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Air Fuel Ratio - what is the target number to shoot for?
- Thread starter DOUGGN
- Start date
That would be during WOT correct? Cruise would be around 14.6?Shoot for 10.8 for starters.
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fastblackracing
Well-Known Member
- Joined
- Apr 7, 2009
Depends on the boost/hp level that you intend to operate at I have found as HP goes up the safe A/F ratio should go down. On a 600 hp TR you would need a richer setup than you would on a 400 hp TR. What are looking to run for boost and HP?
Before I installed it wideband I was running 22 psi with alky and no knock on the scanmaster. I don't have any idea what HP that would be. Now that I have the wideband I would like to fine tune and then go to a TA49 turbo and Eric Marshalls new chip with wideband correction. I just want to verify that the wideband is correct.Depends on the boost/hp level that you intend to operate at I have found as HP goes up the safe A/F ratio should go down. On a 600 hp TR you would need a richer setup than you would on a 400 hp TR. What are looking to run for boost and HP?
Took the car to work this morning and made a short log of WOT. Looks like the AFR was 10.5 - 10.9 and O2 was .750 - .800 on a 0-95 run. Had no spark knock. I did notice that the transmission shifted gears at about 4900 rpm - it this correct? The AFR with the cruise on was about 14.6
Dreamcar86
Active Member
- Joined
- Apr 13, 2006
Took the car to work this morning and made a short log of WOT. Looks like the AFR was 10.5 - 10.9 and O2 was .750 - .800 on a 0-95 run. Had no spark knock. I did notice that the transmission shifted gears at about 4900 rpm - it this correct? The AFR with the cruise on was about 14.6
Now that you have wideband ditch the factory O2 readings. The factory O2 is not very useful.
the answer to your question depends on what your trying to do with the car as a max effort track tune and a mild street tune have different targets.if your car is running good and clean and your happy and nothing is knocking and afr is holding steady how about leaving it alone for now until you get the bigger turbo?razor also has a sticky in the alky section which is very good.
I agree - just wanted to make sure it was OK before I did change the turbo. In terms of running "clean" not sure about that - kinda smells rich at idle. I will check out what Julio has to say.the answer to your question depends on what your trying to do with the car as a max effort track tune and a mild street tune have different targets.if your car is running good and clean and your happy and nothing is knocking and afr is holding steady how about leaving it alone for now until you get the bigger turbo?razor also has a sticky in the alky section which is very good.
I don't notice any flutter - as far as leaning it out - I'm kinda scared I will pop a head gasketMine at 10.8 seems to have a flutter sort to speak, it doesn't seem to run as clean, almost like a miss-fire, I set it at 11.3 and it really cleaned it up and it pulls really hard. I tried 11.5 and it didn't pick up any MPH however I did get some knock.
if you don't want to hurt anything don't push it.wideband sensors can also read different only way to know is to pull plugs and look.sounds like you have a nice cushion something a lot of guys on the board don't tune for but your engine will thank you.you can look at wideband readings at idle and come down or up on fuel pressure a lb or 2 if your worried about a rich idle but it may not be rich at all.
thanks for the input - do you have any opinion on the shift point of the trans at 4900 rpm - is this in range or normal?if you don't want to hurt anything don't push it.wideband sensors can also read different only way to know is to pull plugs and look.sounds like you have a nice cushion something a lot of guys on the board don't tune for but your engine will thank you.you can look at wideband readings at idle and come down or up on fuel pressure a lb or 2 if your worried about a rich idle but it may not be rich at all.
I followed the gnttype instruction last year. I just wasn't sure I there was any way to verify the setting by how and when the trans actually shifted. I don't want the trans to shift too soon and burn up the clutches.range is fine,the tv adjustment procedure is on gnttype.org.you can get more rpm manual shifting.
I did install a shift kit/upgrade and external trans cooler a while ago - that is when I did the adjustment on the TV cable. From what I have read, even if the trans has a shift kit it can still have problems if the TV cable is out of calibration. When I did the trans kit, after re-adjusting the TV cable there where more lines showing after the install than before. I did the adjustment procedure a couple time just to make sure it was right.if your trans is stock I would start preparing for a buildup or at least go with a shiftkit especially if you start turning the boost up or get a bigger turbo.
thanks for the input - do you have any opinion on the shift point of the trans at 4900 rpm - is this in range or normal?
That's what I shift at roughly. My cam peaks around 48oorpm and stock is 4400rpm peak, so that's plenty. Stick with the high 10's AFR too. My car goes quicker at 11.0 or a hair leaner, but it's still fast even at 10.5 or richer so I run a cushion on the street. HGs are harder to do than give up a pony or two from a richer than needed AFR imho.
in my experience the trans is the first thing tht needs attention when the power is up especially if the car has a good tire on it.on the last buick I played with,the guy stated his goals and we pulled it out before he even drove the car.
I guess the next thing to be looking forward to is a transmission.That's what I shift at roughly. My cam peaks around 48oorpm and stock is 4400rpm peak, so that's plenty. Stick with the high 10's AFR too. My car goes quicker at 11.0 or a hair leaner, but it's still fast even at 10.5 or richer so I run a cushion on the street. HGs are harder to do than give up a pony or two from a richer than needed AFR imho.
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