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Discussion Starter #1
hey all,

just had the kinetix hiflo cats and hitech catback system installed on my car and had a before and after dyno..

1st up i will say i got these for a good price (props to Malcolm) and I was really after nothing more than a nice sounding exhaust note for my Z - my reasoning was that if i wanted noticeably more performance out of it then i would be phoning APS and going the whole hog - which is a very tempting option next year sometime hehehe...

Anyway, a nice sounding exhaust was all i was after - as long as it didnt make me the Sheriff of Riceville like some of the other exhausts you hear around town hehe...
Any gain in kw/hp/Tq was secondary as i thought even a 10-15kw gain would be almost unnoticeable in my bum dyno hehehhe..

I left the **** printout at the shop tho so i cant scan it in for the next few days, but if anyone wants to have a guess as to the gains/losses then go for it??? hi-tech proponents out there will be surprised, if not a little annoyed at the true kw gain of these systems - but like i said it was the sound i was really after when looking for an exhaust...

I must say though, the exhaust note is 100% nicer sounding than stock with almost no droning - at 110kph on the freeway it can be heard with the radio off and windows up, but it really is negligible and is not headache inducing - a mother in law or your drunk GF will give you a headache in quarter the time hehe...
And like a lot of people have said before - when u hit the gas it sounds like a totally different car - a 'Zamborghini' as i think Frosty once described it and thats very accurate haha.. it definitely sounds very nice.. and there is even a tiny bit of crackle and fizz when you let off the gas at certain revs sometimes which sounds awesome and exactly what i was looking for !!

According to my Recta-dyno however, i have noticed at about 5000rpms and above is the biggest difference, the engine doesnt seem to run out of puff as before with the stock system - it just keeps going to redline !! Also around 2500-3000rpm upwards it seems a lot more responsive and the throttle just feels a lot sharper and 'crisp' overall...

Overall - definitely worth it for the awesome new soundeffects !!!
 

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Is this a guessing before you share the numbers with us?

I couldn't come to grips with the, almost 20kw numbers that were being quoted, and figured around 5kw for the exhaust. Exhaust plus cats I'd say 8 kw.

As you say it sounds much better than stock and I always thought that there was a noticeable improvement in performance not to be confused with the "better sound, better performance" proposition.

I hope the Lada Niva now goes like a Datsun 120Y.
 

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I'll guess 7kw

I need you to let me listen!!!!!!
 

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I love the sound of the Hi-Tech too, and the beauty is that it look like stock exhaust. I just have mine installed through DavidC, But have no idea how many KW gain in the paper.
 

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What does a stock 350Z pull on the dyno?

With the cats, I'm going to guess that its in the low 170's.
 

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Discussion Starter #8
OK guys heres the dyno sheet - you were all wrong haha !!

the Baseline reading was pretty much 158kw at the wheels, which I thought was a bit too low for a 206kw crank car, but the dyno guy said it wasnt too far behind an XR6 turbo (240kw crank, 184 dyno) so he was quite surprised at the reading.

Anyway, the before and after runs were done about 2 hours apart, 1st one at 9am, 2nd one at about 11am and i think the temp difference might have been about 8-10ºC because it warmed up fairly quickly.. Both were done in 4th gear because the dyno was not sposed to go over 200kph for some reason, safety or something.

So lookin at the sheet, total peak kw gain was only about 2kw, but where the stock engine really 'dies' and seems to lose power at about 5300rpm the hitech keeps the power going nice and smooth.. thats very noticeable when driving

im really surpised though there is not more gain on the sheet around 3000-4000rpm as thats where i think i can notice the biggest difference - maybe thats a case of it being a lot more responsive and free revving as opposed to actual kilowatt gain???

Murray - the car had probably a 5-10minute drive with the hitech on, probably not long enough for the ECU to re-learn or whatever it does.. but after doing about another 200kms in it since, i definitely think it seems to rev harder and easier and generally feels like a different (and better) car overall... Nissan should definitely have used this exhaust as OEM !!

You just cannot beat the sound either - it just purrs along in any gear and sounds awesome at 3Krpms and above... From what i can remember of hearing CAR's hitech a few months ago, my car seems louder, possibly due to the cats or possibly due to me not remembering exactly how loud his car was... either way, it sounds awesome

For the perth guys - WOT thru 3rd and 4th gears thru the Tunnel sounds absolutely awesome - thank god there were no kodak cops around that day haha !!

WE NEED MORE TUNNELS HAHAHA
 

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That is so strange ... your curve does not look much like my one. Neither does your stock curve look like the other baseline curves I've seen.

Normally the 'stock' curve looks kinda like the blue line in your graph (ie. Hi-tech one) as it flattens out over the last 2000rpm or so. The Hi-tech one (at least my one) keeps climbing all the way to 6,500rpm (ie. more like your red curve, but without the 'wobble' at 130kph).

the Baseline reading was pretty much 158kw at the wheels, which I thought was a bit too low for a 206kw crank car, but the dyno guy said it wasnt too far behind an XR6 turbo (240kw crank, 184 dyno) so he was quite surprised at the reading.

Every dyno produces a different 'number', so don't worry about the numbers For example (from what I gahter) on the APS dyno stock 350Z pull 140 - 145kW. Different numbers, that's all.

So lookin at the sheet, total peak kw gain was only about 2kw

2kW is less than what most people get as a variation between different runs. Usualy when you do 3 runs in a row (with no changes to the car) then there's up to 5kW difference in readings just due to the different conditions. So what your dyno says is really that maybe you have had no gains, or maybe there's couple more kW to be extracted by doing more runs ... either way, it's saying that your peak power figure has not changed much (if at all). We're talking about 1.3% difference in your two readings.

ps. This is what my curve looks like (with Hi-tech fitted) ... this is on the APS dyno:
 

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If you really want to improve the sound, replace your filter with a pod.

When I put the HiTech on, as I said on MY350Z.com I thought it sounded a bit more aggro and metallic. Its the note the Z33 should have come with.

With my Popcharger, that top half of the rev range sounds like a race car.
 

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158kW at the tyres in stock form sounds about right. That's what most people dyno in Shootout mode, I've noticed. You can expect around a 20-25% drivetrain loss on most 2WD cars (which puts your reading spot-on), and the loss from 4th gear and your 1:1 ratio gear is negligble enough to be written off in "sampling error".

As such, I'm really hard-pressed to explain why your car doesn't crest 160kW+ on the chassis dyno with your mods. If you can feel those gains then fair enough, and your power curve does match mine.

I notice that there's no "Shootout mode" logo on your dyno graph (which is meant to standardise figures and compensate for temperature, air pressure, when providing a figure) and given your temperature differential it could somewhat explain the loss in power. Still, your car isn't turbocharged so a temperature change shouldn't be responsible for that much power loss. Most of us are pulling in the mid 160's.
 

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Given the numbers for your XR6T, it could be that your dyno doesn't read as high as the models popular in the Eastern states. A friend of a friend has a stock XR6T ute that pulls a consistent 220kW on two different chassis dynos, of different make (one at Croydon Racing Development and the other at Unigroup).

Of course, with Ford's build quality (and I use the term loosely), he could have gotten one of those "lucky" motors that was built right.
 

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Hey Ross aren't you going to install the Popcharger as well? I don't think it will generate more kW but the sound will improve further.

Friday was a very hot day in Perth so that may account for the "less than expected" result as your second run was done later.

I'm sure you agree that there is a noticeable improvement in performance which doesn't really seems to equate to 2 kW. I doubt if you would notice 2kW.
 

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Those figures don't sound right. 4th gear can't give you a true indication anyway as it isn't 1:1.
As you said you feel it in the bum dyno so that is all that matters!
 

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Originally posted by mickyboy@Dec 20 2004, 02:31 AM
Those figures don't sound right. 4th gear can't give you a true indication anyway as it isn't 1:1.

Honestly, I don't think it makes too much of a difference (and nor do the people I've spoken to, both that own dynos and have a vested interest and those that don't).

When I had my car up on the rollers, the first 2 runs were in 4th and the 3rd run was in 5th. They were all within around 3-4kW of each other, which is standard sampling error.


A chassis dyno can never give you a true "figure" anyway. The dyno only measures torque at the tyres, speed (and I'm not certain they all do this), and maybe A/F ratios and boost. Note that it never measures your engine's RPM so it has to guess, or do the math after consulting a table if the software knows how fast your car goes at certain RPMs in whatever gear.

Since power = torque x rpm x constant, if it doesn't know the RPM it can't give you a true power figure. Unless the dyno software has figures for your specific make and model of vehicle, those figures once again will be meaningless.

While there's a linear relationship between speed and RPM in-gear, cars in stock form will have their speedos over-read and so unless whoever compiled the data in the first place used a GPS those numbers won't be accurate again.

It has to know what your tyre diameter and final drive numbers are to work out from the measured figure what the drive-shaft torque is since those two things amplify the torque figure.

So if your dyno operator isn't keeping his software up to date, either his dyno won't have that data for your car or it might have outdated data that's not accurate.

Even if it has all that data from a test vehicle, if your tyres are over or under-inflated from whatever the dyno software says it should be, your figures are out again.

This is on top of the standard sampling error you're going to get. And the change in atmospheric conditions that are inevitable, and not compensated for by the dyno software on nang's runs.


People forget that the purpose of a dyno is to look at the torque curve. The numbers are approximate (given those other factors above), and even shootout mode can only guesstimate what kind of compensation the measured figures need to give a standardised figure unless those dynos come with enough weather-measuring equipment to rival a weather station.

The torque curve is fuller in the upper half of the rev range, and the bum dyno is telling the nang that his car pulls far harder at high RPM compared to stock. At any rate, if it goes better and sounds better then it was worth the money.
 

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nang3 - if you're really put out by the figures, I'd suggest taking it back to the same dyno and running it again early in the morning. Preferably be there first thing in the morning so there's as little heat and car-exhaust air in the workshop as possible. You might also want to ask them why Shootout Mode wasn't enabled on your last set of runs, and make sure it is enabled this time.

If an arbitrary number doesn't matter to you, then the fact that your car pulls harder through the rev range and doesn't choke at high RPM, while the noise puts a smile on your dial, tells you that there has been an improvement.


I only put my car up on the dyno for a lark and check out the curves - my power curve rises linearly since my torque curve is flat as a tack (there's only approximately a 10% torque increase from idle to peak on mine).
 

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Yep, like you said if he can fell it then it was worth it.
Personally I don't like dynos to compare car X with car Y (or X to X) for that matter. Too many variables as you mentioned above.
To me, dynos are part of the aftermarket conspiracy theory for manufacturers to make us part with our money on upgrades that do little or nothing, but make our small heads swell?

TRUST THE BUTT DYNO!
 

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Nice one Ross - Who really cares what gains you get anyway. I'm sure it sounds **** hot with the exhaust and Popcharger now.

Even if you only get 1kw gain you've still got enough to blow away most guys or give then a helluva good run for their money.

So when you coming round to give me a listen and compare the sound of the plenum?????

Oh yeah, and I'll take the inside lane on the freeway on ramp this time!!!
 

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Hey, what's happened to our signatures?????
 

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Originally posted by mickyboy@Dec 20 2004, 03:33 AM
To me, dynos are part of the aftermarket conspiracy theory for manufacturers to make us part with our money

Well, dynos have their uses. You just need to use them correctly.

For mechanics, they can measure gains before and after modifications to see what kind of changes they bring to the powertrain. Its not like humans are sensitive enough to pick up minor changes.

But the dyno is mainly a tuner's tool. If you're working with the timing, its the easiest way to be able to rev the engine to redline under load and measure your A/F ratio and knock levels, and make tweaks the settings, while also having access to all your other tools should you need them.

While you can road tune (and I have heard pretty positive things about Hitman[/urk] and his road tuning) where can you constantly rev your engine out without attracting the wrong kind of attention, or worry about colliding with another vehicle?

You'll also need an engine management system that permits you to make on-the-fly changes to road tune. Older ECUs need to have the code "burnt" in a separate device before being installed. The stock Z33 ECU can be programmed via the Consult port, but it takes 25 minutes (and interrupting it during the burn basically writes off your ECU).


The problem is that people see some number, and think its the be-all and end-all. Other people believe it, and need to get into a pissing contest. In the end, people have forgotten what the original purpose of the device is.

Its like brand name decals on cars. The original purpose of them is sponsorship. Companies had to pay people (or offer them discounts) to get their parts into the cars and let everyone know what they used. But, somewhere down the line, it became cool and now your average idiot pays to advertise someone's product! Not only are they paying full price for the gear (if they even have it at all), but they're also paying for a sticker to let everyone else know that you know what a cool brand is.
 
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