750 o2s at 20lbs boost too lean?

[Timbuick]

hi guys, posted this a while back on Eric's site, but would like to widen responses.
Last time I ran my new combo up to 20 lbs boost my scan master recalled 750 O2s on the scan master at WOT.
Does this seem too lean?
I had no KR at all.
Current combo is Te34 , Dutt neck I/C and ally with tt 5.6 street chip.
I don't yet have wide band and was wondering if I should add a little more fuel as insurance.

 

[TurboDave]

There's NO way of knowing with a narrowband O2 sensor. But you're fairly safe showing no knock retard. Assuming you trust your knock sensor.

As you can see here. On this run I was showing 721 on the narrowband, while showing a good steady 11.1 air/fuel ratio at 20# of boost.

Narrowband numbers are meaningless without something to back them up, and vary from sensor to sensor.

 

[Ttype6]

hi guys, posted this a while back on Eric's site, but would like to widen responses.
Last time I ran my new combo up to 20 lbs boost my scan master recalled 750 O2s on the scan master at WOT.
Does this seem too lean?
I had no KR at all.
Current combo is Te34 , Dutt neck I/C and ally with tt 5.6 street chip.
I don't yet have wide band and was wondering if I should add a little more fuel as insurance.

Narrow band means nothing. The important thing is you have no spark retard. Your a/f ratio is probably good. When my wide band shows good a/f ratio my narrow band shows 830s.

 

[BIGPSI]

my car has always ran good at 740 to 780 on the O2's

 

[Mr.Spool]

a wideband will eliminate the guessing,but i wont tune 750s with pump gas/alky.770's-800 is what i like to see on the narrowband upstairs and 0 knock,you didn't mention single or duel nozzle and that changes things.on a small turbo stock motor single nozzle combo it may not knock at 750 but your not far from it and on the street with traffic and temperature changes i like the richer afr.

 

[Dan SS2471]

You didn't mention how long you went WOT. You should really wind it out to the top of 3rd. 750s at 65 MPH can change pretty dramatically when you're staying in it up to say, 95+ MPH. If you're racing it, you want to be able to safely cover the WOT stab thru the entire 1320'.

Dan

 

[Timbuick]

You didn't mention how long you went WOT. You should really wind it out to the top of 3rd. 750s at 65 MPH can change pretty dramatically when you're staying in it up to say, 95+ MPH. If you're racing it, you want to be able to safely cover the WOT stab thru the entire 1320'.

Dan

I don't recall exactly how long I was at WOT, but not very long as it was a highway run, about 90mph as I recall.
the ally is a single nozzle system.
Before I fitted the new alky chip the non alky version gave me pretty rich o2s in the region of 780-820 but felt a bit fat on the tune. As soon as I fitted the alky chip it ran fast and quick.
Thanks for the responses, I guess that a wide band set up is the only way to drive it and know what's happening.

 

[Pronto]

Out of curiosity, what octane ratings do you get in the UK?

 

[Timbuick]

Out of curiosity, what octane ratings do you get in the UK?

Mm slightly tricky. Apparently the US and UK have different octane rating systems. our advertised 95 octane is probably nearer US 93 rating. This is what I use plus ally on the street. I use 100 octane at the track which is about 95 US, I think.
Since fitting the new alky chip the car seems to perform so much better than my home tuning (adding fuel/timing at the chip) and I have not seen knock.
That said the car has been in hibernation for the past few months, shortly emerging for spring.

 

[Razor]

hi guys, posted this a while back on Eric's site, but would like to widen responses.
Last time I ran my new combo up to 20 lbs boost my scan master recalled 750 O2s on the scan master at WOT.
Does this seem too lean?
I had no KR at all.
Current combo is Te34 , Dutt neck I/C and ally with tt 5.6 street chip.
I don't yet have wide band and was wondering if I should add a little more fuel as insurance.

Typically I would say too lean. If I had a customers car and stabbed the throttle and O2's came down quickly from 800's to mid 700's.. I would look into adding more fuel or making sure fuel pressure was keeping up with boost.

If you have a G-tech or track... you can start way richer and work your way down on fueling. If the car picks up as you lean it out.. fine. Not start lean then add fuel.

 

[Timbuick]

Thanks Razor,
As soon as the car goes back on the road I'm going to add 10% at the chip and start saving for Wideband.
Its difficult, as you guys know to watch FP guage, boost guage and scantool all at once. I have a RJC boost controller turned up quite a bit and the boost does come on fast and I think, but dont know that FP is rising 1:1 with boost.

 

[williamsGN]

Hit both buttons at once and see at what MPH your running 750. If you have a TT chip, then adjust for more fuel at 1st gear or wide open depending on where your 750 reading is at.