Stillen header issue finally fixed
 

I ordered my headers last week, got them yesterday and just finished installing them after way too many hours (I HIGHLY reccomend spending the money on a mechanic) and they lined up perfectly. I mounted them attached to my gtm resonated test pipes and it lined up to my greddy ti c catback with no issues, it is a tad loud tho

:roflpuke2:

Oh yeah... vids please!

Didn't know they had an issue, mine fit perfect. With you all the way on the install.......let someone do it who has a lift, the right tools and small hands. Now that I know how difficult it is, would never do it again.

How did you get out the 02's? Also didn't realize the 02's self weld themselves and screwed both of them up also. Not cheap.

There were a couple of people that had issues with them lining up - including someone who had to cut their HFC and re-weld it.

Damn, looks like I missed a bullet for a change. Usually take them in the middle of the chest and go down hard.

For sure was blindsided by the 02 issue. Just hope everyone knows the 02's are $425.00 each, basically weld themselves into the exhaust manifolds and not try and take them out while still on the car or you can screw them up very easily. (like me)

Please do all of us a favor and dyno your car so we know exactly what we are getting performance wise. I did intake, headers and exhaust at the same time so to my knowledge there is no baseline. Guessing between 4-6 real world hp gain.

What's up with all this Stillen exhaust quality related issues??? Really lost all respect that I had for them.

For the O2 sensors I used a penetrating lubricant called nok rust, I poured it on and instantly the sensors started coming off with no resistance, the second I started to feel the smallest bit of resistance I'd pour more on. Took me maybe 45 second per sensor

Denny, I'm thinking maybe you missed this thread of mine? -> http://www.the370z.com/intake-exhaus...-vid-dyno.html

Obviously I did. Thanks!

This shooting for the moon stuff doing mods sure is fickle at times. Is the power gain worth it.....obviously, no. Would I probably do it again knowing how to do the 02 sensors. Maybe. Still a real, real tuff job.

Thanks again.

Semtex

After reading your post on headers closer, guessing maybe the bullet probably hit me after all. Perhaps the headers are the real reason the Stillen exhaust didn't fit properly as I did both at the same time and the Stillen CBE sure as heck hit the cross member. Thanks again for enlightening me.

Also, weren't they promoting something like 20 hp gains? It is typical to get 5-6 out of shorty headers, but 3 hp really is on the low side in my opinion.

Well, the thing about advertised gains, I've noticed, is that it's always the gain if that's the only mod and everything else is stock. In other words, it wouldn't surprise me if one really could get a gain of 20hp from just the headers -- if that's the only thing they did. As I'm sure you're well aware, once you start doing multiple mods, diminishing gains comes into play. I did the headers after I had already done the CBE and HFCs and intake. If you look at my dyno from the intake, for example, I got a nice gain out of that, even though I did them after the CBE and HFCs (+14.7 whp). But I think by the time I got to the headers, everything in my intake/exhaust was already pretty well opened up, hence any additional gain from the headers was minimal. Here's a link to my journal thread, btw. You can use it as a jumping off point to all my other dyno charts along the way if you want. http://www.the370z.com/members-370z-...blue-370z.html

The other thing about gains, is that it applies to the peak output.

It never makes claims based off an average increase...the only thing some of them do is post dyno charts, but even those can be a finaggled. And, Dyno runs have a fault in that they show results only under wide-open throttle, and not under a given throttle condition or varying engine load...or going down the road at 45MPH (overall efficiency increases) - or accelleration between 45 and 75....

For example, a turbo can boost top-end HP by a TON under WOT conditions, at a given RPM or above. Looks great on paper - makes 700WHP. However, the torque curve is jacked, and from 3K and below, it makes less HP...

All I know is that the more air (and fuel at the correct ratio and dispertion) I get through an engine, the more power it will make.

I'm not sure I agree that the fact dyno runs are performed under WOT is a fault. The purpose of dynos is to do before/after comparisons. As long as both runs are done with the same amount of throttle, then you have an apples to apples comparison and the dyno runs have served their purpose. I would venture to say that it's far easier to perform two dyno runs with your foot planted all the way to the floor than it would be to perform them with your foot holding the throttle at exactly, say, 65% to WOT. Now, if you could hook up something to dial in exactly the amount of throttle you want without even using the gas pedal, then that'd be pretty cool, and people could start using dynos to compare numbers at different loads. But until doing something like that becomes feasible/practical, I don't see any other good way of doing it other than foot to the floor, do you?

Not so sure I agree on this one. Really was sponsored at one time by a dyno shop (actually two of them) and seen quite a few cars have headers added, then dynoed right after and not what I've found from my personal past experience. It's always the weak link you're trying to fix and the system works as a team to optimize the entire system. For example adding headers to a Z06 is not cost effective as the factory put on damn good exhaust manifolds on the car and quite a few of the LS3 guys are doing Z06 exhaust manifolds instead of headers. Obviously my feeling is headers on the 370Z is also very cost ineffective. Especially if you do like me and booger up both 02 sensors.

If the exhaust manifold was the major weak link, it will show regardless of what other mods are present. CFM is..... CFM. Frankly was surprised as to how good the stock manifold was mfg as they look more or less like headers and were port matched better than the Stillen headers.. Wimpy tubing and not equal length, besides that....headers.

Obviously the stock cats are a major weak link and personally got a 12 hp gain just from doing cats.

Bingo on the average power output within the intended rpm range, Bingo on being a huge air pump and Bingo on manipulated dyno results.

Read Chapter 1 (Basic Engine Theory) in John Lingenfelters book as he emphasizes application plus what he calls "The Golden Power Rule": Always emphasize power within the rpm range where the engine spends a majority of time.

The guy who ports my heads (Trevor Johnson) at one time worked for the Nickens Bro pro stock team and just talking with him at his shop has really further enlightened me quite a bit. He does exactly the same porting heads on the flow bench as he never pays much attention to peak flow.....it's average flow within the lift range of the cam. He'll back cut valves which hurts peak flow but helps lower lift flow to get a better average.

Truthfully whenever I do a mod typically post peak hp gain at peak hp, but privately have a spreadsheet that computes average hp gain and average hp gain within a simulated 1/4th mile run. This is the one I really look at, not the dyno sheets. The dyno sheets are just input for the spreadsheet.

In my Corvette On I-635 from a second gear punch ending up racing a turbo car that made over 100 hp more peak power. Immediately started pulling him but saw him start to pull me and catch up. This didn't last long as soon as he shifted out of his peak power, the car lost momentum and I kept walking. Still average power that wins races.

No question people whom sell performance items pick an area of the curve which supports the most gain, quotes that figure and are not afraid of finding "Optimal Conditions". One unintentional aspect I see people do is they take a hot car, dyno it and post the output. Then they put the mod on letting the car cool, redo and it shows a gain. My car shows over a 10 hp difference between hot and optimal temperatures and the only mod was letting it set for a while.

I'm curious to see/hear more on the GReddy Ti-C exhaust...

Sometimes true gains do not show up on the dyno and again, your right on. Just ran through my spreadsheet increasing the rev limit to 8000 rpm from 7500 rpm. The net effect is a 5 hp average gain in each of the first three gears. What does that mean? Dunno.......waiting for final tuning and some track time, but would guess a half to over a full car length.

How about air intake temps while you're moving? Did a lot of research logging actual intake temps ending up fabricating a ram air type intake to direct air directly into the Gen 3 filters. Also put a lot of heat barrier on the Gen 3 intake tubes and in particular the MAF's.

On a cool motor my actual intake temps are a low as 3 degrees over ambient and in everyday driving 8 degrees over ambient. So what does this mean? In every day driving was able to lower the temps by 10 degrees vs stock Gen 3. If you go by the 1% increase in power rule by lowering intake temps 10 degrees.......2-3 hp throughout the entire rpm range.

Lowering your water temps from 200 degrees to 160 degrees is worth another2-3 hp almost throughout the entire range.

Just doing those things will give you a 1-3 car length advantage in the quarter mile. About getting more 02 into an engine.