AVCS - Intake and Exhaust Timing

[KoolBRZ]

Should I get my AVCS and MAF scaling nailed down first then?

[solidONE]

Originally Posted by KoolBRZ

@thambu19, since these things go hand-in-hand, which ones should we do first? I've been using your PFI-to-DI table as a given, then changing my AVCS to get only 2-3% scavenging. Without getting into logs, I can say that backing off my AVCS has resulted in a richer AFR than requested, rather than a leaner AFR. I've also bumped up my Base Timing B by 2 degrees in the 100% DI areas. So far IAM stays at a solid 1, and FLKC at 0.

I'm curious how your cam timing is effecting your afr particularly at the 1500~3500 range going WOT. I'm getting some pretty crazy looking fluctuations at that range at peak loads presumably from the scavenging effect of the cam timing and the long tube headers. I've tried to address it with changes to the Engine Load Limiter tables without much success.

Here's a most recent one I took:http://datazap.me/u/solidone/af-lear...3112-3130-3124

Can you share with me what your AFRs are looking like at that range?

Here's a log with the cam timing being recorded last month. I've not made any changes to my cam timing tables, so the above log should have similar cam timing: http://datazap.me/u/solidone/plm3-ca...zoom=1513-1873

[thambu19]

Originally Posted by KoolBRZ

Should I get my AVCS and MAF scaling nailed down first then?

Yes cams first along with fueling finally spark to knock limit

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[thambu19]

Originally Posted by solidONE

I'm curious how your cam timing is effecting your afr particularly at the 1500~3500 range going WOT. I'm getting some pretty crazy looking fluctuations at that range at peak loads presumably from the scavenging effect of the cam timing and the long tube headers. I've tried to address it with changes to the Engine Load Limiter tables without much success.

Here's a most recent one I took:http://datazap.me/u/solidone/af-lear...3112-3130-3124

Can you share with me what your AFRs are looking like at that range?

Here's a log with the cam timing being recorded last month. I've not made any changes to my cam timing tables, so the above log should have similar cam timing: http://datazap.me/u/solidone/plm3-ca...zoom=1513-1873

With 2% o2 I. Exhaust the sensor will read 16. Oem s limit to 1%. So if you are seeing 16 then you really are running stock incylinder

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[thambu19]

Originally Posted by thambu19

With 2% o2 I. Exhaust the sensor will read 16. Oem s limit to 1%. So if you are seeing 16 then you really are running stock incylinder

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That is if you are sure it is scavenging

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[solidONE]

Originally Posted by thambu19

That is if you are sure it is scavenging

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I'm pretty sure it is, because the fluctuations start when the intake cam climbs to 40* advance and the exhaust toward 35* retard. Once the exhaust cam retard settles below -30* at 3300rpm, so do the AFR. Although the lean spike right where the cam timing gets aggressive is not the only concern, but also the fluctuation immediately after it. It will go from leaner than target to richer like a wave until it settles past 3500rpm.

http://datazap.me/u/solidone/af-lear...4863-4859-4848

I also need to adjust the target AFR at the peak ranges. I guess I've been lucky that the computer somehow richens up the mixture for me at peak power to around 12.0:1 even though I've been targeting 12.5~12.3...

Edit: anyhow, hope you're enjoying your vacation, and the wifey is not mad about you doing this on your vacation lol

[thambu19]

Originally Posted by solidONE

I'm pretty sure it is, because the fluctuations start when the intake cam climbs to 40* advance and the exhaust toward 35* retard. Once the exhaust cam retard settles below -30* at 3300rpm, so do the AFR. Although the lean spike right where the cam timing gets aggressive is not the only concern, but also the fluctuation immediately after it. It will go from leaner than target to richer like a wave until it settles past 3500rpm.

http://datazap.me/u/solidone/af-lear...4863-4859-4848

I also need to adjust the target AFR at the peak ranges. I guess I've been lucky that the computer somehow richens up the mixture for me at peak power to around 12.0:1 even though I've been targeting 12.5~12.3...

Are you using a blower? If you are not I won't have so much overlap to start with.

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[KoolBRZ]

Originally Posted by solidONE

I'm curious how your cam timing is effecting your afr particularly at the 1500~3500 range going WOT. I'm getting some pretty crazy looking fluctuations at that range at peak loads presumably from the scavenging effect of the cam timing and the long tube headers. I've tried to address it with changes to the Engine Load Limiter tables without much success.

Here's a most recent one I took:http://datazap.me/u/solidone/af-lear...3112-3130-3124

Can you share with me what your AFRs are looking like at that range?

Here's a log with the cam timing being recorded last month. I've not made any changes to my cam timing tables, so the above log should have similar cam timing: http://datazap.me/u/solidone/plm3-ca...zoom=1513-1873

Are you running the OFT cam tables for ESC? I've backed off the advance/retard of the AVCS timing for Intake and Exhaust. I'm looking for the ideal cam timing before I rescale my MAF. 7 degrees less Intake advance and 5 degrees less of the Exhaust retard. I also advanced Base Timing B 2 degrees in the areas where DI is 100 %, below 3000 rpms though. I loaded a tune with 4 degrees, but haven't driven it yet.

[solidONE]

Originally Posted by thambu19

Are you using a blower? If you are not I won't have so much overlap to start with.

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Nope. Completely NA. I just uploaded the cam tables somebody loaded for these headers. There hasn't been much knock correction going WOT, and I gained about 20 ft/lb of torque and WHP over my previous setup at 4500rpm, which makes me a very happy guy, using the current cam tables. But of course, I'm open to your suggestions before I start tweaking the cam timing tables. Should I start with adjustment to just the exhaust cam timing to reduce overlap?

Old setup vs new setup. Both catless headers.


new setup initial baseline vs after some adjustments:

[solidONE]

Originally Posted by KoolBRZ

Are you running the OFT cam tables for ESC? I've backed off the advance/retard of the AVCS timing for Intake and Exhaust. I'm looking for the ideal cam timing before I rescale my MAF. 7 degrees less Intake advance and 5 degrees less of the Exhaust retard. I also advanced Base Timing B 2 degrees in the areas where DI is 100 %, below 3000 rpms though. I loaded a tune with 4 degrees, but haven't driven it yet.

I'm running the cam tables someone posted for these headers, not sure who did them. I can't say I'm not happy with them, given the amount of gains I'm getting.

[thambu19]

Originally Posted by solidONE

I'm pretty sure it is, because the fluctuations start when the intake cam climbs to 40* advance and the exhaust toward 35* retard. Once the exhaust cam retard settles below -30* at 3300rpm, so do the AFR. Although the lean spike right where the cam timing gets aggressive is not the only concern, but also the fluctuation immediately after it. It will go from leaner than target to richer like a wave until it settles past 3500rpm.

http://datazap.me/u/solidone/af-lear...4863-4859-4848

I also need to adjust the target AFR at the peak ranges. I guess I've been lucky that the computer somehow richens up the mixture for me at peak power to around 12.0:1 even though I've been targeting 12.5~12.3...

Edit: anyhow, hope you're enjoying your vacation, and the wifey is not mad about you doing this on your vacation lol

Haha wife is okay. Puerto Rico is nice. Lovely.

Looking at your AFR spiking at below 2K rpm your header has a long scavenging length. Preferable for good low end torque.

[thambu19]

Originally Posted by solidONE

Nope. Completely NA. I just uploaded the cam tables somebody loaded for these headers. There hasn't been much knock correction going WOT, and I gained about 20 ft/lb of torque and WHP over my previous setup at 4500rpm, which makes me a very happy guy, using the current cam tables. But of course, I'm open to your suggestions before I start tweaking the cam timing tables. Should I start with adjustment to just the exhaust cam timing to reduce overlap?

Old setup vs new setup. Both catless headers.


new setup initial baseline vs after some adjustments:

You lost some torque below 3K? Anyway you can keep your old cam settings below 3K and get the best of both worlds?

[thambu19]

Originally Posted by KoolBRZ

Are you running the OFT cam tables for ESC? I've backed off the advance/retard of the AVCS timing for Intake and Exhaust. I'm looking for the ideal cam timing before I rescale my MAF. 7 degrees less Intake advance and 5 degrees less of the Exhaust retard. I also advanced Base Timing B 2 degrees in the areas where DI is 100 %, below 3000 rpms though. I loaded a tune with 4 degrees, but haven't driven it yet.

Since he is purely on headers without a blower his setup will be a lot different.

How did the new timings work out? Did you keep everything the same after 3K?

[solidONE]

Now, I know this thread is about cam timing and not fueling but since it was mentioned in this thread about having the AFR set to as rich as 11.8 I would like to address it here. I will move it if requested by OP to a more suitable thread.

Anyhow, I've always assumed that the reason why Shiv had the AFR's dialed that rich was to account for the AFR fluctuation due to inaccurate intake temp compensation tables causing AFR to go lean in hot temperature. I figure that was done as a safety measure. I've dialed my OL fueling table to target 12.3:1 afrs instead of the OTS tables of 11.8:1 to try to maximize power output as everything I've read suggest that the highest burning velocity for gasoline happens at 12.5:1.

Here's the fuel table I'm running currently with my new long tube headers compared to shiv's OTS rom fuel table:


Here's the difference between my current table compared to OTS table:
[IMG]https://scontent-dfw1-1.xx.fbcdn.net/hphotos-xal1/v/t1.0-9/12316480_1009646262434995_4501593154456980711_n.jp g?oh=a50a7c8a97fc***aa446cf25be6b0901&oe=577490F4[/IMG]

You'll notice that its quite a bit richer at 2200rpm above 1.0 load. That was suggested by @Kodename47 to address the lean spike (as lean as 16.1:1) I was seeing with the new headers and cam timing tables. It's also richer at .60~.70 loads at 2000~5200rpm. That was done to try to get some more knock resistance over the OTS rom at part throttle. I've actually ran this fueling table, without the additional fuel enrichment at 2200rpm, with my previous setup along with modified ignition advance calibrations with much less knock correction both in mid-load and at peak power on 91 octane fuel than the 91 octane OTS STG2 EL roms provided by Vishnu Tuning.

Also, I compared the new cam timing table with the OTS stage 2 EL roms, and the one I'm currently running actually has less overlap than the OTS rom at peak power. Although it has much more intake cam advance at the lower end. presumably to try to maximize the scavenging effect of the new long tube headers.

Long Tube Intake Cam Table:


OTS EL Intake Cam Table:


Intake Cam Difference:


Long Tube Exhaust Cam:


OTS Exhaust Cam:


Exhaust Cam difference: