Valve 2000 Race UNDERSIZE SET (4) 9×38.5mm 45 degree Exhaust

Valve 2000 Race UNDERSIZE SET (4) 9×38.5mm 45 degree Exhaust

$198.00

SKU: 20009EVUS Category: Tags: ,

Valve 2000 Race UNDERSIZE SET (4) 9×38.5mm 45 degree Exhaust

$198.00

SKU: 20009EVUS Category: Tags: ,

NOT CURRENTLY AVAILABLE

Stainless steel alloy 1,5mm undersize 38.5mm exhaust valve for 2.0 Alfas with standard  9mm stems.

VALVE UNDERSIZE EXHAUST:

With regard to the performance enhancement of our 38.5mm exhaust valve for 2.0 Alfas with standard 9mm stems, there is a theory that the 2mm smaller valve (standard diameter 40mm) 38.5mm reduces over-scavenging in high compression/RPM engines and yields better performance characteristics.  This is correct for pure race engines operating mostly above 7000 rpm.

It is our experience that 1mm oversize (45mm) is more appropriate (and considerably cheaper) in street performance, track day or low compression vintage race engines and actually a bit better at low rpm.

For more info on valve sizing and cylinder head performance, you should acquire a copy of the Jim Kartalamakis book, ALFA ROMEO DOHC HIGH-PERFORMANCE ENGINE MANUEL.  This is pure engineering knowledge from deep experience building, testing, tuning and racing Alfa engines.

For more info on valve sizing and cylinder head performance, buy a copy of the Jim Kartalamakis book advertised at the top of this section.

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