# A/F Ratio

**URL:** <https://forums.speedlife.net/t/a-f-ratio/81377>\
**Category:** SON240sx Automotive\
**Created:** [August 2, 2004, 11:10pm UTC](https://forums.speedlife.net/t/a-f-ratio/81377 "2004-08-02T23:10:21Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![Jacky\_Ngai](https://avatars.discourse-cdn.com/v4/letter/j/3d9bf3/32.png) [@Jacky\_Ngai](https://forums.speedlife.net/u/Jacky_Ngai)\
**Post date:** [August 2, 2004, 11:10pm UTC](https://forums.speedlife.net/t/a-f-ratio/81377/1 "2004-08-02T23:10:21Z")

</div>

just wondering what’s a good # for s13 sr20det blacktop. thanks!

---

<div class="post-metadata">

**Author:** ![Sven](https://avatars.discourse-cdn.com/v4/letter/s/e47c2d/32.png) [@Sven](https://forums.speedlife.net/u/Sven)\
**Post date:** [August 2, 2004, 11:14pm UTC](https://forums.speedlife.net/t/a-f-ratio/81377/2 "2004-08-02T23:14:32Z")

</div>

1. All engines are the same
2. Google next time

But I’m in a good mood today.

> Gasoline can be ignited in a non-stratified charge type engine between limits of roughly 10 to 1 (rich) and 20 to 1 (lean) air/fuel ratios. Most gasolines will burn fastest at ratios in the 12.5 to 13.5 to 1 range. The stoichiometric or chemically correct ratio is around 14.7 to 1 which also results in the lowest average emissions. Best power is obtained with a rich mixture of around 12 to 13.5 to 1.

---

<div class="post-metadata">

**Author:** ![Sven](https://avatars.discourse-cdn.com/v4/letter/s/e47c2d/32.png) [@Sven](https://forums.speedlife.net/u/Sven)\
**Post date:** [August 2, 2004, 11:16pm UTC](https://forums.speedlife.net/t/a-f-ratio/81377/3 "2004-08-02T23:16:51Z")

</div>

PS: Unless you have a wideband O2 sensor the only reading you’ll be able to get is: Close to 14.7/1 … richer … or leaner.

---

<div class="post-metadata">

**Author:** ![\_RSTuning.ca](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/_rstuning.ca/32/6098_2.png) [@\_RSTuning.ca](https://forums.speedlife.net/u/_RSTuning.ca)\
**Post date:** [August 5, 2004, 5:26pm UTC](https://forums.speedlife.net/t/a-f-ratio/81377/4 "2004-08-05T17:26:32Z")

</div>

ideal is 11.5-1 12-1

---

<div class="post-metadata">

**Author:** ![Sven](https://avatars.discourse-cdn.com/v4/letter/s/e47c2d/32.png) [@Sven](https://forums.speedlife.net/u/Sven)\
**Post date:** [August 5, 2004, 5:50pm UTC](https://forums.speedlife.net/t/a-f-ratio/81377/5 "2004-08-05T17:50:14Z")

</div>

> [@Original Drift Master](#):
>
> ideal is 11.5-1 12-1

If you are worried about leaning out and can’t tune it properly I guess … otherwise why dump so much fuel in there?

---

<div class="post-metadata">

**Author:** ![Sasha\_SG](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/sasha_sg/32/5477_2.png) [@Sasha\_SG](https://forums.speedlife.net/u/Sasha_SG)\
**Post date:** [August 5, 2004, 6:56pm UTC](https://forums.speedlife.net/t/a-f-ratio/81377/6 "2004-08-05T18:56:17Z")

</div>

turbo motor. I’d go as far as saying 12.5:1 but not more than that.