whats an acceptable AFR for WOT on sr20det 8.5:1 CR on 93oct? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

opponheimer · 11-16-2007, 11:52 PM

I've seen 11.5 - 11.7

My car's at 11.2 and at top end goes to 12.0, I'm going to lower the boost and try to error solve, a 12.0:1 afr at wot is bad correct?

bardabe · 11-17-2007, 12:10 AM

I made a thread ALL about AFR's u should have searched a wee bit harder.

opponheimer · 11-17-2007, 12:25 AM

http://www.zilvia.net/f/showthread.php?t=134996

thanks man..

So does this mean in actuality my afr is safe under boost? gt2871r at 15psi.

posi rep u btw

KA-T_240 · 11-17-2007, 01:43 AM

your A/F ratio is ok. as least for your setup. Its a bit rich 11.5-11.7 is generally the spoot to tune for. Being a tad rich can be a good thing, adds a bit of saftey. I would be more do you have any timing control? and what for tuning?

smelly240 · 11-17-2007, 03:51 AM

12 is not safe for street driving... i run 11.2-11.5

opponheimer · 11-17-2007, 06:41 AM

Quote:

Originally Posted by mach5camaross

your A/F ratio is ok. as least for your setup. Its a bit rich 11.5-11.7 is generally the spoot to tune for. Being a tad rich can be a good thing, adds a bit of saftey. I would be more do you have any timing control? and what for tuning?

You need to check that link out... 12 is a bit lean, not a bit rich.

Chrischeezer · 11-17-2007, 06:56 AM

12.0 is good!
12.5 is optimal, meaning you will make the most power, BUT you could melt a piston.

opponheimer · 11-17-2007, 07:18 AM

A friend of mine who (inherently) tunes hondas says 12.0 is bad, but he deals with higher comp. motors turbocharged. I'd like to get some descent feedback from some more knowledgeable members on here. Thanks....... this is my DD Btw

rps13drift · 11-17-2007, 08:50 AM

For a turbocharged car you want to be in the lower 11. area under wide open throttle. It provides for rich best torque! and the excess fuel also acts like a cooling method in the combustion chamber getting rid of hot spots on the pistons preventing pre-ignition or detonation. As for you having a lean condition in your upper rpm area try knocking back a few degrees of ignition timimng or did you ever wire your fuel pump to its own relay? If not it drops voltage causing that type of problem in the upper rpms! good luck
-mike-

KA-T_240 · 11-17-2007, 10:41 AM

If your timing is not really really agressive you could be by at 12.0 AFR. Its not the safest.

I asked what was being used for tuning and other stuff, cause either it needs to be tuned richer up top(to be safer) or his fuel system is starting to run out of fuel up top.

The cars I have street tuned have beed to 11.5-11.6 but they have been KA-Ts with decent size turbos running 20psi, differant then a SR yes, but same concept. and for low throttle 14.5.

DrIvEsldEwAyS · 11-17-2007, 05:01 PM

11.1-11.6 is where i try and keep mine

PoorMans180SX · 11-17-2007, 10:48 PM

Listen to Bardabe and his thread. It's a good one.

opponheimer · 11-18-2007, 07:29 PM

Okay well, i was actually running 12.9 Air:Fuel and i just independently wired my fuel pump to its own fusible link and no difference. I'm on gt2871r 0.64 at 10lbs.. I'm surprised it would still do that at such low boost.

Koopa Troopa · 11-19-2007, 04:50 AM

Quote:

Originally Posted by opponheimer

Okay well, i was actually running 12.9 Air:Fuel and i just independently wired my fuel pump to its own fusible link and no difference. I'm on gt2871r 0.64 at 10lbs.. I'm surprised it would still do that at such low boost.

I'd be afraid to run a 12.9 AFR in boost....

PoorMans180SX · 11-19-2007, 11:01 AM

ummm....tune that thing. You might be able to get away with that under medium loads, but WOT? I'd find a way to change that real fast.

Oh, and you should probably get a Walbro or something.

EDIT: I was talking about 12.9 AFR

steve shadows · 11-19-2007, 11:57 AM

Quote:

Originally Posted by smelly240

12 is not safe for street driving... i run 11.2-11.5

who told you that

satan?

12.0 can be safe, anything leaner than that and I cringe.

11.8:1 is good for any gas.

11.5:1 is safe and good compromise tune depending on changes in gas quality over gradient.

My car is tuned at about 11.5:1 to 12.0:1 on 91 octane.

12.0:1 rocking.

Luke is also at 11.8-12.0:1 even though both the dyno plots we did were made at 11.2:1 (so theoretically were about 20hp more on the street at higher afrs (leaner)).

Quote:

Originally Posted by mach5camaross

The cars I have street tuned have beed to 11.5-11.6 but they have been KA-Ts with decent size turbos running 20psi, differant then a SR yes, but same concept. and for low throttle 14.5.

the only thing different is oil squirters under the pistons.

((sr)) kelly · 11-19-2007, 11:59 AM

12.0 is fine

50/50 · 11-19-2007, 12:23 PM

I think more important than the number is "where" you're measuring the AFR.

1. If your coming out the tailpipe using a sniffer (NOT RECOMMENDED) you're good at 12.0. This method of course is not recommended because of inherent inaccuracies but, some of us do it anyway.

2. If your measuring it, like you should, about 16" from the turbine using a wide-band then 11.5 is good. Like someone else mentioned, 12:0 is ideal. At WOT if you're at 12.5 you're heading for trouble.

At that compression ratio 11.5-12 measured at the the second position should be perfect.

Both SR20DETs and KA24DEs have piston oil squirter's.

steve shadows · 11-19-2007, 03:08 PM

Quote:

Originally Posted by 50/50

I think more important than the number is "where" you're measuring the AFR.

1. If your coming out the tailpipe using a sniffer (NOT RECOMMENDED) you're good at 12.0. This method of course is not recommended because of inherent inaccuracies but, some of us do it anyway.

2. If your measuring it, like you should, about 16" from the turbine using a wide-band then 11.5 is good. Like someone else mentioned, 12:0 is ideal. At WOT if you're at 12.5 you're heading for trouble.

At that compression ratio 11.5-12 measured at the the second position should be perfect.

Both SR20DETs and KA24DEs have piston oil squirter's.

not the ka24e

but yeah de has them, it also has a dual timing chain which fails

not a fan of KA

50/50 · 11-19-2007, 03:45 PM

Quote:

Originally Posted by steve shadows

not the ka24e

but yeah de has them, it also has a dual timing chain which fails

not a fan of KA

Correct. So your statement above^^ should probably read "...the only difference is that ka24e's have no piston oil squirters underneath..." otherwise it's generalizing. Just trying to make sure the info here is correct.

I'm 50/50 split between SR and KA but, AFRs are AFRs and some motors prefer it leaner and some rich. Abviously, it's not a good idea comparing the ka to an sr where AFRs are concerned. To add to the original question of the post, it would help on a KA to keep things a tad richer and top it off at 11.5 measured right after the turbine as I mentioned before.

steve shadows · 11-19-2007, 03:56 PM

^????

haha

no every motor is theoretically different

even sr vs. another sr.

It usually has more to do with exact differences in set ups rather than engine design from factory to next engine design from x facotry.

the notion that there is a wide margin of difference in teh AFR a engine likes to make power at is retarded.

in fact AFR doesnt matter worth a shit once yoru between 11-12.

Timing does.

50/50 · 11-19-2007, 04:04 PM

Quote:

Originally Posted by steve shadows

^????

haha

no every motor is theoretically different

even sr vs. another sr.

It usually has more to do with exact differences in set ups rather than engine design from factory to next engine design from x facotry.

the notion that there is a wide margin of difference in teh AFR a engine likes to make power at is retarded.

in fact AFR doesnt matter worth a shit once yoru between 11-12.

Timing does.

That's not what I implied. Let me clarify:

I'm considering stock SR-DET to stock KA with turbo kit. Obviously different setups will determine what AFRs an engine will perform best/ more reliable at, NA, Turbo, NOS NA, NOS Turbo, gas type (octane, chemical composition like methanol, ethanol, diesel etc), internal components etc. But the idea of the original question was to get a "general" idea of what is best. The original poster's question was very general, sr20det 8.5 CR 93 oct, what is considered a good afr. Please don't take me the wrong way. But you obviously need to redeem yourself for the error you made before. On this humble note I would bow and give you the upper hand as you know more than me and I'm a complete idiot. Sorry for wasting your time.

opponheimer · 11-19-2007, 10:59 PM

I'm measuring afrs at 36" from the turbine blade... Dropped boost down a little more and it goes to 12.6 afr.. its odd becasue up until 7k rpms its like 10.5-11.2 (stock ecu) then it jumps to 12.6 in the last 500rpm range.. very weird.

steve shadows · 11-20-2007, 12:16 AM

Quote:

Originally Posted by 50/50

That's not what I implied. Let me clarify:

I'm considering stock SR-DET to stock KA with turbo kit. Obviously different setups will determine what AFRs an engine will perform best/ more reliable at, NA, Turbo, NOS NA, NOS Turbo, gas type (octane, chemical composition like methanol, ethanol, diesel etc), internal components etc. But the idea of the original question was to get a "general" idea of what is best. The original poster's question was very general, sr20det 8.5 CR 93 oct, what is considered a good afr. Please don't take me the wrong way. But you obviously need to redeem yourself for the error you made before. On this humble note I would bow and give you the upper hand as you know more than me and I'm a complete idiot. Sorry for wasting your time.

your not a complete idiot

your a smart guy. lol

dont be so down on yourself.

compression ratio has more to do with timing not octane or richer/leaner.

I mean NA high comp motor likes 13:1 with a good octane/

TUrbo likes 12:1 or just south of that etc.

anyways this is all redundent , every car is diff, you need a dyno or exaust temp and 02 combo on the street to get the afr spot on and timing to make the power bla bla bla

11-16-2007, 11:52 PM	#1
opponheimer Zilvia FREAK! Join Date: Apr 2007 Location: Bikini Atoll Posts: 1,267 Trader Rating: (3) Feedback Score: 3 reviews	whats an acceptable AFR for WOT on sr20det 8.5:1 CR on 93oct? I've seen 11.5 - 11.7 My car's at 11.2 and at top end goes to 12.0, I'm going to lower the boost and try to error solve, a 12.0:1 afr at wot is bad correct? __________________ SR20 & RB20/25/26 in s13/s14 Wiring from $125 to $200.. Best prices EVER.

11-17-2007, 12:10 AM	#2
bardabe Post Whore! Join Date: Aug 2005 Location: SoCal Age: 31 Posts: 4,716 Trader Rating: (10) Rides Gallery: bardabe Feedback Score: 10 reviews	I made a thread ALL about AFR's u should have searched a wee bit harder. __________________ Review Thread

11-17-2007, 12:25 AM	#3
opponheimer Zilvia FREAK! Join Date: Apr 2007 Location: Bikini Atoll Posts: 1,267 Trader Rating: (3) Feedback Score: 3 reviews	http://www.zilvia.net/f/showthread.php?t=134996 thanks man.. So does this mean in actuality my afr is safe under boost? gt2871r at 15psi. posi rep u btw __________________ SR20 & RB20/25/26 in s13/s14 Wiring from $125 to $200.. Best prices EVER.

11-17-2007, 01:43 AM	#4
KA-T_240 Nissanaholic! Join Date: Sep 2005 Location: Moorhead, MN Age: 34 Posts: 1,788 Trader Rating: (0) Feedback Score: 0 reviews	your A/F ratio is ok. as least for your setup. Its a bit rich 11.5-11.7 is generally the spoot to tune for. Being a tad rich can be a good thing, adds a bit of saftey. I would be more do you have any timing control? and what for tuning? __________________

11-17-2007, 03:51 AM	#5
smelly240 Nissanaholic! Join Date: Oct 2006 Location: Philaburbia Age: 43 Posts: 2,137 Trader Rating: (4) Feedback Score: 4 reviews	12 is not safe for street driving... i run 11.2-11.5 __________________ HREs on a S13 - check, 6262 - check, Girlfriend.... - nope

11-17-2007, 06:56 AM	#7
Chrischeezer Zilvia FREAK! Join Date: Jul 2005 Location: earth Age: 37 Posts: 1,406 Trader Rating: (2) Feedback Score: 2 reviews	12.0 is good! 12.5 is optimal, meaning you will make the most power, BUT you could melt a piston. __________________

11-17-2007, 07:18 AM	#8
opponheimer Zilvia FREAK! Join Date: Apr 2007 Location: Bikini Atoll Posts: 1,267 Trader Rating: (3) Feedback Score: 3 reviews	A friend of mine who (inherently) tunes hondas says 12.0 is bad, but he deals with higher comp. motors turbocharged. I'd like to get some descent feedback from some more knowledgeable members on here. Thanks....... this is my DD Btw __________________ SR20 & RB20/25/26 in s13/s14 Wiring from $125 to $200.. Best prices EVER.

11-17-2007, 08:50 AM	#9
rps13drift Zilvia FREAK! Join Date: Oct 2006 Location: NJ BRO!!!! Age: 35 Posts: 1,194 Trader Rating: (6) Rides Gallery: rps13drift Feedback Score: 6 reviews	For a turbocharged car you want to be in the lower 11. area under wide open throttle. It provides for rich best torque! and the excess fuel also acts like a cooling method in the combustion chamber getting rid of hot spots on the pistons preventing pre-ignition or detonation. As for you having a lean condition in your upper rpm area try knocking back a few degrees of ignition timimng or did you ever wire your fuel pump to its own relay? If not it drops voltage causing that type of problem in the upper rpms! good luck -mike- __________________ http://allies-drift.blogspot.com/

11-17-2007, 10:41 AM	#10
KA-T_240 Nissanaholic! Join Date: Sep 2005 Location: Moorhead, MN Age: 34 Posts: 1,788 Trader Rating: (0) Feedback Score: 0 reviews	If your timing is not really really agressive you could be by at 12.0 AFR. Its not the safest. I asked what was being used for tuning and other stuff, cause either it needs to be tuned richer up top(to be safer) or his fuel system is starting to run out of fuel up top. The cars I have street tuned have beed to 11.5-11.6 but they have been KA-Ts with decent size turbos running 20psi, differant then a SR yes, but same concept. and for low throttle 14.5. __________________

11-17-2007, 05:01 PM	#11
DrIvEsldEwAyS Zilvia Junkie Join Date: Apr 2005 Location: Columbia,SC Age: 32 Posts: 351 Trader Rating: (0) Feedback Score: 0 reviews	11.1-11.6 is where i try and keep mine __________________ -1990 240sx hatch sr20det- gt35r, blah blah blah

11-17-2007, 10:48 PM	#12
PoorMans180SX Zilvia.net Advertiser Join Date: Nov 2005 Location: Michigan Age: 33 Posts: 5,431 Trader Rating: (16) Rides Gallery: PoorMans180SX Feedback Score: 16 reviews	Listen to Bardabe and his thread. It's a good one. __________________ Build: http://zilvia.net/f/showthread.php?t=643065 Friends don't let friends buy knock-offs.

11-18-2007, 07:29 PM	#13
opponheimer Zilvia FREAK! Join Date: Apr 2007 Location: Bikini Atoll Posts: 1,267 Trader Rating: (3) Feedback Score: 3 reviews	Okay well, i was actually running 12.9 Air:Fuel and i just independently wired my fuel pump to its own fusible link and no difference. I'm on gt2871r 0.64 at 10lbs.. I'm surprised it would still do that at such low boost. __________________ SR20 & RB20/25/26 in s13/s14 Wiring from $125 to $200.. Best prices EVER.

11-19-2007, 11:01 AM	#15
PoorMans180SX Zilvia.net Advertiser Join Date: Nov 2005 Location: Michigan Age: 33 Posts: 5,431 Trader Rating: (16) Rides Gallery: PoorMans180SX Feedback Score: 16 reviews	ummm....tune that thing. You might be able to get away with that under medium loads, but WOT? I'd find a way to change that real fast. Oh, and you should probably get a Walbro or something. EDIT: I was talking about 12.9 AFR __________________ Build: http://zilvia.net/f/showthread.php?t=643065 Friends don't let friends buy knock-offs.

11-19-2007, 11:59 AM	#17
((sr)) kelly BANNED Join Date: Jun 2007 Location: Zebulon... NC Posts: 1,035 Trader Rating: (6) Feedback Score: 6 reviews	12.0 is fine

11-19-2007, 12:23 PM	#18
50/50 Leaky Injector Join Date: Oct 2006 Location: Atlanta Posts: 129 Trader Rating: (0) Feedback Score: 0 reviews	I think more important than the number is "where" you're measuring the AFR. 1. If your coming out the tailpipe using a sniffer (NOT RECOMMENDED) you're good at 12.0. This method of course is not recommended because of inherent inaccuracies but, some of us do it anyway. 2. If your measuring it, like you should, about 16" from the turbine using a wide-band then 11.5 is good. Like someone else mentioned, 12:0 is ideal. At WOT if you're at 12.5 you're heading for trouble. At that compression ratio 11.5-12 measured at the the second position should be perfect. Both SR20DETs and KA24DEs have piston oil squirter's. __________________ Sick Swapp-eR

11-19-2007, 03:56 PM	#21
steve shadows Post Whore! Join Date: Aug 2003 Location: LA and OC Posts: 8,202 Trader Rating: (5) Feedback Score: 5 reviews	^???? haha no every motor is theoretically different even sr vs. another sr. It usually has more to do with exact differences in set ups rather than engine design from factory to next engine design from x facotry. the notion that there is a wide margin of difference in teh AFR a engine likes to make power at is retarded. in fact AFR doesnt matter worth a shit once yoru between 11-12. Timing does. __________________ Like Me on FaceBook !

11-19-2007, 10:59 PM	#23
opponheimer Zilvia FREAK! Join Date: Apr 2007 Location: Bikini Atoll Posts: 1,267 Trader Rating: (3) Feedback Score: 3 reviews	I'm measuring afrs at 36" from the turbine blade... Dropped boost down a little more and it goes to 12.6 afr.. its odd becasue up until 7k rpms its like 10.5-11.2 (stock ecu) then it jumps to 12.6 in the last 500rpm range.. very weird. __________________ SR20 & RB20/25/26 in s13/s14 Wiring from $125 to $200.. Best prices EVER.

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