Jump to content
SAU Community

Recommended Posts

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 .

Link to comment
https://www.sau.com.au/forums/topic/246930-af-ratio/
Share on other sites

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.

Link to comment
https://www.sau.com.au/forums/topic/246930-af-ratio/#findComment-4291833
Share on other sites

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.

Link to comment
https://www.sau.com.au/forums/topic/246930-af-ratio/#findComment-4294018
Share on other sites

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

Link to comment
https://www.sau.com.au/forums/topic/246930-af-ratio/#findComment-4294323
Share on other sites

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...

Link to comment
https://www.sau.com.au/forums/topic/246930-af-ratio/#findComment-4294639
Share on other sites

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.

Link to comment
https://www.sau.com.au/forums/topic/246930-af-ratio/#findComment-4297070
Share on other sites

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.

Link to comment
https://www.sau.com.au/forums/topic/246930-af-ratio/#findComment-4297084
Share on other sites

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.

Link to comment
https://www.sau.com.au/forums/topic/246930-af-ratio/#findComment-4298320
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Didnt realise RB's had more then 1 head.
    • I'm normally copping my own abuse from neglecting my daily drivers. "Those suspension bushes will last a bit more", "Don't worry about the oil leak, just keep topping it up". The project cars I'm always doing things slowly on them as I'm wanting them to be done better, and neater, and nicer. Luckily I don't have to deal with 18 year old Matt's "Learning to wire" stuff in the project cars. And there's only one piece of wiring I'm displeased about in the Landcruiser, and it's about to be cut out... However, the box loads of parts that have been going through this place lately for the Landcruiser... Brake pads Brake Rotors Full handbrake overhaul Wheel Bearings Seals Swivel hubs Steering Boxes Half the suspension joints Shocks Air bags (Ones to go in the rear springs for towing) Water pump Timing kit Lower timing case Harmonic Balancer Radiator Lots of other little seals and shits Gas struts for the bonnet New power window switches And god knows what else I've forgotten... Ha ha ha I have my fingers crossed the pinion seals don't start leaking on the diffs, that the transfer case doesn't leak, and the gearbox input shaft doesn't leak, nor the rear main seal. As they're about the only seals I haven't replaced in the driveline! I'm seriously eyeing off buying new caliper rebuild kits front and rear brake calipers... I'll probably recheck all the valve clearances soon too, and hopefully, it should be all good and sweet to haul some long distance trips again!
    • Every time I pull my 3x gauges out of the console and see the crack-addict way that I did the wiring, and I just can't bring myself to tear it all apart and "make it nice", because it is currently working. In fact, the last time I was in there I probably made it worse.
    • The best part is when you own the car long enough that you look back and find your OWN ham fisted amateur shit!
    • The annoying part about neglect, is when you start to replace one thing, and find ten more broken things. Ham fisted monkey repairs you normally only find out about when trying to do something unrelated! Ha ha   Neglect you can kind of anticipate the huge costs to fix it all. Ham fistedness is normally a shock the first time your work on a new old car, as everything "looked" good before.
×
×
  • Create New...