ItalianBucwheat

1.Ok...Air/fuel ratio.....What is the average stock ratio....i assume that it does not stay the same all the time...actually i should ask what is the highest the stock air/fuel ratio goes....12/1...12.5/1...11/1?

2.ok What is the highest air fuel ratio the s2000 can handle 14/1 ...
13.5/1?

3.ok To measure air fuel ratio an o2 wideband sensor is needed an other way to read air/fuel ratio?

4.ok Does the car have to be hooked up to a dyno in order for the o2 wideband sensor to read correctly?

5.ok Ahhhh and the final question does anybody know What a safe air/fuel ratio for nitrous is? Is there a rule of thumb Or Just beware?

ok Thanks any other input on air/fuel ratio for normally aspirated s2000
or for s2000 with an indirect wet shot would be great.

Thanks in advance........OK

I am asking for myself and My friend The honey roasted peanut!

HARDtoTOP

well, to answer just two of your questions:

1: My S2000 was running a very rich 10:1 as measured on the dyno before I tuned the VAFC.

2: the wideband sensor can be installed in the car for road use and is usefull if you are a very serious tuner due to its pricetag. The weekend/shadetree mechanic will get all the info he/she needs out of your everyday air/fuel meter

ultimate lurker

1. When measuring after the cat (which makes the reading a little skewed), the typical stock S2000 will see a/f ratios as lean as 12.5-13:1 at lower rpms. This will gradually get richer as rpms increase, until A/F ratios drop into the mid/low 11:1 range by the time you hit the redline.

2. Again, measuring after the cat, you don't want to see A/F ratios any leaner than 14:1, and the car shouldn't really operate there for extended rpm ranges (usually it'll just spike there at certain points). Measuing before cat, on a normally aspirated car, I usually shoot for 13.5:1. But every car is different, and may make peak power at different points. The Mugen ECU runs the car up around 14:1 (after the cat) for much of the rpm band, but you really need to use high octane gas to max benefit according to owners I've talked to.

3. The only way to truly measure the A/F ratio is with a wideband sensor. Using the typical $50 gauge that reads your OEM O2 sensor doesn't tell you much except whether the car is leaner or richer than 14.7:1. That's it. The reason is that the OEM O2 sensor is designed to operate in a linear fashion only from around 14 to 15:1 A/F ratios. Anything richer or leaner is unimportant (has to do with how the ECU operates).

4. You don't have to be on a dyno, but its very difficult to monitor a gauge readout for a wideband while on the road. Thus, you should really have datalogging capability for the wideband, whereever you are testing.

5. Nitrous should typically be run richer than a normally aspirated engine. I would start out with an 11:1 range for safety, and then gradually bring the ratio up to 12:1 with tuning. Anything higher than 12.5:1 is not recommended (by me, everyone has their own opinion) simply because I don't feel the power gains (small) are worth the increasing risk with leaner ratios. For a race car that all goes out the window as you look for max power.

UL

ItalianBucwheat

Ultimatelurker.............rex.........Thanks both i am gaining a better understanding or air fuel ratio's. Thanks now i gotta find a nice tuner shop with both o2 wide and a dyno...okay thanks!