Dynamometer Bull Busters

[Ken Thompson]

From:
Ken Thompson. whistleblowers at hotmail.com

Hello All,
Remember the movie with the punch line, "who ya gonna call?" I have got a be
in my bonnet lately regarding, the advertisements and promotional material
offered up as truth by certain dynamometer manufacturers. How can one expect
to accurately setup one's DIY_EFI ecu, when then equipment on offer is not
capable of doing the job? But how would you know that? when dyno brochures
make some very wild claims.

Enter, the "Dyno Bull Busters".

Prof. Julius Sumner Miller often used the phrase, "why is it so?" Why is it
so, that US made engine dynamometers are not used in Formula One engine
development projects? Why do the top US Nascar teams use Froude Consine
dynamometers, which are made in England? There are US companies whose dynos
are very much Formula One ready, if their advertising and promotional
material can be believed. Here is one US firm that makes some very tall
claims: www.dtsdyno.com These people claim to have a formula one ready dyno
within their stable of dynos. This unit being their PM-15. Now DTS doesn't
actually say "F1 Ready", but they do provide specifications which equate to
the same thing. DTS quote the following specifications:

*   Speed   =   15,000 RPM
*   Power   =   1,500 HP
*   Torque  =   1,500 FT. LB.

DTS provide us with a graphs, showing the absorption characteristics of this
absorber, right up to 15,000 RPM. The north east slope of their graph is the
the line which is determined by the outlet water temperature of this dyno.

/* In order to determine this slope, DTS were required to test this dyno,
right
up to 15k RPM. */

I am very suspicious as to whether this dyno has ever spun at anything
like 15k RPM.

Has DTS fabricated it's test results?

Which commonly made US piston engine will run at 15k RPM? I understand
they have pushrod NASCAR engines running at 9k RPM. How many race
teams (outside of NASCAR) are able to claim, "we can get to 9k RPM?"

Is DIY_EFI the correct venue for canvassing these matters? Somewhere down
the line a dyno will need to come into your test & measurement equation,
this
little exercise will enable you to figure out for yourself, whose dyno is to
be
trusted and who is having a bloody lend of you.

Lets compare some of the features that Froude of the UK build into their
F249 dyno, with the DTS PM-15 dyno from California:
The Froude dyno uses non contact labyrinth seals and a zero water pressure
at
this seal area, while the DTS employs a mechanical seal similar to the Crane
mechanical seal. Crane seals are good seals, but lets check their
limitations as
these limitations are directly proportional to DTSs dyno speed.
Froude has no limiting speed, due to mechanical seals, as their are non.
The Froude dyno uses a high tensile stainless steel rotor of about half the
diameter of the DTSs aluminium (aluminum) alloy rotor. Lets check the rotor
burst speeds of each dyno. The DTS braking principal can be best
described as a paddle in a bucket (flat pocketed disk), while Froude use the
concentric whirling chamber principal. As the DTS dyno speeds up, it
attempts to pump the water out the same way it came in, so a very high
pressure pump is required to push the water through the dyno. On the other
hand Froude ports the inlet water to the centre of the vortex chamber, to an
area of zero back pressure, resulting in a simple passage into the absorber.
Now lets check the SKF precision bearing manual, there they give the
limiting speeds for grease filled, oil bath and oil mist lubricated
bearings.
Oil mist lubrication is standard on all Froude F24 dynos
that run over 6,000 RPM. DTS say their oil bath system is fine at 15,000
RPM. (DTS say a lot of things that I do not believe to be true)

DTS could claim that their dyno was good for 50,000 RPM, but which one
of us can supply a prime mover (engine), we can use to test these DTS
specifications? So their 15k RPM claim remains untested, by us ordinary
rev heads, who can only summon up 7.5k RPM on a good day.

DTS does however owe every single one of us an explanation as to where
their 15,000 RPM specification came from.

By ganging together and demanding the truth, we can force these kinds of
people into a whole new honest way of life. You can help yourselves:

1.   Check the DTS website www.dtsdyno.com and their 15k RPM commentary.
2.   Check the SKF bearing catalogue in the lubrication VS speed section.
From
memory the DTS spindle spec. states that a 2" shaft is used. This will place
the
shaft bearing ID at somewhere between 45mm an 50mm, after the shaft is keyed
or splined for the rotor. The bigger the bearing he lower the limiting speed
of course.
3.   Click this link to start your email message ==> info at dtsdyno.com
4.   Copy and paste the following text into an email message, that asks the
people at DTS to please clarify their specs. If enough of us ask the
question, they will soon get the picture.

-------------------------------------------------------------
To:         The Manager,
              Dynamic Test Systems.
              California. USA.

From:     Your Name

Dear Sir,

We recently visited you site and noticed that you are claiming that your DTS
Powermark dyno is recommended for testing speeds to 15,000 RPM. Please
explain to me how you tested and mapped this absorber's performance to such
high speeds. Please describe the test procedure fully and give full details
of the prime mover (engine / engine transmission) used for this testing. I
note that your high speed driveshaft is of the twin tube design using bonded
rubber in-between two tubes and Lobro CV couplings at each end. Is this the
driveshaft that was used for your 15,000 RPM high speed testing? We note
that
you offer a one size fits all drive shaft solution, yet this philosophy is
diametrically opposed to the recommendations in the selection guide of the
SPICER dynamometer drive shaft designers manual. Please set out your drive
shaft design criteria, as it is obviously different to DANA SPICER'S. I am
interested in the PM-15's usable lower limits as I wish to map my MoTeC M8
ECU that controls my very "pit lane drivable", 5 litre racing car. Will the
PM-15
dyno get down low enough, for mapping at this soft end? Your PM-15
dyno sounds like it is ready for use by Formula One teams like Ferrari,
Williams, McLaren and the F1 engine people like Ford, Mercedes, BMW, Honda,
Renault and Peugeot etc, how many of these people are using, or have ordered
your PM-15 dynamometer?

Thank You,
Regards,
Your Name.
---------------------------------------------------------------------------

How many replies do you think we'll get?

Don't hold your breath.

Please forward your reply, to whistleblowers at hotmail.com

I will keep score and post the results to
www.users.bigpond.com/whistleblowers
This URL will go on line on about the 15th Feb.

Good Luck,
Regards,
K.T.























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