Tuning Afrs

[SS8_Gohan]

agreed, that's why i said "give the context" - fine for the workshop, crappy if the car leaves the workshop.

[KiwiRS4T]

What the japs are really doing? we do not know... I would love to go there personally to check it out.

We have at least two top Japanese tuners in Auckland including one (Soichi from ST HiTec) to whom people bring RBs from all over NZ for a tune but I guess Japan is closer than Auckland for you at the moment!

[PROXIMITY]

We have at least two top Japanese tuners in Auckland including one (Soichi from ST HiTec) to whom people bring RBs from all over NZ for a tune but I guess Japan is closer than Auckland for you at the moment!

so does he go with the leaner tune an less timing or rich ?

And as someone else said would be good to see some fc or other maps of aggresive tunes !

[Toshi]

HKS , APEX , MINS , TRIAL , all famous shop race cars AFR 10.8 at before cat (around same place std O2 sensor).

They are try to 0-300km/h at YATABE also 0-1000m race in 1990s then they found best AFR 10.8.

AFR 11.3 some time engine blow but 10.8 never engine blow.(around 800hp RB engine )

Std R33 25det AFR around 10 also std IMPREZA AFR around 9.5.

So AFR 10.8 is not rich.

I think AFR 12 at muffler is not problem for street car.(FMIC , full exhoust , boost 12-13psi)

But bigger turbo car need richer than AFR12.(Im adjusting AFR 11-11.5 at muffler.This is around 10.8-11.3 at before cat)

[BoostedBarge]

Thanks Toshi, I never knew there was a difference between AFR at muffler and AFR before cat. I have just installed an AFR sensor before the cat. I'll have to keep that in mind...

[DVS JEZ]

Thanks Toshi, I never knew there was a difference between AFR at muffler and AFR before cat. I have just installed an AFR sensor before the cat. I'll have to keep that in mind...

of course there is thats the whole purpose of the cat.

[VB-]

noticed the american's do this alot too. in aus, popular target A:F ratio is 12:1, US etc is 11:1...

[chiksluvit]

HKS , APEX , MINS , TRIAL , all famous shop race cars AFR 10.8 at before cat (around same place std O2 sensor).

They are try to 0-300km/h at YATABE also 0-1000m race in 1990s then they found best AFR 10.8.

AFR 11.3 some time engine blow but 10.8 never engine blow.(around 800hp RB engine )

Std R33 25det AFR around 10 also std IMPREZA AFR around 9.5.

So AFR 10.8 is not rich.

I think AFR 12 at muffler is not problem for street car.(FMIC , full exhoust , boost 12-13psi)

But bigger turbo car need richer than AFR12.(Im adjusting AFR 11-11.5 at muffler.This is around 10.8-11.3 at before cat)

It's an interesting topic, been watching this space for a while and I was hoping for Sydney's top Japanese tuner to respond to this..

it is good to get some insight about this from Toshi

seems like the tuning method between Japanese tuners and Australians are not too different after all, its just the mail order tunes that are richer for margin of safety

[Toshi]

Hey guys,

Just want to add a couple more things here.

Basically, when AFR is rich, piston and cylinder can simply cool down by fuel.

So if you drive stock R33 at the race circuit for 12 hours, it will never blow the engine.

Just for extra information, when Factory Subaru liberty turbo (all stock) made the fastest record (faster than Saab turbo) in 0-100000km in oval circuit at 1989 year (maybe 1988), its AFR was 9.5. If it actually was AFR12, it probably couldn't have completed the circuit.

Factory tune is to be safe but I do know that the Japanese tuners do shave the margin a bit resulting in AFR10.8 at before cat.

The other thing is, adjusting AFR to 12 in summer, it wouldn't be too suitable for winter.

In winter AFR will end up around 13 and i'd say it not too safe on a race circuit.

I hope I was convincing enough.

Just to finish off, I think it'd probably be better in the long run to tell the tuners what exactly you're after; better fuel consumption or higher power and where you'd be using the car. street or circuit because these will all be important factors.

[KiwiRS4T]

so does he go with the leaner tune an less timing or rich ?

And as someone else said would be good to see some fc or other maps of aggresive tunes !

rich - haven't got a map - can't afford him atm!!

[Don Dada]

HKS , APEX , MINS , TRIAL , all famous shop race cars AFR 10.8 at before cat (around same place std O2 sensor).

They are try to 0-300km/h at YATABE also 0-1000m race in 1990s then they found best AFR 10.8.

AFR 11.3 some time engine blow but 10.8 never engine blow.(around 800hp RB engine )

Std R33 25det AFR around 10 also std IMPREZA AFR around 9.5.

So AFR 10.8 is not rich.

I think AFR 12 at muffler is not problem for street car.(FMIC , full exhoust , boost 12-13psi)

But bigger turbo car need richer than AFR12.(Im adjusting AFR 11-11.5 at muffler.This is around 10.8-11.3 at before cat)

With a name like Toshi I'm guessing you are a Jap tuner???

I for one dont mind running my car from 12.0 coming into boost and dropping gradually to 11.0 say from about 6000 up(ie. before the cat).....That way fuel consumption would not be that bad and the extra fuel will be there to protect the engine higher up in the rev range

Is there some thing i am not getting????.....

Is there sooo much power to be gained by leaning out the afr from 11.0 to 12.0 on pump??? or is it that skyline owners are so cheap they cant afford to keep on filling up the juice so they go complaining to their tuners that their fuel consumption has gone out the window after he has raised the boost a couple of psi and retuned the ecu so now its up to him to get more power out of the car BUT maintain its factory consumption rate???

Again i know which way i'd rather have it.....

[Don Dada]

Oh yeh.....and another thing now.....

These million and one dyno sheets here......Where are the afr readings taken from??? before the cat or in the tail pipe???

I'm guessing different shops have different methods right???

[paulr33]

i think most workshops doing a dyno tune on a car would do it with an 02 sensor up the muffler

this saves time and is quicker and easier to perform

how many workshops would remove the factory 02 sensor and put a wideband sensor in the bung on the dump for tuning and then remove it when done ?

[STATUS]

its old school tuning for rich.... even the newer factory euro turbo cars are tuned fairly lean... ie leaner than 12.5... not that we go there often... customer and car determine the tune really.

I've seen perfectly good results from 13:1 and around 500hp on an endurance race car.

[KiwiRS4T]

i think most workshops doing a dyno tune on a car would do it with an 02 sensor up the muffler

this saves time and is quicker and easier to perform

how many workshops would remove the factory 02 sensor and put a wideband sensor in the bung on the dump for tuning and then remove it when done ?

My tuner (Scots not Japanese) gets all his customers to put a second bung in the dump for the wideband.

[scotty nm35]

If youre going to bother putting the bung in, may as well just install the wideband in the dash... Much more practical than climbing under the car and installing it each time.

There isnt much difference in readings from dump to muffler from what I have seen. Perhaps there would be on a stock cat?

[Guilt-Toy]

It can change slightly from downpipe to tailpipe.

Here is a dyno sheet of a car i tuned here, because this car was from a different country and their fuel is not as good as ours I richend it up on the top end. (different altitude also) the higher you go the richer you go, so at home his car is running around 11afr

You can actually see the power raise start to drop exactly where the AFR richens up .5 or less of a AFR

I have a saying, Keep em rich keep em cool. A cool engine is not going to melt unless something is very very wrong.

"skyline owners so cheap because they would rather run 12's to save fuel" what a ridiculous statement. 1 afr on boost will make no difference in fuel economy. Do you drive wide open throttle to work in the morning? if so I hope you don't live near my family.

[simpletool]

I always ask for AFR 11.5 when I go to get a tune. It always comes out at 12.0 or higher. No idea why tuners insist on running leaner for a few percent power and end up with higher temps if you ever use it on the track or highway.

[DVS JEZ]

It can change slightly from downpipe to tailpipe.

Here is a dyno sheet of a car i tuned here, because this car was from a different country and their fuel is not as good as ours I richend it up on the top end. (different altitude also) the higher you go the richer you go, so at home his car is running around 11afr

You can actually see the power raise start to drop exactly where the AFR richens up .5 or less of a AFR

I have a saying, Keep em rich keep em cool. A cool engine is not going to melt unless something is very very wrong.

"skyline owners so cheap because they would rather run 12's to save fuel" what a ridiculous statement. 1 afr on boost will make no difference in fuel economy. Do you drive wide open throttle to work in the morning? if so I hope you don't live near my family.

what the main reason behind richening it up after what i assume is peak torque?

im guessing just to cool it down a little?

do you add more timing in during the enrichment after 6500RPM

[Dose Pipe Sutututu]

what the main reason behind richening it up after what i assume is peak torque?

im guessing just to cool it down a little?

do you add more timing in during the enrichment after 6500RPM

from what I've read to keep the pistons cool, the quicker than move about the more friction & heat it will cause right?

richening up the tune up the top will keep the pistons/rings/ring lands in tack but this sacrifices power output.

and from what toshi has said before and after cat, yes there is a difference, I've had my car on a dyno and the A/Fs were different to what my wideband was reading (pre cat).

Most tuners are save time/money by tuning at the exhaust tip, but I don't believe that's the best way to do it.

I personally have pumped in extra timing after MBT, for my old setup it was around 5600rpm, and the timing for row 17 read something like

Row vs Timing 10/13 11/13 12/13 14/13 15/14 16/14 17/15 18/11 19/11 20/11