Air/Fuel Ratio for Stock FRS @ High RPM - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Decimus · 08-11-2015, 03:42 AM

Trying to educate myself on this topic. Just purchased a AF gauge and will be looking into getting a tune soon.

My question... Does anyone know the AF ratio at high rpm for our cars?

What's the best ratio for power at high rpm?

I've read a bit and it seems like every car is different. Thanks for helping.

MaximeT · 08-11-2015, 04:52 AM

There is no real answer, AFR change all the time for each RPM and Load. It should be 14,7 most of the time.
It will go lower with load/RPM increase.

You want to stay as close as possible to 14,7 as long as you got no detonation or overheating exhaust valves.

Then your tuner will decrease AFR just enough to protect the engine. You don't want the lowest possible AFR, because you will loose at lot of gas and quite a bit of power.

steve99 · 08-11-2015, 08:06 AM

Quote:

Originally Posted by Decimus

Trying to educate myself on this topic. Just purchased a AF gauge and will be looking into getting a tune soon.

My question... Does anyone know the AF ratio at high rpm for our cars?

What's the best ratio for power at high rpm?

I've read a bit and it seems like every car is different. Thanks for helping.

The stock tune runs quite rich at high rpm getting down to 10.7 afr.

most aftermarket tunersnaturally aspirated will target mid to high 11 afr at upper rpm..

Stock tune Primary oen loop fueling table

go_a_way1 · 08-11-2015, 09:40 AM

Quote:

Originally Posted by steve99

.... but is that windows 98??

celek · 08-11-2015, 11:33 AM

WOT high RPMs should be 12.5:1 on regular gas for optimum performance 14.7 is incorrect and will be too lean.
14.7 for cruising.
This is recommended for NA application.

MaximeT · 08-11-2015, 12:11 PM

Quote:

Originally Posted by celek

WOT high RPMs should be 12.5:1 on regular gas for optimum performance 14.7 is incorrect and will be too lean.
14.7 for cruising.
This is recommended for NA application.

I was not suggesting 14,7 for WOT

Decimus · 08-11-2015, 12:34 PM

Quote:

Originally Posted by steve99

The stock tune runs quite rich at high rpm getting down to 10.7 afr.

most aftermarket tunersnaturally aspirated will target mid to high 11 afr at upper rpm..

Stock tune Primary oen loop fueling table

Quote:

Originally Posted by MaximeT

There is no real answer, AFR change all the time for each RPM and Load. It should be 14,7 most of the time.
It will go lower with load/RPM increase.

You want to stay as close as possible to 14,7 as long as you got no detonation or overheating exhaust valves.

Then your tuner will decrease AFR just enough to protect the engine. You don't want the lowest possible AFR, because you will loose at lot of gas and quite a bit of power.

Perfect chart. Yes idle was was sitting at around 14.7.
At WOT above 7k I hit 10.2 and I thought that was really rich.

I'm going to ask if they can keep AF ratio between the suggested 11-12. Thanks for the replies!

stevo585 · 08-11-2015, 01:09 PM

The OFT stage 2 UEL tune seems to run rich at least mine does and I'm at sea level. Its low 11's. I'm sure I'm losing a bit of power.

celek · 08-11-2015, 04:05 PM

Quote:

Originally Posted by MaximeT

I was not suggesting 14,7 for WOT

Yeah but he was talking about high RPM so I figured I would specify. I don't know about you but I dont hover at partial throttle and 6000-7000 RPM

MaximeT · 08-11-2015, 04:17 PM

Quote:

Originally Posted by celek

Yeah but he was talking about high RPM so I figured I would specify. I don't know about you but I dont hover at partial throttle and 6000-7000 RPM

Looking at the journalists video on YouTube, they do that all the time. Which is of course stupid

But I have seen many post (around here) and video where people drive crazy part load road driving rpm. Like JF on Drive TV.

Anyway, sorry, I'm off topic :p

steve99 · 08-11-2015, 07:08 PM

Quote:

Originally Posted by go_a_way1

.... but is that windows 98??

nope XP running cut down theme so it runs better on my old netbook

go_a_way1 · 08-12-2015, 09:45 AM

Quote:

Originally Posted by steve99

nope XP running cut down theme so it runs better on my old netbook

Ahh! I see haha!!

arghx7 · 08-13-2015, 12:27 AM

The AFR is that rich under high speed and heavy load to keep the cat from experiencing accelerated aging. It's to comply with EPA longevity requirements.

Quote:

Originally Posted by celek

Yeah but he was talking about high RPM so I figured I would specify. I don't know about you but I dont hover at partial throttle and 6000-7000 RPM

It's not a big deal if you do. It won't hurt anything although I would change my oil more frequently if that's something that happens regularly.

Coheed · 08-14-2015, 01:43 AM

I'm partial throttle at high rpm all the time. Do you guys every see the track? Not to say it's a regular occurrence, but every time I'm in a canyon or on the track the engine sees a lot of partial throttle high rpm. Especially when I'm sideways.

08-11-2015, 03:42 AM	#1
Decimus BAE Join Date: Nov 2014 Drives: Asphalt FRS Location: SGV Posts: 587 Thanks: 152 Thanked 97 Times in 77 Posts Mentioned: 2 Post(s) Tagged: 2 Thread(s)	Air/Fuel Ratio for Stock FRS @ High RPM Trying to educate myself on this topic. Just purchased a AF gauge and will be looking into getting a tune soon. My question... Does anyone know the AF ratio at high rpm for our cars? What's the best ratio for power at high rpm? I've read a bit and it seems like every car is different. Thanks for helping.

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stevo585 Senior Member Join Date: Feb 2014 Drives: White 2014 BRZ Location: Orlando, FL. Posts: 519 Thanks: 131 Thanked 155 Times in 109 Posts Mentioned: 4 Post(s) Tagged: 0 Thread(s)	The OFT stage 2 UEL tune seems to run rich at least mine does and I'm at sea level. Its low 11's. I'm sure I'm losing a bit of power.

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Coheed Senior Member Join Date: Jun 2012 Drives: DGM BRZ Limited Location: Seattle Posts: 813 Thanks: 209 Thanked 225 Times in 157 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	I'm partial throttle at high rpm all the time. Do you guys every see the track? Not to say it's a regular occurrence, but every time I'm in a canyon or on the track the engine sees a lot of partial throttle high rpm. Especially when I'm sideways.

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