VK45 –Stage 1 Headers/JWT cams/TB/intake

turbocad6 said:
here's how it works


in closed loop the O2 sensor gives feedback as to rich or lean condition...

the computer then compares this actual reading to a predetermined ideal target parameter that it reads from a map & it compensates & adjusts according to the feedback from the O2 sensor.

if it's lean relative to the parameter it wants to see then it will add to the fuel count. eventually it will become rich, it then takes away from the fuel count, it then eventually runs lean & it again adds to the fuel count.

this all happens in milliseconds & it's a constant waveform of rich-lean-rich-lean-rich-lean at many times per second & all oscillating above & below, but right around it's targeted parameter for the most part when everything is working as it should...

what OBDII adds to this is it adds a second O2 sensor downstream from the cat. when a catalytic converter is doing it's job properly the O2 readings should oscillate at a much slower rate than it does before the catalytic converter as a result of the chemical conversion that the catalytic converter is there for. the slowing down of the oscillations is the sole way of the ECU knowing that the catalytic converter is doing it's job efficiently.

so the ECU compares the frequency of the oscillations before the cats to the readings behind the cats... if the rear O2 sensor is changing much slower than the front O2 sensor then it thinks the cat is doing it's job, no trouble codes are generated because every things fine according to what it see's.

where the spacers come into play is, the spacer takes the second sensor element after the cat, which is supposed to be in the direct stream of flow & recesses it into a little cave like chamber that is off to the side of the main exhaust flow. this results in the exhaust gas in the little side chamber changing much less quickly than it would had it been in the main exhaust stream. this slowing down of the changing of the exhaust gas around the sensor obviously results in the readings from that sensor slowing down too. the ecu sees this as the cat is working... this works even with no cats at all because it does the same thing, simply slow down the readings from the second sensor...

I'm not sure if the downstream O2 sensors can be turned off in the flashed rom...
Click to expand...

Couldn't have said it better myself - for reals :)

---------- Post added at 08:34 AM ---------- Previous post was at 08:24 AM ----------
tchuck said:
Damn man, that looks awesome. You have anything to do with that beautiful "Burns" logo placement? :tongue (2):
Click to expand...

No, I didn't but it does make for a great shot :wink (2): shame its going to get coated over......
 
Thought I'd drop this pic on this thread as well. Image quality is weak but headers look full race style, top quality build and perfectly matched lengths, going to maximize whatever exhaust gains possible......

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Looks good. What does your guy think about the single pipe sized for a VQ35 leading back to the muffler?


Sent from my BlackBerry 9800
 
Says its all good and that the 3" Nismo is fully capable of handling the NA flow.......I can only imagine what the long tubes would sound like with a true dual.
 
Treading on thin ice here but Is the "Jizz in my pants dyno" similar in any way to the tried and true "butt dyno"?
 
Another header image for those who are interested. Apologies for the small pic, I have been having trouble posting larger images today. Even at a very small size most of my images are being called out as exceeding size to post.
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Man, they looks so massive. Your shop did good. Alright, get it welded up and coated. We can't wait to hear them.
 
Update - Headers STILL not out for coating, grrr. Setting up jigs and patterns for more headers based on my assembly but really I just want my DD back. Manifold will be back Friday so all the top end re-assembly work can happen then its just a waiting game for the pipes.......
 
argh, that must be so hard, to not know when you will get your ride back.
I'm sure It will be worth the wait though Lance.
 
Feel for ya lance, know you can't wait to get her back and open up that beast. I Keep looking, correction, drooling at the tiny pics, They are just so... Nasty!
 
A steady stream of pictures would help ease the pain =)...looking back would I launch into this if I knew how long it would take? Maybe not, at a bare minimum I'd have set up a loaner car from a friend well in advance, really it's the guinea pig dealeo and the secondary manufacturing option on the pipes that is the time vampire. The next person in line will have the install data or pre-made product and it will take a week at most to make this happen.....
 
So are they going to mass produce the headers? Or it'll be more like ask for it and well make it happen.
 
He's going to make 2 additional sets of the long tubes (one is already spoken for) and 5-10 sets of shorty headers. The M crowd is on board, I think he also has a Titan or two interested as well. Not sure what my break in period (I know we have one or two immediate oil changes planned) will look like so it may be a few more weeks before I get in for a dyno run.

---------- Post added at 03:41 PM ---------- Previous post was at 03:41 PM ----------
tchuck said:
Fixed. :wink (2):
Click to expand...

Hah!
 
Manifold came back amazing BUT headers have been pushed back. I had the choice of taking my FX back today with the stock exhaust manifolds re-installed while the headers are coated then have them removed again and the new units installed. I chose to leave it with him and have everything dialed in as I have a business trip coming up. Going to be over two months down, never in my wildest dreams.........
 
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