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TECNICAL SIDE BENCH TEST - PART II

then close suddenly at the end

engine casing heats up constantly,

the private weather station could

of the test isn’t what you’d say is

this together with the variation

be a difference of 3 to 5°C. All

healthy for the engine and all the

of the allowance/interference, is

important variations considering

rest, the condition of max revs and

what affects the performance of a

the fact that the software “corrects”

minimum load is the most critical

two-stroke engine most. Between

the performances, retaking them

for the crank mechanism (the

one roll and another, besides the

to the performance used as

connecting rod goes into traction,

working conditions of the engine,

reference (usually 20°C, 1013 mbar

the lubrication is critical (knowing that it works with petrol/oil mixture and the oil is scarce) and detonation (due to instantaneous and strong increase of residues in the combustion chamber) is a concern. Having to say goodbye to an engine whilst on a test bench isn’t very nice, so be careful!

AT LEAST THREE CONSECUTIVE “LAUNCHES”

AFTER A FIRST ACCELERATION TO “CLEAN” THE ENGINE, YOU NEED THREE TESTS TO GET RELIABLE RESULTS. IN THE MEANWHILE YOU HAVE TO KEEP AN EYE ON TEMPERATURES keep an eye on and update if

and 50% humidity), according to

necessary the environmental

the environmental conditions that

Something we mentioned in the

conditions of your test room, i.e.

you have put in. Once this “minor

last issue, on a roller test bench,

temperature, pressure and relative

problem” was found, it gave a

unless you have got a brake

humidity. If for the last two, the

further “boost” to the repeatability

that can simulate the actual

values read on any private weather

of my tests. I’ll leave you to work out

resistance to forward movement

station are fine, never be too sure

what caused this “error” originating

(tyres tuning and aerodynamics)

about temperature values. It is

from the private weather station

on the acceleration phase, best

fine for a “stable” environment like

and how you can bypass it with

carburetion on the bench will

your home, or if your test room is

hardly any expense.

never be like best carburetion on

enormous or heated, but at this

the track. Usually, it is much leaner

point, I’m not telling you anything

on the test bench. Obviously, if we

new in this column because you

PRIORITY TO TEST REPEATABILITY

want to have proof, tests must be

probably work in a proper racing

Back to us, as you need three turns

carried out with the proper set up

department, in “normal” conditions,

to see that everything has gone

for that particular condition, and

with the bench placed inside a

well, the three data acquisitions

then enriching carburetion a bit on

small room which is thermally and

have to be overlaid, but they will

the track shouldn’t affect us at all.

acoustically insulated, the engine

never be perfectly the same:

After the first “test” launch, we

is nothing but a stove, which is

the first run, which is actually the

do another three consecutive

there to heat up, and quite a bit

second seeing that we have already

launches to confirm the test,

too, the environment where it is

let it run once to clean the engine,

always keeping a close watch on

(and therefore the indicted air). OK,

might have the temperature at the

the temperate of the engine while

taking a room measuring 3x3 m

exhaust slightly cooler compared

working. Personally, I fix optimum

and 2.20 m high with insulation as

to the next two runs, or there could

range between 50 and 55°C,

an example, like the room I work in,

be micro-skids on the clutch, but

with temperature taken on exit

from beginning to end of the test,

it must be clear that it’s always the

from cylinder head: this way it’s

between the “actual” temperature

same test even if you happened to

believed that the load inside the

and the temperature reading on

see it after months without having

78 VROOM INTERNATIONAL MAGAZINE

Vroom Kart International #183 - September 2016  

In this issue: FANTASTIC 4 Marco Ardigò (Tony Kart/Vortex – KZ), Fabian Federer (CRG/Modena Engines – KZ2), Pedro Hiltbrand (CRG/Parilla –...

Vroom Kart International #183 - September 2016  

In this issue: FANTASTIC 4 Marco Ardigò (Tony Kart/Vortex – KZ), Fabian Federer (CRG/Modena Engines – KZ2), Pedro Hiltbrand (CRG/Parilla –...

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