Wondering if s-afc is right for me.

[Boostin2High]

I was just wondering if there was any reason for me to need a s-afc as of my mods right now..
6-bolt
13G
ARP Head Studs
Cometic Gasket
Thermal R&D 3" exhaust
UICP
BOV Recir.
MBC
Stock fuel system except for 190 Walbro

I found one for a really good price, I'm going to pick it up regardless for future means. Just wondering if there was any reason for me to hook it up asap.
Also looking to get WB02 really soon as well.

 

[snowborder714]

I see no reason to have an S-AFC right now. They are only needed once you want to start tuning or install bigger injectors (up to 660cc or so). And you will also need an wideband O2 and a logger to use the S-AFC.

 

[Boostin2High]

Well once late Xmas comes, I'm gonna have a new setup completely.
50 trim
Ex.Mani
BFMIC
Thinkin 680's
AFPR
Ex. Wastegate
Walbro 250
etc. etc.
MafT
So I'm pretty sure I'll need it by then..Then I'll just need to learn how to use the damn thing..

 

[kenamond]

^^^ Agreed. The logger comes first (along with the ability to make sense of the logs). If you don't plan on going to larger injectors, S-AFC is overkill. If you plan on the bigger injectors, get the S-AFC then or maybe get WB O2 and S-AFC, do some fine-tuning on the stock injectors to get used to everything, then save cash and get the injectors.

 

[Boostin2High]

I know this has probably been , but I was wondering if you knew of any good write ups on learning to tune..I know you say use search, but I was wondering if there were any that you suggest or prefer.?

 

[kenamond]

I've posted this so many times I need to memorize the post number for one of them and just hyperlink it...

The S-AFC takes airflow values from the MAS and lets the user/tuner adjust how much it changes these readings before passing them on to the ECU. Larger injectors mean you have to tell the ECU it's getting less air than it really is...so it pulses the injectors for a shorter time. Since they're larger injectors, they need to be open for a shorter time to deliver the same fuel as smaller injectors. The problem with this is that the ECU doesn't just use those airflow numbers for fuel. It uses them for timing advance as well. Typically, less airflow means more timing advance. So when you use S-AFC, you also end up advancing your timing.

Now, if you go to 550cc injectors, the "lie" is not so big (a white lie. When you go to 660cc injectors, some say that the lie is getting a bit too big. As a result, your timing is *too* advanced, and you end up in a situation where you can't run quite as high of boost before that extra timing advance leads to knock.

You mentioned 680cc injectors, so I figured I'd mention this. I have no first-hand experience with this, but have read plenty about it, so take my words with that grain of salt.

 

[snowborder714]

If you plan on going with 680's, as kenamond said, they are probably too big for the S-AFC to handle or will take A LOT to get them to operate properly. With that said, you can either go a bit smaller and still stay with the S-AFC or go larger and get a chipped ECU or DSMlink. In either of those cases you can run as large of an injector as you want. This way you won't have to worry about maxing them out.

As far as tuning guides, here's a few links from the tech article section. Two of these deal with the S-AFC so you can kind of get a feel as to how it works.
http://www.dsmtuners.com/forums/articles-tuning-ecu/105569-how-safc-works.html
http://www.dsmtuners.com/forums/art...tuning-guide-beginner-intermediate-tuner.html
http://www.dsmtuners.com/forums/articles-tuning-ecu/58403-definitive-piggyback-tuning-guide.html

 

[Boostin2High]

I've posted this so many times I need to memorize the post number for one of them and just hyperlink it...

The S-AFC takes airflow values from the MAS and lets the user/tuner adjust how much it changes these readings before passing them on to the ECU. Larger injectors mean you have to tell the ECU it's getting less air than it really is...so it pulses the injectors for a shorter time. Since they're larger injectors, they need to be open for a shorter time to deliver the same fuel as smaller injectors. The problem with this is that the ECU doesn't just use those airflow numbers for fuel. It uses them for timing advance as well. Typically, less airflow means more timing advance. So when you use S-AFC, you also end up advancing your timing.

Now, if you go to 550cc injectors, the "lie" is not so big (a white lie. When you go to 660cc injectors, some say that the lie is getting a bit too big. As a result, your timing is *too* advanced, and you end up in a situation where you can't run quite as high of boost before that extra timing advance leads to knock.

You mentioned 680cc injectors, so I figured I'd mention this. I have no first-hand experience with this, but have read plenty about it, so take my words with that grain of salt.

..I understand it more now from reading this, than I did from ANY other post that I've read..You didnt have to go that far, but I'm really glad you did and I apreciate it very very much!

 

[Boostin2High]

If you plan on going with 680's, as kenamond said, they are probably too big for the S-AFC to handle or will take A LOT to get them to operate properly. With that said, you can either go a bit smaller and still stay with the S-AFC or go larger and get a chipped ECU or DSMlink. In either of those cases you can run as large of an injector as you want. This way you won't have to worry about maxing them out.

As far as tuning guides, here's a few links from the tech article section. Two of these deal with the S-AFC so you can kind of get a feel as to how it works.
http://www.dsmtuners.com/forums/articles-tuning-ecu/105569-how-safc-works.html
http://www.dsmtuners.com/forums/art...tuning-guide-beginner-intermediate-tuner.html
http://www.dsmtuners.com/forums/articles-tuning-ecu/58403-definitive-piggyback-tuning-guide.html

So do you think 550's will be enough for a 50 trim ~20Lbs of boost..I just want to make sure I get the right stuff.

Thanks alot guys I really appreciate the help

 

[snowborder714]

So do you think 550's will be enough for a 50 trim ~20Lbs of boost..I just want to make sure I get the right stuff.

Thanks alot guys I really appreciate the help

I don't know if they would be enough or not, but I personally wouldn't go with anything smaller than 660's. I searched the members to see who had a 50 trim and to see what size injectors. I looked at about two dozen and only two had 550's. Everyone else had 660's or larger.

 

[Boostin2High]

Damn..that sucks because I really don't have the money to get an eprom AND DSM link. I guess my only option is to wait or run the s-afc with low boost..

Thanks alot though.

 

[klipschaudio]

Quick question, dsmlink replaces a logger and safc, you can log everything to a laptop and make adjustments, correct?

 

[snowborder714]

Quick question, dsmlink replaces a logger and safc, you can log everything to a laptop and make adjustments, correct?

Yes, DSMlink is a logger and a tuner.

Read more about it here:
DSMLink Homepage