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A/f Ratio

WARLORD

By WARLORD,
in Engines & Forced Induction

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WARLORD Veteran

WARLORD

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Posted

i was having a look at my dyno from crd today and noticed that my a/f ratio sits at 12.5 and at the last box it dips to 12 ,now is this to lean or is it ok,

the engine has forged pistons ,rods,race bearings apr head studs.

now ive read that it could be unsafe in a stock engine so how about a forged one??

if i run 102 race fuel at the drags will this keep it safer ?

knock is at 16-25 and if i hit the limiter a 65 will come up.

your opinions would be nice if there is someone in the know about a/F ratios and knows rb engines really well it would be nice to hear from them.

thanks .

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Strik3r Experienced

Strik3r

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i forgot to mention that i also was told that when the bonnet is down and on the street that the air flow meter and power fc will make it a bit richer is this true.

that depends on your intake setup....

if you want our opinions on your tune, take a photo/scan the printout and put it up here. 12.5 might be a tad on the lean side depending on the boost/RPM that its at.. 12-12.2 is ideal for WOT on boost.

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Strik3r Experienced

Strik3r

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looks a little on the lean side to me... like the above posters said, the scaling on the AFR y-axis makes it hard to see fluctuations and pin point exact AFR's, but it looks like 12.5 dropping to 12 just on redline.....

I think 12 - 12.2 dropping to 11.8-12 by redline is a little safer.. I'd want to know how hot your exhaust temps were getting (this can be used as an indication to what your cylinder tempreature is).

Keep in mind, if you do get them to richen it up a bit, you will lose a bit of power. (maybe 20-30kw ??). In the end, you need to trust your tuner and as far as I know, CRD have a pretty good reputation. Perhaps talk to them a bit about your AFR's and explain what your needs are and see what they have to say. If its for a street-only car, then those AFR's are probably fine as its rare that you do more than the occaisional squirt of WOT.

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WARLORD Veteran

WARLORD

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looks a little on the lean side to me... like the above posters said, the scaling on the AFR y-axis makes it hard to see fluctuations and pin point exact AFR's, but it looks like 12.5 dropping to 12 just on redline.....

I think 12 - 12.2 dropping to 11.8-12 by redline is a little safer.. I'd want to know how hot your exhaust temps were getting (this can be used as an indication to what your cylinder tempreature is).

Keep in mind, if you do get them to richen it up a bit, you will lose a bit of power. (maybe 20-30kw ??). In the end, you need to trust your tuner and as far as I know, CRD have a pretty good reputation. Perhaps talk to them a bit about your AFR's and explain what your needs are and see what they have to say. If its for a street-only car, then those AFR's are probably fine as its rare that you do more than the occaisional squirt of WOT.

thanks.

as for temps

oil sits at about 70-80 de

water sits at 68-72

and i run the car at the drags with 102 octan

at the end of a run temp is oil 85 water 73

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Strik3r Experienced

Strik3r

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yea, those are all fine. I was referring to exhaust gas tempreature - it can be used as an indication of how hot your pistons are getting. the higher octane fuel will give you a bit of overhead as far as timing goes, but as long as the tune isn't knocking, that wont be a problem. If your afr's are too lean, you could melt a piston...

gotta talk to your tuner bro - its important to trust what they have done, or if your not happy with it, discuss it with them further. If your own research disagrees with what your tuner is saying, then i guess you need to find a new tuner. No point in second guessing them...

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Beer Baron Grand Master

Beer Baron

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Why oh why do croyden use that afr scaling???

yeah it fking pisses me off. and means you cannot see any changes in AFR unless you get out a microscope. I have no idea what or why they have to hide but it's pretty bad form in my view. and probably not needed either as they certainly have a good reputation for tuning.

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STATUS Grand Master

STATUS

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Posted
yeah it fking pisses me off. and means you cannot see any changes in AFR unless you get out a microscope. I have no idea what or why they have to hide but it's pretty bad form in my view. and probably not needed either as they certainly have a good reputation for tuning.

some times it is impossible to flaten curve to perfection, using that scale makes it internet forum friendly :) safe from know it alls who whould bag a perfectley good tune, but couldnt tune themselves.

i agree it sucks but it probably saves them plenty of headaches.

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STATUS Grand Master

STATUS

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But AFR's dont ever need to be a flat line.

Its the other line that you need the nice smoothness on when drilled down into it

kinda my point, people expect flat lines under power. they should look more like an inverse power curve to some degree.

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