DevldEG

Okay, I haven't installed anything yet but here goes. I have a '93 civic DX... i have everything i believe i need to turbocharge my hatchback. I'm using a 14B i have my manifold, adapter, piping, 1g DSM intercooler, 1g DSM bov, etc. I only want to boost 5psi until I build a d16 to take the limits of the 14B. Because i only want 5psi i believe that my stock 240cc injectors will be sufficient and i will be using an apexi S-AFC and retarding my base ignition timing to about 13degrees BTDC (stock is 16degrees BTDC plus/minus 2 degrees). I just recently read up on the AFC... if i'm not using the DSM 450cc injectors will my timing be advanced? what exactly causes the AFC to advance ignition timing in that case?

I read using -40% with 450cc injectors for 10psi (of course further tuning afterwards)... so I figure using +13% with 240cc injectors for 10psi would work, because taking 40% from 450 equals 270, and adding 13% to 240 equals 271.2 (i rounded up the percent values because that's how it would be on the AFC). I only want to boost half that so i figured +6% or +7% would work... am I right?

I need to know right away because I will be installing everything in a couple of days.

tranceminister

You will need to use the 450cc injectors I'm afraid. Even at 5-6 psi the stock 240's couldn't supply enough fuel. The AFC does NOT add fuel. By using the 450's and AFC, the AFC scales the MAP signal to the ecu to a smaller more recognizable level, so the ecu doesn't know it's under boost. When using 450's the AFC is set at around -38% (every car is different), which only pulses the injectors slower, alowing the 450's to inject more fuel.
The 240 cc's would be maxed out especially under boost. And as for retarding your timing, yes you'll need to retard it somewhat. Try it at the stock timing and if there is no detonation, it's fine.

DevldEG

ok, i have heard otherwise regarding the stock 240cc injectors ability to accomodate 5psi. AFC does not add fuel!? maybe you mean the AFC hack with the DSM 450cc injectors.

"The range of fuel adjustment is +/- 50% at each of the user-defined setting points." -straight from www.apexi-usa.com/electronics_safc.asp

read my original post thoroughly please, i AM already planning on retarding ignition timing. My question regarding ignition timing however had to do with the AFC hack and how I read in other places in this forum that it advances ignition timing somehow.

d16tuner

It advances timing because it tinkers the map voltage going to the ecu and the ecu can't see how much air it is getting and so over-advances timing. Read about it in the truth about the hack thread in engine management. At least I think that is where it was...

tranceminister

Yeah I was going to suggest doing a search for the AFC and advanced timing because I know there was a post about this not oo long ago, where someone dyno'd and got the actual advance in timing. It's probably back a few pages, but it's here somewhere.

RENR

heres that link https://www.homemadeturbo.com/forum/...;threadid=8210

at 5psi i really wouldnt worry too much about timing. IMO i suggest you get some 450cc form a junkyard or ebay. have patience and do it right the first time. i think they go for about 80 bux on ebay.it WILL be worth the money.

DevldEG

i'm really surprised how unhelpful this thread has turned out for me.
regarding the stock fuel injectors limits... the flow rate is 240cc/min. if i go +10% on the AFC, doesn't it just flow +10% BY staying open that much longer? that's how i believed it works. so the limit would just BE 240cc/min, it's flow rate. if i needed it to dispense 240cc i'd keep the fuel injector spraying for a minute... need another 24cc, i'll have them squirt another six seconds (10% of a minute). am i right or wrong?
HOW does going in the positive/negative values with an AFC trigger a CEL with boost? isn't it just boost that triggers the CEL? how does the AFC do it on its own?
Quit with the BASE ignition timing issue, i knew from the start that i would have to retard it a bit. my original question was "HOW does the AFC inadvertently advance ignition timing using the 450cc injectors?" Why exactly?
I'm not really getting answers here. I read the other posts, it seems that because you go negative on the AFC using the 450cc the ignition timing is advanced... so wouldn't the ignition timing be retarded if you went on the positive side? (remember i'm using the stock 240cc injectors)

MarkG

There is a really good thread on the Turbo D16 forum which covers this:

http://www.turbod16.com/viewtopic.php?t=3074

Should clear things up!

MarkG

Read it all, not just the first page!