AVCS - Intake and Exhaust Timing

[freerunner]

20 degrees is a ton of a difference.
Chances are high that you'll throw valve timing too far off from working efficiently, thus ending up with worse fuel efficiency than before.
I'd suggest moving nothing more than 2° at once.

[D-VO]

@steve99 @freerunner

Is that for NA SC or turbo? Or does it matter?

[freerunner]

My answer was in relation to NA engines, but I doubt it will be much different for FI setups.

[freerunner]

I don't know, if my English is good enough to post an explanation, but I try it anyway :

In my understanding, while running low load on low rpm, big heaps of overlap are not needed. What matters though, is getting the intake valve closing and exhaust valve opening spot on the right point.

Exhaust valve has to be opened soon enough to get all burned mixture out of the cylinder, but not too late - in that case the down-moving piston loses the force to pass bottom dead center.

I'm still trying to figure out, how to tune the intake cams. In (my) theory, intake valves should open late without completely avoiding overlap and closing should be late, because the flow of the incoming mixture has low speed.

[Hyperblue302]

I've been following this thread for a couple days now and would like to thank everyone in this thread for all the ideas for changing these tables. I've probably flashed at least 10 tunes this weekend, and right now I'm very happy with the results I have felt. I believe the biggest thing I've noticed working with the avcs tables is I've made sure that no two adjacent cells are more than 5 degrees apart for the intake and 10 degrees on the exhaust. It seems to make for a much smoother power band. Before it seemed like the car would shudder or jerk while cruising or accelerating. All that crap is gone now, best thing I've done to my car so far. Oh, this may be controversial to some, but I toned down the values on the intake table in the .9 load and up from 2600-3400rpm range to take the torque peak out so that the power curve feels more linear to me.

[D-VO]

@Kodename47:

So after about 20 logs, this is what I ended up with.
vvt 1 is intake, vvt 2 is exhaust.



I used pretty much every gear but 1st(6th up to 130), both reducing and increasing overlap, VVT intake and VVT exhaust.

*For anyone else looking at this* Mods are:
Kraftwerks C38 Kit
Crawford BPB
Perrin 2.5" resonated CBE
(Nameless catted overpipe/front pipe with Helmholtz coming soon)

[Wayno]

Can you re-upload pictures please?

Originally Posted by 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:


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:

[solidONE]

Originally Posted by Wayno

Can you re-upload pictures please?

Hmm.. I wonder what happened. I never removed those photos. Let me see if I can find them. My current tune is quite a bit from the one in that post though.

edit: Check the original post and the photos should be back up.

Here's the difference between a modified Vishnu STG2 map on Tomei El vs Long tube with the map I was running in that post for shits and giggles. The current tune has a slightly taller torque mound and makes a bit more peak power than this one.

[Wayno]

Originally Posted by solidONE

Hmm.. I wonder what happened. I never removed those photos. Let me see if I can find them. My current tune is quite a bit from the one in that post though.

edit: Check the original post and the photos should be back up.

Here's the difference between a modified Vishnu STG2 map on Tomei El vs Long tube with the map I was running in that post for shits and giggles. The current tune has a slightly taller torque mound and makes a bit more peak power than this one.

Thanks, i suspected it was madsb's nameless tables, just wanted to confirm.

[solidONE]

Originally Posted by Wayno

Thanks, i suspected it was madsb's nameless tables, just wanted to confirm.

I'd no idea who made the cam table but they worked pretty damn good aside from the super lean spot.

[shr133]

Here are my current tables for an auto.........





Have you guys done any tuning on the DI angle?????
Had to fix this map seams to run much better.....

[Kodename47]

Originally Posted by shr133

Here are my current tables for an auto.........





Have you guys done any tuning on the DI angle?????
Had to fix this map seams to run much better.....

Pics don't work

What mods etc?

[shr133]

ok they show on my computer.... I'll have to ck it out......

filter, short ram intake, trd exhaust and no pvc......

[Wayno]

They don't work on tapatalk, they do on the website, so don't worry about it.