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Author Topic: Slow Spool Up On Hybrid Turbo (tune related)  (Read 6708 times)
ThomasHH
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« Reply #15 on: June 16, 2022, 07:57:19 AM »

Nothing to do with ECU, purely engine/tuning knowledge of basic and DI systems.

Does this mean that his problem was mechanical and not software related?
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prj
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« Reply #16 on: June 16, 2022, 08:21:32 AM »

Does this mean that his problem was mechanical and not software related?
The solution to his problem is summarized in the first reply to his post.
If you don't understand, then you need to do a lot more reading before messing with ECU's.

It is applicable to any engine and ECU with cam adjustment, the only thing extra with DI is to make sure scavenging is active so that injection pressure and angle is correct to prevent blowing fuel out the exhaust, but the ECU takes care of that for you as long as you are in the right mode.
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« Reply #17 on: June 16, 2022, 01:11:24 PM »

FWIW on non-DI motors, my experience with VVT (on ME7) and spool is that it is negligible (though measurable). I have not tuned DI cars personally, but I would imagine scavenging has a much much more profound effect on spool.
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BlackT
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« Reply #18 on: June 16, 2022, 01:23:36 PM »

Everything needed is in the thread.
If you don't know what valve timing or scavenging is and how to adjust this, then time to start reading.

Nothing to do with ECU, purely engine/tuning knowledge of basic and DI systems. Scavenging on DI is overlap without blowing fuel out the exhaust, nothing more.
As to how this is beneficial for spool, really helps if you read some books on the subject or at least understand how an ICE works instead of playing Excel spreadsheet all day!
Maybe stupid question but:
Is it possible to make similar on 1.8T with cams that have overlap?
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Blazius
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« Reply #19 on: June 16, 2022, 01:32:06 PM »

Maybe stupid question but:
Is it possible to make similar on 1.8T with cams that have overlap?


Thats what VVT does. Or you mean changing injection start time or something ?
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prj
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« Reply #20 on: June 16, 2022, 01:54:56 PM »

FWIW on non-DI motors, my experience with VVT (on ME7) and spool is that it is negligible (though measurable). I have not tuned DI cars personally, but I would imagine scavenging has a much much more profound effect on spool.
I don't know how to put it otherwise, but you are just wrong.
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BlackT
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« Reply #21 on: June 16, 2022, 01:58:52 PM »

Thats what VVT does. Or you mean changing injection start time or something ?
Yes you are right, so not possible to make anything better.

Only maybe will fuel in exhaust manifold spool turbo   faster?  But that also doesent have sense that fuel will not burn without oxigen
Also PRJ say "without waste fuel"

I must read more about that, it is new zone to me.
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nyet
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« Reply #22 on: June 16, 2022, 03:29:10 PM »

I don't know how to put it otherwise, but you are just wrong.

Given that the stock VVT settings on ME7 already extend well into the meaty part of spool, there isn't that much difference delaying changeover a bit further. Yes, it makes some difference, but if you have big turbo, its going to take a long fucking time to even get to the stock changeover range. Unless I'm missing something obvious.
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« Reply #23 on: June 16, 2022, 05:51:51 PM »

Yes you are right, so not possible to make anything better.

Only maybe will fuel in exhaust manifold spool turbo   faster?  But that also doesent have sense that fuel will not burn without oxigen
Also PRJ say "without waste fuel"

I must read more about that, it is new zone to me.

VVT is amazing specially on these(1.8t / 2.7) engines, on lower RPM it can easily bring 30-50 Nm more torque than without on an 1.8T , and I've seen logs with spool improvement of 300-500 rpm, this isn't a new topic but I dont agree with nyet either.
Think,what does VVT do ? It creates overlap, overlap creates intertial supercharging and improves scavenging. There is a limit where it stops being beneficial  vs boost loss through overlap though.
This is why I dont recommend putting both NA cams in 1.8T they have a decent amount of overlap, but in a turbo engine you dont need since you can use VVT, use one for duration/more lift but not both,anyway optimising a build is a whole different topic.

The fuel dumping spool myth is pretty common in diesel world afaik, it will not improve spool but you will crack a piston Cheesy Dumping fuel and retarding timing different thing however it likely still wont be beneficial because you will loose power/torque, people forget about this all the time, torque spins the crank it determines your RPM gain/s and RPM determines your flow rate so actually you might spool lower than before.
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prj
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« Reply #24 on: June 16, 2022, 10:47:13 PM »

The bypassed air due to valve overlap creates more flow over the turbine helping spool.
Once turbo spools up, the backpressure overpowers the effect at some point... so the overlap is ramped back down. Basics of cam timing tuning applicable to all engines with variable cam timing.

On a MPI engine, you are blowing unburned fuel into the exhaust during the overlap stage, as the bypassed charge is already mixed with fuel in the intake manifold.
Extreme examples on factory cars are Evo IX and Evo X, where as much as 30% goes straight out the tail pipe as black smoke during spool, because of the large adjustment range of MIVEC and fairly aggressive timing. VAG's early 20 degrees is very mild in comparison, but much better for fuel consumption. However the Evo's spool much better.

On a DI engine you can retard the injection angle so that no fuel is injected until the exhaust valve is closed.
As this is relevant during spool up you don't run out of injection window either. This is what the scavenging combustion mode does on S18.
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ThomasHH
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« Reply #25 on: June 17, 2022, 01:04:17 AM »

The bypassed air due to valve overlap creates more flow over the turbine helping spool.
Once turbo spools up, the backpressure overpowers the effect at some point... so the overlap is ramped back down. Basics of cam timing tuning applicable to all engines with variable cam timing.

On a MPI engine, you are blowing unburned fuel into the exhaust during the overlap stage, as the bypassed charge is already mixed with fuel in the intake manifold.
Extreme examples on factory cars are Evo IX and Evo X, where as much as 30% goes straight out the tail pipe as black smoke during spool, because of the large adjustment range of MIVEC and fairly aggressive timing. VAG's early 20 degrees is very mild in comparison, but much better for fuel consumption. However the Evo's spool much better.

On a DI engine you can retard the injection angle so that no fuel is injected until the exhaust valve is closed.
As this is relevant during spool up you don't run out of injection window either. This is what the scavenging combustion mode does on S18.


Oh nо..., I just started reading and you told me everything ... Why did you do that?

Next time, keep your knowledge to yourself and don't waste my pleasure of learning it myself.
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nyet
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« Reply #26 on: June 17, 2022, 09:42:34 AM »

VVT is amazing specially on these(1.8t / 2.7) engines, on lower RPM it can easily bring 30-50 Nm more torque than without on an 1.8T , and I've seen logs with spool improvement of 300-500 rpm, this isn't a new topic but I dont agree with nyet either.

Sorry, maybe i didn't express what i meant clearly; I didn't mean to say VVT doesn't do anything; i meant to say (at least on the 2.7t), changing the *stock* VVT changeover point gives you limited gains as the stock point is already fairly high.
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ME7.1 tuning guide (READ FIRST)
ECUx Plot
ME7Sum checksum checker/corrrector for ME7.x

Please do not ask me for tunes. I'm here to help people make their own.

Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your experience.
prj
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« Reply #27 on: June 17, 2022, 10:25:38 AM »

The way you made it sound is that vvt is useless.
Changeover is at a reasonable place yes.
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Vollmer
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« Reply #28 on: June 28, 2022, 12:54:22 PM »


Oh nо..., I just started reading and you told me everything ... Why did you do that?

Next time, keep your knowledge to yourself and don't waste my pleasure of learning it myself.

LOL!

Another example of the know-it-alls arguing, while saying you are too stupid to understand it.
Good thing they don't either. Usually because their experience is limited scope.

Pretentious and arrogant. This place has some of the most toxic people. I laugh, as not to take it seriously and feel sick.
Whats funny is looking up their own "noob" posts from 10 years ago, and how much their attitudes have changed.
Bullied become the Bullies.

The information here is a completely disorganized mess, with many of the downloads and information removed and redacted.
Many people here end up being shit-peddlers and scammers. Very little is community oriented unless you are one of the resident assholes from several years back.
"The information is in the thread". It's like a group chant. The information is out there to do anything and everything known to mankind. So?

If you want honest information regarding, look elsewhere for practical examples from multi-million dollar organizations with higher maturity level than these folk. .
Check out the "aggressive" Dual VVT on the Volvos used to maintain flat tq through the rev-range. The Evo MIVEC example was great, unfortunately you will still have to battle the moron who will argue dragsters with "Stage 5" cams lock out phasing.
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BlackT
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« Reply #29 on: June 28, 2022, 01:52:12 PM »

If you have problems there is a clinic for that.
There is no place like this forum, where you get EVERYTHING free. The things like mcmess, me7logger, chk corrector, all tips for IDA even. I will not talk about knowlage about ICE engines you can get here.
Again all is free, made by people who invest years and years, money and sweat to give it, free
If you can't see that  than you have serious problem.
98% problems of 5V engines are covered on this forum. If that is not enought for someone than he does not belong anywhere near car with ICE engine.

It is not same to ask same question 5 years ago and today, when you have all on plate today and there is no mistery about ME7
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