Thanks semtex.

+1 REP

Different jurisdictions have different methods for emissions testing, so it depends on where you live. These will pass with flying colors where I live, because all they do here is hook up their computer to your OBDII port to check for codes (aka CELs). If you're clean and haven't had any recent codes, you pass. They don't bother looking under the car to verify you have cats, and they don't put a sniffer in the pipe anymore (unless it's a really old car with no OBDII). If they did use sniffer on my car I'd be screwed. lol

Sorry I got to the party late. semtex, you are an awesome man for going to the trouble of doing all the work (install, dynos, posting).

I have a few questions. The before and after dynos, are there multiples of each or just one of each? If there are multiple dyno runs, are they averaged together and shown on a single line? Or are these the best of each session?

The reason I ask is because these before and after graphs look to be, at most, about 10 hp or 10 ft/lbf away from one another at the greatest delta. I've witnessed hundreds of dyno sessions where back to back runs were not as consistant as these two are.

I fully understand you went from a very efficient setup to another very free flowing setup (the difference compared to stock would be much easier to see). The sound difference alone is reason enough to justify the cost in my book (if the sound you are after is achieved), but after looking at the graphs so long I'm wondering what gains were really made. I'm all for lowend torque over highend hp everyday of the week. I just want to know more about the graphs posted so I can make my own conclusion pertaining to the gains.

One more question, I'm not on here very often and I don't know you, does your car have an automatic or manual? (can't see the videos at work)

Thanks for your time.

Multiple runs were made, and all of them consistently showed loss of peak hp, as well as the same deltas in the low and mid-ranges. The two lines on the Dyno Dynamics are the best from each session. But within each session, the multiple runs were within +/- 2whp of each other, max. That's how consistently this car dynos. Indeed, you can see this in both the pre-installation dyno charts that I posted, as well as in the DynoJet sheet that I posted.

I'm referring to this one (baseline from 4/7):
http://www.the370z.com/members/semte...n-04-07-10.jpg

And this one (post-installation from 4/23):
http://www.the370z.com/members/semte...ced-042310.jpg

If you look at the first one above, the baseline from 4/7, you can clearly see that the two runs are on top of each other. There really is no variation at all. Heck, the peak outputs are just .5whp from one another. But when you overlay the best run from 4/23 on top of the best run from 4/7, that's when you see variation in the low and mid ranges:

http://www.the370z.com/members/semte...2310-sheet.jpg

Keep in mind though that the dyno is just confirming what I could already feel. The gains aren't monumentally huge or anything; it's not like the effect one feels from installing a turbo. But it is noticeable none the less (to me at least). So I'm quite sure the gains are real. But you're entitled to draw your own conclusions to the contrary if you so choose, obviously. We purposely didn't overlay all the runs from 4/23 over the runs from 4/7 because with so many lines on the graph, it would be just too crowded/cluttered to see what's going on, especially when the gains are so modest. In other words, the deltas are quite small, visually speaking, so they'd be much harder to see if we had like 5 lines on the sheet for hp and another 5 for torque. With the DynoJet run, I had no baseline for comparison, so there was no reason not to display all runs made that day. The purpose of the DynoJet run was just to compare its numbers against those from a Dyno Dynamics dyno.

My car is is a 6MT, to answer your other question.

So let me ask you guys this. Are Semtex's current specs pretty much the upper limit we can hope to achieve with simple bolt on mods and staying NA? What I am asking, is 315-320 whp and ~255ft/lbs torque the upper limit we can hope to achieve with relatively simple upgrades?

Once you have LTH, CBE, Pulleys, Lightweight Clutch/Flywheel and CAE, does the next step have to be some form of Force Induction to go beyond his current numbers?

Thanks for answering all my questions. After the additional information you've given me, I have come to my own conclusions but not to the contrary. It would be a good day to have a VQ if every mod produced this type of result.

Going from stock to these headers would be interesting to see now.

I'd like to thank you again for going to the trouble to do all this. I know the direction I'm going now.

It does seem that way...especially since Semtex has about almost all the bolt ons to go N/A for this car as possible.

You know what kinda confuses me though? This car has made more power before. I dyno'd after the underdrive pulley went on, back in May of '09. Check it out. I hit 330whp. This either shows how finicky dynos can be. Or it shows that my car has lost power as it's broken in, had more miles put on, etc. But I only now have 10,500 miles! So it's not like it's all worn or anything.

http://www.the370z.com/members/semte...ced-052009.jpg

^^^^Hmmmmm....This is a very interesting point Semtex

Dirty filter(s) on the intake?
Different variables (weather, how warm the car was, etc.)?

Did you change your wheels and tires between the runs? Differences in wheel dimension could be the cause because of this. When trying to research how to compute exact optimal rpm shift points using dyno runs and gear ratios, it was mentioned that changes in the wheel diameter and the contact surface area could affect the dyno data results.

http://www.datsuns.com/Tech/torquehp.htm
http://www.datsuns.com/Tech/whentoshift.htm

No.
Maybe.

No.

price range?

What?

Pricing info is in original thread here: http://www.the370z.com/intake-exhaus...ders-here.html