64 replies to this topic

[fezzasus]

I dont think OBD-Tuner runs lean. It's a computer that does exactly what you want it to do. If it runs lean then a mechanical failure can be the culprit or you did not programmed it right.

Correct me when I'm wrong.

 

 

 

The AFR from the OBD tuner is much higher than the AFR for the standard map. 

[siztenboots]

you could have AFR 11:1 , 12:1 , 13:1 , power output would be within 1%

 

where as ignition timing , if you retarded by about 2 degrees, that could reduce bhp by 4 to 5% ( AFR kept same at 13:1 )

[slindborg]

hate the use of bhp in this thread

 

250*hp at 2000rpm , completely different to 250*hp at 7000rpm

 

Torque is much more dangerous to engine internals

 

Torque is what an engine actually produces, as you well know

 

I guess the GM testing wouldnt show where the NOS was injected (ie at Idle, or peak torque or peak power)

[siztenboots]

 

hate the use of bhp in this thread

 

250*hp at 2000rpm , completely different to 250*hp at 7000rpm

 

Torque is much more dangerous to engine internals

 

Torque is what an engine actually produces, as you well know

except Harley's which just make noise

[TFD]

 

I dont think OBD-Tuner runs lean. It's a computer that does exactly what you want it to do. If it runs lean then a mechanical failure can be the culprit or you did not programmed it right.

Correct me when I'm wrong.

 

 

 

The AFR from the OBD tuner is much higher than the AFR for the standard map. 

 

 

If you have a wideband you can correct this yourself is it not? If it runs lean (at top), add fuel. If this can't be corrected to the desired AFR-target then perheps something is wrong with your injectors of fuelpump not coping with the demanded amount of fuel?

 

@Slindborg: No idea when or were they injected the shot. Producing 180ish bhp on itself without NOS I would guess it was not at idle. 

 

2nd Edit: I've just read the title again... Safe MAX power is a sort of contradiction. I dont think it's safe to be on the max. Whatever.... gigling with words and bored at work lol

Edited by TFD, 18 November 2014 - 12:10 PM.

[slindborg]

depends on the definition of safe...

 

Safe, yes you can be at max... reliable, maybe not, but its possible to be reliable too.

 

although you could argue the max before breakage, is the limit before something "unsafe", as in if a rod breaks at 100bhp, but you are running 200bhp and not had it break, then you are simply running on borrowed time of reliability etc.

[fezzasus]

 

 

I dont think OBD-Tuner runs lean. It's a computer that does exactly what you want it to do. If it runs lean then a mechanical failure can be the culprit or you did not programmed it right.

Correct me when I'm wrong.

 

 

 

The AFR from the OBD tuner is much higher than the AFR for the standard map. 

 

 

If you have a wideband you can correct this yourself is it not? If it runs lean (at top), add fuel. If this can't be corrected to the desired AFR-target then perheps something is wrong with your injectors of fuelpump not coping with the demanded amount of fuel?

 

 

The observation wasn't at maximum power, it was across the rev and boost ranges so unlikely to be an issue with fuelling. I have observed it on two separate cars.

[slindborg]

just offset the required learning point

[Bargi]

I dont think OBD-Tuner runs lean. It's a computer that does exactly what you want it to do. If it runs lean then a mechanical failure can be the culprit or you did not programmed it right. Correct me when I'm wrong.    

  The AFR from the OBD tuner is much higher than the AFR for the standard map. 

Have you got the comparative numbers?

[fezzasus]

I'll need to dig out the original Z22Se map data

[CHILL Gone DUTCH]

You can always change the AFR target if your worried by your settings

[oakmere]

Dose adding fuel do much for cooling the engine as I was lead to believe the effect is negligible? Adding lots of fuel slows the burn speed of the mixture effectively retarding ignition.

[fezzasus]

Dose adding fuel do much for cooling the engine as I was lead to believe the effect is negligible? Adding lots of fuel slows the burn speed of the mixture effectively retarding ignition.

 

It's pretty significant, even working within the limitations of strict engine testing protocols we can shave about 50 deg. C off the exhaust temps*

 

*obviously depends on the engine

[oakmere]

Yes that's quite a bit!

[slindborg]

When calibrating some air cooled engines, we could only control temps with fuel.... Could strip upto 100degC off the temps if left long enough.

[siztenboots]

there should be a parameter you can adjust, tau factor

[Exmantaa]

Isn't that something to do with (cold) wall fuel film evaporation etc.?   Basically transient throttle response, like the acceleration pump effect on carbs...

Edited by Exmantaa, 19 November 2014 - 11:48 AM.

[siztenboots]

Isn't that something to do with (cold) wall fuel film evaporation etc.?   Basically transient throttle response, like the acceleration pump effect on carbs...

yes , the puddle factor on the back of the valve

[slindborg]

ohh xtau, thats a headfuck to get right

[Mangham54]

geeks

Edited by Mangham54, 19 November 2014 - 12:39 PM.