Welcome to the North American Subaru Impreza Owners Club Thursday August 21, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Engine Management & Tuning

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 09-13-2012, 04:32 PM   #26
68Cadillac
Scooby Specialist
 
Member#: 95901
Join Date: Sep 2005
Chapter/Region: SWIC
Location: Las Vegas, USA
Default

Quote:
Originally Posted by Paidfor View Post
What your ROM cells say and what the ACTUAL AFR is....is a different story.
I've seen that. You may need to redo your MAF table and/or Injector size in the ROM. Once I get my MAF and Injector dialed in the AFR measured by the wide-band is usually +/- 0.2 from Target AFR.
* Registered users of the site do not see these ads.
68Cadillac is offline   Reply With Quote
Old 09-13-2012, 09:01 PM   #27
ProfessWRX
Scooby Specialist
 
Member#: 323379
Join Date: Jun 2012
Vehicle:
06 WRX

Default

All those quotes say nothing of it being every car in that range. In fact they say words like "generally" and "should" and "most." That leaves quite a bit of wiggle room to completely negate your argument.

Just because they all say the same thing doesn't mean it's proof either.

And I've never heard of a car's commanded being the same as actual WITHOUT a tweaked tune for that exact thing... but this also in no way means it can't happen. Just that "most" "generally" "should" fall in that first group.
ProfessWRX is offline   Reply With Quote
Old 09-13-2012, 09:05 PM   #28
Black94Snake
Scooby Specialist
 
Member#: 274499
Join Date: Feb 2011
Chapter/Region: NESIC
Location: RI
Vehicle:
2007 CGM VF'd WRX
12.70 @ 108.4mph

Default

Quote:
Originally Posted by 68Cadillac
I've seen that. You may need to redo your MAF table and/or Injector size in the ROM. Once I get my MAF and Injector dialed in the AFR measured by the wide-band is usually +/- 0.2 from Target AFR.
My car actually did the same thing. I am using a stock meter in a stock box, with stock injectors... And I always see a richer mixture than the Target AFR.
Black94Snake is offline   Reply With Quote
Old 09-14-2012, 12:44 AM   #29
lukeskywrx
Scooby Specialist
 
Member#: 59837
Join Date: Apr 2004
Chapter/Region: SWIC
Location: Arizona
Vehicle:
2004 Spec-C Type RA
What MAF? -Speed Density!

Default

Large scale manufacturing with many precise electrical parts, there is going to be some drift car to car but only one rom so the tuning has to accomodate all the expected variance.

You also have to remember there are no absolutes when trying to compare between different engines as design plays a big role. What works for a 4g63 is not going to work the same for a turbo EJ engine. Evo motors tend to run leaner (closer to 12/1) than EJs, but they also run less timing and have longer strokes and higher compression. A friends 951 turbo Porsche runs 12/1 under boost and has no problems because that engine is OK doing that.

And I would not look at what commercial tuners as the "best way" either, they have to cover their bases since customers blowing up motors is bad for business. Better to be richer and more conservative than risk a broken piston trying to eek out a touch more torque. I am always more conservative tuning others cars than I am my own, I keep a close eye on everything and my CEL flashes if I get knock but I know most normal people will just keep going if there is a problem.

Last edited by lukeskywrx; 09-14-2012 at 12:52 AM.
lukeskywrx is offline   Reply With Quote
Old 09-29-2012, 01:06 AM   #30
Airboy
Scooby Specialist
 
Member#: 72829
Join Date: Oct 2004
Chapter/Region: W. Canada
Location: Calgary, Canada
Vehicle:
2006 WRX
MHI-TF06-18K

Default

I will throw in a couple of "data points" here.
Background info:
-gas is 94 octane with (up to 10%) Ethanol
-Wideband is in the (Cobb) Downpipe bung
-Injector scalar is used to change AFR

First plot: Injector scalar changed by 5%.


Second plot: Injector scalar changed by 3% and then back (to check repeatability). This group of plots is not directly comparable to the set above as the ignition curves are slightly different.
Airboy is offline   Reply With Quote
Old 09-29-2012, 02:26 AM   #31
Alistairh
Scooby Newbie
 
Member#: 268286
Join Date: Dec 2010
Chapter/Region: W. Canada
Location: Edmonton
Vehicle:
2011 STi
Dark Grey

Default

in the second set of plots, are you running more advance?

It seems like what was mentioned originally can be true, and that a slightly leaner (~11.5:1) AFR seems to make (slightly) more peak torque.

However I think there is a lot more at play here on modern engines with AVCS and variable ignition timing. It's not like the earlier days of EFI where more values were static, and the AFR was really your only way to generate power.

But I'm probably just stating the obvious Awesome thread though!
Alistairh is offline   Reply With Quote
Old 11-09-2012, 09:16 AM   #32
fastblueufo
Scooby Specialist
 
Member#: 212154
Join Date: May 2009
Chapter/Region: South East
Location: Ed@fastperformancetuning.com
Vehicle:
02 billet crank
pauter rods, pt5857, E85

Default

I just saw this thread and wanted to add my findings. Although I messed with this years ago, my finding was that although a leaner afr produced more power, it wasn't enough to make me want to run a lean afr, even on race fuel.

The car was a n/a mustang gt. No ecu just straight carb for afr and distributor controlling advance. I started at 13.0, 12 and 11 afr. The power difference was slightly less than 10 hp going from 13 to 11 afr. That's with no timing added or subtracted due to timing controlled by rpm's and the distributor.

On same car same day I ran 12 afr and added 4* advance to the distributor and picked up close to 40hp at the wheels. So timing plays a lot larger role in producing hp than afr ever would.

To me its not worth tuning to a lean afr to produce power, go rich and find a good balance between boost and timing to make power on whatever octane fuel your running.
fastblueufo is online now   Reply With Quote
Old 11-09-2012, 11:18 AM   #33
Phatron
Scooby Guru
 
Member#: 36033
Join Date: Apr 2003
Chapter/Region: SCIC
Location: Tuning Lab
Vehicle:
CEO PhatBottiTuning
2006 STi GTX3582 + Meth

Default

For anyone that says leaner AFR's are ok....especially leaner AFR's and LESS timing....I would love to see EGT data on that. Even going from 11 to 11.5 can increase EGT's ~300-400*.....now you start taking away timing its going to increase ~50* with every degree.

I've had an EGT gauge in my wrx since 2003 and in my STi since 2006 and have never found any leaner tuning strategy be EGT friendly. Or even make enough extra power to be worth the diminishing safety net.

And as far as the places that post up 11.5-12 AFR plots in PPB.....i ask everytime i see one what the EGTs were on the car and the answer everytime has been "the car didnt have a gage".

From my pov tuning to 10.8 and having a nice EGT safety window available if the car develops a leak and leans out to 11.8 a much better strategy than tuning the car to 12:1 and having it lean out to 13:1 during a leak and melting holes in the pistons.

And as someone already mentioned.....heres a JDM Version8 fueling map....8.88 Targets.....how do the people that always bring up washing cylinder walls and getting fuel in the oil explain how stock subaru motors survive the stock fueling mapping?


Last edited by Phatron; 11-09-2012 at 11:37 AM.
Phatron is offline   Reply With Quote
Old 11-09-2012, 03:21 PM   #34
fastblueufo
Scooby Specialist
 
Member#: 212154
Join Date: May 2009
Chapter/Region: South East
Location: Ed@fastperformancetuning.com
Vehicle:
02 billet crank
pauter rods, pt5857, E85

Default

@phatron- keep on tuning brother. I feel the same way about afr tuning unless your just after every ounce of power. Even trying to use afr to speed up flame propogation is rather pointless. As for egt, I've always looked at having two types of high egt. One from leaner afr and one from retard timing with the latter not being of much harm to the engine.

With regards to the fueling table, those are not target values. Those values are only enrichment or enleanment of the base fuel curve set by the maf scale. They could have scaled the injectors and maf to different values and made the table more accurate to actual afr values. I think they could have accomplished the same goal by making the maf scale a 3d table.

I think a whole different team of engineers tuned the jdm cars from the rest as most of the jdm tunes look to use a different strategy than say the usdm tunes. Even though the fuel is a better octane in japan, you can just tell that a lot of the tunes were done with a different mindset.

Ed
fastblueufo is online now   Reply With Quote
Old 11-09-2012, 03:25 PM   #35
Phatron
Scooby Guru
 
Member#: 36033
Join Date: Apr 2003
Chapter/Region: SCIC
Location: Tuning Lab
Vehicle:
CEO PhatBottiTuning
2006 STi GTX3582 + Meth

Default

yeah...with regards to the JDM mapping its amazing how smooth and perfect some of the timing, boost, fueling and avcs are in various roms....compared to how ours look like 2 monkies were ****ing on a keyboard.
Phatron is offline   Reply With Quote
Old 11-09-2012, 03:38 PM   #36
reid-o
Scooby Specialist
 
Member#: 103631
Join Date: Dec 2005
Location: Mililani, Hawaii
Vehicle:
2004 STI
Black

Default

Wouldn't the safety window depend largely on the EGBP? I don't notice such swings in EGT when I'm playing with a lot of the bigger turbine turbos like the 6266 and the 35r as compared to a 60mm turbine on the 30r or a stock location turbo with a smaller A/R, which I try to keep to the guidelines that you both suggest here. I noticed that most of the larger turbines and a/r turbos drop egts too much below 11:1 to the point where I need to increase timing to bring torque back up. I've found that 11.2 or near 11:1 seems to produce a bit more torque on the larger turbines. I do try to stay below 11 if the car is running some type of 63 housing or some strange hybrid turbo.
reid-o is offline   Reply With Quote
Old 11-09-2012, 03:53 PM   #37
ecbmxer
Scooby Newbie
 
Member#: 228059
Join Date: Oct 2009
Chapter/Region: MAIC
Location: Pittsburgh, PA
Vehicle:
2010 WRX
Spark Silver Metallic

Default

If we're still talking about the OP's statement, I think it's the difference between best in theory and best in practice. I haven't read that book, but the theoretical "best" AFRs are probably based on some ideal calculations of in-cylinder pressure or heat release. It may not even take into account using a liquid fuel and all the complex mixing that goes on (lots of times iso-octane and n-heptane are used in place of gasoline or diesel in numerical calculations). I would trust the advice/experience of the known tuners who commented above over theory of a generic engine (unless he has some nice CFD models with reacting flow and heat transfer).
ecbmxer is offline   Reply With Quote
Old 11-11-2012, 04:12 AM   #38
jkopinga
Scooby Newbie
 
Member#: 220799
Join Date: Aug 2009
Chapter/Region: International
Location: Taiwan
Vehicle:
2006 Impreza WRX
WRC Blue

Default

I have done several AFR tests on a LOAD based Dynapack and my conclusion was when running PUMP Fuel (RON98 ~ MON93) that best Power was around 11 - 11.5 AFRs. I tried leaning out as lean as 12.2 and got no extra power but more knock activity. I tried richening up in the hope to be able to add more timing and gain more power but that didn't work out. I went as rich as 10.4 AFR and instantly lost 40 BHP. There was no way timing was going to recover that.

On a TMIC I would use 10.8 ~ 11.2 AFRs thereabouts.
On a FMIC I would use 11.2 ~ 11.5 AFRs thereabouts.

There is typically much more Torque/Power to be had from properly dialling in AVCS on a LOAD based dyno than playing with AFRs.


My 2 cents,

Jasper.
jkopinga is offline   Reply With Quote
Old 11-11-2012, 10:17 PM   #39
reid-o
Scooby Specialist
 
Member#: 103631
Join Date: Dec 2005
Location: Mililani, Hawaii
Vehicle:
2004 STI
Black

Default

Quote:
Originally Posted by jkopinga
I have done several AFR tests on a LOAD based Dynapack and my conclusion was when running PUMP Fuel (RON98 ~ MON93) that best Power was around 11 - 11.5 AFRs. I tried leaning out as lean as 12.2 and got no extra power but more knock activity. I tried richening up in the hope to be able to add more timing and gain more power but that didn't work out. I went as rich as 10.4 AFR and instantly lost 40 BHP. There was no way timing was going to recover that.

On a TMIC I would use 10.8 ~ 11.2 AFRs thereabouts.
On a FMIC I would use 11.2 ~ 11.5 AFRs thereabouts.

There is typically much more Torque/Power to be had from properly dialling in AVCS on a LOAD based dyno than playing with AFRs.

My 2 cents,

Jasper.
I hoped that this isn't too off topic, but when doing your tests with the tmic and fmic, what was your final strategy for iat compensation for timing? With the temp sensor in the end tank outlet I'm not clear on what to set the compensation to. I've tried the following strategy: 0 out the compensation and tune for best torque while watching heat soak. I let the sensor come back to baseline before pulls, the temp of the first pull. Sometimes it takes quite awhile. I note the average peak temp from logs and then pull 2 degrees for ever 5 degree rise past the noted peak temp and start applying the compensation from then on.
Anyone else have a better strategy other than constant logging in daily driving?
reid-o is offline   Reply With Quote
Old 03-26-2014, 02:13 PM   #40
grangepack
Scooby Newbie
 
Member#: 375989
Join Date: Dec 2013
Chapter/Region: International
Location: Uganda
Vehicle:
97 ej207 v9 gf8

Default

Quote:
Originally Posted by NSFW View Post
For example:

I hope that means you can show us a couple of your own dyno sheets, showing how much more power you were able to get with 11:1 vs 12:1. Because that would be awesome.



I've seen a couple of his dyno sheets (via email) showing 12:1 on pump gas and totally reasonable power. And I've seen other tuners post dyno sheets showing 11.5:1 or leaner, here on NASIOC, and get raked over the coals for allegedly making time bombs out of their customers' cars. We all know exactly what would happen if he posted in PPB.

There are people in the world who crave the respect and admiration of the pseudonymous masses of NASIOC, and there are people who don't. Why would you expect someone in the latter group to even thing about posting something contentious here? It's not going to happen, and frankly it makes me wonder how much interesting, useful stuff doesn't get posted here because of the way NASIOC reacts to anything out of the ordinary.



Nobody is questioning that fact. Least of all me. I heartily agree that a search of the dyno sheets posted here will show damn near all of them right around 11:1. And that's why I tuned my own car to 11:1.

But that fact only indicates that 11:1 is popular. And that only tells me that its probably pretty safe.

I do remember seeing one post where a tuner with one of the bigger companies (Cobb or Perrin, I think) said that there was no measurable loss of power until the mixture got down into the mid 10s, or something in that range. But that is the only thing I've seen here (or at RomRaider) where someone described trying multiple AFRs and studying the results.

Let me be clear about something - if I thought 12:1 had a very high probability of making more power with no more risk, I would have at least tried it by now. By my guess is that if there are gains, they're small. And i have no idea what the risks are. And I'm too chicken to experiment with my own motor, so I'm following the crowd on this one, and I'm OK with that.

I know that there are plenty of people who say it's horribly dangerous to run 12:1 at WOT with pump gas, but there are also plenty of people who think that PTFB makes your motor lean out because there's "too much air." Or, you need a tune to safely run a TBE on any Subaru other than the STI. And so on. You know as well as I do that there's a ton of misinformation in this echo chamber. I believe nothing I read here, until/unless I've seen it tested, or better yet tested it myself.

"Everybody does it" is not particularly persuasive, especially in an environment where people are routinely ridiculed for doing unusual things, and more especially when I know a guy who looks an awful lot like a counterexample to the conventional wisdom.

I know you're one of the few who thinks outside of the box around here (I'm running your MBC+BCS setup, for example), so your reaction to this question really caught me by surprise.

Now that's real talk....

About to try out a 91octane map with 11.5 afrs. Coming from a tune that had alot of mid 10s. This scares me abit..
grangepack is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
PA: Prosport oil temp, oil pressure, afr/battery voltage gauges and more MRF582 Interior/Dressup/Audio & Security 13 02-25-2010 12:53 PM
Your setup and ignition adv. @ peak torque and redline wittmer25 Built Motor Discussion 15 07-11-2008 07:40 PM
FS: Green Innovate DB digital AFR gauge WRX match and a few Maddad gauges Cyclops Interior/Dressup/Audio & Security 5 05-13-2008 01:04 PM
how much torque and hp from spt intake and heatshield? blacksti07 Newbies & FAQs 23 04-20-2008 02:03 PM
Torque and HP Curves Kenneth Stolz Normally Aspirated Powertrain 0 03-09-2001 02:07 PM


All times are GMT -4. The time now is 07:47 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.