AVCS Tuning

[HolyCrapItsFast]

Chuckle, woops, yup 4.8v - more like 360 g/s :tard: Yeah - the map is similar to the one you PM'd me, also nearly as aggressive in terms of advance at the top. I suspect I can push it to the maximum 30* intake and still gain. Then I need to start thinking about Exhaust AVCS. Looking at some other maps out there, I've seen advances up to 32* in the mid RPMs regions - mine only extends to 20 currently, so looks like there is a lot of scope to push it there as well.




Definitely going to continue trying to advance at that RPM band as far as I can push it. Interestingly enough, fueling barely changed this time, pretty spot on. I'm running an 80mm intake now, and it's obviously not enough... Should probably move to a 4" and be done with it. Who knew you could squeeze so much out of a Dom3 xtr - makes me wonder what I could do with a Dom 5 and some decent tuning to get better spool.

Be careful... do your research first if you are going to a 4 inch... You start running into resolution issues in the low end of the maf when you go much past 83mm. The flow past the sensor is just to little for it to register accurately and you run into sloppy idle and low speed trims.

What boost are you hitting right now at 4.8 volts. If you are not going to go much past what you are now then I say you would be fine with an 83mm... KStech or something like that. If you need much more than that then I say it is time for speed density and a standalone.

 

[Td_d]

Always wondered whether a bigger MAF housing would mess with closed loop, guess that's my answer...

I'm hitting my target boost of 1.7bar at that voltage. My build is good for 2bar :tard: but not sure I'll push it that far. Will definitely take it up to 1.8bar. Ok, who am I kidding, will probably be tempted to take it up to 2. That's an extra 5 psi, not marginal...

I have a feeling SD is in my future. I wish there was an OS SD solution for the GR's, I like the daily drive resolution of the OEM Ecu.

 

[HolyCrapItsFast]

Holy turbo pressure Batman! Hmmm you might need to go SD if you want that kind of pressure and flow imo or give up some drivability.

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[HolyCrapItsFast]

True... you could probably get away with it if you run it like 1000 minimum and a 4 inch. Yuo would have to be the guinea pig. Lol.

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[Td_d]

Holy turbo pressure Batman! Hmmm you might need to go SD if you want that kind of pressure and flow imo or give up some drivability.

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What? What? Hehehe... well I didn't get the frikkin thing sleaved for no reason - viva Darton And from the compressor maps I've seen, the Dom 3 XTR's really wake up from 26psi on - so up to 29psi should still be comfortably within the compressor map sweet spot. What boost are you running at the moment?

Running a 1000 RPM idle would not bother me - I was running 1050 for quite a while without any hassles.

 

[HolyCrapItsFast]

What? What? Hehehe... well I didn't get the frikkin thing sleaved for no reason - viva Darton And from the compressor maps I've seen, the Dom 3 XTR's really wake up from 26psi on - so up to 29psi should still be comfortably within the compressor map sweet spot. What boost are you running at the moment?

Running a 1000 RPM idle would not bother me - I was running 1050 for quite a while without any hassles.

I'm only running 20 psi and I'm kissing 500whp now... But that is probably the E85 and high compressions pistons doing that... Oh and my SPEC C HEADS and 272 cams!!!! Woot!

 

[HolyCrapItsFast]

I'm dynoing it local at No-Limit motorsports on their DynoDynamics... I already have a refference dyno from last year on that dyno and I want to use that as the gauge. When I sqaure everything away with my exhaust leak that is, but right now all the vertual dyno solutions are telling me I'm very close to 500whp and I believe it thus far.

here is my current AVCS...

 

[Td_d]

I'm only running 20 psi and I'm kissing 500whp now... But that is probably the E85 and high compressions pistons doing that... Oh and my SPEC C HEADS and 272 cams!!!! Woot!

Damn... good flow is a better substitute for boost, that's for sure. I've really gotta try and get those cams in - I was looking at 268's, but the order was duffed. I've sure it's holding be back plenty at the top...

 

[Td_d]

here is my current AVCS...

Yeah, that's close to what I'm running - 10's below 1 load, ramping up to 28 currently above that, and tapering off rapidly to 0 at about 6000. Similar shape.

 

[Td_d]

Yeah, that's what I had on order - Kelford 268's. Would make a big difference. Could probably go more aggresive, like 272's.

 

[HolyCrapItsFast]

I have amazing drivability with my 272's but BC 272's are not Kelford 272's. The kelford have a more aggressive profile

I'll be posting a dyno sheet soon enough but you are more than welcome to drop by and take it for a spin yourself! :tup:

 

[Td_d]

Chuckle, now you're just teasing. I'd love to go to the States again, last time I was there was in 2005 in NY, and for some corporate conference and set of meetings - other than getting hammered and gorging on Pakistani food. And my wife really wants to see New York.

So as not to look like I'm whoring my own thread - played around with new AVCS (intake) settings this evening - finally bumped the top end to 30*, and smoothed out some of the transitions between RPMs.

Holy shit... I hit 4.84v. In 3rd gear (6900 Rpms). Same boost as before. That basically tells me that if I had to take her to early 7000's in 4th, I would max the MAF.

Oh - and another not so minor observation - the torque at the low end is butt clenching now. I hit a load of 2 - at 2800 Rpms :shock: - and given my MAF scaling hack, it's probably more like 2.2. Damn...

Another interesting observation - I find that on the first run after I flash the Rom, I can get some pretty serious knock at the low end, increasing load areas - 2800 to 3000 rpms - which then basically disappears on the next drive.

And lastly (I know I need to work on the OP and building up the knowledge base upfront, but I'm hoping these questions and observations are adding to the thread!) - this question is targeted at the hardcore experienced mechanics on here - Scott? Reks? I've noticed something very weird on my intake right versus intake left AVCS - and I'm not sure whether it's a quirk after a new flash, or a mechanical issue (I need to further examine later, post flash logs to see if there's a trend). At spool up - so I'm assuming lower oil pressure - the right intake AVCS lags the left intake significantly sometimes - 10-12* - then catches up - and overshoots signficantly. I saw it go up to 53*on one run (left intake was close to target at 31*). WTF? The GR's no longer have banjo bolt filters, right? Solenoids? What should I look for - or am I being paranoid?

 

[Td_d]

The only year that had the Banjo bolt filter was the 04 STi.
I would keep an eye on that AVCS sensor, sounds like shes going bad to be honest.

I hadn't thought of the most obvious answer, thanks! Makes sense - I mean 53* is not even possible on the hardware. I was checking the logs today - same thing, even after a couple of drives - the right intake number lags, then races ahead. I'll see if I can pull one of one of the GR's in the shop and test the theory.

AVCS tuning is easy when you really sit down and do it. Its used primarally for trying to spool the car faster and hold boost longer up top for the smaller turbos. If your running a larger than say a 20G then you need to leave it be. I always say, Im the sledge hammer of tuning so if your about to throw crazy words and numbers at me, Im gonna get confuzzled and make Fuji answer!!! I learned to tune the old fashion way, I just did it! I hit 305WHP 323WTQ on my 04 STi at stage 2. She had more I believe but I wasnt knowledgable enough at that time. I was comming to full boost at 2700 RPM's using AVCS to spool the turbo faster. I played with the AVCS again to make boost hold out at 19 PSI to redline. Ive seen other applications of AVCS but they caused nominal gains at best.

Hmm - ok - so you figure for a Dom 3 xtr / GT3076 and up size turbo, rather leave the high load mid RPMs (up to 4400) at the stockish numbers? There's no doubt by pushing it out to 30 I've gained at the top. Too aggressive?

What do you usual use the exhaust AVCS for - top end? I see in the stock GR maps, it's 17* everywhere, and then a huge advance up to 40 in the very light cruise under 1g/rev areas - I'm sure that's for emissions?

 

[Td_d]

That's pretty much the same approach I've taken at the lower RPMs, relatively gradual though, with a little more focus on the torque than spool, for driveability. It really shifts the curve around if you get it right. I've dropped quite a bit of timing - up to 7* - not only to aid spool, but I found as I started pushing the intake AVCS upwards in the spool area, it started to knock like crazy if I didn't tone down timing (with the AFR's corrected). I guess you are raising the effective compression ratio of the engine.

Be very keen to see the results of that 35R on Edwin's car. Christ... Edwin in a 500whp+ STI. There's a scary thought...

 

[Td_d]

At least the stock cams are a known quantity for me in terms of tuning the intake AVCS - I've got quite a couple of references from people who've done it, and 30* is not uncommon (can push it more, but I'm not willing to go that aggresive). One thing for sure on the stock cams is that after 4400 rpms you have to drop intake advance rapidly, otherwise it's counterproductive.

New cams will mean starting the AVCS map from scratch - which doesn't bother me. Considering ordering those Kelford 272's or 268's (I'm thinking with decent AVCS tuning, the 272's can still be driveable).

 

[Td_d]

FP Black? Holy shit...

 

[toomes]

Maybe the profile, but the load and degrees are unrealistic for an STi unless he is running some un-godly turbo and some after market timing mechanism. Even then the profile doesn't make sense to me unless you could elaborate. :tup: I'm just trying to understand this

Plus will an Evo profile be good on a Subaru? I've had a look at some Evo profiles and none of them seem similar but I only sampled a few. I have been comparing AEM maps lately.

The VE of an EVO is so far greater than that of a Subaru that their maps are very similar down low, but mid + top they are polar opposite. They are so efficient that in some cases, you take a degree or two away. Ill see if my buddy MR_turco on EVOM forums has a map section from his car that I can post. Its insane to look at and try to compare. Timing is all 0's and 1's instead of like 15-20's lolol.

 

[HolyCrapItsFast]

Yes... I have been reading an EVO tuning guide and the maps that they show in there are very different indeed but the ones I'm seeing do have high numbers like in the 30's and 40's. I'll post some up tomorrow at work... Quite interesting actually.

 

[Td_d]

Yup, whilst the theory might be the same, there are so many variables, I'd be inclined to incrementally test rather than follow a set of maps. That being said, there are some useful threads out there with dyno data showing the effect on hp and torque at various levels on the ej257. I'm relatively happy with my intake maps now, going to slowly start raising exhaust in the high load spool regions, to see the effect.

One thing you really need to watch for is smooth fueling at these spool ranges...

 

[toomes]

FWIW, I only ran 8 degrees max AVS, but again that was with 11.5mm Kelford 272's at intake. 11.0mm exhaust 272 Kelford as well. SUPER aggressive. My heads flowed hard-core and I didn't even have a 1mm oversized valve!! It was a nuts 5 angle port job