Thread: AFR debate thread..
10-29-2011, 09:55 PM #1
AFR debate thread..
The power you would gain from leaning it out, would not benifit you as much as you think, imo your lean in mid range as this is still a decent amount of boost.
Ride that thing.
10-29-2011, 10:33 PM #2
10-29-2011, 11:01 PM #3
Mid range is a tad bit on the lean side, but if its not coming into boost is fine, a OEM subaru sti runs 14s up until 6 psi of boost.
Unless there is something CRAZY on these 4 tec motor, because i have been tuning for 9 years. Moving 1 point on from 11’s to 12’s will be good for about 5-10 whp, depending on how shitty the ignition is. The ski will have a larger saftey net at that afr and will be less prone to pulling any timing or seeing knock.
But again i speak more so from the car world. But a 4 stroke is a 4 stroke and boost is boost.
Hell, on pump gas making 500+ at 30 PSi on gt35s we run as low as 10.5 afr near redline.
I do how ever know the timing curve on the 4 tec’s is very aggresive in which why i think the richer afr will help.
I will do back to back testing tommorow and report rpm loss.
10-30-2011, 06:53 AM #4
Do as others have suggested and check the calibration again on the O2. Ditch the 50s and get a set of 48s, get a reflash or change the ECU for better mapping. You can then play with the boost reference line attachment location (before or after TB) to see what suits your needs better.
A lot of these guys are running the begi setup (dual FPRs) with good sucess. The Rude fuel controller is also another solution for controling the fuel or simply wait until later this month for the new Dynojet system.
10-30-2011, 07:21 AM #5
The tip in response your speaking of, is not from a lean idle, but tuning issue else where. I’m assuming the tps enrichment or boost enrichment map is off. I understand this is not something normal users can adjust. Has no one used an AEM FIC on these boats? They offer tps enrichment, full fuel mapping, ignition adjustment, logging, And can have a map clamp!
I guess what he was saying though, since he cannot change these tables, he will have a lean spot unless he richens things up.. Just sad to see from a tuning point :/
10-30-2011, 08:41 AM #6
10-30-2011, 08:44 AM #7
Ok, but its not stumbling because the afr is at 14 at idle, it stumbles because the computer is not compensating for the sudden blip of throttle, so you have a lean spot.. Your running richer at idle as well as the tip in.. Causing this lean spot to go away.
You have a untuned ski, that just happeneds to run good.
Not sure how much time you spend idling, but its not going to load up, your fuel economy will suck. This running your ski at 12 13 afr at idle is a bandaid to bad tuning.
Heres a sti i tuned on pump gas. It idles and cruises at around 15 afr.... Once floored it has no stumbles or break ups. tuned for around 10.8-11.2 afr at wot. Although he was maxing his walbro 255 pump here so fuel pressure so bouncy causing a jumpy afr. I target these afr’s at higher power levels. I will note on a simpler build i will run 11.6-11.8 afr wot.
10-30-2011, 09:05 AM #8
Holy crap Batman. I dont think I will ride any more till I get my ski tuned. Man I sure am lucky it just happens to run good.
10-30-2011, 09:09 AM #9
10-30-2011, 09:35 AM #10
I have excellent fuel economy. I can cruise at around 6000 and ride forever. In fact it gets way better economy than when it was stock.
Never said I cruise at 12.0 afr. Pay attention
Congratulations on being such a great tuner.
You did manage to get one thing right.................It aint your problem.
Have a nice day. I am going to ride my untuned ski.
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