Chris81

iTrader: (1)

What is the avg. Air/Fuel ratio for a stock or near stock motor?

I had some weird dyno results yesterday and i'm thinking i'm leaner than I should be.. my mods are in sig.

My dyno results went like this:

1st pull: SAE 311.7 rwhp and 334 rwtq, A/F about 13.9 - 14.2 across the board.. with an OPEN CUTOUT

2nd pull: SAE 316 rwhp and 332.7 rwtq, A/F same as the 1st pull, OPEN CUTOUT

3rd pull: SAE 315.6 rwhp and 331.3 rwtq, A/F 13.5-13.7.. thru the stock exhaust (SS/WS6 muffler) (wideband moved from the cutout to the tailpipe)

Questions:

Is my A/F ratio too lean? I don't remember near stock LS1's running quite that lean..

And, why in the world didn't my hp/tq fall when I capped it up? I know for a fact that it runs better at the track open (the cutout is located about under the back right seat).

I don't have Atap or anything but we do have an older scan tool at my dad's work i'm going to use tomorrow, the only thing is it doesn't show KR. I'm also going to check little things like the fuel filter etc.. but my main worry is the A/F. I figured my numbers were a little low considering I trap the same as some M6's with LS6 intakes and headers in my area.

Sorry for the long post, any help would be great..

Chris

Chris81

iTrader: (1)

I'll try to get some dyno graphs up soon, and Mods.. if this is in the wrong section please move it.

Chris

red ws6 99

My TA was set for 13:1 from the factory (PE tables). Of course, since COT tables were also enabled the AFR could drop down to 11.75 depending on certain conditions. You would probably want to be at 12.5 or so on the dyno, which would give you a 13:1 on the street. You are very lean, your AFR will .5 or so higher on the street than on the dyno. Since you are running so lean you will not be making any power (capped or uncapped). Do not be getting on it until you get the car richer, it wont last long that lean. If you have not done any signifant mods, then you need to check the fuel pressure, it should be about 58 at idle and drop a couple pounds or so up top. If its not, then you will need to check the filter, pump, regulator. The filter is the easiest. Pump and regulator require the tank to be dropped or an access panel cut inside the car.

Gary

Chris81

iTrader: (1)

I'm going to check the filter as soon as I get to the shop tomorrow, I think that might be it and i'm thinking that this has happened in the past week or so because when I ran it at the track last time (11/29/03) the MPH kept going up all night as the weather got better and it never "acted" lean then.. as far as the MPH falling off etc..

A couple of friends of mine said they thought they heard it detonating a bit on the dyno but I was in the car and didn't hear it.. I thought KR could kick in and pull timing so that it wouldn't detonate? (as bad anyways)

Thanks for the response.

Chris