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Stillen Headers Installed


dernt
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sniped from AC:

A long while back, I bought some used Stillen headers from ebay. The seller claimed they were professionally welded due to a cracked flange. Well this guy's idea of a professional weld involved his drunken buddy hitting the inside of the flange with a buzz box stick welder. But since these things are quite a commodity these days, I figured I keep them and fix them. So after grinding his mess off and having a friend do a nice job, I sent them off to Jet-Hot to get them coated along with some cats. They have been collecting dust for many months. I got the bug to do the job today, so I started on what I hope is the more difficult (drivers) side. I ran out of daylight due to a couple of trips to Sears for tools and the auto store for bolts. It's not a difficult job, but I'm doing it in a gravel driveway with no helper and limited tools.

 

After a short break in period for the coating, I will take it to the dyno and post results compared to my baseline with stock exhaust. I might put a flowmaster on as well.

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98Silver and Pezzy are right. I bought these from ebay a while back, repaired them, and sent to Jet-Hot for coating. My right manifold was destroyed, so my Pathfinder got quieter with these on. Pre-header install my best dyno was 137.6 RWHP @ 4700 rpm and 167 ft-lb. torque at 3500 rpm. Gonna try for a dyno pull this week time permitting. I will post better installed pics later, but right now it's dark outside. Please no cracks about my oily valve covers.

 

LH%20header.jpg

 

 

RH%20header.jpg

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Dude, you'd better get going on that SC pretty quick, or you won't have anything left but a pile of rust and pitted aluminum! :)

 

Bah!, sandblast and powdercoat. Rust is slower than me.

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Lookin good. Anyone have a passenger side cat they wanna sell? My pathy has been throwing a front passenger 02 sensor code forever, replaced both front/rear sensors and everything and a code still come sup, im thinking clogged or bad cat..

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Bah! Who da man? Who da man? Dernt da man! Dernt da man!

 

I knew that the pathy had low HP on the ground but would never have guessed under 140....was that with your intake? That 15 or so from the cams sounds really good now!

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Yep, that's with the Stillen CAI. I think the pathfinder is rated at 160 HP at the flywheel, if so, 137 hp is less than 15% loss through drive train.

 

I have cats, but I think I want to sell as a pair. They have 160,000 miles on them, but I was not throwing codes with them. I'll post in classified.

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The dyno results are in. First let me say I did not post any qualitative results prior to the dyno because with the exception of the truck being quieter now, I felt no difference.

 

I do not understand why the files differ from the print out, but relative to each other, they sort of agree. One month ago, prior to my header install, I had a baseline dyno pull, and I had another this morning. Ok to drag out the suspense......one month ago the humidity on the dyno data read 12-13%, today it read 37-39%. I am assuming humidity is deleterious to performance and I doubt the validity of the RH numbers, but it was a heck of a lot more humid today than a month ago. Also, ambient temperature was 83-85 one month ago, and 86-87 today which probably had little to no effect.

 

pre headers 134 HP and 163 ft-lb (from dyno file)

post headers 135 HP and 168 ft-lb (from dyno file)

 

Now the print out results were as follows:

 

pre headers 137.6 HP and 167 ft-lb (print out)

post headers 138 HP and 171 ft-lb (print out)

 

I have no explaination for the discrepency in the printed data handed to me vs. the computer files I copied today.

 

Now, before you all go psycho, there is a problem with the air-fuel ratio. It is lean @ ~ 13.5:1 to 14:1 in some places. Like a dummy, I have not changed my fuel filter in eons, so I am hoping that will help. But I don't think I'm gonna go for a dyno based on a fuel filter swap.

 

So if you are dying for that 1 HP and 5 ft-lbs. of torque, hunt down those Stillens and you will be in business. The power and torque gain was consistant through most of the rpm range.

 

Blue is with headers, Red is without. The upper curve is torque of course, and lower is HP.

dyno.jpg

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Is this with stock exhaust and cats, or something newer? Stock timing? 87 octane? What elevation? ;)

 

stock exhaust, as far as I know, R50 timing is not adjustable, so yes, stock timing (clue me in if I can change it), 93 octane, 100-150 ft elevation.

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Is it a 3.3L engine? Assuming so, since it's a 98. Loosen off the distributor, and give it a turn. Same as the WD21 Pathfinders.

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