Torque dip reasoning solved?

[zohare]

I agree its a totality of many factors, as the vets here stated some can fixed with tuning, namely smoothing of direct and port injection mix. Has anyone else seen the dyno from ft86speedfactoy's borla uel equipped car? Significant reduction for not going fi. Supports that its acoustics... and as its also been said, the final thing will likely be the intake manifold. Further supported by the fact the dip doesnt exist in turbod cars... cams probably aren't it. It feels just like my Miata she. The variable intake system is functioning poorly... feels like a dam second stage at like 4500. Miata was exactly the same

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[Kodename47]

Originally Posted by Gords_zenith

This may be true, but you didn't need to add the last part about people refusing to understand the why part, when I clearly made an attempt. Also, judging from your condenscending tone you must be the expert and not the F1 engineers that wrote the article. Hmmm.... But thanks for your added info. I agree what hou said but to add another piece, the intake has clearly been designed with the utmost attention to hp, as those power figures that nameless is getting with only a header and 3" exhaust, wouldn't be possible if it wasn't. So I go back to ignition timing as being a main culprit to the torque dip. This is also supported by the dyno graph of nameless showing that it simply only shifted the torque dip to earlier in the Rpms and also a shorter duration.
Cheers.

So you completely ignored my posts then? With the Nameless manifold you get a dip earlier but the original dip is still there to some extent. This will be due to the intake manifold! Don't forget that these create acoustics too due tho the runner lengths, which are quite long on this engine. Would be interesting to see how ITBs would change that with new tuned runner lengths.

And you're theory of timing is muted as re-tuning the ecu cannot remove the torque dip even when the ignition timing has been corrected as well as a whole range of other parameters. I'm not saying what the article says is wrong, its just not relevant here.

[86drift]

Torque dip is due to the runners on the standard headers being too short.
When designing my headers we couldn't see an easy way to get the runners long enough to make a 4-2-1 system (looks like Nameless has it sorted). So we made a tuned length 4-1 as getting the correct length runners was easier.

[Hawaiian]

Originally Posted by Kodename47

So you completely ignored my posts then? With the Nameless manifold you get a dip earlier but the original dip is still there to some extent. This will be due to the intake manifold! Don't forget that these create acoustics too due tho the runner lengths, which are quite long on this engine. Would be interesting to see how ITBs would change that with new tuned runner lengths.

And you're theory of timing is muted as re-tuning the ecu cannot remove the torque dip even when the ignition timing has been corrected as well as a whole range of other parameters. I'm not saying what the article says is wrong, its just not relevant here.

No dip here, and the stock manifold. Just the P&L catted header, and @FA20Club.com tune

[Kodename47]

Originally Posted by Hawaiian

No dip here, and the stock manifold.

Well that definitely shows a dip in the usual place on the non-cat'd version, also the dyno starts at 3k where the torque seems to be rising.... Could there be an earlier dip like the Nameless one? The cat's version looks better but seems there's something happening to the torque earlier on too.

Please don't think I'm digging at either of those manifolds, clearly some of the best we've seen to date. As stated above, with this sort of intake/exhaust tuning will be a trade off somewhere. I feel we may have been provided with decent low end torque for town driving which meant that the mid section was sacrificed.

[cf6mech]

Originally Posted by FR-S Matt

Get a turbo. Issue resolved.

+1

[Acree]

Originally Posted by mad_sb

It has been shown time and again that the dip is NOT just tuning related. Yes, it can be reduced in depth and duration by a small margin with tuning alone. However, what has show the complete ability to remove the dip and in some cases create a mound of power where the dip used to be is long tube headers.

Simply put the "dip" is a culmination of compromises that can be removed with BOTH hardware and software.

Short and simple. Forget what everyone is saying. This is the best and most correct answer.

-Andrew

[Hawaiian]

Originally Posted by Kodename47

Well that definitely shows a dip in the usual place on the non-cat'd version, also the dyno starts at 3k where the torque seems to be rising.... Could there be an earlier dip like the Nameless one? The cat's version looks better but seems there's something happening to the torque earlier on too.

Please don't think I'm digging at either of those manifolds, clearly some of the best we've seen to date. As stated above, with this sort of intake/exhaust tuning will be a trade off somewhere. I feel we may have been provided with decent low end torque for town driving which meant that the mid section was sacrificed.

I was there for these pulls. As far as the drop down in the uncatted version, that was due to the way the pulls were done. He would rev up when 1-4 shifting, but let the car wind down to 2800 before starting the pull and going wot. That curve is just from him getting on the throttle.

As far as the catted version, i wonder if the restriction from the cat causes backpressure to give it that extra in the torque dip. I would like to leave my car with a tuner to let them go at it for a while, i am sure they could really flatten that line out.

[Kodename47]

Originally Posted by Andrew@Autolux

Short and simple. Forget what everyone is saying. This is the best and most correct answer.

Not really an answer though! The OP is asking what the cause of the dip is, and you're saying that the answer is to throw parts at the car and tune it...... helpful!! Sometimes people would like to understand these things rather than just being told how to remedy them Could also mean a different fix might be possible and be a cheaper alternative to what's available at the moment as we're still in early stage development.

[mad_sb]

Originally Posted by Gords_zenith

This may be true, but you didn't need to add the last part about people refusing to understand the why part, when I clearly made an attempt. Also, judging from your condenscending tone you must be the expert and not the F1 engineers that wrote the article. Hmmm.... But thanks for your added info. I agree what hou said but to add another piece, the intake has clearly been designed with the utmost attention to hp, as those power figures that nameless is getting with only a header and 3" exhaust, wouldn't be possible if it wasn't. So I go back to ignition timing as being a main culprit to the torque dip. This is also supported by the dyno graph of nameless showing that it simply only shifted the torque dip to earlier in the Rpms and also a shorter duration.
Cheers.

It is not ignition timing the timing GOES UP in the dip. The airflow drops, load drops, timing goes UP. See attached log of a dyno pull on the stock map with full ignition advance. You can clearly see the dip as it is reflected in the airlfow and engine load. Also notice the timing peaks in the middle of the dip. THe verticle blue line is the end of the dip right around 4700 rpm.

[mad_sb]

Originally Posted by Kodename47

Not really an answer though! The OP is asking what the cause of the dip is, and you're saying that the answer is to throw parts at the car and tune it...... helpful!! Sometimes people would like to understand these things rather than just being told how to remedy them Could also mean a different fix might be possible and be a cheaper alternative to what's available at the moment as we're still in early stage development.

The answer has been given but people are ignoring it because it is not what they want to hear. It is a combination of OEM manifold designs (intake and exhaust) and conservative (emissions and fuel economy focused) OEM tuning.

[Dimman]

Originally Posted by Gords_zenith

This may be true, but you didn't need to add the last part about people refusing to understand the why part, when I clearly made an attempt. Also, judging from your condenscending tone you must be the expert and not the F1 engineers that wrote the article. Hmmm.... But thanks for your added info. I agree what hou said but to add another piece, the intake has clearly been designed with the utmost attention to hp, as those power figures that nameless is getting with only a header and 3" exhaust, wouldn't be possible if it wasn't. So I go back to ignition timing as being a main culprit to the torque dip. This is also supported by the dyno graph of nameless showing that it simply only shifted the torque dip to earlier in the Rpms and also a shorter duration.
Cheers.

So you are doing exactly what I have condescendingly noted of failing to make an effort to understand what's going on.

Better tell Visconti and all the tuners that it's just ignition timing, and the dip will disappear from every tuned car.

[WingsofWar]

Discussed, and acoustics have been noted to be the greatest effect of this phenomenon.

Also please shift your paradigm, as its not a dip but more of a switch, its the end of extreme scavenging during low RPM.

[Gords_zenith]

Well if that is true, than my apologies. I was only trying to show that maybe timing is the key culprit, but like everyone has pointed out, it's clearly the intake runner length combined with avcs that plays a bigger role.