dyno result

Archives of Posts to the NZ MX5 List back in 2002
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jeff

dyno result

Post by jeff » Mon Jul 29, 2002 3:51 pm

Warning! Technical gearhead rambling...


I had my car dyno'd the other day, and the result was a somewhat underwhelming 52 kW (67 hp ?!) ... how does this compare with anyone else's results? (I searched but didn't see anything)


I know the US dynojets read higher, but that still leaves a deficit of 60+ hp which I just can't see being consumed by the drivetrain! The car runs great BTW, pretty quick. This was my "baseline" pre-mod run :)


This was on the Autech dyno at Shore Performance, Akl. My '96 purple beastie is an 1800 with 4-1 headers, catless 2" MazdaSpeed exhaust and cone filter, FWIW.


TIA -

Jeff

underpowered and lovin' it

Gary Morrison
Need, more, 5-ing, time....
Need, more, 5-ing, time....
Posts: 100
Joined: Sun Jun 04, 2006 3:24 pm
Location: Wellington

dyno result

Post by Gary Morrison » Mon Jul 29, 2002 4:30 pm

Jeff,

Those mods you have done are known to lose about 60 hp, so the dyno is spot
on. You need more Voodoo to replace what has been lost.

Gary

Gary Morrison
Need, more, 5-ing, time....
Need, more, 5-ing, time....
Posts: 100
Joined: Sun Jun 04, 2006 3:24 pm
Location: Wellington

dyno result

Post by Gary Morrison » Mon Jul 29, 2002 4:46 pm

Hi again Jeff,

Seriously though, talk to Fletch. He has had experiences of this sort, and had
some conclusions as a result. Of most importance is consistency for a before
and after ( if you are doing that) rather than any absolute. With the Link ECU
and MiataLinkLab software you can run your own dyno plots on actual road.

Personally I have had experience using the NZ designed Dynapak dyno (bolts to
the driven wheel hubs) and found them to be closer to the US results, also I
have measured my car and another club members car with an ignition signal
recording technique, which was then processed by a guy in the USA with his
self written dyno software. The results from this were close to the Dynapak
ones, and still below the US Dynojet ones (which as you say are considered
optimistic.) None of these results were down by 60hp though!

Gary

Fletch
Yes. I might just know (Trusted Advisor)
Yes. I might just know (Trusted Advisor)
Posts: 119
Joined: Thu May 18, 2006 10:11 pm
Location: Auckland

dyno result

Post by Fletch » Mon Jul 29, 2002 5:48 pm

Many many moons ago, in the dim dark distant past, I wrote an article for the
club magazine, where I visited Torque Performance (then in New Lynn), and had
my car dynoed.

My car , which at the time, had a Jackson Racing Header and cat-back exhaust,
and a Greddy foam cone-intake filter recorded 90 HP. At the same time, we
also measured Chic's car. His engine was obviously not running its best,
oil-smoke billowing out of it, and measured 81 HP.

US Dynojet dynos typically show a stock 1.6 as having 90 odd HP, and cars with
similar mods to my own as about 7 to 10 more... so considering that Chics car
was sick, the Torque Performance dyno probably reads about 5-10 HP low.

Since that time, Chic's got a new engine, and I've re-built the one Chic had,
including shaving the head, port&polished, big cams, Link ECU...

Don't currently have a reading for it, but I hope to get one next weekend. On
Sat 3rd of Aug, NZ Performance Car mag are having a Dyno day, where you can
get your car on the rollers and a power print-out for $50 (half the normal
fee).

I'm expecting/hoping for 120+ HP.


Not sure why your dyno reading is so low? BTW, 52kw is 69HP, but I'm guessing
you were looking for more than 2 extra? :-)

I'd discuss it with the operator... Ultimately, as long as it gives
consistent readings, you can use it to see percentage improvements, but I'd
still see if they acknowledge that its calibrated differently, is known to
give low readings, or any other logical explanation. Also, what were the
torque figures?

For some reason, the Torque Performance dyno gives HP numbers that look
reasonable, but the torque figures are actually exactly double what is
considered the "normal" HP/Torque relationship. I will be discussing this
with Robin (the owner) at torque performance next weekend.

BTW, as far as I understand, every-one is welcome to come along and have a go,
or just watch... there'll probably be some impressive cars there, if you're
interested...

Fletch.
Red '90. Many n/a mods and Link ECU

jeff

dyno result

Post by jeff » Mon Jul 29, 2002 6:01 pm

Gary -
I'm actually thinking of getting the Voodoo knob polished and thermal-coated. WOuld that help? ;)

Or maybe I should go all out and get the car repainted Voodoo-yellow with a huge trans-am style Pollo-Rampante on the bonnet ! Choice, man :)

ok, seriously. I'll be doing an "after" dyno run, so the relative change is important to me. Although the absolute numbers are still pretty, ah, embarassing... Here's some cheerful figures though, my avg at-the-wheel torque was ~185 Nm, or a touch more than peak rated engine torque for the non-voodoo 2001 engine (181 Nm). Cool, I feel better now.

Funny observation - there were periodic (approx once per second) puffs of black smoke shooting out the exhaust near redline! wot, no flames? ;) I guess the ECU is just dithering into richness, or something. Engine's fine of course.

cheers,
Jeff-the-verbose

lou Girardin

dyno result

Post by lou Girardin » Tue Jul 30, 2002 8:07 am

Sounds strange, US forums quote 18 - 20% drivetrain power loss, so you should
see approx 70 - 75 wkw. Still, if it's going well why worry.
Lou

lou Girardin

dyno result

Post by lou Girardin » Tue Jul 30, 2002 10:44 am

Re: dyno resultSorry ,but I don't see how a roller dyno can be within 2hp of
an engine dyno. What about parasitic losses from the drive train and tyre
friction? Unless you're talking about an inertia type dyno which calculates
these losses and gives an engine figure. Mazda NZ has one of these and showed
100 - 105 kw when my car was NA. Is this what Torque Performance have?
Lou

Gary Morrison
Need, more, 5-ing, time....
Need, more, 5-ing, time....
Posts: 100
Joined: Sun Jun 04, 2006 3:24 pm
Location: Wellington

dyno result

Post by Gary Morrison » Tue Jul 30, 2002 11:32 am

Gary -
I'm actually thinking of getting the Voodoo knob polished and
thermal-coated. WOuld that help? ;)

Nah, you just need titanium, its much faster...

jeff

dyno result

Post by jeff » Tue Jul 30, 2002 1:47 pm

I think I know why the dyno I used is off ... they didn't have any way to tell what revs I was doing - the X axis of the graph is road speed (no ignition pulse measurements) so they're calculating it somehow from the roller resistance. Also, the torque/power curves never crossed, although I'm not sure if that's relevant to a metric dyno run! (US graphs always cross at 5252 rpm)

according to this calculation, I'm at (180Nm x 6000 rpm)/9551 = 113 kW, or about double the dyno figure. <shrug> Actually, that seems too high... (151 hp at the wheels! )
http://www.textronpt.com/institute/courses/mmodule1.htm

Also, if you have 18" and 14" wheels+tyres which weigh the same and are the same height (same leverage and inertia), then it shouldn't affect the dyno reading, no?

Jeff (geeking out)

Gary Morrison
Need, more, 5-ing, time....
Need, more, 5-ing, time....
Posts: 100
Joined: Sun Jun 04, 2006 3:24 pm
Location: Wellington

dyno result

Post by Gary Morrison » Tue Jul 30, 2002 2:21 pm

Hi Jeff,

That sounds like a weird setup. The dyno I have used needs to know what gear
you're in, gear ratio, wheel diameter, diff ratio etc. It can then determine
revs etc.

Gary

Charles & Morven Lynch

dyno result

Post by Charles & Morven Lynch » Tue Jul 30, 2002 8:00 pm

The dyno I have used needs to know what gear you're in, gear ratio, wheel diameter, diff ratio etc
That's a point, did they ask if yours was a 1.6 or a 1.8?
I seem to remember that when Fletch and I got our cars dyno'ed, we thought that they had used the wrong gearing figures .The MX5 they had tested prior to our ones was Oggies supercharged 1.8. Our figures weren't as bad as yours though!

I've driven your car, Jeff. It feels normal therefore the reading can't be right. Have you tried calling them for an explanation?

PS
You have to admire Fletch's bravery in going to the performance car Dyno day. I'm betting his car will have the lowest reading of the day and will be slagged off in the magazine AGAIN!.

Cheers
Chic
[...]

Gary Morrison
Need, more, 5-ing, time....
Need, more, 5-ing, time....
Posts: 100
Joined: Sun Jun 04, 2006 3:24 pm
Location: Wellington

dyno result

Post by Gary Morrison » Tue Jul 30, 2002 9:26 pm

Yeah Fletch, really taunt them... leave a hairdryer on the passenger seat,
or a box of curlers or something!

From badcat@xtra.co.nz Fri Apr 27 16:26:21 2007
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Date: Tue, 30 Jul 2002 22:36:55 +1200
Subject: Re: dyno result
From: "ken.newell" <badcat@xtra.co.nz>
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Yeah - but does the respect of a teenager too stupid to understand which end
of a baseball hat is the FRONT important?


(and VERY few of them can actually DRIVE)


Ken
Ex-cosworth sierra -pulsar GTIR - now happy with my 2nd hairdressers car.


On 30/7/02 9:26 PM, "Gary Morrison" <gm@paradise.net.nz> wrote:

[...]

Graeme Naisbitt

dyno result

Post by Graeme Naisbitt » Tue Jul 30, 2002 10:41 pm

yeah, and when they wear their hats that way - you can't tell whether
they're coming or going...

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