VVT Tuning Noise - ADDED: Comparison Video

[donoman]

@Dezoris I am also concerned. I don't think it's pinging/knocking but it doesn't exactly sound like VTEC, yo. It sounds like my Honda Insight valves when the motor was cold and the oil needed to be changed.

[Dezoris]

Originally Posted by donoman

Sounds to me like valvetrain noise. Or a cam chain. Something like that. It's not a good sound.

It does sound "raspy" like the old E46 M3's... not sure if that's a good thing though.

I had the aggressive VVT tuning removed from the tuning and noise was gone. No one has been able to explain mechanically what is causing the noise so I opted for safety.

[donoman]

@Dezoris

Thanks for the reply. How would I go about removing the aggressive VVT tuning on my OFT? I understand this question may be out of scope but I thought I would ask.

I ran an experiment today:
1) Smooth, light acceleration from start to high RPM - No buzzing
2) Hard acceleration from start to high RPM - Buzzing
3) Light accel around 4000 RPM - no buzzing
4) Hard accel around 4000 RPM - Buzzing

What I found is that the noise is not dependent on RPM as much as it is dependent on load. With that said, do the VVT maps account for load?

If they don't, then there is something being stressed in the motor due to load, which is causing the sound. This would make the hypothesis that the sound is due to valve overlap (or even simple mechanical resonance) a bad one. I believe both valve overlap and mechanical resonance should rear their ugly heads at a specific RPM, not necessarily a specific load.

[ztan]

Originally Posted by donoman

What I found is that the noise is not dependent on RPM as much as it is dependent on load. With that said, do the VVT maps account for load?

If they don't, then there is something being stressed in the motor due to load, which is causing the sound. This would make the hypothesis that the sound is due to valve overlap (or even simple mechanical resonance) a bad one. I believe both valve overlap and mechanical resonance should rear their ugly heads at a specific RPM, not necessarily a specific load.

The VVT maps are based on load/RPM and do change quite significantly as the throttle opens up at the top end. Open them up with ROMRaider and have a look. Kodename47 also has some nice VVT overlap spreadsheets that let you look at where the overlap numbers change.

[donoman]

@ztan thanks for the advice!! Will check it out tonight. Is there a way for me to edit own VVT map and is it safe?

[ztan]

Originally Posted by donoman

@ztan thanks for the advice!! Will check it out tonight. Is there a way for me to edit own VVT map and is it safe?

You can edit your own VVT (AVCS) maps, make sure you have a good grip on what you are trying to achieve and be able to log your engine well. I log knock parameters (FBKC, FLKC, IAM), fuelling trims and afr, and also calculate volumetric efficiency to see how well my engine is swallowing air.

Lots of good threads on NASIOC and other Subaru sites about engine tuning in general.

http://igotasti.com/vBforum/archive/...hp/t-4616.html
Td_d: "Do not take the process of AVCS tuning lightly. You will blow shit up."

[OkieSnuffBox]

Originally Posted by Dezoris

I had the aggressive VVT tuning removed from the tuning and noise was gone. No one has been able to explain mechanically what is causing the noise so I opted for safety.

I'm amazed that you still don't understand how cam timing and overlap can affect induction noise.


You remember the old Honda/Acura AEM intakes? The specifically used tuned resonance to force more air into the cylinder.


Or like these guys that modify the intake manifold to take advantage of intake reversion to increase midrange torque. http://www.metricmechanic.com/produc.../baby-six-m20/


Or like many cars today that have dual-stage intake manifolds one for low rpm and one for high rpm.




It's not difficult to understand, really.

[Dezoris]

Originally Posted by OkieSnuffBox

I'm amazed that you still don't understand how cam timing and overlap can affect induction noise.


You remember the old Honda/Acura AEM intakes? The specifically used tuned resonance to force more air into the cylinder.


Or like these guys that modify the intake manifold to take advantage of intake reversion to increase midrange torque. http://www.metricmechanic.com/produc.../baby-six-m20/


Or like many cars today that have dual-stage intake manifolds one for low rpm and one for high rpm.




It's not difficult to understand, really.

I am not arguing the concept. But in the case of my motor it made virtually no difference in power delivery on dyno or in drivability. I have heard all the arguments as well and listened to multiple tuners explain not only VVT overlap and optimization but also tuners talk about how optimizing timing to increase power at higher RPM is safe too, and all the promises. The tuners generally want one thing, to show better results on a dyno. I have lost a lot of faith in plenty of tuners for this platform and and companies from owning this car.

And in this case the VVT optimizations it raised red flags, and everyone who was in the car who heard the "resonance" said it sounded horrible. At to have it at 3000-4000 rpm under partial throttle every shift is absurd for.daily driving.

[donoman]

@Shiv@Openflash Any chance you have a "non-aggressive VVT" tune available for OFT as Perrin has provided @Dezoris for their tune? I love everything about the OFT Stage 1 tune except the sound is very concerting.

Thanks in advance!

[OkieSnuffBox]

Originally Posted by donoman

@Shiv@Openflash Any chance you have a "non-aggressive VVT" tune available for OFT as Perrin has provided @Dezoris for their tune? I love everything about the OFT Stage 1 tune except the sound is very concerting.

Thanks in advance!

It is like a public concert. Were you looking for disconcerting or concerning?




I just find this all quite humorous. Buy a lightweight, loud, rough riding sports car, start modifying it and then complain about a brief harmless noise when accelerating hard.

[chaoskaze]

The real answer is EZ30 swap!! Ok I will show myself out...

[Shady195]

Originally Posted by donoman

@Shiv@Openflash Any chance you have a "non-aggressive VVT" tune available for OFT as Perrin has provided @Dezoris for their tune? I love everything about the OFT Stage 1 tune except the sound is very concerting.

Thanks in advance!

Part of what makes the OFT Stage 1 tune for those without headers so good is the aggressive VVT where the torque dip is concerned.

[donoman]

Originally Posted by OkieSnuffBox

I just find this all quite humorous. Buy a lightweight, loud, rough riding sports car, start modifying it and then complain about a brief harmless noise when accelerating hard.

It doesn't matter whether it's my Porsche, my BMW or my Scion, I'm always looking for the best. "Harmless" is an assumption ... it just doesn't sound smooth like the VTEC hitting on my Honda's. I've never owned a Subaru before, so that may be what is tripping me out. I've never heard this kind of noise in any German car.

[OkieSnuffBox]

Originally Posted by donoman

It doesn't matter whether it's my Porsche, my BMW or my Scion, I'm always looking for the best. "Harmless" is an assumption ... it just doesn't sound smooth like the VTEC hitting on my Honda's. I've never owned a Subaru before, so that may be what is tripping me out. I've never heard this kind of noise in any German car.

You do understand the difference between VTEC and VVT, right?