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F-150 3.7 Engine
21 messages, Last post on Jun 12, 2012 at 6:18 PM
You are in the Ford F-Series Forum.- Your Host is kcram
What is this discussion about? Ford F-150, Ford F-250, Ford F-350, Engine, Truck
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#15 of 21 The TRUTH by wwest
Jun 08, 2012 (10:12 am)
[quote=BigMcLargeHuge;1771479]2011 Ecoboost owner here, and was hoping to get some clarity on the operation of the twin-turbo V6 from experienced tuners and mechanics.I was arguing with someone (That would be me) who claims the turbos operate like NOx. I.e. boost is either all or nothing (assuming he'd never driven the Ecoboost because it certainly feels like an incremental building of boost).
No, my position has always been that EcoBoost/Twinforce simply uses the wastegate as an extention of the throttle plate. Once the engine reaches PEAK POWER (accelerator pedal position ~mid-point...throttle plate fully open?) in N/A mode the wastegate begins being gradually closed in order to bring on higher, boosted, power levels.
Perhaps he is used to old big turbos with significant lag, but from his experience, he assumes that all turbine wheels are very heavy, and therefore the purpose of the waste gate is to allow exhaust to bypass the exhaust wheel, the turbine stationary (not stationary, but NOT producing boost) until the 'naturally aspirated' V6 has 'torqued out' and then the waste gate is closed, and being at full throttle, only then is enough exhaust gas produced to spin the turbine.
Pretty well stated except for "my assumption" "all turbine wheels are heavy" which is clearly a relative issue.
A few of his assumptions did not make sense to me: first off, he assumed that the Ecoboost uses positive-displacement turbines that are very heavy, so if the waste gate was closed at anything under half-throttle, the engine would be choked out by backflow.
Insofar as I am aware there is NO such animal as a positive displacement turbocharger. Turbines are ALWAYS heavier then the design engineer would like.
He even went so far as to compare it to a Boeing 727 turbojet (about 1meter in diameter) saying that turbines take tremendous energy to spin at all. I found that disproportional scale a bit ridiculous, and that example also ignores the fact that even large turbines can idle, thus so should a small turbine spin at the speed of exhaust gases passing through it.
This statement was made in the context of the fact that early on in the life of the 727 it was discovered that on final approach there was a need, requirement, to keep the turbines somewhat spooled up in case the sink rate (wind shear) became to great or the need for a go-around arose.
This is not my first turbocharged vehicle, so my understanding of the ecoboost is that:
1) the turbos are not positive displacement, (agree, absolutely) as a seized turbo only saps power, since gases can still pass through, just without spinning the intake impeller.
It would be my opinion that a stalled impeller/turbine assembly, assuming a closed wastegate, would severely sap the engine power.
2) the wheels are lightweight alloys with low-friction bearings, so the waste energy of combustion (even at idle) can spin the turbine wheel (albeit slowly) (I've listened to EB trucks with aftermarket exhaust and the whistling noise at all rpms is the turbine wheel breaking up the flow of the exhaust, ie spinning, correct?)
No dispute.
3) boost is mild under mild load/accel and ramps up as load/accel is demanded. It's not all/nothing.
No, boost is essentually ZERO until the engine's peak power point is reached under load.
4) the waste gate remains closed until manufacturer max boost is achieved. Then the waste gate opens to prevent over spinning the turbo.
Correct, except over-spinning the turbo would not be the initial issue if the design is correct, over-boosting the engine would be.
5) there are vent valves / blow-off valves on the intake side that allow the turbo to pressurize up to that point, but only allow appropriate intake pressurization in combination with throttle-plate position (because too much air would cause predetonation).
Modulating the wastegate position suffices as a "vent valve". Blow off valves are used only to release boost pressure if/when the accelerator pedal is released while/when the engine is under boost.
6) back pressure on the engine is low, like lower than a catalytic converter, as cats can't equalize rotating speed with the flow of exhaust. Certainly not enough to seize and engine if exhaust is allowed to pass through it at less than full throttle.
No opinion.
Am I on the right track citing literature from other turbocharged engines or is EB so different as I cannot claim these points?
I must side with Ford, and likely the USPTO, on this point. The EcoBoost/twinForce design concept is quite radically different from traditional/historical super or turbo charging designs. Traditional designs did not use DBW to migrate the throttle function from one means, the throttle plate, to another, the wastegate. Most simply used engine vacuum, or lack thereof, really, to control teh closing of the wastegate.
Or am I totally off and EB waits until it 'torques out' in 'NA mode' and turbochargers use waste gates like a 'clutch' to engage like opening a NOS bottle?
No, not like a clutch, at least not in the on or off sense, more like as extention of the throttle plate functionality.
Experienced descriptions are much appreciated. Thanks in advance.[/quote]
I hope this helps to clarify my position...
One additional point. In my personal opinion it would be desireable for the wastegate position to be controlled, modulated, such that the impeller, when ever possible, be always spooled up right to the level of being in NEUTRAL, no boost, but no drag on the incoming airflow rate. Basically no "work" being done.
#16 of 21 Oh noo.... Wwest by bigmclargehuge
Jun 08, 2012 (11:46 am)
Wwest, every single face in the room ( including the smileys at the bottom ) have a broader intellect than you.You ADMITTED you were guessing, your statements are not only intellectually unfounded, they are the complete and total opposite of reality, despite all available evidence.
Ignorant would be one thing, but to read and come up with your conclusions is worse.
Your message of pure unadulterated lies? You should be so proud, lol
#17 of 21 Wwest gets owned by yet another more knowledgeable poster by bigmclargehuge
Jun 08, 2012 (12:05 pm)
Your opinion of yourself can't possibly be this inflated?I mean really, what are the odds that 100% of persons you disagree with have more experience than you, and yet you are the only person on earth who 'gets it?'
Impossible. You've had the wrong 'message' for years. Get over yourself.
WWEST I love when people know everything there is to know about something when they have absolutely 0 actual experience with what theyre talking about.
You idea of manifold vaccum is 100% incorrect. The prescense of vacuum in the manfold is what keeps the wastegate CLOSED in traditional systems. If the wastegate was always open under vacuum conditions, no boost pressure would ever be generated as all of that precious exhaust gas would be bypassing the turbine the entire time preventing boost generation.
The fact is, the wastegate OPENS as the desired boost psi is realized in the manifold.
This is such basic turbo operation theory im actually a little embarrassed to have to explain this to you.
Makes me wonder.......... have you EVERY owned or even driven a turbo vehicle?
The very existence of a vacuum pump on a mid 90s diesel chevy truck is only to keep the wastegate closed until desired boost psi is realized.
On a conventional gas engine (gas engines make vacuum because of the presence of a throttle plate-- diesels do not) manifold vacuum "sucks" the wastegate closed allowing the turbing to spin which of course makes the compressor spin (they are rigidly connected) which generated boost psi in the manifold.
thats all for now............... class dismissed.
#18 of 21 Always on boost when power is applied. by bigmclargehuge
Jun 08, 2012 (12:27 pm)
I'm well aware of forced inductions benefits at high altitude,But it is also extrapolated down to sea level. Same functionality, only slightly less efficiency.
So yes, while I sincerely doubt that 20-30% estimate I don't doubt that at the elevation you most commonly drive the engine is on-boost more of the time than an equivalent here in the Seattle area.
That's only of total time in motion. 100% of the time a boosted engine is being used for things that make engines matter, they are on boost.
Only time off-boost is coast, braking, idling, or very low-speed steady-state (43mph on a flat road).
All acceleration involves boost, and in 'mixed' driving with as many up-hill sections as down (obviously), 20-30% is a fine estimate at 16,000 ft or 600.
Your supposition of 1% is based on an embarrassing understanding of the mechanism involved (particularly wastegate operation).
#19 of 21 Re: 3.7 vs 3.5 Ecoboost [wwest] by bigmclargehuge
Jun 10, 2012 (3:19 pm)
Replying to: wwest (Jun 08, 2012 7:53 am)
"..I asked those that tune and work on turbocharged engines..." Right, clearly no conflict of interest in that group, nor any narrowly focussed intelligence either.
Narrowly focused intelligence, eh? Seems like it ended up being Willard West that had the narrowly focused intelligence over there.
I do not "guess" if my statements are not intellectually well founded and knowledgeable of the subject matter I would not expose myself to the type of false ridicule that you so willingly provide.
Intellectually well founded eh? Not only did you reverse in your head what was actually being described on Ford Motorparts, you were certainly 'guessing' at everything else
I prever evidence... which I always had, just not recorded
I'm quite comfortable that my message gets through to enough readers to make my time worthwhile.
Glad you're so proud of spewing BS for SEVERAL YEARS!
#20 of 21 This discussion is... by kcram HOST
Jun 12, 2012 (5:45 pm)
...about the 3.7L V6 base engine, not the 3.5L EcoBoost V6. I've given you guys some rope, but I'm breaking out the scissors.kcram - Pickups/Wagons/Vans+Minivans Host
- temj12 (Jun 12, 2012 6:18 pm)
Replies to this message:
#21 of 21 Re: This discussion is... [kcram] by temj12
Jun 12, 2012 (6:18 pm)
Replying to: kcram (Jun 12, 2012 5:45 pm)
Thank you! This has gone on too long.
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