I would like some info on what would be a ideal air fuel ratio for a na Z to make the most power, because im going to have my ecu reflashed again. I was told to have the airl fuel start out at a 13.0 then go to a 13.4 at redline.

Thanks Glen

 

From my knowledge - though it maybe somewhat limited
14.7 at idle > 13.3-13.5 through the meat of the rpm band and maybe tapering off to around 13 at redline (to be safe/conservative)

 

I've had my z since aug 04' and I really do appreciate all of the information on this site, especially the steps that were outlined for getting ready to upgrade your vehicle. I know that I will not be adding any tt's or sc's to the car or anything else in that price range. Although I am very interested in geting just another little bit of HP. I was looking into upgrading or changing the ECU and its been very difficult to find out; what the cost is, what the best option is, and what the results will be, meaning how much HP will i gain on the dollar? I'am willing to spend (i know its not much) $1,000.00 to $2,000.00 range what could I do for that price and get the most hp.

thank you

 

vitod,
that's kinda a tough price range, but i'd probably do
jwt popcharger, UR pulley, cats, plenum spacer, and technosquare or AAM ECU flash. These would require the least amount of labor cost

that'd get you around 20-25 more hp or so

hard to say what'd be the best though cause it depends on what you can live with.

A lot of people would say screw some of those things and to get a different clutch/flywheel or 3.9 final drive and those would be good choices too

other people say that the car has quite a bit of power stock and the things that need improvement are the handling. So tires and sway bars might be something to look into in that case.

Or some sort of combo. You're going to have to learn about those parts though to figure out which seems right for you

 

I just had my ECU flashed 600 bucks + shipping. In terms of HP, I don't know if I gained much, but the car does feel much smoother now. The flash eliminates the speed limiter, raises the rev limiter, and allows the TB plate to open 100% above 5500 rpms - along with adjusting the fuel and timing maps.

In my case, I was running a bit lean down low, so I might have actually lost HP in the lower RPMs as the car was richened up a bit, but I notice more power up top, so all in all, a +. Getting my A/F ratios corrected is the most important thing.

On a N/A car, there is limiting tuning that can be done so gains will be minimal. If you find your car to be running rich, like in the 11's or below, there is decent power to be had at those RPMs where the car is rich. You can add some timing back in up top, but that's about the extent of the tuning that can be done.

My shop where I dyno'd suggested the split second FTC1 box for tuning - allows for fuel and timing control. Expect to pay 500 + tuning to get it setup.

Without most of the bolt-ons, skip any A/F or timing adjustment. If it were my money, and based on my experience, here's how I would spend $2K(figuring you do all installs)
1.) Hotchkis TVS - $400 + $60 alignment
2.)Test pipes or HFCs - $200-$500 depending on which you choose
3.) UR Crank pulley - $230 includes belts
4.) plenum or plenum spacer - $200-$500 depending on choice
5.) whatever you have left spend on an exhaust of your choice

 

Agree!

 

Right now my z is running a bit lean after all my head work and jwt cams installed. Im at 14.6 to a 13.8 at redline so i need to have the fuel richened up, because i have so much more air coming in and leaving. So the best air fuel would be to have it at around 13.3 or so for the most power im thinking. Anyways I still put down 264 rwhp std in my automatic Z with a smoothing factor of a 5 on a winpep7 dynojet with the latest software upgrade. I hope for more hp after a throttle body upgrade and custom ecu reflash again.

Thanks again Glen

 

Mean peak power is achieve at roughly 12.3:1....anything leaner or richer will reduce power.

Contrary to popular opinion, leaner mixtures do not produce more power above roughly 12.3:1.

 

That's the case on NA cars? On my previous car I ran an AFR and gained some power leaning the car out from the 12's to the 13's. I trust you know more than me, but I was under the impression that the leaner the better in terms of making power - not necessarily for the motor. My shop that I dyno at tunes FI to around 12.3, but NA to 13-13.5. Any thoughts on why?

I had my ECU reflashed and my A/Fs were in the 14's for the first half of the RPM band. I haven't run the car on the dyno since I got it back, but from what you stated, you would say I would gain power in the lower RPMS since the reflash 'supposedly' richened up that part of the RPM range?

Always trying to learn

 

So for NA 13.1-13.4 would be good to make max power.

Thanks Glen