[Rory]

I want to monitor my car closely and make sure the tune is ok, what sort of AFR should I have to be running safely?

At what point should I be worried? I see its going from about 15 down to 12 on WOT, is this a healthy number?

Im running a stock car with mhd stage 1 map.

http://datazap.me/u/rory/log-1455987...ata=4-18-19-24

[135Pats]

What kind of fuel?

I can give you a simple and incomplete answer, or we can get into a big discussion about stoich.

Sparknotes: On pump gas and a modest tune; i'd want to see AFRs enrichen to something in the ballpark of 11.5:1 up top. A bit leaner is OK; but starts to become more a matter of risk tolerance with a lean burn. If we're dealing with Ethanol, different ballgame.

[Rory]

Pump gas ( as you americans would say ) US 93octance UK 98RON.

My log is from mhd stage 1 93Octane. I was a bit worried it seemed a bit lean at 13:1 area for a while.

[Sgop335]

Was going to answer the afr question, when i saw large throttle closure?

[Rory]

Originally Posted by Sgop335

Was going to answer the afr question, when i saw large throttle closure?

I think that was traction control , oops

[jtswole]

At first glance, it looks super lean, but not running much timing. But, I'm not familiar with pump gas tunes and how lean you can run them.

[b1mmr]

Sub'd

[Sgop335]

Originally Posted by Rory

I think that was traction control , oops

Pump gas, are you running e10? Thats what we have around here. Stoich ratio for e10 is about 14 (pure gas is 14.7) and max power around 12. Also the shape of the power curve is such, one can err on the richer side. So at boost 11.3 -12.3 is a good range for e10. At low boost, na 14 or so.

[135Pats]

Originally Posted by Sgop335

Pump gas, are you running e10? Thats what we have around here. Stoich ratio for e10 is about 14 (pure gas is 14.7) and max power around 12. Also the shape of the power curve is such, one can err on the richer side. So at boost 11.3 -12.3 is a good range for e10. At low boost, na 14 or so.

Agreed; well put.

I wasn't under the impression ethanol had made its way into UK fuel. Awesome if it has though!

[Rory]

Originally Posted by Sgop335

Pump gas, are you running e10? Thats what we have around here. Stoich ratio for e10 is about 14 (pure gas is 14.7) and max power around 12. Also the shape of the power curve is such, one can err on the richer side. So at boost 11.3 -12.3 is a good range for e10. At low boost, na 14 or so.

This is shell v power 98 octane UK so 93 octane US, I dont add anything to it. Shell say it has up to 5% ethanol , which is the same as their standard petrol.

Ive been reading a lot about n54 AFRs today, and popular opinion seems to be it runs a little leaner than you might expect being a direct injection engine.

Russel at BMS tuning said on another forum :
"Typical values are 15:1 at light engine loads decreasing to around 12.5:1 under heavy engine loads and high rpm".

---

This is pretty consistent from what Ive logged so far. Still have to get a log from the new V6 map, had a quick drive of it earlier and seems smooth and strong.

[135Pats]

Originally Posted by Rory

This is shell v power 98 octane UK so 93 octane US, I dont add anything to it. Shell say it has up to 5% ethanol , which is the same as their standard petrol.

Ive been reading a lot about n54 AFRs today, and popular opinion seems to be it runs a little leaner than you might expect being a direct injection engine.

Russel at BMS tuning said on another forum :
"Typical values are 15:1 at light engine loads decreasing to around 12.5:1 under heavy engine loads and high rpm".

---

This is pretty consistent from what Ive logged so far. Still have to get a log from the new V6 map, had a quick drive of it earlier and seems smooth and strong.

DI motors tend to run a bit leaner since the burn is more consistent and precise with injection happening in the combustion chamber. On/under lean cruise/NA, they run way 'lean' relative to what you'd traditionally see in a port fueled car.

You should see the N55s....Now those things want to be run LEAN.

[dreyo27]

What about with about 40% e85?