Re: fuel economy, was :Re: 8v prices

[SCIROCCO2@t-online.de (Dirk Schneider)]

>>it's striking that the PL16v needed more than my KR 16v,
>>I expected it to be vice versa as for the valve-timing,
>>the intake valves open earlier on the KR and should let more unburned fuel
>>into the already opened outlet valves. Well therory and real life...

> Well, isn't the PL in the Cabrio?  Or are they both in regular Sciroccos?

no the KR is in the convertible ( that is 100kg heavier than the usual 16v )
and the PL is in the usual 16v Scirocco.


> The other thing to consider is the tune of the engine.  0.2l/100 on two
> different cars isn't a big enough difference to say broadly that "the PL
> uses more gas than the KR".

again you didn't get me right today.
maybe I should write in german ?

it's not the question that the PL uses 0,2l more/100km than the KR,
but I expected the KR ( with 10HP more, hotter cams, heavier car & wider
wheels)
to use MUCH MORE fuel than the PL which is actually not true.

got it ? :-)

> Nevertheless, danke fuer die Information Dirk.  Ich persoenlich finde's
> cool, dass der 16v-motor weniger verbraucht, als der 8-Ventiler.  Heil
> Technik! :)

The DX-8v (GTi) engines with the K-Jetronic are known to consume
a lot of fuel when driven fast ( and you have to drive a GTi fast.. )
There is even a word for that more-consumption here in the VW-scene
it's called "GTi-Zuschlag" :-)

I assume that this high consumtion is due to the inefficient K-jetronic.
I had almost the same engine ( EX-code,: same geometry, similar timing )
but that was equipped with the 2E2 carburator ( delicate but efficient )
and had very good gas per mileage, like all EX-equipped Sciroccos do.

Basically the DX engine itself should have better gas per mileage
than a JH engine, because the compression of the DX is higher than the JH.
and according to the Witzsche formula
nth=1-1/(E^(x-1))
where nth is the thermal efficiency,
E is the compression and x=Isentropenexponent (~1.4)
so simply speaking the efficiency rises with the compression of the engine.


viele Grüße
Dirk




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