Volvo RWD 120-130 Forum

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122 Upgrades 120-130 1967

posted by  someone claiming to be cameron on  Fri Apr 25 09:50 CST 2003 [RELATED]

I found that, with the lowest boost pulley (which maxes out at 4lbs with my current setup) that at idle, the gauge shows 20" vacuum. At 70mph steady on the throttle, it shows >15" vacuum. But the moment you mash the gas pedal, the gauge immediately snaps to 4lbs boost and stays there while the revs increase. At revs below approximately 1500 the boost takes a moment to build (a short moment). At higher speeds, the transition from vacuum to boost is very, very quick.

Lots of people are interested in 'how much boost' an engine is running. The pulley I'm using produces 4lbs on my engine. This same pulley with a stock head and stock exhaust produces notably more boost (7 or 8lbs if I remember right) but much LESS power. John (Parker) ran a stock engine (B20F) and stock exhaust at 10lbs, then changed the head, cam and exhaust - but ran the same pulley. Boost dropped to 6 or 7, horsepower increased by 30.

It's not so much how much boost you run, it's how much air and fuel you can get through the engine.

Best,

Cameron
Rose City






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New 122 Upgrades [120-130]
posted by  someone claiming to be mgreader  on Thu Apr 24 12:52 CST 2003 >


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