SAFC tuning theory

[strutto]

Show us your AFR'S

Your not guuna pick on me are ya???

This was done on 5-6psi... (No factory bleed, DIY bleed closed).

The dip gets worse with more boost...

The heatsoak of the stock intercooler is clearly evident.

[hippy]

hey how do i know whats what on the graph??

are they just 4 different runs??

and whats the ideal af ratio??

[EnricoPalazzo]

there are 4 runs each differnt colour of pattern of line. The upward hill lines are the max power. The bottomw jagged lines are a/f ratios.

an ideal afr on a turbo car is 12:1

meaning 12 paers air to one part fuel.

on a na car its about 14.8:1 me thinks

Question: Why the hell on your dyno graph do u run real lean when it gets to red line around 6500-7000rpm???? Dangerous?

[EnricoPalazzo]

Strutto why would u allow the car to be dynoed in 2nd gear?????? THis would not really give a realistic power at wheels value. The value would be highly inflated

[strutto]

Enrico: Not sure why the graph runs lean at the end... The car was only run to 6500-6700 before the dyno operator backed off... Looking at the graph here, the lean AFR's aren't under power, so I assumed this was just the AFR's going into decelleration mode?

Even so, nothing goes over 12.5 which isn't "too" bad.

To be honest, I don't think the dyno operator really knew what he was doing. I certainly wont be going back to that establishment...

As for 2nd gear? Mines auto... Trying to keep the auto in 3rd or 4th when flooring it from low revs is impossible. Kickdown takes over and your in 2nd gear again

Noones ever successfully explained to me why dyno runs need to be done in a certain gear anyway... If it's to do with the ratios, how can we compare between say, a bombadore and an r33 on the dyno... Even if they both run in 4th (1:1), the diff ratios are different anyway...

Thoughts?

[Steve]

Looks like he did a 2nd gear run too. the fuel leaning out is taking foot off pedal.

strutto, if that was fully stock (which it appears) that dyno shows a nice healthy engine - ripe for the modding:)

hippy, it appears to me that street tuning is something that takes a bit of experience. Not too many tuners around these days that do it anymore, infact I dare you to tell me the name of one in Adelaide:) The road side of things is good for off boost and driveability, but you need to get the car on a dyno for a final trim and to make sure everything is ok.

Also, just do be careful you dont go crazy and pull too much fuel, just because you dont have a huge amount of mods, doenst mean you cant smash ring lands if you pull too much fuel.

[Steve]

Well the reason people say to do the run in 1:1 gear is that power is a function of torque and rpm.

Imangine if you use a lower gear, the mechanical advantage will be higher, therefore the torque will be higher, giving a higher power figure.

That is until you get to peak power, which will read the same, as the wheel speed is alot slower for the same rpm (as in a higher gear) but as the torque is higher due to mechanical advantage, the difference is cancelled out.

My understanding anyways, and I do have the 3rd gear and 4th gear dynos with the same power to prove the theory:)

[Steve]

Hippy, sorry for all the whoring:(

Back on track - get your car on a dyno you tigh arse:p

Also, if you want to check base timing, I have a timing light you can borrow.

[strutto]

Steve: Good info, thanks!

Stock? 3" Front and Cat back. Stock dump. Stock filter. 5-6psi. BCPR6ES gapped at 0.8...

[Steve]

Hmm, well if you have got a 3" from front pipe back, you 'should' be getting more than 5-6psi. Stock boost is 5psi to 5000rpm then 7 psi to redline, you should have a couple of extra pounds with cat back..

dynos not bad though, I didnt read the previous posts and didnt realise it was an auto till after I posted:)

[strutto]

This was done on 5-6psi...  (No factory bleed, DIY bleed closed).

Hmm, well if you have got a 3" from front pipe back, you 'should' be getting more than 5-6psi.  Stock boost is 5psi to 5000rpm then 7 psi to redline, you should have a couple of extra pounds with cat back.

Yea, I have disabled the factory bleed and use my own incabin bleed. This was closed during the dyno runs. Factory wastegate opens at 5psi I believe. The extra 1psi or so up high is due to the less restrictive exhaust I reckon...

[firebladejr]

interestingly enough, my safc was used to richen the mixtures up top....

It did 5 runs on the dyno in 4th gear and by richening the mixtures (+9%)from about 5k onward (75%throttle) I was able to gain a healthy 17rwkw and totally eliminate pinging. The car has a much fatter power curve and feels 100% better on the road. Plus I have the peace of mind that it isn't pinging and is safe to run at 12psi.. I'd go dyno tuning over road tuning unless you really know what you're doing.

[hippy]

hey steve whens the next dyno day?? maybe u can tune my car ... how do i use that timing light u got?? .. i dont' even know what it is LOL

[Guest INASNT]

hippy u r gonna fark your engine up man.

it only takes about 30mins for someone that knows what they are doing to tun your car on the dyno!!

also fyi i could get my gfriends old 1.3 litre mazda 323 to wheel spin in 1st gear, so spinning the 33 in first is no biggie!

[hippy]

it is for me, since its an auto .. and i'm just pressing the accelerator ..

[hippy]

and yeah i was just playin around with it .. its all back to 0 correction now ... i'm not that stupid LOL

[Steve]

hippy, I know you dont like spending money, but your tight fistedness never ceases to amuse me:D

if you dont spend a few bucks getting it tuned properly, it will only cost you money when you have to rebuild the engine:p

[EnricoPalazzo]

haha hippy the tightest skyline owner ever. and come to think of it he offered to take me to lunch for all the trouble i spent on his car haha. I knew i should have taken him up on that, he would still be wingin about it now muhahah.

[Steve]

Depends on where he takes you for lunch:D

[hippy]

i was thinkin of taking him to maccas down the street ... LOL