jeffw

I was wondering, does strictlyZ.com pay you to display their website as your avatar?
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Jeff

jeffw

Cool.

Here's a graph of your dat:

Traffic

Always wondered what B&B stood for.

The gain looks miniscule to me, although I bet if anyone can ever crack the ECU there'd be more significant gains. Let's see what HKS, GReddy and Apex'i can do.

TJZ

Actually those are pretty good gains from an exhaust system. Check out the scale on the y-axis. For only an exhaust, that's definately good.

Namagomi

yeah, ok, you get a little more performance for 800 bucks, but yick, check out stricklyz, they have a QT video of the exhaust. it sounds like a piston is lose in the block or something

TJZ

Granted, the sound isn't as good as I would have hoped, there are still those who would be more concerned about the performance for the cheap price (compared to other exhausts).

VR3

Whats up with the stock hp 229.1 @ 6200? I'm I reading it right Just seems awfully low.

TJZ

Finally decide to get the glowing name VQ? hehe

westpak

iTrader: (19)

I am not familiar with dynos but I am familiar with jet engine testing and they are normally corrected for temperature, pressure and humidity that way you can compare apples and apples, when you test and engine in one test cell you should expect the same or close to the same results at another even though you have more variables than with dyno's come into play such as size of test cell and calibration of the etest cell. With the dynos we are seeing from 229 in this case up to 244 which I think is a big difference I would have assumed that you would see +- 5 at the most.

westpak

iTrader: (19)

I guess, like I said I am not familiar with dyno testing, but if I think the same way I do for testing they are measuring horse power should be the same no matter what machine is used you are measuring a parameter and should be the same once corrected otherwise it is useless to have anything dynoed what is the point, you ould have a horse power reading with an asterix saying it was done with such and such dyno, what is that equivalent to?? If that is the case there should be correction factors taking into account the different dynos so again you can compare apples and apples.

I assume there is an organization that establishes the requirements for dyno testing? Such as type of machine, corrected temperature, pressure, humidity and testing procedure. If so then everyone should be the same or be able to correct based on the machine used. Like I said I know nothing about dynos I am just using the logic I have.

NissaNZ

They should check their dyno machine, it might be broken.

In the video it sounds like somebody tootin' their horn.

scalbert

Having worked on the DAQ in several Jet engine test cells I do agree with the assessment. There are a few points missing about automotive chassis dyno's. Jet engine dyno's do run correction calculation based on ambient conditions to bring everything equal as you mentioned. But most Jet engines are run on a mechanical basis once turning; the dyno operator might make slight adjustments to get the engine running the way they want it to.

All decent chassis dyno's also monitor and correct for ambient conditions. There is one problem though; many do not get their equipment calibrated such as their humidity sensors which tend to drift. But even with two perfectly set up dyno's, there can be variances. But these differences are, for the most part, related to the cars and not the dyno. There are the obvious manufacturing issues where not all engines are created equal, this can account for a 1% - 2% variance at most (or at least that should be the most). But the one area which is most often overlooked, which shows up today more than ever, are the ECU adjustments.

One thing the ambient compensation cannot account for is the ECU varying the fueling and particularly the ignition timing with changing intake and coolant temperatures. A Jet engine does not have constant spark control, i.e. no timing advance, you light it and it goes. The automotive engines have varying ignition timing and it appears that the OBD-II vehicles are much more susceptible to ambient changes than previous versions. With 40 degree cooler air and 20 degree cooler coolant temps there could be as much as 5 - 6 degrees ignition advance difference, depending on the vehicle, this could easily equate to 10+ HP variance, again depending on the vehicle.

So no amount of external correction can compensate for ECU controlled actions.

Case in point, and excuse me here I do not own a 350Z but followed various links to this site and was reading this thread. A dyno test was done back in September on a CL-S6; they measured the coolant temp on separate runs and noticed that when the coolant temp increased from 180 F to just over 200 F they lost 7 HP and the same in torque. I recently ran some tests of my own by varying the IAT value seen by the ECU and a drop of 35 degrees resulted in a base ignition advance change of 1 - 2 degrees. Last summer just after trading in my '01 CL-S for a '03 CL-S6 I dyno'd my car with 800 miles on the clock and hit 241 WHP (with mods of course). Some thought it was too low but I knew that my coolant was at the 200 F mark, fans turned on while on the dyno and the ambient temps were near 90 F just outside of Atlanta, it was not run in ideal conditions. Had I had a few more miles on the car, kept the coolant temps lower (now solved with a lower stat and fan switch) and had cooler intake temps I would have hit over 250 F.

I am going back to the dyno soon to further test these issues by varying all parameters. Why do I mention this on a Z forum, because the basics of current OBD-II mandated ECUs are similar between makes. Some suffer greater variances than others but all will have less power in less than ideal conditions which SAE ambient correction factors can't touch.

BigBadBuford

Different dynos do show different numbers. If I am correct, Dynojet dynos usually show higher numbers than a Mustang dyno. I think Dynojets are the more common of the two, but it wouldnt surprise me if you were running on a Mustang dyno. I know when the LS1 guys dyno on a Dynojet, they usually put down 300-320 rwhp, and on a Mustang it is usually around 280.
Either dyno is a good way to tell if your mods made a difference, but your baseline run and your other runs should be on the same type of dyno, if not the same one.
The other factor that plays in would be if the dyno operator was doing the pulls in 4th or 5th gear. The cars are supposed to be dynoed in a gear that is 1:1, but most 6 speed cars have a 1:1 4th gear. If you were in 4th you would show a lower peak hp number. I think we are also going to see a fairly high amount of drivetrain loss, on the order of 18-20% since it is a RWD car and has an independent rear. The carbon fiber driveshaft helps, but I dont think it would make more than a 1% difference.

westpak

iTrader: (19)

Thanks scalbert for info, ok so basically dyno runs by themselves are useless since you can't compare apples to oranges and there is no uniform rule for all dynos. So basically the only thing is to compare before and after runs to see the increase or decrease in HP and Torque done with the same dyno and assume that the 5 HP increase will be what you are looking for not the exact HP number and assume the runs were done identical, ie same conditions, same gear and same gas. And hope the vendor is being honest with dyno's and not manipulating the runs.

droideka

What's up, scalbert?!? droideka here from a-cl.com

Yuichi

iTrader: (1)

The car sounds MUCH better in person. I emphasize the MUCH part. If any of you guys are located in So Cal, or AZ I can try and arrange with the 2 owners that own the mufflers and they are very happy with the sound.

I talked to B&B at the SEMA convention and they say its very hard to record the sound and put it on the web. Trust me you guys need to hear it in person. I might have one soon on my car in the Nor Cal area.

If anyone can maybe do a good sound recording for me please shoot me a e-mail at Service@StrictlyZ.com. I'm not a expert when it comes to sound clips but if someone can enlighten me I would be more then willing to try and do another clip.

scalbert

Well, not exactly, it can be used as an indication. But you should always be mindful of the conditions and not take the number as an absolute (unless it is for the better. ) It would be interesting to see dyno numbers on a Z with varying coolant temps.

General chassis dynos are not like FAA regulated Jet engine dynos (my experience in your area was with JT8-200 engines), not all are kept in proper condition.

Not to throw another wrench into the issue but this still isn't always a good test. Lets say you drive one hour to a dyno and are imediately strapped down. Assuming it took several minutes to get hooked up there has already been plenty of heat soak. The test is run and X value is acheived.

Now your car get's pulled off and part(s) are put on. Two hours later (two hours of cooling down with the hood open) the car is put back on the dyno and re-run. This time it is run with a cooler engine and X + 20 is acheived. Does this mean that the mods gave 20 HP, maybe but more than liklely the cooler engine accounted for part of it.

Just IMO though...

scalbert

Well hello there. I saw the newer screen name and assumed it was you...

importriders

Actually what I think he was trying to say is that because of the ECU continually making adjustments it does not matter what adjustments are made externally(i.e. SAE correction). It is not a difference between dynos but more a difference in what the ECU is doing at the time of the test. You can have different results from the same car on the same dyno for different runs if the ECU changed parameters from run to run.

EDIT: Ooops..see that he replied to your post already.

jeffw

Oops. I'll fix that on the next one. Didn't see you made use of the multi tabs in Excel. Here's the combo chart: