A separate question, I know cars have knock sensors next to cylinder walls. Is it feasible to have vibration sensors (accelerometers) on the engine in various angles to measure how much the engine is vibrating? It is used on aircraft parts to measure the conditions of engine and power-train parts, transmissions, gearboxes, drive-shafts, bearings, etc.
Thanks.

[old greg]

Originally Posted by bambbrose

turbo oil feed??!!

Scavenge, more likely. That turbo is pretty much on a level with the oil sump, a gravity drain would never work. You can sort of see in this photo that your yellow banjo bolt (the pump inlet) is connected to your red tube. I believe that line is the turbo oil scavenge, and the unmarked line (red banjo bolt) is the oil return to the sump. The blue line confuses the hell out of me, it appears to be a redundant drain line but that doesn't make much sense.

What I find odd is that the FA has the same boss on top of the head where the (blue) oil line banjo bolt is on the 1.6T. The fact that it's plugged with a bolt is interesting, that means it's an actual threaded hole. It seems to me then, that the FA and the 1.6T must have the same cylinder heads (why else put an apparently useless hole in the right hand cylinder head of the FA?). And what's really interesting is that, if the hole serves no purpose on the FA, it must have been put there specifically for the 1.6T, which would mean that the head was designed with the turbo motor in mind.

Given that the 1.6T is destined to be put to use in the WRX, STI, FXT and LGT it's a much more important engine (investment wise) to Subaru than the FA20. That would imply that the cylinder head was actually designed for the 1.6T and was parts-binned out for the FA20. This would solve one of the minor mysteries surrounding the engine; Why is it called the FA, when the FB came out first? I think that the FA20 is not so much a destroked/debored/renamed FB25, as it is a stroked/bored high compression FA16.

This would also possibly explain Dimman's missing torque.

Originally Posted by Dimman

E) They want to re-create the history of the 4AGE, and have an over-ported (slow intake velocity and high rpm needed for torque) intro head, and the better small port comes later.

Who knows...?

If the ports are sized for a 250+ hp turbo motor, it would certainly explain the mediocre low/medium range torque. But on the plus size, it would imply that there is a lot of flow potential from the stock heads (and hopefully, good knock suppression). So a set of big cams, some stiffer valve springs and a raised rev limiter could make a big difference in performance. And then there's the F.I. potential...

[old greg]

Originally Posted by Soravia

I think it's for adjusting the cams, since most boxers sit far up on the engine bay, there's plenty of room to put stuff in the back of the engine than up front.

The engine in the AS1's will be mounted ~9 inches further back than in previous Subarus. There will be very little room behind the engine.

Originally Posted by Soravia

Will making vertical grooves on the piston skirt (without cutting too much into it to reduce strength) help enable higher RPM?

No.

Originally Posted by Soravia

How much of a harmonic is affecting higher engine RPM. (The pulley fore of the crank)

Very little. The EJ engines do not have harmonic dampers and can run aftermarket lightweight main pulleys with no risk of shortened engine life. There is no reason to believe that the FB will be any different.

Originally Posted by Soravia

Will changing crank and rod (increase rod length, reduce the crack turn radius) enable higher RPM?

The stroke will not be the limiting factor of the stock engine. Stiffer valve springs, and possibly upgraded bearings and stronger connecting rods and bolts will be the first things to look into. And you'll need much more aggressive cams to make the extra revs worthwhile

Originally Posted by Soravia

Not considering combustion process, what are other mechanical factors of the engine pieces that limit higher RPM? I see that F20C can rev to 9,000 RPM red line and it's just an inline 4. Boxers are supposed to be better at higher RPM operations.

Valve weight, valve spring stiffness, steepness of cam profile, connecting rod strength, crankshaft strength, the weight of the piston/pin/rod assembly, peak piston acceleration (based on stroke and rod/stroke ratio), bearing quality, oil pressure/flow to those bearings and probably a few other things as well.

Originally Posted by Soravia

I'm talking about having the FA20 run at 8,500 RPM making power all the way there without taking it to a race engine builder.

That may be possible depending on the flow characteristics of the stock cylinder head ports/valves. Otherwise it will require head work at the very least. You're going to have to pull the motor no matter what, and if you need to change the rods or bearings you'll need to split the crankcase to do it. So whether or not you have to take the motor to a professional depends on how much you are willing to, or are capable of doing yourself.

Originally Posted by Soravia

A separate question, I know cars have knock sensors next to cylinder walls. Is it feasible to have vibration sensors (accelerometers) on the engine in various angles to measure how much the engine is vibrating? It is used on aircraft parts to measure the conditions of engine and power-train parts, transmissions, gearboxes, drive-shafts, bearings, etc.
Thanks.

Sure.

[Dimman]

Originally Posted by bambbrose

Do you think the VTC and the variable lift mechanisms can both be enclosed in the front?

Do modern Subaru boxers use chains or belts for the cams?

If it is a variable lift mechanism, why only the intake?

My post was for my missing torque conspiracy, not the mystery piece.

Sorry for the confusion.

I don't actually know if this is using a lift system.

I think I read somewhere that the Subaru system on the later EJ's does only lift on the intake side, though, and only one of the valves. Not 100% sure though, so I'll have to look into that.

Edit: At least two reviews indicate that it has great mid-range. This means the over-ported theory should be out.

Is it Occam's Razor the thing about simplest explanations?

Extension of the auto-trans 3SGE BEAMS (saves time and cost) applied to Subaru's current H4 architecture (reduces inertia and friction) with the Yamaha-co-developed D4-S system (increase combustion efficiency). This allows more BMEP from more pressure (CR bump) better combustion (D4-S) and reduced losses (H4 with roller rockers and likely newer anti-friction coatings). Conventional cam phasing and BEAMS-derived valve and valve events will put intake air speeds at 4800 for torque and 7000 for hp. 'Extra BMEP' is spread around to either side of the 4800 torque peak. Peak is approximately 168 lb-ft and maintains 90% until 6600 rpm (giving 151 lb-ft). Likewise it is possible that it also produces 90% of peak 1000-2000 rpm earlier. This gives the flat peak without resorting to extra tech and is completely plausible.

Quoted figure ('Preliminary' is underlined in the Scion spec sheet) is chaff.

[old greg]

Originally Posted by old greg

I think that the FA20 is not so much a destroked/debored/renamed FB25, as it is a stroked/bored high compression FA16.

Recent magazine reviews have pretty much confirmed this for me. Car & Driver relay that Subaru says the FA and FB are almost completely unrelated, and that the turbo engine will be based on the FA. Further, Automobile Magazine claim that the FA is physically smaller than the FB. That would suggest a smaller bore pitch, which would make sense if you were designing a smaller displacement engine.

[serialk11r]

Dimman I'm not sure that you can even make strong assumptions based on intake speed with a direct injection system in place; Supposedly they're a game changer. Is it not curious that Toyota uses no lift control on engines with D-4S?

[Silverpike]

Originally Posted by Soravia

I have a question.

I see that FA20 engine has coated piston skirts for reduced friction which is supposed to be part of enabling higher RPM operations. I like higher RPM engines.

Will making vertical grooves on the piston skirt (without cutting too much into it to reduce strength) help enable higher RPM?

Not only will that not work, you will get a ton of blowby and burn oil like it's going out of style. Not a good idea. :P

How much of a harmonic is affecting higher engine RPM. (The pulley fore of the crank)

On modern engines, very very little.

Will changing crank and rod (increase rod length, reduce the crack turn radius) enable higher RPM?

Generally speaking, yes. However, there's a lot of other things required to make this happen. Oiling on the bottom end, bearing clearances, and a whole entire set of top-end changes need to go with this idea.

Not considering combustion process, what are other mechanical factors of the engine pieces that limit higher RPM? I see that F20C can rev to 9,000 RPM red line and it's just an inline 4. Boxers are supposed to be better at higher RPM operations.

Boxes are absolutely not better than inline engines at high RPM. Not sure where you got this idea. The F20C made a lot of design tradeoffs to get it to rev that high, which IMHO aren't such great tradeoffs (I'm not an RPM guy at all BTW).

I'm talking about having the FA20 run at 8,500 RPM making power all the way there without taking it to a race engine builder.

From the mechanical specs I've seen so far, it would take >$10k in parts and a complete rebuild to make this motor do that with any reliability.

A separate question, I know cars have knock sensors next to cylinder walls. Is it feasible to have vibration sensors (accelerometers) on the engine in various angles to measure how much the engine is vibrating? It is used on aircraft parts to measure the conditions of engine and power-train parts, transmissions, gearboxes, drive-shafts, bearings, etc.
Thanks.

You could, but what would you do with this information?

[Soravia]

I was thinking along the lines of using that when engines get modded from stock form. Getting vibe info would be great to know how the new parts or tunes are doing in the engine during the combustion process. On aircraft, this can even help maintain A/C generator (alternator).

Thanks for the explanations. What design compromises did Honda engine use to make power on higher RPM like that? I see that it is a very tall motor.