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4.00" to 3.90" Pulley swap worth it?

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Old 06-11-2013, 11:40 AM
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black98c5
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Default 4.00" to 3.90" Pulley swap worth it?

I'm running a 4.00" 8-rib pulley on my F1C Procharger with Flip-Drive and I/W 8" Crank Pulley at the moment, making ~19-21 psi (depending on weather). I'm looking at dropping pulley sizes to gain another ~2-3psi. Would going to a 3.90" pulley do the trick or should I just go to the 3.85"? I know it's a very small difference between the 3.90 and 3.85, but worry about belt slip...

I'm not showing any signs of belt slip with the current 8-rib 4.00" pulley that's on there now and want to keep it that way if I go down in pulley size.

TIA
Old 06-11-2013, 11:48 AM
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fotoboy
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.1 on pulley is worth typically 1 lb of boost.
Old 06-11-2013, 11:49 AM
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robert miller
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Originally Posted by black98c5
I'm running a 4.00" 8-rib pulley on my F1C Procharger with Flip-Drive and I/W 8" Crank Pulley at the moment, making ~19-21 psi (depending on weather). I'm looking at dropping pulley sizes to gain another ~2-3psi. Would going to a 3.90" pulley do the trick or should I just go to the 3.85"? I know it's a very small difference between the 3.90 and 3.85, but worry about belt slip...

I'm not showing any signs of belt slip with the current 8-rib 4.00" pulley that's on there now and want to keep it that way if I go down in pulley size.

TIA
3.85
Old 06-11-2013, 12:24 PM
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Milan
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Originally Posted by fotoboy
.1 on pulley is worth typically 1 lb of boost.
Not when your blower has a 5.4:1 step up ratio
Old 06-11-2013, 01:55 PM
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black98c5
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Originally Posted by Milan
Not when your blower has a 5.4:1 step up ratio
Meaning harder to spin the blower, there for less boost return from reduction in pulley size?

Last edited by black98c5; 06-11-2013 at 01:59 PM.
Old 06-11-2013, 03:54 PM
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kromberg
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Originally Posted by black98c5
Meaning harder to spin the blower, there for less boost return from reduction in pulley size?
He is saying that with a higher step blower, you will make more than 1 psi for 0.1" reduction in pulley size.
Old 06-11-2013, 04:03 PM
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black98c5
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Originally Posted by kromberg
He is saying that with a higher step blower, you will make more than 1 psi for 0.1" reduction in pulley size.
Maybe a 3.90" is all I would need then. My F1C has the 5.0 Step up ratio.
Old 06-11-2013, 11:38 PM
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b16gsr
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Originally Posted by black98c5
Maybe a 3.90" is all I would need then. My F1C has the 5.0 Step up ratio.
F1C is a 5.4 step up unless you have something custom.

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