this thread is a summary of my story with mod`ing my `05 non-rev AT 350Z :
first i did a dayno for my Z befor i do any mods and i got only 212 WHP from it where is the rest
then i installed APS 2.5" TD exhaust and i gained 17 WHP (which is good from exhaust only) :

<a href="http://s273.photobucket.com/albums/jj206/Darkness1975/?action=view&current=scan0001.jpg" target="_blank"><img src="http://i273.photobucket.com/albums/jj206/Darkness1975/scan0001.jpg" border="0" alt="dayno sheet"></a>

not to mention the low end WHP/Trq that i lost (the car is slower in acceleration but butt dayno and top speed is good)
after that i add Berk HFC + k&N drop air filter, i lost -0.46 WHP :

<a href="http://s273.photobucket.com/albums/jj206/Darkness1975/?action=view&current=daynoAPSB_HFC.jpg" target="_blank"><img src="http://i273.photobucket.com/albums/jj206/Darkness1975/daynoAPSB_HFC.jpg" border="0" alt="dyno APS2.5 Berk_HFC"></a>

even i lost more low end but again butt dayno and top speed is good
now i installed MD iso thermal plenum spacer ,i gained almost 4 WHP WTF ??? i should get 10-15 WHP (butt dayno much much better than b4)

<a href="http://s273.photobucket.com/albums/jj206/Darkness1975/?action=view&current=Spacer-dayno.jpg" target="_blank"><img src="http://i273.photobucket.com/albums/jj206/Darkness1975/Spacer-dayno.jpg" border="0" alt="Spacer APS2.5 HFC"></a>

every body is talking about my Air/Fuel Ratio need to be adjusted ,so i need to tune my car
now i`m between getting the Apexi (S-AFC) or UTEC (turbo xs or any outher) to tune my car ,i know this Q i should ask it in the tunning section but maybe some can help (since its related to exhaust parts) :
1) will i gain my lost WHP from tunning ?
2) is it true that the ECU will take over the S-AFC after a short while and return to the factory ratio so its worthless i should go with UTEC case closed ?
there is a big difference in price so is it worth it .
p.s : i`m not going F/I , at least for a long time

 

safc will be useless for you. get it tuned and let us know. also, use SAE correction factors, using DIN could be your entire problem as far as numbers go. do you have winpep and the runfiles? if not, get them

 

100 degree?? lol...

 

I would get Osiris. Has many uses (diagnostics) that you can continue to use down the line. Add a little fuel and I think you'll pick up a few ponies for sure. As far as you know, the car may be retarding timing with your current AFR. The heat soak doesn't help either.

 

thank you guys for your replays
can u go easy on me !!
what do u mean by :
use SAE correction factors ?
using DIN could be your entire problem as far as numbers go ??
do you have winpep and the runfiles? if not, get them?

 

How could you “lose bottom end torque”, and claim “the car is slower in acceleration” but on the other hand state your “butt dyno and top speed is good??? Butt dyno is not going to be able to determine top end gains… however, you will be able to tell if there is low to mid torque… so to say you lost torque and the car doesn’t accelerate, but your butt dyno tells you its good make no sense.

Sorry, but I don’t understand your description.

As for A/F – yes, you are running a bit lean which means your mods are working and a tune to add fuel will (should) give you the trq you lost (that your butt dyno doesn’t realize).

 

ok, first of all your initial dyno runs were between 80-90 degrees and the last three were between 95-100... this is def an issue. you probably gained more top end then you realize; try to go a day with similar ambient temperature as your first pulls in order to achieve consistency.

dont expect gains advertised by vendors/manufacturer. they usually are inflated numbers, or simply bs made up figures.

 

+1
Changes in ambient temperature make a big difference. As air temperatures go up, not only the air density goes down, but the ECU also pulls out timing.

Both of which reduce power.

Whenever possible, try to do all your comparative dynos with the same atmospheric conditions. Humidity, temperature and pressure.

You can also use a tune. Many areas of your plots show A/F running around 14-15 in the upper midrange. That is too high.

You may also be experiencing inaudible ping because of it. If it is happening, the ECU will pull out additional timing and reduce power from that point and higher.

Tony

 

I bet it's a kitten that's saying "I are steeling ur horzpowerz" or something.

 

claim “the car is slower in acceleration” >> at the first then you can feel the pulles hard and then fly better than b4 >>“butt dyno and top speed is good , thats what i ment !

and guys what about #2) is it true that the ECU will take over the S-AFC after a short while and return to the factory ratio so its worthless

 

 

I dunno 'bout that, but this kitty eatz dataz from serverz~ Lol~

 

ahaaaa ,,,ok lool
thanks for the laughter

 

Cue the roflcopter!

 

lolz~ :-)

 

^^^^^ I can haz laughing floor?????

 

 

I don't see a problem with the air:fuel ratio. What did you tuner say?

 

horsepower hobbits, distant cousins of the underpants Gnomes

 

i thought they may have been cowboys.